before the 1970s , the majority of high - grade musculoskeletal tumors involving the distal femur were treated with transfemoral amputation owing to an unacceptably high rate of recurrence associated with local resection [ 10 , 19 , 31 , 47 ] .
as effective chemotherapeutic regimens were developed , limb salvage using various techniques gained popularity among orthopaedic oncologists [ 1 , 11 , 19 , 20 , 24 , 37 , 45 , 49 , 60 , 69 ] . today , with effective neoadjuvant chemotherapy , limb salvage is indicated in as much as 90% of patients with musculoskeletal malignancies involving the distal femur [ 6 , 7 , 14 , 44 , 5355 , 57 ] .
numerous studies document relatively high implant survival after limb salvage for tumors involving the distal femur [ 3 , 4 , 8 , 26 , 27 , 29 , 35 , 43 , 44 , 50 , 54 , 55 , 57 , 61 , 71 ] .
studies that are available , however , do not stratify patients on the basis of tumor grade , stage of disease , or life expectancy to define the disease - specific survival of implants .
this makes it difficult for surgeons to accurately predict how long the implants will last for a given patient population and life expectancy . additionally , there are limited data available with which to compare implant survival of contemporary modular implant designs with older custom - designed implants no longer in use [ 8 , 44 , 48 , 70 ] .
critics of a cemented endoprosthetic reconstruction technique cite rates of aseptic loosening from 8.4% to greater than 30% [ 2 , 30 , 38 , 63 ] as the main rationale for abandoning its use in favor of newer designs . given the paucity of long - term data concerning cemented distal femoral implants and the heightened interest in alternate fixation designs , we sought to answer the following four questions : ( 1 ) do newer cemented modular implant designs have improved survivorship compared with older custom - designed components ? ( 2 ) does tumor grade or stage influence implant survival ?
( 3 ) what is the typical long - term functional result after a cemented distal femoral replacement ?
we retrospectively reviewed the electronic and paper charts of all 254 patients who underwent cemented distal femoral endoprosthetic reconstructions for musculoskeletal tumors between december 1980 and december 2008 .
we excluded 68 patients : 39 patients had distal femoral reconstructions or a diagnosis other than musculoskeletal tumor ; 27 with a tumor - related diagnosis were skeletally immature and underwent distal femoral reconstruction with the intent to perform multiple expansion procedures at a later date , possibly including complete prosthesis exchange ; two patients underwent reconstruction with a cementless implant .
we previously reported our results of expandable and cementless implants for tumors of the distal femur [ 16 , 17 , 36 , 64 ] and did not include them in the current analysis .
these exclusions left 186 patients : 98 ( 53% ) males and 88 ( 47% ) females .
their mean age at the time of surgery was 29.0  years ( range , 1279  years ) .
we further divided the 186 patients into three subgroups based on disease grade or stage : group 1 ( n  =  43 ) were patients with low - grade malignancy ( stage ia or ib ) , parosteal osteosarcoma , or benign diagnoses ; group 2 ( n  =  122 ) was comprised of patients with high - grade localized disease ( stage iia or iib ) ; and group 3 ( n  =  21 ) included patients with stage iii primary malignancy of the distal femur , along with patients with metastatic carcinoma to the distal femur , and the single cases of myeloma and lymphoma ( table  1 ) .
the latter group was treated as a single cohort owing to similarity in life expectancy among patients with these four diagnoses . at the most recent followup ,
the minimum followup was 1  month ( mean , 96  months ; range , 1336  months ; median , 54.5  months ) for all patients and 1  month ( mean , 130.4  months ; range , 1336  months ) for the 121 surviving patients .
eight patients were lost to followup but were well at the time of the last evaluation ( range , 313  months ) .
