Computer modeling is then used to create a 3-dimensional physical model of the patient's distal femoral bone, which is sent to the surgeon. The manufacturer identifies the perimeter of coverage of the trochlear implant on this model. If deemed necessary based on the presence of significant osteophytes or bony defects in or near the native trochlea, the surgeon may physically remove osteophytes from the model and communicate these changes by returning the model to the implant manufacturer. The final design for the trochlear implant is then created after surgeon approval.

If changes are made during the design review, during surgery the surgeon will modify the real trochlear groove in the same manner as was done on the physical model. For this reason, it is imperative that the physical model be available for visual examination in the operating theatre.

It must be noted that patellofemoral arthroplasty is not a substitute for a patellar realignment procedure. Patella tracking must be evaluated for instability and soft tissue imbalance (Lonner, 2004; Grelsamer, 2000). Malalignment of the patella is determined through physical examination and standard radiographic evaluation. Assessment of patellar tracking is important in pre-operative planning, as patellar instability is the most often reported cause of dysfunction after patellofemoral arthroplasty. Tightness of the lateral retinaculum is often associated with lateralization and patellar tilt, which may be determined upon physical examination. Examination of medial structures for deficiency should also be carried out, as well as assessment of the tibial tuberosity (Q angle). Axial and lateral radiographs are often sufficient to quantify measures of patellar malalignment, including patella alta or baja, medial-lateral displacement and patellar tilt. Treatments are generally customized to each patient, although it remains to be determined if there are one or more standard procedures that will be optimal for most patients (Grelsamer, 2000).

#### **5.2 Intra-operative technique**

A standard midline incision is made to expose the patellofemoral joint, and the patella is everted or tilted 90. The length of the incision is typically two-thirds the length of a standard total knee incision because tibial exposure is not necessary. The margin of cartilage to be removed is determined by placing the patient-specific drill guide onto the trochlea. Because the cartilage remnants on the trochlea will initially not permit a proper fit of the patient-specific custom drill guide, the surgeon first approximates the proper position of the drill guide (using the CT-created physical bone model as a template). The surgeon outlines the drill guide with methylene blue and by way of a ring curette removes the cartilage inside that outline. Osteophytes are removed as necessary. The patient-specific drill guide is then placed on the subchondral bone of the trochlea and moved slightly back and forth until

The peri-operative technique for patient-specific patellofemoral arthroplasty has been previously described (Sisto & Sarin, 2007; Sisto et al, 2010; Lombardi, 2011) and consists of

A CT scan of the patient's knee is obtained using the following settings as specified by the

If changes are made during the design review, during surgery the surgeon will modify the real trochlear groove in the same manner as was done on the physical model. For this reason, it is imperative that the physical model be available for visual examination in the

It must be noted that patellofemoral arthroplasty is not a substitute for a patellar realignment procedure. Patella tracking must be evaluated for instability and soft tissue imbalance (Lonner, 2004; Grelsamer, 2000). Malalignment of the patella is determined through physical examination and standard radiographic evaluation. Assessment of patellar tracking is important in pre-operative planning, as patellar instability is the most often reported cause of dysfunction after patellofemoral arthroplasty. Tightness of the lateral retinaculum is often associated with lateralization and patellar tilt, which may be determined upon physical examination. Examination of medial structures for deficiency should also be carried out, as well as assessment of the tibial tuberosity (Q angle). Axial and lateral radiographs are often sufficient to quantify measures of patellar malalignment, including patella alta or baja, medial-lateral displacement and patellar tilt. Treatments are generally customized to each patient, although it remains to be determined if there are one or more standard procedures that will be optimal for most patients (Grelsamer, 2000).

A standard midline incision is made to expose the patellofemoral joint, and the patella is everted or tilted 90. The length of the incision is typically two-thirds the length of a standard total knee incision because tibial exposure is not necessary. The margin of cartilage to be removed is determined by placing the patient-specific drill guide onto the trochlea. Because the cartilage remnants on the trochlea will initially not permit a proper fit of the patient-specific custom drill guide, the surgeon first approximates the proper position of the drill guide (using the CT-created physical bone model as a template). The surgeon outlines the drill guide with methylene blue and by way of a ring curette removes the cartilage inside that outline. Osteophytes are removed as necessary. The patient-specific drill guide is then placed on the subchondral bone of the trochlea and moved slightly back and forth until

pre-operative planning, intra-operative technique, and post-operative management.

manufacturer of the prosthesis (Kinamed Incorporated, Camarillo, California, USA):

 Scan Region: 5mm distal to the femoral condyles to 10mm proximal to the patella. Computer modeling is then used to create a 3-dimensional physical model of the patient's distal femoral bone, which is sent to the surgeon. The manufacturer identifies the perimeter of coverage of the trochlear implant on this model. If deemed necessary based on the presence of significant osteophytes or bony defects in or near the native trochlea, the surgeon may physically remove osteophytes from the model and communicate these changes by returning the model to the implant manufacturer. The final design for the

**5. Peri-operative technique**

**5.1 Pre-operative planning**

 Voltage: 120 to 140 kV; Amperage: 200 to 300 mA;

operating theatre.

**5.2 Intra-operative technique**

trochlear implant is then created after surgeon approval.

it seats in its intended position as determined by the CT scan. Two headless nails are then used to secure the drill guide and the three holes are drilled. The holes are then thoroughly irrigated to remove any debris that may be present.

The trochlear prosthesis is designed to be used in conjunction with a standard off-the-shelf all-polyethylene patellar button of onlay design with a 25 mm radius of curvature. The residual patellar thickness is the same as with total knee arthroplasty.

During trialing, particular attention is paid to potential subluxation or catching within the limitations of a patient under anesthesia (Lonner, 2004). If realignment is necessary, balancing is carried out in the same manner as a non-prosthetic or total knee arthroplasty. To correct patellar tilt or lateral displacement of the patella, a proximal realignment procedure such as a lateral retinacular release, medial plication, vastus medialis obliquus advancement, and/or medial patellofemoral ligament repair may be carried out (Grelsamer, 2000). In the presence of a high Q angle, a distal realignment procedure such as transfer of the tibial tuberosity may be carried out to correct alignment of the extensor mechanism (Grelsamer, 2000). Any realignment or soft-tissue balancing strategy should be oriented toward addressing specific identifiable pathology (Grelsamer, 2000).

Cementing is carried out in standard knee arthroplasty fashion. Particular care needs to be taken to avoid cement seepage into the notch or other compartments. The cartilage of the other compartments must be kept moist throughout the procedure to avoid deterioration. Patellofemoral tracking is again evaluated and soft tissue corrections are carried out as necessary to ensure optimal patellar tracking.

#### **5.3 Post-operative management**

The need for prophylaxis against deep venous thrombosis has not been shown for patellofemoral replacement surgery. Postoperative rehabilitation consists of range of motion exercises as with any knee arthroplasty. As a rule, though, progress will be much quicker than with total knee arthroplasty patients. Immediate full-weight bearing is allowed. Physical therapy to restore quadriceps strength is encouraged. Twisting activities are discouraged, but no additional specific activity modifications are recommended.

#### **6. Clinical results**

Previous investigators have reported on clinical results obtained with off-the-shelf and patient-specific patellofemoral arthroplasty.

#### **6.1 Results with off-the-shelf implants**

Published clinical results with off-the-shelf patellofemoral implants have been previously reviewed in detail (Lonner, 2007; Sisto & Sarin, 2008; Gupta et al, 2010; Charalambous et al, 2011). These references cover twenty one studies that each involved from 14 to 306 patients who received 8 different off-the-shelf designs, with follow-up ranging from 6 months to 21 years. These reports demonstrate that clinical results with off-the-shelf patellofemoral implant designs have been highly variable.

The Australian national joint replacement registry reports that the cumulative revision rate at five and seven years for off-the-shelf patellofemoral implants used in the setting of primary osteoarthritis is 15.2% and 22.4%, respectively (Australian Orthopaedic Association, 2010).

Patient-Specific Patellofemoral Arthroplasty 309

longer-term follow-up, the validated "Total Knee Function Questionnaire" (Weiss et al, 2002) was adapted and administered via telephone to each patient from the abovementioned prior study. The questions were designed to assess the status of each patient's

The questionnaire was completed for all 25 knees (Table 1). No knees from the original study were lost to follow-up. At a mean duration of 11.3 years (range, 7.8 to 14.9 years) from the index arthroplasty, all 25 patellofemoral arthroplasties were still in place and all patients reported themselves as being very satisfied. There were no reports of weakness, instability, or additional surgery. Two patients reported that despite their patellofemoral arthroplasty, they were not participating in sports activities. All patients experienced some pain, but not enough to warrant medication. All 22 patients said they would undergo the procedure

This 11 year follow-up study demonstrates that patient-specific patellofemoral arthroplasty is a safe and effective treatment for patients with isolated patellofemoral arthritis of the knee. These results compare favorably with those involving off-the-shelf patellofemoral arthroplasties that have been reported on over the past 30 years (Leadbetter et al, 2005;

Progression of arthritis into the tibiofemoral compartment is a recognized complication of patellofemoral replacement; when symptomatic, this scenario leads to conversion to a total knee arthroplasty. Progression is more likely to develop when the disease patellofemoral arthritis does not have a clear origin, such as idiopathic arthritis (Grelsamer, 2006). Despite attempts to balance the extensor mechanism, patellar maltracking after patellofemoral arthroplasty can occur, especially when the patient pre-operatively demonstrates high level

Our (DJS and RPG) collective experience with patient-specific patellofemoral arthroplasty dates back to 1995 and consists of 91 cases in 79 patients through May 2011. Patients in our cohort generally fall into one of two categories: those having a "normal" femoral trochlear sulcus angle, with or without patellar tilt; and those having a femoral sulcus angle greater than 145, i.e. a shallow or even convex trochlea dysplastic trochleas will exhibit a crossing sign on a true lateral radiograph (Bollier and Fulkerson, 2011). The following case studies

Patient J.O. is a 49 year old male who initially presented with severe anterior knee pain 14 years ago after sustaining a twisting injury to his knee that was treated with arthroscopic surgery followed by a soft tissue realignment procedure two years later. During this time, he developed progressive and disabling anterior knee pain. He could not walk up or down

Physical examination revealed severe anterior knee tenderness with severe crepitus and grinding in the retro-patellar space. He had no ligament instability and no medial or lateral joint line tenderness. All provocative tests for meniscal and ligamentous injury were

stairs without assistance and could not kneel, squat or climb without severe pain.

Leadbetter et al, 2006; Lonner, 2007; Sisto and Sarin, 2008; Gupta et al, 2010).

patellofemoral arthroplasty as well as their degree of knee function.

again.

**6.3 Complications**

**7. Case studies**

malalignment and/or dysplasia.

serve as illustrative examples.

**7.1 Normal trochlear anatomy**

#### **6.2 Results with patient-matched Implants 6.2.1 Prior investigation**

In an earlier published investigation (Sisto and Sarin, 2006), 100% survivorship with excellent or good Knee Society scores was reported at a mean duration of follow-up of 73 (range, 32 to 119) months. The study was a retrospective review of a consecutive singlesurgeon series of patient-specific patellofemoral arthroplasties performed between March 1995 and August 2002. There were 25 patellofemoral arthroplasties performed in 22 patients (three staged bilaterals), 16 of whom were female. Mean age at the time of index arthroplasty was 45 (range, 23 to 51) years.

Only patients whose medial and lateral compartments scored less than or equal to 1 point on the Ahlback scale were indicated for patellofemoral arthroplasty. The patellofemoral compartments for all knees scored at least 4 points. The mean pre-operative Knee Society functional score was 49 points, and the mean pre-operative Knee Society objective score was 52 points.

There were 18 excellent and 7 good results at 73 months of follow-up. The mean postoperative Knee Society objective score was 91 (range, 82 to 96) points, and the mean postoperative Knee Society functional score was 89 (range, 81 to 94) points. All patients exhibited good to excellent Knee Society Score status and no patient had required additional surgery or had component loosening.

### **6.2.2 Eleven year follow-up**

The objective of the eleven year follow-up study was to evaluate the longer-term success of patient-specific patellofemoral arthroplasty in the original patient cohort. For assessment of

Table 1. The original cohort included 25 patellofemoral arthroplasties (PFAs) in 22 patients. Each patient from the original cohort answered via telephone the above-listed questions, which were selected and adapted from the validated "Total Knee Function Questionnaire" (Weiss et al, 2002). All patients were successfully contacted and no knees were lost. Average time from index patellofemoral arthroplasty to completion of the questionnaire was 11.3 years (range, 7.8 to 14.9 years).