we obtained prior approval from our institution s office for protection of research subjects ( ucla irb # g08 - 10 - 100 - 01).table  1diagnosesdiagnosisnumber of patientsgroup 1 ( low grade )  giant cell tumor18 ( 9.7% )  parosteal osteosarcoma14 ( 7.5% )  chondrosarcoma ( low grade)7 ( 3.8% )  desmoid of bone3 ( 1.6% )  chondroblastoma1 ( 0.5% )  total group 143 ( 23.1%)group 2 ( high - grade localized )  osteosarcoma ( classic high grade)102 ( 54.8% )  chondrosarcoma ( high grade)7 ( 3.8% )  malignant fibrous histiocytoma5 ( 2.7% )  ewing s sarcoma2 ( 1.1% )  synovial sarcoma2 ( 1.1% )  malignant giant cell tumor1 ( 0.5% )  leiomyosarcoma1 ( 0.5% )  fibrosarcoma1 ( 0.5% )  alveolar soft parts sarcoma1 ( 0.5% )  total group 2122 ( 65.6%)group 3 ( stage iii / disseminated )  osteosarcoma ( stage iii)11 ( 5.9% )  metastatic disease4 ( 2.2% ) 
malignant fibrous histiocytoma2 ( 1.1% )  fibrosarcoma2 ( 1.1% )  myeloma1 ( 0.5% )  lymphoma1 ( 0.5% )  total group 321 ( 11.3%)total all groups186 ( 100.0% ) from the charts , we recorded the index diagnosis and disease stage at the time of presentation ( according to the system described by enneking et al . [ 22 , 25 ] ) , length of followup , postoperative function scores , implant type and manufacturer , and any major postoperative events ( systemic or local complications , repeat surgery for any reason , revision of stemmed components , and/or local recurrence ) .
all endoprosthetic reconstructions were performed by the same surgeon ( jje ) , and all tumor resections followed generally accepted oncologic principles [ 7 , 12 , 14 , 15 ] . a longitudinal medial incision extended from the tibial tubercle proximally following the course of the sartorius muscle , and the neurovascular bundle
all previous open biopsy sites were left in continuity with the resected mass ; needle biopsy sites were ignored .
the femoral and tibial osteotomies were made with the intention that postreconstruction leg lengths would be equal .
a rotating - hinge knee mechanism was used in all cases that incorporated an 8-mm all - polyethylene nonmetal - backed tibial component .
the distance between the distal end of the metal femoral component and the undersurface of the all - polyethylene tibial component when assembled was 17  mm . to ensure leg length equality ,
the femoral osteotomy was made 1  cm longer than the femoral component length , and 7  mm of proximal tibia was resected .
the location of the patella relative to the joint line was never a conscious consideration .
the level of resection was marked on the femur proximally with an osteotome , followed by a slightly more proximal mark on the femur and a mark on the proximal tibia ( distal to the level of resection ) .
a final mark was placed at the most anterior aspect of the femur to ensure proper femoral component rotation as the location of the linea aspera was not always exactly posterior .
after the femoral osteotomy , the proximal marrow was sent for frozen - section analysis to confirm a negative marrow margin .
a trial tibial component was placed , and in all cases , an intraoperative radiograph was obtained to ensure placement perpendicular to the mechanical axis of the tibia . the trial hinge mechanism was reduced , and restoration of the preresection extremity length and rotation were verified using marks previously made on the proximal tibia and femur .
the neurovascular bundle was palpated to ensure there was not excessive tension on the vessels , and a doppler probe at the ankle confirmed the presence of the posterior tibial and dorsalis pedis pulses .
the all - polyethylene tibial and patellar components were cemented first , followed by the femoral component separately .
all patients were administered 100  mg solu - cortef ( pfizer inc , new york , ny ) before placement of the femoral component , and the prosthesis was introduced slowly to avoid causing a fat embolism .
implants were manufactured by one of three companies : stryker / howmedica ( mahwah , nj ) , techmedica ( camarillo , ca ) , and dow - corning wright corp ( arlington , tn ) .
the 156 implants ( 83.9% ) manufactured by stryker / howmedica used the kinematic rotating - hinge mechanism .
the 28 implants ( 15.1% ) manufactured by techmedica used the noiles rotating hinge , whereas the two ( 1.1% ) manufactured by dow - corning wright used the lacey rotating - hinge knee ( figs .  1 , 2 ) .
initially , the first 101 ( 54.3% ) prostheses were custom designed by two of the senior authors ( jmk , jje ) as a one - piece femoral component .
seventy - three of 101 custom implants were co - cr - mo alloy components manufactured by howmedica .
the bodies were casted using the lost - wax method , and the casted stems , based on the zickel nail design , were welded to the body .
all patellae were resurfaced using a nonmetal - backed all - polyethylene single central - pegged component.fig . 
c(a ) a custom endoprosthesis featuring a body casted by the lost - wax method and used from 1980 to 1985 is shown .
the stem , based on the zickel nail design , was welded to the body .