In an earlier published investigation (Sisto and Sarin, 2006), 100% survivorship with excellent or good Knee Society scores was reported at a mean duration of follow-up of 73 (range, 32 to 119) months. The study was a retrospective review of a consecutive singlesurgeon series of patient-specific patellofemoral arthroplasties performed between March 1995 and August 2002. There were 25 patellofemoral arthroplasties performed in 22 patients (three staged bilaterals), 16 of whom were female. Mean age at the time of index

Only patients whose medial and lateral compartments scored less than or equal to 1 point on the Ahlback scale were indicated for patellofemoral arthroplasty. The patellofemoral compartments for all knees scored at least 4 points. The mean pre-operative Knee Society functional score was

There were 18 excellent and 7 good results at 73 months of follow-up. The mean postoperative Knee Society objective score was 91 (range, 82 to 96) points, and the mean postoperative Knee Society functional score was 89 (range, 81 to 94) points. All patients exhibited good to excellent Knee Society Score status and no patient had required additional

The objective of the eleven year follow-up study was to evaluate the longer-term success of patient-specific patellofemoral arthroplasty in the original patient cohort. For assessment of

How satisfied are you with your PFA? Very Dissatisfied: 0 out of 25

If you have pain, where is the pain coming from? Inside of Knee: 3 out of 25

Table 1. The original cohort included 25 patellofemoral arthroplasties (PFAs) in 22 patients. Each patient from the original cohort answered via telephone the above-listed questions, which were selected and adapted from the validated "Total Knee Function Questionnaire" (Weiss et al, 2002). All patients were successfully contacted and no knees were lost. Average time from index patellofemoral arthroplasty to completion of the questionnaire was 11.3

Does this knee feel weak or unstable? No: 25 out of 25

Would you undergo PFA with this custom implant again? No: 0

Yes: 0

Yes: 0

Yes: 0

No: 23 out of 25 Yes: 2 out of 25

No: 25 out of 25

Never: 25 out of 25

Yes: 25 out of 25

Often (>1 per day): 0

Somewhat Satisfied: 0 out of 25 Very Satisfied: 25 out of 25

Sometimes (1-2x per week): 0

Kneecap area: 21 out of 25 Outside of Knee: 1 out of 25

49 points, and the mean pre-operative Knee Society objective score was 52 points.

**Question Answer** Has your custom PFA been replaced? No: 25 out of 25

Does your PFA keep you from doing anything that you

Have you had additional surgery on this knee since your

How often do you take pain medication because of pain in

**6.2 Results with patient-matched Implants**

arthroplasty was 45 (range, 23 to 51) years.

surgery or had component loosening.

**6.2.2 Eleven year follow-up**

years (range, 7.8 to 14.9 years).

would like to do?

PFA?

this knee?

**6.2.1 Prior investigation**

longer-term follow-up, the validated "Total Knee Function Questionnaire" (Weiss et al, 2002) was adapted and administered via telephone to each patient from the abovementioned prior study. The questions were designed to assess the status of each patient's patellofemoral arthroplasty as well as their degree of knee function.

The questionnaire was completed for all 25 knees (Table 1). No knees from the original study were lost to follow-up. At a mean duration of 11.3 years (range, 7.8 to 14.9 years) from the index arthroplasty, all 25 patellofemoral arthroplasties were still in place and all patients reported themselves as being very satisfied. There were no reports of weakness, instability, or additional surgery. Two patients reported that despite their patellofemoral arthroplasty, they were not participating in sports activities. All patients experienced some pain, but not enough to warrant medication. All 22 patients said they would undergo the procedure again.

This 11 year follow-up study demonstrates that patient-specific patellofemoral arthroplasty is a safe and effective treatment for patients with isolated patellofemoral arthritis of the knee. These results compare favorably with those involving off-the-shelf patellofemoral arthroplasties that have been reported on over the past 30 years (Leadbetter et al, 2005; Leadbetter et al, 2006; Lonner, 2007; Sisto and Sarin, 2008; Gupta et al, 2010).

#### **6.3 Complications**

Progression of arthritis into the tibiofemoral compartment is a recognized complication of patellofemoral replacement; when symptomatic, this scenario leads to conversion to a total knee arthroplasty. Progression is more likely to develop when the disease patellofemoral arthritis does not have a clear origin, such as idiopathic arthritis (Grelsamer, 2006). Despite attempts to balance the extensor mechanism, patellar maltracking after patellofemoral arthroplasty can occur, especially when the patient pre-operatively demonstrates high level malalignment and/or dysplasia.

## **7. Case studies**

Our (DJS and RPG) collective experience with patient-specific patellofemoral arthroplasty dates back to 1995 and consists of 91 cases in 79 patients through May 2011. Patients in our cohort generally fall into one of two categories: those having a "normal" femoral trochlear sulcus angle, with or without patellar tilt; and those having a femoral sulcus angle greater than 145, i.e. a shallow or even convex trochlea dysplastic trochleas will exhibit a crossing sign on a true lateral radiograph (Bollier and Fulkerson, 2011). The following case studies serve as illustrative examples.

#### **7.1 Normal trochlear anatomy**

Patient J.O. is a 49 year old male who initially presented with severe anterior knee pain 14 years ago after sustaining a twisting injury to his knee that was treated with arthroscopic surgery followed by a soft tissue realignment procedure two years later. During this time, he developed progressive and disabling anterior knee pain. He could not walk up or down stairs without assistance and could not kneel, squat or climb without severe pain.

Physical examination revealed severe anterior knee tenderness with severe crepitus and grinding in the retro-patellar space. He had no ligament instability and no medial or lateral joint line tenderness. All provocative tests for meniscal and ligamentous injury were

Patient-Specific Patellofemoral Arthroplasty 311

Patient D.B. is a 56 year old woman with anterior knee pain since her teenage years. Nonoperative treatments had included activity modification, prescription and over-the-counter

 Fig. 5. A 56 year old female with bilateral isolated end-stage patellofemoral arthritis, with bilateral trochlear dysplasia (A, B), treated with patient-matched patellofemoral prostheses. Post-operative Merchant views (C) demonstrate proper orientation of patellofemoral implant components. Placement, fit, and alignment of both patient-specific trochlear implants were confirmed by the manufacturer using the patient-specific CT bone models

prior to final polishing (D, E). See section 7.2 for additional case details.

D E

A B

**7.2 Trochlear dysplasia**

C

negative. The radiographs revealed severe patellofemoral arthritis and no medial or lateral joint line abnormalities (Fig 4).

Fig. 4. A 49 year old male with isolated end-stage patellofemoral arthritis, without evidence of trochlear dysplasia as seen in pre-operative Merchant view (A), treated with a patientmatched patellofemoral prosthesis and all-polyethylene patella button. Post-operative anterior-posterior (B), lateral (C), and Merchant (D) views demonstrate proper orientation of patellofemoral prosthesis. Placement, fit, and alignment of the patient-specific trochlear implant was confirmed by the manufacturer using the patient-specific CT bone model prior to final polishing (E). See section 7.1 for additional case details.

The patient was initially treated with medications, heat, physical therapy and hyalgan injections without relief, and he remained symptomatic and disabled. In October 2009, he underwent a patient-matched custom patellofemoral arthroplasty of the right knee (Fig 4). Post-operatively, he has done remarkably well and has returned to his previous employment at the Los Angeles County Sheriff's Department. He currently has no pain and does not require any medications. He can ambulate up and down stairs without assistance and can kneel, squat and climb without pain.

## **7.2 Trochlear dysplasia**

310 Recent Advances in Hip and Knee Arthroplasty

negative. The radiographs revealed severe patellofemoral arthritis and no medial or lateral

A B C

to final polishing (E). See section 7.1 for additional case details.

and can kneel, squat and climb without pain.

D E

Fig. 4. A 49 year old male with isolated end-stage patellofemoral arthritis, without evidence of trochlear dysplasia as seen in pre-operative Merchant view (A), treated with a patientmatched patellofemoral prosthesis and all-polyethylene patella button. Post-operative anterior-posterior (B), lateral (C), and Merchant (D) views demonstrate proper orientation of patellofemoral prosthesis. Placement, fit, and alignment of the patient-specific trochlear implant was confirmed by the manufacturer using the patient-specific CT bone model prior

The patient was initially treated with medications, heat, physical therapy and hyalgan injections without relief, and he remained symptomatic and disabled. In October 2009, he underwent a patient-matched custom patellofemoral arthroplasty of the right knee (Fig 4). Post-operatively, he has done remarkably well and has returned to his previous employment at the Los Angeles County Sheriff's Department. He currently has no pain and does not require any medications. He can ambulate up and down stairs without assistance

joint line abnormalities (Fig 4).

Patient D.B. is a 56 year old woman with anterior knee pain since her teenage years. Nonoperative treatments had included activity modification, prescription and over-the-counter

Fig. 5. A 56 year old female with bilateral isolated end-stage patellofemoral arthritis, with bilateral trochlear dysplasia (A, B), treated with patient-matched patellofemoral prostheses. Post-operative Merchant views (C) demonstrate proper orientation of patellofemoral implant components. Placement, fit, and alignment of both patient-specific trochlear implants were confirmed by the manufacturer using the patient-specific CT bone models prior to final polishing (D, E). See section 7.2 for additional case details.

Patient-Specific Patellofemoral Arthroplasty 313

patellofemoral arthroplasties that have been reported on over the past thirty years (Leadbetter et al, 2005; Leadbetter et al, 2006; Lonner, 2007; Sisto and Sarin, 2008; Gupta et

We believe the key elements that contribute to the success of patient-specific patellofemoral arthroplasty are as follows: (a) a strict inclusion criteria based on pre-operative radiographic evaluation; (b) a meticulous attention to soft-tissue balance and patellofemoral tracking at the time of arthroplasty; and (c) a patient-specific design and manufacturing methodology that ensures accurate and precise anatomic fit while simultaneously providing proper

Ackroyd CE, Newman JH, Evans R, Eldridge JD, Joslin CC (2007) The Avon patellofemoral

Ahlback S (1968) Osteoarthritis of the Knee. A Radiologic Investigation. *Acta Radiol Diagn*

Arnebjornsson AH and Ryd L (1998) The use of isolated patellar prostheses in Sweden 1977-

Bengs BC and Scott RD (2006) The effect of patellar thickness on intraoperative knee flexion and patellar tracking in total knee arthroplasty. *J Arthroplasty*, Vol. 21, pp. 650–655. Blazina ME, Fox JM, Del Pizzo W (1979) Patellofemoral replacement. *Clin Orthop Rel Res,*

Bollier M and Fulkerson JP (2011) The role of trochlear dysplasia in patellofemoral

Charalambous CP, Abiddin Z, Mills SP, Rogers S, Sutton P, Parkinson R (2011) The low

Conley S, Rosenberg A, Crowninshield R (2007) The female knee: anatomic variations. *J Am*

Feinstein WK, Noble PC, Kamaric E, Tullos HS (1996) Anatomic alignment of the patellar

Fulkerson JP (2004) *Disorders of the Patellofemoral Joint*. 4th Edition. Philadelphia, PA.

Grelsamer RP (2000) Current concepts review. Patellar malalignment. *J Bone Joint Surg,* Vol.

Grelsamer RP (2006) Current concepts review. Patellofemoral Arthritis. *J Bone Joint Surg,*

Gupta RR, Zywiel MG, Leadbetter WB, Bonutti P, Mont MA (2010) Scientific Evidence for

Kooijman HJ, Driessen AP, van Horn JR (2003) Long-term results of patellofemoral

Leadbetter WB, Ragland PS, Mont MA (2005) The appropriate use of patellofemoral

the Use of Modern Patellofemoral Arthroplasty. *Expert Rev Med Devices*, Vol. 7, No.

arthroplasty. A report of 56 arthroplasties with 17 years of follow-up. . *J Bone Joint*

contact stress patellofemoral replacement: High early failure rate. *J Bone Joint Surg,*

arthroplasty: five-year survivorship and functional results. . *J Bone Joint Surg,* Vol.

al, 2010) and can be carried out more efficiently.

**9. References**

89-B, pp. 310-5.

*(Stockh)*, Vol. 277, pp. 7-72.

Vol. 144, pp. 98–102.

Vol. 93-B, pp. 484-9.

82-A, pp. 1639–1650.

1, pp. 51-66.

Vol. 88-A, pp. 1849–1860.

*Surg,* Vol. 85-B, pp. 836–40

patellofemoral alignment and medial-lateral constraint.

1986. *Int Orthop*, Vol. 22, No. 3, pp. 141-4.

National Joint Replacement Registry of Australia, Annual Report (2010).

instability. *J Am Acad Orthop Surg*, Vol. 19, No. 1, pp. 8-16.

*Acad Orthop Surg*, Vol. 15 (suppl 1), pp. S31–S36.

groove. *Clin Orthop Rel Res,* Vol. *331*, pp. 64–73.

arthroplasty. *Clin Orthop Rel Res,* Vol. 436, pp. 91–99.

Lippincott Williams & Wilkins.

pain medications, steroid and visco-supplementation injections, nutritional supplements, and physical therapy. Serum laboratory studies had not been suggestive of inflammatory arthritis.

Imaging studies demonstrated severe patellofemoral dysplasia and an absence of arthritis outside the patellofemoral compartment (Fig 5). She had undergone arthroscopies of both knees. She underwent patient-matched custom patellofemoral arthroplasty in September 2008 for her right knee and in December 2008 for her left knee.

Despite the chronically subluxed position of her patellae pre-operatively, an extensive intraoperative lateral release and medial plication have been sufficient to maintain her patellae centered within the patient-matched custom trochlear implant (Fig 5). She flexes easily to at least 120 degrees. The patient considers the procedure a success.

Fig. 6. Comparison of (A) pre-operative and (B) post-operative anterior-posterior patellar offset for the right knee described in Figure 5. Post-operative measurements were based on the known geometry of the patient-matched patellofemoral implant and the all-polyethylene patella selected at the time of surgery. In the presence of pronounced trochlear dysplasia (Figures 5A and 6A), treatment with a patient-specific patellofemoral arthroplasty prosthesis resulted in an insignificant net change in patellar offset (0.6 mm).