( b ) an extramedullary porous coating was added to the prosthesis used from 1985 to 1990 , which acts as a scaffolding for soft tissue ingrowth .
( c ) a contemporary modular endoprosthesis used since 1990 features titanium segments and co - cr - mo alloy morse tapers that prevent cold welding.fig . 
2the lacey , kinematic , and noiles rotating - hinge mechanisms used in this series are shown .
( a ) a custom endoprosthesis featuring a body casted by the lost - wax method and used from 1980 to 1985 is shown .
the stem , based on the zickel nail design , was welded to the body .
( b ) an extramedullary porous coating was added to the prosthesis used from 1985 to 1990 , which acts as a scaffolding for soft tissue ingrowth .
( c ) a contemporary modular endoprosthesis used since 1990 features titanium segments and co - cr - mo alloy morse tapers that prevent cold welding .
the lacey , kinematic , and noiles rotating - hinge mechanisms used in this series are shown . before the introduction of the continuous passive motion ( cpm ) machine , patients initially were immobilized in a cast for 2 to 3  weeks before physical therapy . since the introduction of the cpm machine in the early 1980s , all patients were placed into a cpm machine in the operating room .
motion was commenced from 5 extension to 30 to 45 flexion and gradually increased to greater than 90 flexion before discharge .
a towel roll under the heel was used three times daily for 1 hour to ensure full extension was achieved . on the third postoperative day , patients were made weightbearing as tolerated with ambulatory supports and a knee immobilizer , which were used for 6 to 8  weeks .
the cpm machine was used at home for 12 hours a day for 1  month to help ensure maximum flexion was achieved .
patients were followed every 2 to 3  weeks for the first 2  months after surgery , then on a quarterly basis for 2  years , semiannually for an additional 2  years , and annually thereafter .
radiographs of the affected limb were obtained at each postoperative visit , along with quarterly chest radiographs and semiannual chest ct .
postoperative function was evaluated for each patient using the musculoskeletal tumor society ( msts ) function score .
one hundred sixty of the 186 patients ( 86.0% ) were available for functional evaluation and did not undergo amputation during the followup period . patient and
prosthesis survival rates and 95% confidence intervals ( cis ) were determined for all three groups using the kaplan - meier product - limit method .
prosthesis survivorship was determined for custom and modular implants separately using revision of the stemmed components for any reason as an end point . for purposes of implant survival
, we did not include surgery attributable to failure of the bushings , the axle , or the metal tibial bearing component , all of which were managed successfully without the need for revision of major stemmed components .
implant and patient survival curves for the two types of implants and three grades or stages of malignancy were compared using the log - rank method .
statistical analysis was performed using a commercially available statistics package ( r , version 2.9.0 , the r foundation for statistical computing , vienna , austria ) .
modular implants had greater survivorship ( p  =  0.011 ) than those of a custom design , with a 15-year survivorship rate of 93.7% versus 51.7% ( fig . 
35 stemmed components ( 18.8% ) were revised : 32 revisions were performed owing to mechanical failure , whereas an additional three revisions were necessary owing to nonmechanical complications .
thirty - one custom - casted stems were revised ; 19 were revised for aseptic loosening of the femoral stem , nine for fatigue fracture , two for infection , and one for local recurrence .
only four of 85 forged modular components were revised : three for aseptic loosening and one for a fatigue fracture of a casted ( not forged ) morse taper component .
failure of the rotating - hinge mechanism necessitated replacement of the bushings and/or axle without revision of the stemmed components in 22 patients ( 11.8% ) at a mean of 159.7  months ( range , 1.6291.1  months ) from the index procedure ; six of these patients ( 3.2% ) ultimately required a second bushing change . using revision of the stemmed components for any reason as an end point ,
overall prosthesis survival rates at 10 , 20 , and 25  years were 77.2% , 57.9% , and 50.2% , respectively ( fig . 
3a  b kaplan - meier survivorship analyses show ( a ) custom ( n  =  101 ) versus ( b ) modular ( n  =  85 ) implant survival .
4the kaplan - meier survivorship analysis shows overall prosthesis survival ( n  =  186 ) .
the dashed lines represent the 95% ci.table  2implant survival , patient survival , and overall limb salvage datasurvival5  years10  years15  years20  years25  years%95% ci%95% ci%95% ci%95% ci%95% cilowerupperlowerupperlowerupperlowerupperlowerupperimplant survival  low grade ( n  =  43)83.3%71.9%96.5%73.5%58.5%92.3%73.5%58.5%92.3%61.2%40.1%93.6%30.6%7.2%100.0%  stage iia / iib ( n  =  122)89.8%83.5%96.5%78.4%68.2%90.2%55.7%41.6%74.7%50.7%35.8%71.7%45.0%29.7%68.4%  stage iii ( n  =  21)85.7%63.3%100.0%nananana  custom ( n  =  101)83.5%75.2%92.7%69.2%58.1%82.4%51.7%39.1%68.4%48.7%35.9%66.0%42.2%29.4%60.7%  modular ( n  =  85)93.7%87.9%99.9%93.7%87.9%99.9%93.7%87.9%99.9%nana  overall ( n  =  186)87.7%82.2%93.7%77.2%68.7%86.7%61.6%50.1%75.7%57.9%45.6%73.5%50.2%36.8%68.5%patient survival by diagnosis  low grade ( n  =  43)100.0100.0100.0100.0100.0  stage iia / iib ( n  =  122)65.3%56.9%74.9%57.7%48.7%68.4%56.0%46.8%67.0%56.0%46.8%67.0%56.0%46.8%67.0%  stage iii ( n  =  21)25.6%11.6%56.4%nananana  overall limb salvage91.3%86.7%96.3%89.0%83.5%94.8%85.2%77.9%93.1%78.8%68.6%90.6%78.8%68.6%90.6%ci  =  confidence interval ; na  =  not available .  
kaplan - meier survivorship analyses show ( a ) custom ( n  =  101 ) versus ( b ) modular ( n  =  85 ) implant survival .
the kaplan - meier survivorship analysis shows overall prosthesis survival ( n  =  186 ) .
implant survival , patient survival , and overall limb salvage data ci  =  confidence interval ; na  =  not available .
modular implant survival was greater ( p  =  0.001 ) than patient survival for those in disease groups 2 and 3 .
all patients initially diagnosed with low - grade or aggressive benign tumors ( group 1 , n  =  43 ) survived ( fig .  5 ; table  2 ) .
the 10- , 20- , and 25-year disease - specific survival rates for patients diagnosed with high - grade localized disease ( group 2 ) were 57.7% , 56.0% , and 56.0% , respectively ( fig . 
the 5- and 10-year disease - specific survival rates for patients diagnosed with stage iii sarcomas , metastatic disease , lymphoma , and myeloma ( group 3 ) were 25.6% and 0% , respectively ( fig .  7 ; table  2).fig . 
analysis shows survival among patients with low - grade or benign disease ( group 1 ; n  =  43).fig . 
6the kaplan - meier survivorship analysis shows survival among patients with high - grade localized ( stage iia / iib ) disease ( group 2 ; n  =  122 ) .
7the kaplan - meier survivorship analysis shows patient and prosthesis survival among patients with stage iii primary sarcoma , metastatic disease to the distal femur , myeloma , or lymphoma ( group 3 ; n  =  21 ) .
the kaplan - meier survivorship analysis shows survival among patients with low - grade or benign disease ( group 1 ; n  =  43 ) .
the kaplan - meier survivorship analysis shows survival among patients with high - grade localized ( stage iia / iib ) disease ( group 2 ; n  =  122 ) .
the kaplan - meier survivorship analysis shows patient and prosthesis survival among patients with stage iii primary sarcoma , metastatic disease to the distal femur , myeloma , or lymphoma ( group 3 ; n  =  21 ) .
the dashed lines represent the 95% ci . among the 160 patients for whom we had functional evaluations and who retained their implants , the mean postoperative msts score was 86.7% ( mean score , 26.0 ; range , 1129 ) .
the postoperative rom on final assessment revealed mean flexion of 110.0 ( range , 45140 ) , mean passive extension to 1.3 ( range , 040 ) , and mean active extension lag of 6.9 ( range , 0120 ) .
a postoperative flexion contracture was observed in seven patients , with a mean value of 10.0 ( range , 540 ) .