## **8. Conclusion**

In this chapter we have reviewed the topic of patellofemoral arthroplasty from historical, technical, and clinical perspectives. The design rationale, peri-operative techniques, and 11 year clinical results of patient-matched patellofemoral arthroplasty have been reviewed and discussed. Experience with patient-matched trochlear implants in the setting of normal and dysplastic femoral trochleas have also been presented.

Patient-specific patellofemoral arthroplasty is a safe and effective treatment for patients with isolated patellofemoral arthritis. The results compare favorably with off-the-shelf patellofemoral arthroplasties that have been reported on over the past thirty years (Leadbetter et al, 2005; Leadbetter et al, 2006; Lonner, 2007; Sisto and Sarin, 2008; Gupta et al, 2010) and can be carried out more efficiently.

We believe the key elements that contribute to the success of patient-specific patellofemoral arthroplasty are as follows: (a) a strict inclusion criteria based on pre-operative radiographic evaluation; (b) a meticulous attention to soft-tissue balance and patellofemoral tracking at the time of arthroplasty; and (c) a patient-specific design and manufacturing methodology that ensures accurate and precise anatomic fit while simultaneously providing proper patellofemoral alignment and medial-lateral constraint.

#### **9. References**

312 Recent Advances in Hip and Knee Arthroplasty

pain medications, steroid and visco-supplementation injections, nutritional supplements, and physical therapy. Serum laboratory studies had not been suggestive of inflammatory

Imaging studies demonstrated severe patellofemoral dysplasia and an absence of arthritis outside the patellofemoral compartment (Fig 5). She had undergone arthroscopies of both knees. She underwent patient-matched custom patellofemoral arthroplasty in September

Despite the chronically subluxed position of her patellae pre-operatively, an extensive intraoperative lateral release and medial plication have been sufficient to maintain her patellae centered within the patient-matched custom trochlear implant (Fig 5). She flexes easily to at

63.9 mm 64.5 mm

Fig. 6. Comparison of (A) pre-operative and (B) post-operative anterior-posterior patellar offset for the right knee described in Figure 5. Post-operative measurements were based on the known geometry of the patient-matched patellofemoral implant and the all-polyethylene patella selected at the time of surgery. In the presence of pronounced trochlear dysplasia (Figures 5A and 6A), treatment with a patient-specific patellofemoral arthroplasty prosthesis

In this chapter we have reviewed the topic of patellofemoral arthroplasty from historical, technical, and clinical perspectives. The design rationale, peri-operative techniques, and 11 year clinical results of patient-matched patellofemoral arthroplasty have been reviewed and discussed. Experience with patient-matched trochlear implants in the setting of normal and

Patient-specific patellofemoral arthroplasty is a safe and effective treatment for patients with isolated patellofemoral arthritis. The results compare favorably with off-the-shelf

resulted in an insignificant net change in patellar offset (0.6 mm).

dysplastic femoral trochleas have also been presented.

A B

2008 for her right knee and in December 2008 for her left knee.

least 120 degrees. The patient considers the procedure a success.

arthritis.

**8. Conclusion**

**23**

*Germany*

**Fixation of Periprosthetic Supracondylar Femur**

**Fractures Above Total Knee Arthroplasty –**

**The Indirect Reduction Technique with the**

*4Department of Trauma and Orthopaedic Surgery, Bethesda Hospital, Stuttgart*

Supracondylar fractures of the femur after total knee arthroplasty are an uncommon but highly challenging injury (Streubel et al., 2010). The management of distal femoral fractures following a total knee replacement can be complex and requires the equipment, perioperative support and surgical skills of both trauma and revision arthroplasty services (Johnston et al., 2011, Nauth et al., 2011). The incidence of periprosthetic supracondylar femur fractures after total knee arthroplasties ranges from 0.3% to 2.5%. A patient with revision total knee arthroplasty has a significantly higher risk of supracondylar fracture above the prosthesis (2-4%) (Merkel & Johnson, 1986; Berry, 1999). Interprosthetic femoral fractures tend to occur more frequently in the supracondylar region above total knee arthroplasty components (Mamczak et al., 2010).  A biomechanical study has shown that notching of the anterior cortex significantly lessens the load to failure by decreasing the bending strength by 18% and the torsional strength by approximately 40% (Lesh et al., 2000). In a retrospective study, the clinical results of 1089 consecutive total knee replacements demonstrated no difference in knees managed with or without anterior femoral notching (Ritter et al., 2005). This finding emphasises the potential for osseous remodelling to decrease the risk of

**1. Introduction**

**Condylar Blade Plate and the Minimally**

*1Department of Trauma Surgery Klinikum am Steinenberg, Reutlingen*

*3Department of Trauma Surgery, Friedrich-Schiller-University, Jena*

**Invasive Technique with the LISS**

K. Kolb1, P.A. Grützner2, F. Marx3 and W. Kolb4

*2Department of Trauma Surgery Unfallklinik Ludwigshafen*

## **Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty – The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive Technique with the LISS**

K. Kolb1, P.A. Grützner2, F. Marx3 and W. Kolb4

*1Department of Trauma Surgery Klinikum am Steinenberg, Reutlingen 2Department of Trauma Surgery Unfallklinik Ludwigshafen 3Department of Trauma Surgery, Friedrich-Schiller-University, Jena 4Department of Trauma and Orthopaedic Surgery, Bethesda Hospital, Stuttgart Germany*

### **1. Introduction**

314 Recent Advances in Hip and Knee Arthroplasty

Leadbetter WB, Seyler TM, Ragland PS (2006) Indications, Contraindications, and Pitfalls of Patellofemoral Arthroplasty. *J Bone Jt Surg*, Vol. 88-A(Suppl 4), pp. 122-137. Lombardi AV (2011) Patellofemoral Arthroplasty: Custom Inlay Technique Offers a Patient

Lonner JH (2004) Patellofemoral Arthroplasty. Pros, Cons, and Design Considerations. *Clin*

Lonner JH (2007) Patellofemoral Arthroplasty. *J Am Acad Orthop Surg*, Vol. 15, No. 8, pp.

Merchant AC, Arendt EA, Dye SF, Fredericson N, Grelsamer RP, Leadbetter WB, Post WR,

Sisto DJ and Sarin VK (2006) Custom Patellofemoral Arthroplasty of the Knee. *J Bone Jt Surg*,

Sisto DJ and Sarin VK (2007) Custom Patellofemoral Arthroplasty of the Knee. Surgical

Sisto DJ and Sarin VK (2008) Patellofemoral Arthroplasty with a Customized Trochlear Prosthesis. *Orthopedic Clinics of North America*, Vol. 39, No. 3, pp. 355-62. Sisto DJ, Henry J, Sisto M, Sarin VK (2010) Patient-Specific Patellofemoral Arthroplasty.

Sisto DJ and Sarin VK (2011) Custom Patellofemoral Arthroplasty of the Knee: An Eleven

Weiss JM, Noble PC, Conditt MA, Kohl HW, Roberts S, Cook KF, Gordon MJ, Mathis KB

Year Follow-Up. *Transactions of the Orthopaedic Research Society*, p. 1239, Long Beach,

(2002) What functional activities are important to patients with knee replacements?

McKeever DC (1955) Patellar prosthesis. *J Bone Joint Surg,* Vol. 37-A, pp. 1074–1084.

Total Knee Design. *Clin Orthop Rel Research*, Vol. 466, pp. 3059-3065. Pierson JL, Ritter MA, Keating EM, Faris PM, Meding JB, Berend ME, Davis KE (2007) The

arthroplasty. *J Bone Joint Surg*, Vol. 89-A, pp. 2195–2203.

Technique. *J Bone Jt Surg*, Vol. 89-A(Suppl 2), pp. 214-225.

*Techniques in Knee Surgery*, Vol. 9, pp. 188-192.

*Clin Orthop Rel Res.* Vol. 404. pp. 172-188.

pp. 142-144, San Diego, California, USA.

*Orthop Rel Res,* Vol. 428, pp. 158–165.

Vol. 88-A, No. 7, pp. 1475-1480.

California, USA.

495-506.

Specific Approach. *Annual Meeting of the American Academy of Orthopaedic Surgeons*,

Teitge RA (2008) The Female Knee. Anatomic Variations and the Female-Specific

effect of stuffing the patellofemoral compartment on the outcome of total knee

Supracondylar fractures of the femur after total knee arthroplasty are an uncommon but highly challenging injury (Streubel et al., 2010). The management of distal femoral fractures following a total knee replacement can be complex and requires the equipment, perioperative support and surgical skills of both trauma and revision arthroplasty services (Johnston et al., 2011, Nauth et al., 2011). The incidence of periprosthetic supracondylar femur fractures after total knee arthroplasties ranges from 0.3% to 2.5%. A patient with revision total knee arthroplasty has a significantly higher risk of supracondylar fracture above the prosthesis (2-4%) (Merkel & Johnson, 1986; Berry, 1999). Interprosthetic femoral fractures tend to occur more frequently in the supracondylar region above total knee arthroplasty components (Mamczak et al., 2010).  A biomechanical study has shown that notching of the anterior cortex significantly lessens the load to failure by decreasing the bending strength by 18% and the torsional strength by approximately 40% (Lesh et al., 2000). In a retrospective study, the clinical results of 1089 consecutive total knee replacements demonstrated no difference in knees managed with or without anterior femoral notching (Ritter et al., 2005). This finding emphasises the potential for osseous remodelling to decrease the risk of

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

revision (Dennis, 2001).

would be characterised as follows (Kregor et al., 2001):

tissue envelope around the fracture itself.

without bone grafts (Streubel et al., 2010; Kolb et al., 2010).

fixation for supracondylar femur fractures above total knee arthroplasty.

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 317

The reported complications of operative treatment included deep infection (3%), fixation failure (4%), non-union (9%), and revision surgery (13%) (Herrera et al., 2008). The treatment of periprosthetic fractures around the knee can be challenging for a number of reasons (Healy et al., 1993; Kim et al., 2006; Rhinelander, 1972): (1) these fractures occur in patients with poor bone stock that can compromise potential fixation; (2) the majority of these patients are elderly and, because of their age may have retarded fracture healing; (3) the epiphyseal and frequently the intramedullary blood supplies of the distal femur are interrupted after total knee arthroplasty; (4) after a fracture of the distal part of the femur immediate reduction of total bone blood flow by nearly 50% through the physiological vasoconstriction in both the periosteal and intramedullary vessels further impairs blood supply; (5) the attachment of the ligamentous structures to the fracture fragment may predispose these knees to potential instability, necessitating the use of a constrained prosthesis with all their potential problems. The wide metaphyseal and diaphyseal spaces, osteopenia, and distal extension of the fracture often associated with these elderly patients can result in suboptimal internal fixation (Ricci et al., 2006). Fractures with stable prostheses are best treated with some meeans of internal fixation and without stem

Ideally, the treatment of a supracondylar femoral fracture above a total knee arthroplasty

In practice, flexible intramedullary nails, rigid retrograde IM nails, angled blade plates, cobra plates, dynamic condylar screws and Ilizarov external fixators have been used (Althausen et al., 2003; Beris et al., 2010; Chettiar et al., 2009; Gliatis et al., 2005; Maniar et al.,

Fixation with conventional compression plates, though for the most part successful, has its limitations (Kubiak et al., 2006). Conventional plate osteosynthesis (CPO) with rigid fixation has shown a high complication rate that includes delayed or non-union, infection, hardware failure and re-fracture after plate removal (Bostman, 1983; Claes et al., 1999; Finsen & Benum, 1986; Hidaka & Gustilo, 1984; Kenwright & Goodship, 1989; Kessler et al., 1992;

(Mast et al., 1989) pioneered the indirect reduction technique without disturbance of the soft

The concept of the indirect reduction technique is to provide reduction of the fracture through traction across the intact soft tissues and decreased surgical dissection of the fracture site (Mast et al., 1989). Minimally invasive plate osteosynthesis (MIPO) have been introduced to go one step further (Krettek et al., 1997). Locked plate fixators improved the stability of plate osteosynthesis significantly (Streubel et al., 2010; Kolb et al., 2010). The combination of locked plate fixators and the MIPO technique allows for plate osteosynthesis

The aim of this report is to describe new planning methods and new techniques of internal

1996; McLaren et al., 1994; Rorabeck & Taylor, 1999; Zehntner & Ganz, 1993).

Mulier et al., 1997; Noorda & Wuisman, 2002; Riemer et al., 1992; Stoffel et al., 2003).

fracture should an anterior notch occur (Dennis, 2001). Additionally, should an anterior notch of the distal part of the femur occur, the surgeon should consider implantation of a femoral component with an attached diaphysis-engaging stem to support the weakened distal part of the femur (Dennis, 2001).

Motions of stiff knees under anaesthesia have a high risk of periprosthetic supracondylar femur fractures (Diehl et al., 2006).