seven systemic complications occurred in seven patients , including four cardiac arrhythmias , and single cases of chemotherapy - related fungal sepsis , acute leukemia , and steroid - induced avascular necrosis of multiple joints .
one hundred four local complications occurred in 88 patients ; a single complication occurred in 72 patients , and 16 patients experienced multiple complications .
complications included mechanical failure in 54 ( 29.0% ; fig .  8) , superficial wound - related issues in 13 ( 7.0% ) , local recurrence in 13 ( 7.0% ) , temporary peroneal nerve palsy in seven ( 3.8% ) , deep infections in six ( 3.2% ) , cement extrusion through a vascular channel in three ( 1.6% ) , flexion contracture in three ( 1.6% ) , patellofemoral subluxation in two ( 1.1% ) , positive oncologic margins in two ( 1.1% ) , and stress fracture in one ( 0.05% ) .
thirty - two were stemmed component revisions and 22 involved replacement of the bushings only , as described previously .
six of 13 patients with local recurrence were treated with an amputation , and seven were palliated .
eight of the 13 patients ( 61.5% ) with local recurrence ultimately died of their disease , and five of the 13 ( 38.5% ) are alive .
of the five patients who currently are alive , four remain disease - free at 50 , 141 , 166 , and 205  months .
one patient currently is alive with metastatic pulmonary disease at 38  months after the index procedure .
eighteen of the 186 patients ( 9.7% ) ultimately required amputation after either the index or later revision procedure and were categorized as having failed limb salvage efforts .
the reason for amputation was infection in nine patients , local recurrence in six , positive surgical margins in two , and metastasis to the pelvis in one.fig . 
8a  d the common modes of mechanical failure seen in this series of cemented rotating - hinge distal femoral endoprostheses from 1980 to 2008 are shown .
( a ) a radiograph shows aseptic loosening of a custom - casted femoral stem 24  years after the index reconstruction .
the absence of extramedullary porous coating on the proximal body is evident . in our series
, there were 22 total instances of aseptic loosening : 19 custom and three modular .
( b ) fatigue fractures of a custom - casted femoral stem ( right ) and femoral body ( left ) are illustrated .
there was only one fatigue fracture of a modular component , which was a casted ( not forged ) morse taper segment . in our series
( c ) an axial photograph shows a fractured hollow , custom - casted femoral body .
( d ) in our series , there were 22 failures of the rotating - hinge bushings , as illustrated in this photograph , 15 custom and seven modular .  
the common modes of mechanical failure seen in this series of cemented rotating - hinge distal femoral endoprostheses from 1980 to 2008 are shown .
( a ) a radiograph shows aseptic loosening of a custom - casted femoral stem 24  years after the index reconstruction .
the absence of extramedullary porous coating on the proximal body is evident . in our series
, there were 22 total instances of aseptic loosening : 19 custom and three modular .
( b ) fatigue fractures of a custom - casted femoral stem ( right ) and femoral body ( left ) are illustrated .
there was only one fatigue fracture of a modular component , which was a casted ( not forged ) morse taper segment . in our series
( c ) an axial photograph shows a fractured hollow , custom - casted femoral body .
( d ) in our series , there were 22 failures of the rotating - hinge bushings , as illustrated in this photograph , 15 custom and seven modular .
historically , a debate existed among orthopaedic oncologists regarding which was the most durable method of reconstruction after distal femoral resection .
although high long - term implant survival and functional scores have been reported with a wide variety of reconstructive methods [ 5 , 7 , 14 , 44 , 5355 , 57 , 65 ] , our experience with osteoarticular allografts between 1975 and 1979 was poor , and in 1980 we abandoned this method of reconstruction in favor of a cemented endoprosthetic technique [ 13 , 14 , 51 ] .
recently , critics of this technique have cited high rates of aseptic loosening as the major reason for using alternative fixation methods [ 2 , 38 ] .
such criticism does not consider the potential improvement in cemented implant survival over historical rates attributable to design modifications .
we asked the following four questions : ( 1 ) do newer implant designs perform better than older custom - designed implants ? ( 2 ) does tumor diagnosis influence implant survival ?
( 3 ) what is the typical long - term functional result after distal femoral replacement ?
( 4 ) what are the complications associated with endoprosthetic reconstruction of the distal femur ? the major limitations of this study are its retrospective design , the lack of a control group , and the lack of a prestudy power analysis .
first , musculoskeletal tumors are rare , and although a prospective design certainly would enhance the validity of our conclusions , it would be exceedingly difficult to amass a large series of patients prospectively .
second , comparison to a control group is virtually impossible because other methods of reconstruction were used only rarely at our institution . in the absence of a prestudy power analysis ,
we have limited our conclusions to address the differences in survival rates and refrained from drawing conclusions when no difference was seen in the data .
the questions addressed at the start of this paper will be addressed in light of these few but important limitations . largely owing to the low incidence of musculoskeletal sarcomas , few studies document the long - term durability of contemporary cemented distal femoral endoprostheses ( table  3 ) .
published implant survival rates vary from 46.3% to 93.0% , potentially a reflection of heterogeneous patient and implant study populations .
when compared with primary total joint implants , the modifications made to cemented endoprosthetic designs have been relatively few .
these modifications include the addition of extramedullary porous coating , the development of modular segments , and the use of forged metals that have the potential to reduce the incidence of fatigue fracture [ 8 , 28 , 45 , 62 ] .
the evolution of the implants used at our institution reflects this general development of endoprosthetic design ( table  4 ) .
the data presented here suggest the use of contemporary modular components improve the durability and longevity of the cemented prosthesis when used in distal femoral applications .
although custom - casted stems can last two to three decades , modular designs maintain the intrinsic benefit of immediate availability and the ability to intraoperatively tailor components based on the resection level .
numerous authors [ 8 , 43 , 48 , 70 ] have similarly reported modular endoprostheses survive longer than historical custom - designed implants
. in our series , the mean time to revision of the four failures among modular implants was 12.5  months ( range , 1.621.4  months ) , indicating these failures were possibly the result of technical error rather than implant design ( fig . 
three of four modular failures were attributable to aseptic loosening , likely the result of poor cement technique as noted previously .
the fourth failure of a modular implant was attributable to fatigue fracture of a casted , not forged , morse taper segment , emphasizing the importance of this particular design feature .
the revision implants for the three cases of aseptic loosening have outlasted the original primary reconstructions .
currently , the mean time from revision surgery for these patients is 138.6  months ( range , 107.4181.2  months ) .
all four patients who underwent revision of a modular implant still maintain successful limb salvage .
although an improvement in survival was seen in this series , we recognize the need for novel implant designs in special circumstances , such as short residual periarticular segments , which we have dealt with by designing a custom implant with cross - stem pin fixation .
a compressive intramedullary device based on wolff s law ( compress ; biomet inc , warsaw , in ) was developed to improve fixation in such situations and to reduce the need for custom - designed cemented implants .
five- to 10-year reports of implant survivorship after the use of this device have been promising [ 2 , 38].table  3review of the available literaturestudyyearnumber of patientsmean followup ( years)implant survivorship / revision ratemean msts scoreamputationinfectionlocal recurrence09  years1014  years1519  years 20  yearsbradish et al .
1993612 - 6042%7e , 19 g , 15f , 20p8.2%8.2%4.9%capannna et al . 1994954.375%20e , 43 g , 12f , 9p7.4%5.0%5.3%rougraff et al .
1994341132.4%76.7%26.0%na11.0%malawer and chou 1995313.580.0%80.0%na12.9%19.4%0.0%choong et al . 1996323.56.7%6e , 14 g , 9f , 3p0.0%3.3%3.1%kawai et al .
2008228968.6%46.3%na9.2%12.7%5.3%current study2010186887.7%77.2%61.6%50.2%86.7%9.7%3.2%7.0%numbers ( as reported ) converted to percentages for ease of comparison ; according to the 1987 scoring system described by enneking et al .