Table 1. Risk factors for periprosthetic supracondylar femur fractures above total knee arthroplasty modified according to (Diehl et al., 2006 ; Nauth et al., 2011)

Most periprosthetic femur fractures occur between two and four years after a total knee arthroplasty (Ehrhardt & Kuster, 2010). The number of these cases may rise quickly, given the projection that, by the year 2030, the implantation of total knee arthroplasties will increase to 3.48 million in the United States, an increase of 673% compared with 2005. The most frequent mechanism of injury is a low-velocity fall onto the knee in combination with torsion or axial compression, with a smaller proportion resulting from high-energy trauma (e.g., motor vehicle accidents) (Su et al., 2004)

The complication rate of these fractures is between 25% and 75%. Conservative treatment of displaced fractures with casting results in malalignment (25-100%), non-union (20-35%), loss of motion of the knee, and inability to maintain reduction of the fracture (Kolb et al., 2009). Surgical treatment provides the best restoration of mechanical alignment to the limb, permits early mobilisation to avoid the complications of prolonged bed rest, and may maximise healing potential in a region where blood supply is already compromised by providing stable fixation (Rorabeck & Taylor, 1999). In 1970, the AO (Arbeitsgemeinschaft für Osteosynthesefragen) published the first results of 112 supracondylar femoral fractures treated according to their principles using a condylar plate, a fixed angle device, with 74% good or excellent results (Wenzl et al., 1970).

The reported complications of operative treatment included deep infection (3%), fixation failure (4%), non-union (9%), and revision surgery (13%) (Herrera et al., 2008). The treatment of periprosthetic fractures around the knee can be challenging for a number of reasons (Healy et al., 1993; Kim et al., 2006; Rhinelander, 1972): (1) these fractures occur in patients with poor bone stock that can compromise potential fixation; (2) the majority of these patients are elderly and, because of their age may have retarded fracture healing; (3) the epiphyseal and frequently the intramedullary blood supplies of the distal femur are interrupted after total knee arthroplasty; (4) after a fracture of the distal part of the femur immediate reduction of total bone blood flow by nearly 50% through the physiological vasoconstriction in both the periosteal and intramedullary vessels further impairs blood supply; (5) the attachment of the ligamentous structures to the fracture fragment may predispose these knees to potential instability, necessitating the use of a constrained prosthesis with all their potential problems. The wide metaphyseal and diaphyseal spaces, osteopenia, and distal extension of the fracture often associated with these elderly patients can result in suboptimal internal fixation (Ricci et al., 2006). Fractures with stable prostheses are best treated with some meeans of internal fixation and without stem revision (Dennis, 2001).

Ideally, the treatment of a supracondylar femoral fracture above a total knee arthroplasty would be characterised as follows (Kregor et al., 2001):

316 Recent Advances in Hip and Knee Arthroplasty

fracture should an anterior notch occur (Dennis, 2001). Additionally, should an anterior notch of the distal part of the femur occur, the surgeon should consider implantation of a femoral component with an attached diaphysis-engaging stem to support the weakened

Motions of stiff knees under anaesthesia have a high risk of periprosthetic supracondylar

distal part of the femur (Dennis, 2001).

**General Femur**

Osteoporosis Female gender

Rheumatoid arthritis Arthrofibrosis

Removal of cement Implantation error

Motion under anaesthesia Endosteal ischemia

arthroplasty modified according to (Diehl et al., 2006 ; Nauth et al., 2011)

Revision total knee arthroplasty Malalignment of the prosthesis

Table 1. Risk factors for periprosthetic supracondylar femur fractures above total knee

Most periprosthetic femur fractures occur between two and four years after a total knee arthroplasty (Ehrhardt & Kuster, 2010). The number of these cases may rise quickly, given the projection that, by the year 2030, the implantation of total knee arthroplasties will increase to 3.48 million in the United States, an increase of 673% compared with 2005. The most frequent mechanism of injury is a low-velocity fall onto the knee in combination with torsion or axial compression, with a smaller proportion resulting from high-energy trauma

The complication rate of these fractures is between 25% and 75%. Conservative treatment of displaced fractures with casting results in malalignment (25-100%), non-union (20-35%), loss of motion of the knee, and inability to maintain reduction of the fracture (Kolb et al., 2009). Surgical treatment provides the best restoration of mechanical alignment to the limb, permits early mobilisation to avoid the complications of prolonged bed rest, and may maximise healing potential in a region where blood supply is already compromised by providing stable fixation (Rorabeck & Taylor, 1999). In 1970, the AO (Arbeitsgemeinschaft für Osteosynthesefragen) published the first results of 112 supracondylar femoral fractures treated according to their principles using a condylar plate, a fixed angle device, with 74%

Intramedullary stems Constrained prosthesis

Screw holes around the knee Anterior femoral notching

femur fractures (Diehl et al., 2006).

Patient depending factors

Bone disease (M. Paget)

Neurologic abnormalities

**Surgery dependant factors**

Osteolysis due to wear Stress shielding

**Prosthesis dependant factors**

(e.g., motor vehicle accidents) (Su et al., 2004)

good or excellent results (Wenzl et al., 1970).

Steroid abuse

Malalignment Infections

In practice, flexible intramedullary nails, rigid retrograde IM nails, angled blade plates, cobra plates, dynamic condylar screws and Ilizarov external fixators have been used (Althausen et al., 2003; Beris et al., 2010; Chettiar et al., 2009; Gliatis et al., 2005; Maniar et al., 1996; McLaren et al., 1994; Rorabeck & Taylor, 1999; Zehntner & Ganz, 1993).

Fixation with conventional compression plates, though for the most part successful, has its limitations (Kubiak et al., 2006). Conventional plate osteosynthesis (CPO) with rigid fixation has shown a high complication rate that includes delayed or non-union, infection, hardware failure and re-fracture after plate removal (Bostman, 1983; Claes et al., 1999; Finsen & Benum, 1986; Hidaka & Gustilo, 1984; Kenwright & Goodship, 1989; Kessler et al., 1992; Mulier et al., 1997; Noorda & Wuisman, 2002; Riemer et al., 1992; Stoffel et al., 2003).

(Mast et al., 1989) pioneered the indirect reduction technique without disturbance of the soft tissue envelope around the fracture itself.

The concept of the indirect reduction technique is to provide reduction of the fracture through traction across the intact soft tissues and decreased surgical dissection of the fracture site (Mast et al., 1989). Minimally invasive plate osteosynthesis (MIPO) have been introduced to go one step further (Krettek et al., 1997). Locked plate fixators improved the stability of plate osteosynthesis significantly (Streubel et al., 2010; Kolb et al., 2010). The combination of locked plate fixators and the MIPO technique allows for plate osteosynthesis without bone grafts (Streubel et al., 2010; Kolb et al., 2010).

The aim of this report is to describe new planning methods and new techniques of internal fixation for supracondylar femur fractures above total knee arthroplasty.

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

system takes into account the height of the fractures (Table 2, Su et al., 2004).

Fracture Type Fracture Height

displacement of the fracture (Dennis, 2001).

arthroplasties created by (Su et al., 2004)

muscle groups (Figgie et al., 1990; Dennis, 2001).

**3. Treatment options**

**3.1 Non-operative treatment**

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 319

into account both the status of the prosthesis (that is, whether it is intact or failing) and the

(Su et al., 2004) developed their classification system because patients are increasingly being treated operatively and the bone stock of the distal segment continues to be considered a key limiting factor to obtaining adequate fixation (Herrera et al., 2008). Their classification

I Fracture above the femoral component

II Fracture above the femoral component,

III Fractures below the tip of the femoral

The goals of treating supracondylar femoral fractures above total knee arthroplasties are to obtain and maintain good postfracture alignment and stability to allow an early range of motion and bone healing (Culp et al., 1987; Rorabeck & Taylor, 1999; Dennis, 1998; Ehrhardt & Kuster, 2010). Acceptable alignments exhibit translations that are less than 5 mm, angulations that are less than 5°-10°, minimal rotations, less than 1 cm of femoral shortening, and proper tibiofemoral prosthetic joint alignments (DiGioia & Rubash, 1991). High malunion rates are common in association with varus, flexion, and internal rotation deformities typically seen as a result of forces exerted by the adductor and gastrocnemius

The non-operative options include skeletal traction, application of a cast, pins and plaster, and cast bracing (Dennis et al., 2001). Traction has a high complication rate and is no longer an option. According to Rorabeck & Young, only fracture type I can be treated conservatively, 4-6 weeks with a cast and 6 weeks of mobilisation with a brace (Chen et al., 1994). However, this treatment may be associated with difficulty in maintaining the reduction, a prolonged period of immobilisation, reduced knee functions, malunion and non-union (McGraw, P.; & Kumar, A., 2010). Conservative treatment was followed by nonunion in 20% and mal-union in 23% of the cases evaluated (Culp et al., 1987). Casting resulted in an average loss of motion of 26° (Culp et al., 1987). Of these fractures, 29%

eventually required operative care (Harlow & Hofmann, 1994; Dennis, 2001).

Table 2. Classification system of supracondylar femoral fractures above total knee

component

component

fracture reaching the tip of the femoral

### **2. Preoperative assessment**

Preoperative clinical evaluation involves questions related to general factors that include smoking, peripheral vascular and neurological status, nutritional status, comorbidities such as diabetes, alignment of the injured leg, pre-injury range of motion of the knee, knee extensor mechanism, signs of loosening of the prosthesis (weight dependant pain, knee instability, reduced walking distance), infection and activity level. Radiographic assessment includes anterior posterior (a.p.), lateral and oblique radiographs of the knee and femur including the hip and former radiographs if available (Diehl et al. 2006; Ehrhardt & Kuster, 2010). Specifically, the lateral radiograph is used to assess (Kregor et al., 2001) the following: 1. the integrity of the femoral component-bone interface to assess potential loosening, 2. the bone block attached to the femoral component, and 3. the position of the cement mantle and flange for the femoral component. Modern CT scans provide more information concerning the integrity of the femoral-bone interface to assess potential loosening of the prosthesis (Kregor et al., 2001; Ehrhardt & Kuster, 2010). Both the type and classification of fractures and the type of prosthesis should be known preoperatively because this information is very important for choosing the right treatment option (Ehrhardt & Kuster 2010). The operative report should be available whenever possible (Ehrhardt & Kuster, 2010).

#### **2.1 Classification**

The classification system that is the most valuable to management was created by Rorabeck & Young (Fig. 1, Rorabeck & Taylor, 1999; Dennis, 2001). Their classification system takes

Fig. 1. The Classification system of supracondylar femoral fractures above total knee arthroplasties created by (Rorabeck & Young, 1999)

into account both the status of the prosthesis (that is, whether it is intact or failing) and the displacement of the fracture (Dennis, 2001).

(Su et al., 2004) developed their classification system because patients are increasingly being treated operatively and the bone stock of the distal segment continues to be considered a key limiting factor to obtaining adequate fixation (Herrera et al., 2008). Their classification system takes into account the height of the fractures (Table 2, Su et al., 2004).

Table 2. Classification system of supracondylar femoral fractures above total knee arthroplasties created by (Su et al., 2004)

## **3. Treatment options**

318 Recent Advances in Hip and Knee Arthroplasty

Preoperative clinical evaluation involves questions related to general factors that include smoking, peripheral vascular and neurological status, nutritional status, comorbidities such as diabetes, alignment of the injured leg, pre-injury range of motion of the knee, knee extensor mechanism, signs of loosening of the prosthesis (weight dependant pain, knee instability, reduced walking distance), infection and activity level. Radiographic assessment includes anterior posterior (a.p.), lateral and oblique radiographs of the knee and femur including the hip and former radiographs if available (Diehl et al. 2006; Ehrhardt & Kuster, 2010). Specifically, the lateral radiograph is used to assess (Kregor et al., 2001) the following: 1. the integrity of the femoral component-bone interface to assess potential loosening, 2. the bone block attached to the femoral component, and 3. the position of the cement mantle and flange for the femoral component. Modern CT scans provide more information concerning the integrity of the femoral-bone interface to assess potential loosening of the prosthesis (Kregor et al., 2001; Ehrhardt & Kuster, 2010). Both the type and classification of fractures and the type of prosthesis should be known preoperatively because this information is very important for choosing the right treatment option (Ehrhardt & Kuster 2010). The operative

The classification system that is the most valuable to management was created by Rorabeck & Young (Fig. 1, Rorabeck & Taylor, 1999; Dennis, 2001). Their classification system takes

Fig. 1. The Classification system of supracondylar femoral fractures above total knee

arthroplasties created by (Rorabeck & Young, 1999)

report should be available whenever possible (Ehrhardt & Kuster, 2010).

**2. Preoperative assessment**

**2.1 Classification**

The goals of treating supracondylar femoral fractures above total knee arthroplasties are to obtain and maintain good postfracture alignment and stability to allow an early range of motion and bone healing (Culp et al., 1987; Rorabeck & Taylor, 1999; Dennis, 1998; Ehrhardt & Kuster, 2010). Acceptable alignments exhibit translations that are less than 5 mm, angulations that are less than 5°-10°, minimal rotations, less than 1 cm of femoral shortening, and proper tibiofemoral prosthetic joint alignments (DiGioia & Rubash, 1991). High malunion rates are common in association with varus, flexion, and internal rotation deformities typically seen as a result of forces exerted by the adductor and gastrocnemius muscle groups (Figgie et al., 1990; Dennis, 2001).

### **3.1 Non-operative treatment**

The non-operative options include skeletal traction, application of a cast, pins and plaster, and cast bracing (Dennis et al., 2001). Traction has a high complication rate and is no longer an option. According to Rorabeck & Young, only fracture type I can be treated conservatively, 4-6 weeks with a cast and 6 weeks of mobilisation with a brace (Chen et al., 1994). However, this treatment may be associated with difficulty in maintaining the reduction, a prolonged period of immobilisation, reduced knee functions, malunion and non-union (McGraw, P.; & Kumar, A., 2010). Conservative treatment was followed by nonunion in 20% and mal-union in 23% of the cases evaluated (Culp et al., 1987). Casting resulted in an average loss of motion of 26° (Culp et al., 1987). Of these fractures, 29% eventually required operative care (Harlow & Hofmann, 1994; Dennis, 2001).