; e  =  excellent , g  =  good , f  =  fair , p  =  poor , according to the 1987 msts scoring system ; all uncemented implants ; neither revision rates reported nor survivorship analysis done ; reported as percentage of good or excellent clinical results ; data for all limb salvage reconstructions reported ; percentage of implants revised reported ; data given for all 73 patients who had limb salvage ( including rotationplasties , allograft and allograft - prosthetic composites , and others ) ; data for implants at all anatomic sites reported ; median ; function for all sites reported at 83.3% with no significant difference between anatomic sites ; functional outcomes only evaluated ; data reported for all 63 implants ; 83 of 144 patients reported who survived greater than 5  years ; only patellofemoral complications reported ; includes 162 fixed - hinge knees and 173 rotating - hinge knees ; survival of rotating - hinge knees only shown ; all prostheses custom - made ; kaplan - meier survivorship of implant ; msts  =  musculoskeletal tumor society ; na  =  not available or not studied.table  4distal femoral implant evolution at university of california los angeles*dateimplant designmanufacturer / featurestumor group ( n  =  186)19801990custom ( jje / jmk)stryker / howmedica73  kinematic rotating hinge  made of vitallium  casted hollow body by lost - wax method  welded zickel nail stem  extramedullary porous coating added in 1985 techmedica28  all - titanium one piece  noiles hingetotal custom implants10119902003modularstryker / howmedica53  kinematic rotating hinge  forged modular replacement system  titanium segments  extramedullary porous coatingdow - corning wright2  modular titanium  lacey hinge20032008modularstryker global modular replacement system30  kinematic rotating hinge  forged modular components  titanium segments  extramedullary porous coating  larger axle and bushings  press - fit stem option ( none in this series )  cobalt - chrome morse tapertotal modular implants85 *  all components in this series were cemented ; all tibial components were nonmetal - backed , all - polyethylene ; all used a rotating - hinge knee mechanism ; all patellar components were all - polyethylene , nonmetal - backed , with a single central peg.fig . 
9a  b ( a ) an ap radiograph of the femur shows aseptic loosening of the femoral stem 12  months after endoprosthetic reconstruction with a contemporary modular implant .
we suspect this occurred owing to last - minute rotational adjustment of the stem as the cement was curing .
( b ) a lateral radiograph shows the femur 12  years after revision to a larger cemented stem and in this case with cross - stem pin fixation , which is our preferred method of reconstruction for the majority of failures attributable to aseptic loosening .
review of the available literature numbers ( as reported ) converted to percentages for ease of comparison ; according to the 1987 scoring system described by enneking et al . ;
e  =  excellent , g  =  good , f  =  fair , p  =  poor , according to the 1987 msts scoring system ; all uncemented implants ; neither revision rates reported nor survivorship analysis done ; reported as percentage of good or excellent clinical results ; data for all limb salvage reconstructions reported ; percentage of implants revised reported ; data given for all 73 patients who had limb salvage ( including rotationplasties , allograft and allograft - prosthetic composites , and others ) ; data for implants at all anatomic sites reported ; median ; function for all sites reported at 83.3% with no significant difference between anatomic sites ; functional outcomes only evaluated ; data reported for all 63 implants ; 83 of 144 patients reported who survived greater than 5  years ; only patellofemoral complications reported ; includes 162 fixed - hinge knees and 173 rotating - hinge knees ; survival of rotating - hinge knees only shown ; all prostheses custom - made ; kaplan - meier survivorship of implant ; msts  =  musculoskeletal tumor society ; na  =  not available or not studied .
distal femoral implant evolution at university of california los angeles * *  all components in this series were cemented ; all tibial components were nonmetal - backed , all - polyethylene ; all used a rotating - hinge knee mechanism ; all patellar components were all - polyethylene , nonmetal - backed , with a single central peg .  
( a ) an ap radiograph of the femur shows aseptic loosening of the femoral stem 12  months after endoprosthetic reconstruction with a contemporary modular implant .
we suspect this occurred owing to last - minute rotational adjustment of the stem as the cement was curing .
( b ) a lateral radiograph shows the femur 12  years after revision to a larger cemented stem and in this case with cross - stem pin fixation , which is our preferred method of reconstruction for the majority of failures attributable to aseptic loosening . by stratifying patients according to disease grade and/or stage
, we found a comparison of implant to patient survival provides a useful measure of disease - specific implant efficacy ( fig . 
patients with low - grade tumors have a normal life expectancy and thus should expect to outlive their prostheses . as a result , this group almost certainly will require at least one revision procedure in their lifetime .
however , none of the patients with disseminated , stage iii disease outlived their prosthesis in this series . for patients with high - grade localized disease ( stage iia / iib ) ,
overall prosthesis survivorship remained greater than patient survival up to a critical time , at which point the rate of prosthetic failure became greater than patient survival .