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

(Table 3, Kolb et al., 2009).

Bone graft (n, % early/later

> 15/3 (75%/15%)

total knee arthroplasties (from Kolb et al., 2009).

 Of the total numbers of conventional plate osteosynthese an average of 32% (range, 0-75%) primary bone grafts were used. A mean of 10% (range, 0-50%) of those with conventional plate osteosynthesis (CPO) had an implant failure and developed a non-union

Infection Implant

failure

2 (40%) 1 (20%) 0 0 Normal

4 (40%) 0 5 (50%) 5 (50%) Varus 7° 5

2 (30%) 0 0 0 Valgus 5°

6/2 (40%/13%) 0 3 (20%) 3 (20%) Shortening 2

0 0 0 0 Varus

Table 3. Complications of conventional plate osteosynthesis (CPO) of fractures above fixed

The indirect reduction technique allows for the use of longer plates with less pullout force acting on the screws due to improvement of the working leverage and significant stress reduction in the plate (50%-85%) (Kolb et al., 2009; Gautier & Sommer, 2003; Stoffel et al., 2003). Various methods have been used to enhance fixation using internal fixation (McGraw, P.; & Kumar, A., 2010). In severely osteoporotic bone, polymethylmethacrylate can be used to enhance screw fixation (Zehentner & Ganz, 1993). An intramedullary autograft is another option to help restore bone stock and achieve quadric-cortical fixation of the screws (Tani et al., 1998). However, this technique has not been widely used because of donor-site

Combining medial strut allografts with compression plates allows for fixation of severe osteoporotic fractures and failures of initial open reduction and internal fixation (Wang & Wang, 2002). Three patients with very low and comminuted fractures exhibited good results using intramedullary fibular strut allografts without donor-site morbidities(Kumar

The epiphyseal and frequently the intramedullary blood supplies of the distal femur are interrupted after total knee arthroplasty (Healy et al., 1993). Immediate reduction of total bone blood flow after a fracture of the distal part of the femur through physiological

morbidity, particularly in elderly patients (McGraw, P.; & Kumar, A., 2010).

0 0 0 Normal

0 0 0 0 Valgus 3° 1

Non-union (n, %)

Results of fixation

alignment

alignment

(range, 0-10°)

cm 3 (20%) Valgus 17° 1 (7%) Varus 2° 1

(7%)

(23%)?

(33%) Valgus 5° 2 (66%)

Fig. 2. Schematic of treatment options for supracondylar femoral fractures above total knee arthroplasties. TKA=total knee arthroplasty, PMMA=polymethylmethacrylate

#### **3.2 Operative treatment**

Several options are available to provide secure internal fixation of supracondylar fractures of the distal femur (Fig. 2, Ayers, 1997; Kolb et al., 2009). Many factors must be considered in choosing the most appropriate management method for these fractures including the patients general health, prefracture ambulatory status, fracture pattern, location, displacement, and type of implant (Su et al., 2004). Periprosthetic fractures above total knee arthroplasties have particular risks for failure, including wide metaphyseal and diaphyseal spaces, osteoporosis, small distal femoral fragments, and prosthetic anchorage pegs reducing the sites for fixation (Kolb et al., 2010). Surgical options include intramedullary devices, condylar buttress plates and, - more recently, – locking plates (internal fixators) that are typically placed in a submuscular manner (Herrera et al., 2008).

#### **3.3 Coventional plate osteosynthesis**

The two basic types of fixed angle devices are the condylar screw plate and the 95° condylar blade plate. They work best for more proximal fractures and when there is minimal comminution of the distal fragments (Ayers, 1997; Su et al., 2004). The advantages of the 95° condylar plate are that no bone has to be removed from the distal fragment when this device is inserted and that the blade is relatively thin (Healy et al., 1993). The blade can therefore, be placed closed to the lugs of the femoral component and close to the anterior femoral flange (Healy et al., 1993). Usually, the entry site for the blade chisel is at a height of 2.5-3 cm above the prosthetic joint line, depending on the configuration of the fracture and the prosthetic design (Moran et al., 1996). However, the angled 95° condylar blade plates do not provide sufficient stability in osteoporotic bone and might interfere with the fixation lugs of

Fig. 2. Schematic of treatment options for supracondylar femoral fractures above total knee

Several options are available to provide secure internal fixation of supracondylar fractures of the distal femur (Fig. 2, Ayers, 1997; Kolb et al., 2009). Many factors must be considered in choosing the most appropriate management method for these fractures including the patients general health, prefracture ambulatory status, fracture pattern, location, displacement, and type of implant (Su et al., 2004). Periprosthetic fractures above total knee arthroplasties have particular risks for failure, including wide metaphyseal and diaphyseal spaces, osteoporosis, small distal femoral fragments, and prosthetic anchorage pegs reducing the sites for fixation (Kolb et al., 2010). Surgical options include intramedullary devices, condylar buttress plates and, - more recently, – locking plates (internal fixators) that

The two basic types of fixed angle devices are the condylar screw plate and the 95° condylar blade plate. They work best for more proximal fractures and when there is minimal comminution of the distal fragments (Ayers, 1997; Su et al., 2004). The advantages of the 95° condylar plate are that no bone has to be removed from the distal fragment when this device is inserted and that the blade is relatively thin (Healy et al., 1993). The blade can therefore, be placed closed to the lugs of the femoral component and close to the anterior femoral flange (Healy et al., 1993). Usually, the entry site for the blade chisel is at a height of 2.5-3 cm above the prosthetic joint line, depending on the configuration of the fracture and the prosthetic design (Moran et al., 1996). However, the angled 95° condylar blade plates do not provide sufficient stability in osteoporotic bone and might interfere with the fixation lugs of

arthroplasties. TKA=total knee arthroplasty, PMMA=polymethylmethacrylate

are typically placed in a submuscular manner (Herrera et al., 2008).

**3.2 Operative treatment**

**3.3 Coventional plate osteosynthesis**

the femoral component, and the polymethylmethacrylate (Zehntner & Ganz 1993, Chen et al. 1994). Of the total numbers of conventional plate osteosynthese an average of 32% (range, 0-75%) primary bone grafts were used. A mean of 10% (range, 0-50%) of those with conventional plate osteosynthesis (CPO) had an implant failure and developed a non-union (Table 3, Kolb et al., 2009).

Table 3. Complications of conventional plate osteosynthesis (CPO) of fractures above fixed total knee arthroplasties (from Kolb et al., 2009).

The indirect reduction technique allows for the use of longer plates with less pullout force acting on the screws due to improvement of the working leverage and significant stress reduction in the plate (50%-85%) (Kolb et al., 2009; Gautier & Sommer, 2003; Stoffel et al., 2003). Various methods have been used to enhance fixation using internal fixation (McGraw, P.; & Kumar, A., 2010). In severely osteoporotic bone, polymethylmethacrylate can be used to enhance screw fixation (Zehentner & Ganz, 1993). An intramedullary autograft is another option to help restore bone stock and achieve quadric-cortical fixation of the screws (Tani et al., 1998). However, this technique has not been widely used because of donor-site morbidity, particularly in elderly patients (McGraw, P.; & Kumar, A., 2010).

Combining medial strut allografts with compression plates allows for fixation of severe osteoporotic fractures and failures of initial open reduction and internal fixation (Wang & Wang, 2002). Three patients with very low and comminuted fractures exhibited good results using intramedullary fibular strut allografts without donor-site morbidities(Kumar et al., 2008).

The epiphyseal and frequently the intramedullary blood supplies of the distal femur are interrupted after total knee arthroplasty (Healy et al., 1993). Immediate reduction of total bone blood flow after a fracture of the distal part of the femur through physiological

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

success.

stability.

3. Preserving blood supply The present concept still

4. Early protective motion for rehabilitation because pain was abolished and union

assured

and techniques.

fracture care.

approaches,

interface

2. Rigid fixation, absolute

stability

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 323

The most notable change in the treatment of diaphysael fractures has been the shift from the mechanical to the biological aspects of internal fixation. The preservation of the viability and integrity of the soft tissue envelope of the metaphysis has been recognized as the key to

Stabilisation with different grades of stability, from high (absolute stability) to low (relative stability). Appropriate construct stability. Stability by compression or splinting, as the fracture pattern and the injury require. The joint surfaces require anatomical reduction with absolute stability. The majority of

diaphyseal fractures are treated with relative stability methods (eg. intramedullary or extramedullary splinting).

Preservation of the blood supply to soft tissues and bone by careful handling and gentle reduction techniques and a newly designed bone-implant

interface

Early and safe

functional care

mobilisation of the part and the patient. Early active motion can also be carried out because splint fixation is stable enough to allow postoperative

Today the dominant theme in the

Major changes have occurred in the timing of the different steps of metaphyseal reconstruction, as well as in the fixation methods

The comprehensive classification of long bones has helped predict

emphasises that the blood supply through the soft tissues and bone is the most important aspect in

techniques are mandatory, - implants with new bone-implant

Table 4. Comparison of AO principles from 1970 and 2006 (from Wagner and Frigg, 2006).

treatment and outcome.

fixation of fractures of the diaphysis is the biology of bone and the preservation of the blood supply to bony fragments, and no longer the quest for absolute

vasoconstriction in both the periosteal and intramedullary vessels by nearly 50% further impairs blood supply (Rhinelander, 1972). Fractures above total knee arthroplasties may have greater tendencies to non-unions than do distal femoral fractures not associated with arthoplasties (Moran et al., 1996). Microangiographic studies have demonstrated that much of the vascular supply to the callus area derives from the surrounding soft tissue (Rhinelander, 1972). Conventional plate osteosynthesis produces compression between the implant and the bone and probably further impairs the blood supply (Fig 3 Healy et al., 1993; Wagner, 2003). Plates interfere significantly with the periosteal blood supply, resulting in bone necrosis (Perren et al., 1988). Direct manipulation of bone fragments in conventional plate osteosynthesis is a major cause of devitalisation of the bone fragments (Leunig et al., 2000). Medial dissection of soft tissue can disrupt this important blood supply and is, thus, to be avoided (Mast et al., 1989).

The extreme difference in healing time between conservative treatment (3 months) and compression fixation (15 months) indicates that the circumstances can be improved (Perren, 2003). Bone union depends on respecting the capacity of the soft tissues to maintain vascular supply to the bone, on the reduction of the fracture, and on applying the technique that best provides the necessary stability for union to occur (Wagner & Frigg, 2006). Surgical treatment should take biological, biomechanical and surgical aspects into account (Table 4, Korner et al., 2003).

vasoconstriction in both the periosteal and intramedullary vessels by nearly 50% further impairs blood supply (Rhinelander, 1972). Fractures above total knee arthroplasties may have greater tendencies to non-unions than do distal femoral fractures not associated with arthoplasties (Moran et al., 1996). Microangiographic studies have demonstrated that much of the vascular supply to the callus area derives from the surrounding soft tissue (Rhinelander, 1972). Conventional plate osteosynthesis produces compression between the implant and the bone and probably further impairs the blood supply (Fig 3 Healy et al., 1993; Wagner, 2003). Plates interfere significantly with the periosteal blood supply, resulting in bone necrosis (Perren et al., 1988). Direct manipulation of bone fragments in conventional plate osteosynthesis is a major cause of devitalisation of the bone fragments (Leunig et al., 2000). Medial dissection of soft tissue can disrupt this important blood supply and is, thus,

The extreme difference in healing time between conservative treatment (3 months) and compression fixation (15 months) indicates that the circumstances can be improved (Perren, 2003). Bone union depends on respecting the capacity of the soft tissues to maintain vascular supply to the bone, on the reduction of the fracture, and on applying the technique that best provides the necessary stability for union to occur (Wagner & Frigg, 2006). Surgical treatment should take biological, biomechanical and surgical aspects into account (Table 4,

> Influences through clinical experiences and experimental

Applied science concerning:

As a consequence, indirect reduction techniques were

AO principles NOW (Wagner & Frigg, 2006)

Fracture reduction and fixation to restore anatomical relationships. Reductions need not be anatomical but only axially aligned in the diaphysis and the metaphysis. Anatomical reduction is required for intra-articular reductions. The principles of articular

fracture care:

surfaces,

stable fixation of the articular fragments, and

investigations

and bone,

thinking.

developed

to be avoided (Mast et al., 1989).

AO principles THEN (Müller

Korner et al., 2003).

1. Anatomical precise

et al., 1970)

reduction

Table 4. Comparison of AO principles from 1970 and 2006 (from Wagner and Frigg, 2006).

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

LISS fixator are attributable to three factors (Kregor et al., 2001):

metaphyseal/diaphyseal component of the fracture, 3. the ability to place 3 or 4 screws even in small distal fragments.

between the fixator and the bone required (Kolb et al., 2010).

**3.7 Osteosynthesis with the locking compression plate (LCP) and polyaxial locking**

In September 1998, Professor Michael Wagner (of the Wilhelminen Hospital in Vienna) questioned whether it was possible to make the LISS screw-head hole compatible with conventional bone screws (Frigg, 2003). As a result the locking compression plate (LCP) was developed. It has a combined plate hole, which allows for the use of conventional bone screws or locked screws. The possibility of using the LCP as a compression plate (> primary fracture healing), an internal fixator (> secondary fracture healing) or in a specific combination (hybrid fixation) allows for ideal plate anchorage that is adapted to the bone

**(LISS)**

**plates**

(Frigg, 2003; Wagner, 2003).

the distal fragment,

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 325

The LISS has theoretical advantages for the treatment of supracondylar femoral fractures above well-fixed total knee arthroplasties (Kolb et al., 2010). Broadly, the advantages of the

1. The ability to place multiple fixed-angled locked screws, offering improved stability of

2. the ability to place percutaneous screws in the proximal femur without dissection of the

The bridge-plating technique produces minimal biological damage with locked flexible fixation (Ehinger et al., 2011; Thielemann et al., 1988; Rozbruch et al., 1998; Perren, 2002; Gautier & Jakob, 2004). The minimally invasive plate-osteosynthesis technique leaves the blood supply largely intact and reduces blood loss compared with the conventional plate osteosynthesis using a standard approach (Mast et al., 1989; Krettek et al., 1997; Grützner et al., 1997; Farouk et al., 1998; Krettek et al., 2001; Althausen et al., 2003; Kolb et al., 2003). It avoids the need for precise reduction and exposure of the bone, thus reducing surgical trauma (Thielemann et al., 1988; Gerber et al., 1990; Ganz et al., 1991; Rozbruch et al., 1998; Perren, 2002). The locked plates provided significantly greater fixation stability than the standard plate, blade plate, condylar buttress plate, dynamic condylar screws, or the retrograde nail in biomechanical studies involving axial loading with mild to moderate osteoporotic femurs (Egol et al., 2004; Ganz et al., 1991; Koval et al., 1997; Marti et al., 2001; Salas et al., 2011; Zlowodzki et al., 2004). The probability of periprosthetic fracture of the locking plate compared to the retrograde IM nail (in a deterministic finite element model of each construct type) was higher under the applied loading conditions (locking plate 21.8% versus IM nail 0.019%) (Salas et al., 2011). By using an internal fixator with locked screw heads, the screw loading is primarily bending and not pullout (Gautier & Sommer, 2003; Wagner & Frigg, 2006). Locked screws provide improved anchorage and safety and they cannot be stripped during their insertion because they limit the torque applied to the screw thread (Perren, 2003, Fig 3a and 3b). The pull out resistance of the LISS is increased with convergent screws in the femoral condyle. These plates are particularly useful in the presence of a proximal femur implant as they allow unicortical screw fixation that overlap the distal part of the proximal implant, thereby avoiding a stress riser between the two implants (McGraw & Kumar, 2010). Blood supply to the bone is preserved, and no contact

**3.6 Minimally invasive osteosynthesis with the Less Invasive Stabilisation System**

#### **3.4 Plate osteosynthesis with the indirect reduction technique**

The concept of biological internal fixation entails preserving the biologic reactivity of the tissue as much as possible (Rozbruch et al., 1998). This process includes careful tissue dissection, epiperiosteal bone dissection, and indirect reduction of the fracture to avoid the stripping and de-vascularisation of bone fragments (Rozbruch et al., 1998). (Mast et al., 1989) pioneered the indirect reduction of fractures without disturbance of the soft tissue envelope around the fracture and reduced blood loss. One example of an indirect reduction method is the distraction of fragments using a distractor, an external fixator, a plate or traction applied to a limb (Wagner & Frigg, 2006). The fragments are reduced using ligamentotaxis, minimising the extent to which they are manipulated and preserving their blood supply (Babst et al., 2001; Rüedi et al., 1998; Wagner & Frigg, 2006; Vidal et al., 1979). Primary grafting, which is often used in CPO is not necessary (Kolb et al., 2009; Ricci et al., 2005; Ricci et al., 2006). Minimally invasive techniques (i.e., MIPO) go one step further (Krettek et al., 1997). The bridging plate is one of the early developments of an internal fixator (Brunner & Weber, 1982). Recent developments are the Schuhli nut developed by Mast (Kolodziej et al., 1998), the Zespol plate (Ramotowski & Granowski, 1991), the point contact fixator (PC-Fix) (Tepic et al., 1997), the less invasive stabilisation system (LISS) (Frigg et al., 2001), and the locking compression plate (LCP) (Frigg, 2003). Healing has been accelerated with the PC-Fix, so that it removal is possible after only 3 months (Wagner & Frigg, 2006). Local infection resistance has been improved, such that 750 times more Staphylococcus aureus were required to produce the same incidence of infection with the PC-Fix as with the dynamic compression plate (Arens et al., 1999).

#### **3.5 Minimally invasive osteosynthesis with internal fixators and retrograde nails**

Internal fixators and retrograde nails have advantages in minimally invasive osteosynthesis (MIO) compared to the condylar plate (Ehrhardt & Kuster, 2010). Numerous studies (Chettiar et al., 2009; Gliatis et al., 2005; Henry, 1995; Mittlmeier et al., 2005; Murrell & Nunley, 1995; Platzer et al., 2010; Rolston et al., 1995; Smith et al., 1996) recommend nailing in the posterior cruciate ligament retaining femoral component with an open box. The supracondylar nail preserves the fracture haematoma, does not require extensive soft-tissue stripping, and provides fair stability to the fracture (Figgie et al., 1990; Gardner et al., 2004; Gliatis et al., 2005; Kolb et al., 2008; Mittlmeier & Beck 2005; Stedtfeld et al., 2004). Problems associated with the use of a retrograde nail include malalignment due to a poor starting point, flexion malalignment as a result of the knee flexion required for access to the joint during reaming and nail placement, and insufficient distal stability (Horwitz & Kubiak, 2010). The intercondylar distance must be at least 11mm or 12 mm to accommodate the nail, and the knee flexion must be at least 60° (Diehl et al., 2006; Kolb et al., 2010; Rolston et al., 1995). Small distal fragments should have enough space for at least two screws (Diehl et al., 2006, Kolb et al., 2010; Mittlmeier et al., 2005). Many systems include an interference screw that can be placed in the most distal screw hole to convert the nail to a fixed-angle device (Horwitz & Kubiak, 2010). However, these systems still fail because the osteoporotic cancellous bone is inadequate, and it is not uncommon for a distal femoral fracture to drift into valgus at the site of the nail fixation (Horwitz & Kubiak, 2010). Angular correction and additional stability can be achieved bx placing blocking screws in the distal fragment (Stedtfeld et al., 2004). In a retrospective study, 14 supracondylar periprosthetic fractures obtained good functional outcomes, a low complication rate and 100% fracture unions (Chettiar et al., 2009).

#### **3.6 Minimally invasive osteosynthesis with the Less Invasive Stabilisation System (LISS)**

The LISS has theoretical advantages for the treatment of supracondylar femoral fractures above well-fixed total knee arthroplasties (Kolb et al., 2010). Broadly, the advantages of the LISS fixator are attributable to three factors (Kregor et al., 2001):

324 Recent Advances in Hip and Knee Arthroplasty

The concept of biological internal fixation entails preserving the biologic reactivity of the tissue as much as possible (Rozbruch et al., 1998). This process includes careful tissue dissection, epiperiosteal bone dissection, and indirect reduction of the fracture to avoid the stripping and de-vascularisation of bone fragments (Rozbruch et al., 1998). (Mast et al., 1989) pioneered the indirect reduction of fractures without disturbance of the soft tissue envelope around the fracture and reduced blood loss. One example of an indirect reduction method is the distraction of fragments using a distractor, an external fixator, a plate or traction applied to a limb (Wagner & Frigg, 2006). The fragments are reduced using ligamentotaxis, minimising the extent to which they are manipulated and preserving their blood supply (Babst et al., 2001; Rüedi et al., 1998; Wagner & Frigg, 2006; Vidal et al., 1979). Primary grafting, which is often used in CPO is not necessary (Kolb et al., 2009; Ricci et al., 2005; Ricci et al., 2006). Minimally invasive techniques (i.e., MIPO) go one step further (Krettek et al., 1997). The bridging plate is one of the early developments of an internal fixator (Brunner & Weber, 1982). Recent developments are the Schuhli nut developed by Mast (Kolodziej et al., 1998), the Zespol plate (Ramotowski & Granowski, 1991), the point contact fixator (PC-Fix) (Tepic et al., 1997), the less invasive stabilisation system (LISS) (Frigg et al., 2001), and the locking compression plate (LCP) (Frigg, 2003). Healing has been accelerated with the PC-Fix, so that it removal is possible after only 3 months (Wagner & Frigg, 2006). Local infection resistance has been improved, such that 750 times more Staphylococcus aureus were required to produce the same incidence of infection with the PC-Fix as with the

**3.5 Minimally invasive osteosynthesis with internal fixators and retrograde nails**  Internal fixators and retrograde nails have advantages in minimally invasive osteosynthesis (MIO) compared to the condylar plate (Ehrhardt & Kuster, 2010). Numerous studies (Chettiar et al., 2009; Gliatis et al., 2005; Henry, 1995; Mittlmeier et al., 2005; Murrell & Nunley, 1995; Platzer et al., 2010; Rolston et al., 1995; Smith et al., 1996) recommend nailing in the posterior cruciate ligament retaining femoral component with an open box. The supracondylar nail preserves the fracture haematoma, does not require extensive soft-tissue stripping, and provides fair stability to the fracture (Figgie et al., 1990; Gardner et al., 2004; Gliatis et al., 2005; Kolb et al., 2008; Mittlmeier & Beck 2005; Stedtfeld et al., 2004). Problems associated with the use of a retrograde nail include malalignment due to a poor starting point, flexion malalignment as a result of the knee flexion required for access to the joint during reaming and nail placement, and insufficient distal stability (Horwitz & Kubiak, 2010). The intercondylar distance must be at least 11mm or 12 mm to accommodate the nail, and the knee flexion must be at least 60° (Diehl et al., 2006; Kolb et al., 2010; Rolston et al., 1995). Small distal fragments should have enough space for at least two screws (Diehl et al., 2006, Kolb et al., 2010; Mittlmeier et al., 2005). Many systems include an interference screw that can be placed in the most distal screw hole to convert the nail to a fixed-angle device (Horwitz & Kubiak, 2010). However, these systems still fail because the osteoporotic cancellous bone is inadequate, and it is not uncommon for a distal femoral fracture to drift into valgus at the site of the nail fixation (Horwitz & Kubiak, 2010). Angular correction and additional stability can be achieved bx placing blocking screws in the distal fragment (Stedtfeld et al., 2004). In a retrospective study, 14 supracondylar periprosthetic fractures obtained good functional outcomes, a low complication rate and 100% fracture unions

**3.4 Plate osteosynthesis with the indirect reduction technique**

dynamic compression plate (Arens et al., 1999).

(Chettiar et al., 2009).

The bridge-plating technique produces minimal biological damage with locked flexible fixation (Ehinger et al., 2011; Thielemann et al., 1988; Rozbruch et al., 1998; Perren, 2002; Gautier & Jakob, 2004). The minimally invasive plate-osteosynthesis technique leaves the blood supply largely intact and reduces blood loss compared with the conventional plate osteosynthesis using a standard approach (Mast et al., 1989; Krettek et al., 1997; Grützner et al., 1997; Farouk et al., 1998; Krettek et al., 2001; Althausen et al., 2003; Kolb et al., 2003). It avoids the need for precise reduction and exposure of the bone, thus reducing surgical trauma (Thielemann et al., 1988; Gerber et al., 1990; Ganz et al., 1991; Rozbruch et al., 1998; Perren, 2002). The locked plates provided significantly greater fixation stability than the standard plate, blade plate, condylar buttress plate, dynamic condylar screws, or the retrograde nail in biomechanical studies involving axial loading with mild to moderate osteoporotic femurs (Egol et al., 2004; Ganz et al., 1991; Koval et al., 1997; Marti et al., 2001; Salas et al., 2011; Zlowodzki et al., 2004). The probability of periprosthetic fracture of the locking plate compared to the retrograde IM nail (in a deterministic finite element model of each construct type) was higher under the applied loading conditions (locking plate 21.8% versus IM nail 0.019%) (Salas et al., 2011). By using an internal fixator with locked screw heads, the screw loading is primarily bending and not pullout (Gautier & Sommer, 2003; Wagner & Frigg, 2006). Locked screws provide improved anchorage and safety and they cannot be stripped during their insertion because they limit the torque applied to the screw thread (Perren, 2003, Fig 3a and 3b). The pull out resistance of the LISS is increased with convergent screws in the femoral condyle. These plates are particularly useful in the presence of a proximal femur implant as they allow unicortical screw fixation that overlap the distal part of the proximal implant, thereby avoiding a stress riser between the two implants (McGraw & Kumar, 2010). Blood supply to the bone is preserved, and no contact between the fixator and the bone required (Kolb et al., 2010).

#### **3.7 Osteosynthesis with the locking compression plate (LCP) and polyaxial locking plates**

In September 1998, Professor Michael Wagner (of the Wilhelminen Hospital in Vienna) questioned whether it was possible to make the LISS screw-head hole compatible with conventional bone screws (Frigg, 2003). As a result the locking compression plate (LCP) was developed. It has a combined plate hole, which allows for the use of conventional bone screws or locked screws. The possibility of using the LCP as a compression plate (> primary fracture healing), an internal fixator (> secondary fracture healing) or in a specific combination (hybrid fixation) allows for ideal plate anchorage that is adapted to the bone (Frigg, 2003; Wagner, 2003).