the rate of modular implant survival , however , continued to exceed patient survival with high - grade localized disease to 15  years .
as long - term survival of patients with high - grade disease approaches 70% to 80% [ 3941 , 46 , 52 , 66 , 67 ] , the improved longevity of modular implants seen in this series supports the notion that a cemented endoprosthesis will continue to provide a durable method of reconstruction.fig . 
modular implants performed better than custom implants , with 15-year survival rates of 93.7% versus 51.7% , respectively .
patients with low - grade or benign disease and long - term survivors with high - grade localized disease should expect to undergo at least one revision procedure in their lifetime .
modular implants performed better than custom implants , with 15-year survival rates of 93.7% versus 51.7% , respectively .
patients with low - grade or benign disease and long - term survivors with high - grade localized disease should expect to undergo at least one revision procedure in their lifetime .
the functional scores were high for the majority of patients who underwent endoprosthetic distal femoral reconstructions ( table  3 ) .
functional scores are assigned subjectively , and although newer scoring systems have attempted to eliminate subjective terminology , a precise and accurate measurement of function remains elusive . despite these limitations , however , our results confirm the findings of previous studies , that favorable long - term function is possible after cemented distal femoral endoprosthetic reconstructions . the most common local complications in our patients included mechanical failure , tumor recurrence , and infection .
all 54 cases of mechanical failure ( including modular and custom implants ) were salvaged with revision to a larger stem , cross - stem fixation , or new components . similar to findings described elsewhere , mechanical failures of this nature did not seem to compromise the overall limb salvage effort [ 59 , 68 ] .
five of 19 patients with wound - related complications that occurred after the index procedure required an amputation , and among an additional six patients who had a deep infection after a second or third procedure , four required an amputation . the total amputation rate in this series for all wound - related complications after either the index or revision procedure was nine of 25 ( 36.0% ) .
we previously reported our preferred method of caring for patients with wound - related issues after endoprosthetic replacement .
local recurrence portended a poor prognosis in this series as 61.5% of patients had died by the time of the most recent followup .
our study reports the improved survival of cemented distal femoral endoprostheses during the past three decades .
contemporary modular forged implants performed better than the custom - designed prostheses of the 1970s and 1980s . although failures may occur , mechanical complications can be revised and potentially outlast the original reconstruction .
we recognize revision procedures will be necessary for patients with long - term life expectancy , and the need for continued improvement in reconstruction techniques and implant design , as high - grade disease - specific survival rates may continue to improve .
 backgroundadvocates of newer implant designs cite high rates of aseptic loosening and failure as reasons to abandon traditional cemented endoprosthetic reconstruction of the distal femur.questions/purposeswe asked whether newer , modular distal femoral components had improved survivorship compared with older , custom - casted designs.patients and methodswe retrospectively reviewed 254 patients who underwent distal femoral endoprosthetic reconstruction . 
 we excluded two patients with cementless implants , 27 with expandable prostheses , and 39 who had a nontumor diagnosis . 
 this left 186 patients : 101 with older custom implants and 85 with contemporary modular implants . 
 the minimum followup was 1  month ( mean , 96.0  months ; range , 1336  months ) . 
 the tumor was classified as stage iia / iib in 122 patients , stage ia / ib or benign in 43 , and stage iii or metastatic in 21.resultskaplan-meier analysis revealed overall 10- , 20- , and 25-year implant survival rates of 77% , 58% , and 50% , respectively , using revision of the stemmed components as an end point . 
 the 85 modular components had a greater 15-year survivorship than the 101 custom - designed implants : 93.7% versus 51.7% , respectively . 
 thirty - five stemmed components ( 18.8% ) were revised for aseptic loosening in 22 patients , implant fatigue fracture in 10 , infection in two , and local recurrence in one.conclusionscemented modular rotating - hinge distal femoral endoprostheses demonstrated improved survivorship compared with custom - casted implants during this three - decade experience . 
 patients with low - grade disease and long - term survivors of high - grade localized disease should expect at least one or more revision procedures in their lifetime.level of evidencelevel iv , therapeutic study . 
 see the guidelines for authors for a complete description of levels of evidence . 
Level of Evidence
Introduction
Patients and Methods
Results
Discussion