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

**4. Preoperative planning**

Sommer, 2003).

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 327

Indirect reduction and closed fixation techniques are technically much more demanding than an open procedure; thus, accurate preoperative planning is needed to choose the appropriate implant size and length, shape of the plate and the number, position and order of insertion of the screws (Mast et al., 1989). The common issues related to the use of locked supracondylar plates for extraarticular distal femoral fractures are appropriate plate length, malalignment, and interference with total knee arthroplasty pegs (Horwitz & Kubiak, 2010). Plate length is important in patients with osteoporosis, both for fixation of the condylar fragment and to avoid creation of stress risers in the femoral shaft (Horwitz & Kubiak, 2010). Use of a long plate, while leaving some screw holes without screws, provides better fixation with less chance of failure at the proximal part of the diaphysis due to either pullout of the screws or a fracture at the tip of the plate (Sanders et al., 2002). The newer techniques

Fig. 4. The importance of plate-span ratio and plate-screw density in the bridge-plating technique. The schematic drawing shows a mechanically sound fixation of a comminuted diaphyseal fracture of the lower leg. The plate-span ratio is approximately 3, indicating that the plate is three times longer than the overall fracture area. The overall plate-screw density of the construct in this example is 0.43 & screws for a 14-hole plate (from Gautier and

Fig. 3. a left – Longitudinal section through the screw hole of a conventional plate screw. The inclination of the screw is not locked. The screw is tightened with an axial traction of 2000 to 3000 N, the plate is compressed onto the bone producing friction which resists a tangential load of 1000 N (friction = 0.4 x 2500 = 1000 N). Fig. 3. b right – Longirudinal section through the locked screw of an internal fixator. Because of the steep conical surfaces ("Morse cone") the screw locks upon application of minimal torque. Therefore absence of compression between the plate and bone allows either point contact or no contact thus enabling reduction of the contact damage to the blood supply. This type of forece transmission does not depend on axial preloading of the screw (from Perren, 2002).

Polyaxial locking plates (POLYAX Locked Plating Systemt, DePuy, Warsaw, IN, USA), which allow screw angulation within a maximum 40-degree cone, are now available (Haydukewych et al., 2007).  Polyaxial locking plates offer more fixation versatility without an apparent increase in mechanical complications related to loss of reduction (Haydukewych et al., 2007). The non-contact bridging plate for distal femurs (NCB DF, Zimmer, Warsaw, IN, USA) combines conventional plating techniques with polyaxial screw placement and angular stability (Ehrhardt et al., 2008). Results of this combination technique show promise with regard to union and malunion rates in periprosthetic fractures in elderly and osteoporotic patients (Ehrhardt et al., 2008; El-Zayat et al., 2010). In a biomechanical study, the POLYAX supported smaller loads compared with the LISS and NCB while under axial loading (Otto et al., 2009). In addition, the mode of failure of the NCB plate, creating an intra-articular fracture propagating from the distal posterior screw hole, may be of some concern (Otto et al., 2009).

## **4. Preoperative planning**

326 Recent Advances in Hip and Knee Arthroplasty

a) b)

concern (Otto et al., 2009).

Fig. 3. a left – Longitudinal section through the screw hole of a conventional plate screw. The inclination of the screw is not locked. The screw is tightened with an axial traction of 2000 to 3000 N, the plate is compressed onto the bone producing friction which resists a tangential load of 1000 N (friction = 0.4 x 2500 = 1000 N). Fig. 3. b right – Longirudinal section through the locked screw of an internal fixator. Because of the steep conical surfaces ("Morse cone") the screw locks upon application of minimal torque. Therefore absence of compression between the plate and bone allows either point contact or no contact thus enabling reduction of the contact damage to the blood supply. This type of forece transmission does not depend on axial preloading of the screw (from Perren, 2002). Polyaxial locking plates (POLYAX Locked Plating Systemt, DePuy, Warsaw, IN, USA), which allow screw angulation within a maximum 40-degree cone, are now available (Haydukewych et al., 2007).  Polyaxial locking plates offer more fixation versatility without an apparent increase in mechanical complications related to loss of reduction (Haydukewych et al., 2007). The non-contact bridging plate for distal femurs (NCB DF, Zimmer, Warsaw, IN, USA) combines conventional plating techniques with polyaxial screw placement and angular stability (Ehrhardt et al., 2008). Results of this combination technique show promise with regard to union and malunion rates in periprosthetic fractures in elderly and osteoporotic patients (Ehrhardt et al., 2008; El-Zayat et al., 2010). In a biomechanical study, the POLYAX supported smaller loads compared with the LISS and NCB while under axial loading (Otto et al., 2009). In addition, the mode of failure of the NCB plate, creating an intra-articular fracture propagating from the distal posterior screw hole, may be of some Indirect reduction and closed fixation techniques are technically much more demanding than an open procedure; thus, accurate preoperative planning is needed to choose the appropriate implant size and length, shape of the plate and the number, position and order of insertion of the screws (Mast et al., 1989). The common issues related to the use of locked supracondylar plates for extraarticular distal femoral fractures are appropriate plate length, malalignment, and interference with total knee arthroplasty pegs (Horwitz & Kubiak, 2010). Plate length is important in patients with osteoporosis, both for fixation of the condylar fragment and to avoid creation of stress risers in the femoral shaft (Horwitz & Kubiak, 2010). Use of a long plate, while leaving some screw holes without screws, provides better fixation with less chance of failure at the proximal part of the diaphysis due to either pullout of the screws or a fracture at the tip of the plate (Sanders et al., 2002). The newer techniques

Fig. 4. The importance of plate-span ratio and plate-screw density in the bridge-plating technique. The schematic drawing shows a mechanically sound fixation of a comminuted diaphyseal fracture of the lower leg. The plate-span ratio is approximately 3, indicating that the plate is three times longer than the overall fracture area. The overall plate-screw density of the construct in this example is 0.43 & screws for a 14-hole plate (from Gautier and Sommer, 2003).

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

in three in combination with bone cement.

**6. Minimally invasive technique with the LISS**

facilitating the exact positioning of the fixator.

**6.1 Postoperative considerations**

**5.1.1 Postoperative considerations**

motion is initiated.

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 329

prosthetic joint line and, if possible, anterior to the anchorage pegs of the prosthesis (Mast et al., 1989). Indirect reduction is obtained through manual traction or a compressiondistraction device to obtain the appropriate axis, rotation and length of the femur. The plate is then attached to the proximal shaft with a Verbrugge clamp and fixed with screws. At least four divergent plate screws are used for proximal plate fixation. In three patients with severely osteoporotic bone, fractures were stabilised in combination with bone cement to enhance screw fixation. The screws are fully inserted into the cement while it is still soft after the plate is provisionally fixed to the femur, and the screws are tightened after the cement has set. Only one knee had a plate-bone interface failure after 4 weeks. Bone graft was required in only four patients with severely osteoporotic bone with comminution and

Postoperatively, patients are allowed toe-touch weight bearing for 6-8 weeks, except for one patient who has an associated tibial fracture. Two patients are mobilised with a glider cane. After removal of the suction drains on the second postoperative day, continuous passive

The standard anterolateral approach to the distal femur is performed on a radiolucent table with the patient in a supine position (Kolb et al., 2010). Hyperextension of the distal femoral fragment is corrected with the knee flexed over a supracondylar towel bump. Closed indirect reduction through manual traction with control of the axis, rotation and length, and temporary retention of the articular block on the shaft are attained. A 4 cm to 5 cm lateral incision is made over the distal femur. After sharp dissection through the skin and subcutaneous tissue, the iliotibial band is divided in line with its fibres. Atraumatic entry into the area between the vastus lateralis and the lateral femoral condyle (without visualising the metaphyseal part of the fracture) is performed. The perforating vessels are kept intact. The plate is placed slightly more distally than the recommended 1.0-1.5 cm, often directly adjacent to the femoral component to achieve maximal screw purchase (Kregor et al., 2001). The plate is used as an internal fixator and not as a reduction aid. The LISS was temporarily fixated using the aiming device with two 2.0 mm Kirschner wires (Fig. 5). At least four self-drilling monocortical locked screws are used for the articular block, and at least four self-tapping bicortical locked screws are used for the shaft. When interference occurs with an intercondylar box of the femoral component (in four patients), we use shorter self-tapping or periprosthetic screws. In two patients with interference from total hip replacements, periprosthetic locked screws were used in the proximal femoral fragment when the LISS overlapped a hip prosthesis. After a proximal screw pull-out due to malpositioning of the fixator, we obtain a true lateral view of the proximal shaft to ensure that the plate is centred on the bone in the lateral view before inserting the proximal screws, and we perform a mini-open approach over the proximal three holes of the fixator,

We require no intraoperative blood transfusion and no bone graft or soft tissue procedure.

Active physiotherapy and continuous passive motion are initiated on day 2 after removal of the drains. Patients are allowed to partially bear weight (up to 20 kg) for 6 to 8 weeks.

of indirect reduction and subcutaneous or submuscular implant insertion allow for increasing the plate length without additional soft tissue dissection (Gautier & Sommer, 2003). The plate length can be chosen according to the pure mechanical demands of the specific fracture that requires stabilisation (Gautier & Sommer, 2003). The working length has been shown to be the most important factor affecting axial stiffness and torsional rigidity (Stoffel et al., 2003). Increasing the working and plate lengths reduces considerably the von Mises stress in the LISS plate (Duda et al., 2002). In osteoporotic femurs, the use of self-tapping bicortical locking head screws with at least four or five screws in each fragment is recommended (Frigg & Wagner, 2006; Kregor et al., 2001).

As has been shown in total hip replacement, the LISS can be combined with periprosthetic screws, a locking attachment plate, or a cable system. The omission of one screw hole near the fracture site has been shown to significantly decrease, axial stiffness and torsional rigidity (by 64% and 36%, respectively (Stoffel et al., 2003).The number of screws has greater influence over shorter versus longer working lengths (Stoffel et al., 2003). Further more, more than three screws on either side of the fracture did little to increase axial stiffness; likewise, four screws did not increase torsional rigidity (Stoffel et al., 2003). In a biomechanical study locked and hybrid (combining of locked and unlocked) constructs demonstrated similar behaviour in osteoporotic bone; no differences between the locked and hybrid specimens were found at any cyclic interval (Gardner et al., 2006).

The plate-span ratio and the plate-screw density determine the ideal lengthof the internal fixator (Gautier & Sommer, 2003; Rozbruchet al., 1998). The plate-span ratio is the quotient of plate-length and fracture-length, while the plate-screw density is the quotient of the number of screws inserted into the plate and the number of plate holes (Rozbruch et al., 1998).The plate-span ratio should be higher than 2-3 in comminuted fractures and higher than 8-10 in simple fractures (Gautier & Sommer, 2003). The plate-screw densitiy should be below 0.5-0.4 (Fig. 4, Gautier & Sommer, 2003).

## **5. Surgical technique**

The length of the 95° condylar blade plate and the LISS, positioning, and length of the screws are selected using the Association for Osteosynthesis/ASIF templates (Synthes Corporation). Leg length and axial alignment of the contralateral extremity are determined as described by (Kolb et al., 2009). Surgical procedures involved the tool preOp plan, developed by Siemens, to support osteosynthesis planning with regard to the 95° condylar blade plate and the LISS (Less Invasive Stabilisation System) (Synthes, West Chester, Pennsylvania) (Koudela et al., 2010).

#### **5.1 Indirect reduction technique with the condylar blade plate**

The indirect reduction technique is performed with the 95° condylar blade plate (Kolb et al., 2009; Müller et al., 1979; Ostrum & Geel, 1995). The surgical technique includes a standard lateral approach to the distal femur with the patient in a supine position. Hyperextension of the distal femoral fragment is corrected with the knee flexed to 60° over a supracondylar towel bump. After opening the fascia lata, the vastus lateralis muscle is elevated from the linea aspera, and the perforating vessels are preserved when possible. The lateral and anterior aspects of the femur are exposed. The posterior and medial soft tissues are not violated. The blade of the 95° condylar blade plate is inserted along the track previously made by the seating chisel parallel to a k-wire that marks the joint line. The window of the seating chisel is in the middle third of the anterior half of the distal femur, 2.5 cm above the prosthetic joint line and, if possible, anterior to the anchorage pegs of the prosthesis (Mast et al., 1989). Indirect reduction is obtained through manual traction or a compressiondistraction device to obtain the appropriate axis, rotation and length of the femur. The plate is then attached to the proximal shaft with a Verbrugge clamp and fixed with screws. At least four divergent plate screws are used for proximal plate fixation. In three patients with severely osteoporotic bone, fractures were stabilised in combination with bone cement to enhance screw fixation. The screws are fully inserted into the cement while it is still soft after the plate is provisionally fixed to the femur, and the screws are tightened after the cement has set. Only one knee had a plate-bone interface failure after 4 weeks. Bone graft was required in only four patients with severely osteoporotic bone with comminution and in three in combination with bone cement.

## **5.1.1 Postoperative considerations**

328 Recent Advances in Hip and Knee Arthroplasty

of indirect reduction and subcutaneous or submuscular implant insertion allow for increasing the plate length without additional soft tissue dissection (Gautier & Sommer, 2003). The plate length can be chosen according to the pure mechanical demands of the specific fracture that requires stabilisation (Gautier & Sommer, 2003). The working length has been shown to be the most important factor affecting axial stiffness and torsional rigidity (Stoffel et al., 2003). Increasing the working and plate lengths reduces considerably the von Mises stress in the LISS plate (Duda et al., 2002). In osteoporotic femurs, the use of self-tapping bicortical locking head screws with at least four or five screws in each fragment

As has been shown in total hip replacement, the LISS can be combined with periprosthetic screws, a locking attachment plate, or a cable system. The omission of one screw hole near the fracture site has been shown to significantly decrease, axial stiffness and torsional rigidity (by 64% and 36%, respectively (Stoffel et al., 2003).The number of screws has greater influence over shorter versus longer working lengths (Stoffel et al., 2003). Further more, more than three screws on either side of the fracture did little to increase axial stiffness; likewise, four screws did not increase torsional rigidity (Stoffel et al., 2003). In a biomechanical study locked and hybrid (combining of locked and unlocked) constructs demonstrated similar behaviour in osteoporotic bone; no differences between the locked

The plate-span ratio and the plate-screw density determine the ideal lengthof the internal fixator (Gautier & Sommer, 2003; Rozbruchet al., 1998). The plate-span ratio is the quotient of plate-length and fracture-length, while the plate-screw density is the quotient of the number of screws inserted into the plate and the number of plate holes (Rozbruch et al., 1998).The plate-span ratio should be higher than 2-3 in comminuted fractures and higher than 8-10 in simple fractures (Gautier & Sommer, 2003). The plate-screw densitiy should be

The length of the 95° condylar blade plate and the LISS, positioning, and length of the screws are selected using the Association for Osteosynthesis/ASIF templates (Synthes Corporation). Leg length and axial alignment of the contralateral extremity are determined as described by (Kolb et al., 2009). Surgical procedures involved the tool preOp plan, developed by Siemens, to support osteosynthesis planning with regard to the 95° condylar blade plate and the LISS (Less Invasive Stabilisation System) (Synthes, West Chester,

The indirect reduction technique is performed with the 95° condylar blade plate (Kolb et al., 2009; Müller et al., 1979; Ostrum & Geel, 1995). The surgical technique includes a standard lateral approach to the distal femur with the patient in a supine position. Hyperextension of the distal femoral fragment is corrected with the knee flexed to 60° over a supracondylar towel bump. After opening the fascia lata, the vastus lateralis muscle is elevated from the linea aspera, and the perforating vessels are preserved when possible. The lateral and anterior aspects of the femur are exposed. The posterior and medial soft tissues are not violated. The blade of the 95° condylar blade plate is inserted along the track previously made by the seating chisel parallel to a k-wire that marks the joint line. The window of the seating chisel is in the middle third of the anterior half of the distal femur, 2.5 cm above the

and hybrid specimens were found at any cyclic interval (Gardner et al., 2006).

is recommended (Frigg & Wagner, 2006; Kregor et al., 2001).

below 0.5-0.4 (Fig. 4, Gautier & Sommer, 2003).

**5. Surgical technique**

Pennsylvania) (Koudela et al., 2010).

**5.1 Indirect reduction technique with the condylar blade plate**

Postoperatively, patients are allowed toe-touch weight bearing for 6-8 weeks, except for one patient who has an associated tibial fracture. Two patients are mobilised with a glider cane. After removal of the suction drains on the second postoperative day, continuous passive motion is initiated.

## **6. Minimally invasive technique with the LISS**

The standard anterolateral approach to the distal femur is performed on a radiolucent table with the patient in a supine position (Kolb et al., 2010). Hyperextension of the distal femoral fragment is corrected with the knee flexed over a supracondylar towel bump. Closed indirect reduction through manual traction with control of the axis, rotation and length, and temporary retention of the articular block on the shaft are attained. A 4 cm to 5 cm lateral incision is made over the distal femur. After sharp dissection through the skin and subcutaneous tissue, the iliotibial band is divided in line with its fibres. Atraumatic entry into the area between the vastus lateralis and the lateral femoral condyle (without visualising the metaphyseal part of the fracture) is performed. The perforating vessels are kept intact. The plate is placed slightly more distally than the recommended 1.0-1.5 cm, often directly adjacent to the femoral component to achieve maximal screw purchase (Kregor et al., 2001). The plate is used as an internal fixator and not as a reduction aid. The LISS was temporarily fixated using the aiming device with two 2.0 mm Kirschner wires (Fig. 5). At least four self-drilling monocortical locked screws are used for the articular block, and at least four self-tapping bicortical locked screws are used for the shaft. When interference occurs with an intercondylar box of the femoral component (in four patients), we use shorter self-tapping or periprosthetic screws. In two patients with interference from total hip replacements, periprosthetic locked screws were used in the proximal femoral fragment when the LISS overlapped a hip prosthesis. After a proximal screw pull-out due to malpositioning of the fixator, we obtain a true lateral view of the proximal shaft to ensure that the plate is centred on the bone in the lateral view before inserting the proximal screws, and we perform a mini-open approach over the proximal three holes of the fixator, facilitating the exact positioning of the fixator.

We require no intraoperative blood transfusion and no bone graft or soft tissue procedure.

#### **6.1 Postoperative considerations**

Active physiotherapy and continuous passive motion are initiated on day 2 after removal of the drains. Patients are allowed to partially bear weight (up to 20 kg) for 6 to 8 weeks.

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

supracondylar rod

CPO (CP 9 60%, CBP 3 20% (2 with double plating)

rod 4 (36%) CPO 2 (18%) Retrograde nail 1 (9%)

DFN (44%), GSH nail 1 (6%), LISS 9

18 LISS 18 6.2 (3-19)

Peri-Loc Distal Lateral Femur locking plate, Locking Condylar Plate, LISS

LCP 24 (100%) 12 (8-20),

Kolb et al., 2009 21/15 (71%) CP 14 (12-16) 9 (712) 77 KSS score

LISS 23 (1005) 14 (9-21)

Table 5. Results of surgically treated periprosthetic femur fractures above total knee

7/7 (100%) Intramedullary

7 (100%)

6/5 (83%) CPO (Fork Plate) 6 (100%)

11 LISS 5 (45%) Rush

(50%)

Zehntner et al., 1993

McLaren et al., 1994

Moran et al.,

Ochsner et al., 1999

Wick et al., 2001)

Kregor et al.,

Althausen et al., 2003

Wick et al., 2004

Gliatis et al.,

Ricci et al., 2006

O'Toole et al.,

Fulkerson et al., 2007

Streubel et al., 2010

Kolb et al., 2010

arthroplasties

2005

2006

15/15 (100%)

18/18 (100%)

10/10 (100%)

24/22 (92%)

14/11 (79%)

89/61 (69%) Group A (n=28), Group B (n=33)

23/19 (83%)

1996

2001

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 331

7/6 (86%) CPO (CPB 6, 86%) 14 (12-16) 1.4 50 Cain rating

6/6 (100%) GSH nail 8 (100%) 12.4 1.4 69 Freeman

13 LISS 13/13 (100%) ND ND ND

12 (4-16), nonunion 3 (20%)

12 1.3 ND

9 ND ND

ND ND ND

GSH 10 (100%) 12 2.9 59 WOMAC

LISS 14 (100%) ND 1.0 71 own score

Non-union 3 (13%)

months Delayed union 2 (11%) Nonunion 3 (17%)

Delayed union 5 (18%), non-union 3 (11%) group A, delayed union 2 (6%), non-union 5 (15%) group B

Delayed union 2 (11%) 2.5 ND

1.0 ND

2.3 ND

Minimum follow-up 0.5

3.8 (2.2-5.6) system

score

score

ND

81 KSS score

2.5 KSS score

Fig. 5. Temporary fixation of the LISS with the aiming device with two 2.0 mm Kirschner wires.

## **7. Results and conclusions**

The incidence of periprosthetic fractures is increasing as ageing populations throughout the world live longer (Kolb et al., 2010). Despite the increased risk of many of our patients all knees treated with the angled 95° condylar blade plate in indirect reduction technique healed without complications (Kolb et al., 2009). The angled 95° condylar plate in indirect reduction technique is still a good implant with good long-term results (Kolb et al., 2009). It works best in proximal fractures when there is minimal comminution of the distal fragment in the hands of a surgeon experienced with this device (Kolb et al., 2009). A minimally invasive, locked plating system permits stable fixation, early knee motion with good shortto mid-term results, and minimal complications (Kolb et al., 2010, Tables 5 and 6).

Fig. 5. Temporary fixation of the LISS with the aiming device with two 2.0 mm Kirschner wires.

The incidence of periprosthetic fractures is increasing as ageing populations throughout the world live longer (Kolb et al., 2010). Despite the increased risk of many of our patients all knees treated with the angled 95° condylar blade plate in indirect reduction technique healed without complications (Kolb et al., 2009). The angled 95° condylar plate in indirect reduction technique is still a good implant with good long-term results (Kolb et al., 2009). It works best in proximal fractures when there is minimal comminution of the distal fragment in the hands of a surgeon experienced with this device (Kolb et al., 2009). A minimally invasive, locked plating system permits stable fixation, early knee motion with good short-

> Fracture Healing (weeks)

3/3 (100%) CPO (CP) 16 (12-20) 1.1 86 HSS knee

Non-union 2 (50%)

Non-union 1

32 (16-64) Non-union 5 (23%)

(3%)

Mean Followup (years)

ND 3.0 76.3 KSS score

16 (6-40) 2.2 84 KSS score

3.7 ND

Good/Excellent Results (%) Scoring System

score

2.5 25 Own rating system

ND 64 University

knee score

to mid-term results, and minimal complications (Kolb et al., 2010, Tables 5 and 6).

Internal Fixation CPO/MIPO Nailing

Screws 1 (20%)

CPO (67%) Rush pins 2 (7%)

5 (23%), Dual plating 2 (9%), CPB 2 (9%), Barr bolt and AO screws 1 (4%)

35%, CBP 6, 30%)

**7.  Results of surgically treated periprosthetic femur fractures above total knee arthroplasties

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

Retrograde Nail varus 3° 1 (100%), Shortening >2 cm 1 (25%), CPO varus 4° 1

(50%)

Valgus 18° retrograde

Valgus 35° 1 (11%)

Varus 6° 1 (4%), Valgus 7°/9°/13° 1/1/1 (4%)

<5°

Varus/Valgus angulation

Varus 5° 1 (5%) 4/1

(19%)/(5%)

2 (7%) Group A, 4 (12%) Group B

1 (4%) Group A, 1 (3%) Group

Varus 7 1 (5%) 0 0 1 (5%) 1 Revision

B

Table 6. Complications of surgically treated periprosthetic femur fractures above total knee

Kregor et al.,

Wick et al., 2004

Gliatis et al.,

Ricci et al., 2006

O'Toole et al., 2006

Fulkerson et al., 2007

Kolb et al., 2009

Streubel et al., 2010

Kolb et al., 2010

arthroplasties

2001

2005

The Indirect Reduction Technique with the Condylar Blade Plate and the Minimally Invasive … 333

0 0/1 (8%) 0 0 1 Revision

0 0 0 ND

0 1 (6%) 1 (6%)

0 2 (8%) 4 (17%)

0 0 0 0 0

osteosynthesis

1 Revision osteosynthesis 1 Hematoma

1 Above knee amputation 1 Debridement

DCS and Dall-Miles cables, 2 Revision TKA, 1 Excision plasty

osteosynthesis with bone graft and bone cement, 2 Hematomas

6 Revision osteosynthesis

osteosynthesis

0 8 Debridments,

retrograde nail

proximal screw failure

0 1 (5%) 1 Revision

0/1 (6%) 1 (6%) 1 (6%) 1 Revision to

Infection (n, %)

0 0 0 0

0 0 0 0

2 (30%) 0 0 0

0 0 0 0 1 Stress fracture

Varus 1 (17%) 0 0 0 1 Valgus

0 0 0 0

0 0 0 ND

3 (10%) 0 2 (7%) 0 2 Above knee

Implant Failure

0 Intraoperative 1 Death

4 (18%) 0 5 (23%) 4 Revision

0 0 3 Revision

0 3 (20%) 3 Revision

Scondary Surgical Procedure

1 Above knee amputation

amputations

osteosynthesis with bone grafting, 1 Revision TKA,

osteosynthesis

at the proximal locking screw

osteosynthesis, 2 with bone graft

osteotomy

Malalignment Bone graft (n,

0 2 (40%), 1

(20%)

(75%)/(15%)

(40%)/(13%)

6/2

Valgus 3/5° ½ (33/66%)

Valgus 10° 2 (25%)

Varus 7° 5 (23%)

0 15/3

Valgus 5° (0-

Shortening 2 cm 3 (20%), Valgus 17° 1 (7%), Varus 2°

Valgus 10° 1 (17%), Shortening 1 (17%)

Rush rod valgus 13° 2 (50%), 10° 1 (25%),

1 (7%)

10°)

% early/late)

Authors Year

Sisto et al., 1985

Merkel et al., 1986

Cain et al., 1986

Culp et al., 1987

Figgie et al.,

Healy et al., 1993

Zehntner et al., 1993

McLaren et al., 1994

Moran et al.,

Ochsner et al., 1999

Wick et al., 2001

Althausen et al., 2003

1996

1990

Table 6. Complications of surgically treated periprosthetic femur fractures above total knee arthroplasties

Fixation of Periprosthetic Supracondylar Femur Fractures Above Total Knee Arthroplasty –

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