The results of Oxford unicompartmental knee arthroplasty in the United States The clinical outcome of minimally invasive Phase 3 Oxford unicompartmental knee arthroplasty: a 15-year follow-up of 1000 UKAs. Mobile vs. fixed bearing unicondylar knee arthroplasty: A randomized study on short term clinical outcomes and knee kinematics. Mobile-bearing lateral unicompartmental knee replacement with the Oxford domed tibial component: an independent series. Ten- to 15-year results of the Oxford Phase III mobile unicompartmental knee arthroplasty Mid‐term results of Oxford phase‐3 medial unicompartmental knee arthroplasty for medial arthritis in Chinese patients Minimally invasive Oxford phase 3 unicompartmental knee replacement: results of 1000 cases. Minimally invasive Oxford medial unicompartmental knee arthroplasty. A note of caution! Flexion and extension laxity after medial, mobile-bearing unicompartmental knee arthroplasty: a comparison between a spacer- and a tension-guided technique
Aims Approved by the Food and Drug Administration in 2004 , the Phase III Oxford Medial Partial Knee is used to treat anteromedial osteoarthritis ( AMOA ) in patients with an intact anterior cruciate ligament . This unicompartmental knee arthroplasty ( UKA ) is relatively new in the United States , and therefore long-term American results are lacking . Patients and Methods This is a single surgeon , retrospective study based on prospect ively collected data , analysing a consecutive series of primary UKAs using the  Phase III mobile-bearing Oxford Knee and Phase III instrumentation . Between July 2004 and December 2006 , the senior author ( RHE ) carried out a  medial UKA in 173 patients ( 213 knees ) for anteromedial osteoarthritis or avascular necrosis ( AVN ) . A total of 95 patients were men and 78 were women . Their mean age at surgery was 67 years ( 38 to 89 ) and mean body mass index 29.87 kg/m2 ( 17 to 62 ) . The mean follow-up was ten years ( 4 to 11 ) . Results Survivorship of the Oxford UKA at ten years was 88 % , using life table analysis . Implant survivorship at ten years was 95 % . The most common cause for revision was the progression of osteoarthritis in the lateral compartment . The mean knee score element of the American Knee Society Score ( AKSS ) was 50 pre-operatively and increased to 93 post-operatively . The mean AKSS function score was 56 pre-operatively rising to 78 post-operatively Conclusion This ten-year follow-up study of the Oxford UKA undertaken in the United States shows good survivorship and excellent function in a wide selection of patients with AMOA and AVN . Cite this article : Bone Joint J 2016;98-B(10 Suppl B):34–40 There have been concerns about the long-term survival of unicompartmental knee arthroplasty ( UKA ) . This prospect i ve study reports the 15-year survival and ten-year functional outcome of a consecutive series of 1000 minimally invasive Phase 3 Oxford medial UKAs ( 818 patients , 393 men , 48 % , 425 women , 52 % , mean age 66 years ; 32 to 88 ) . These were implanted by two surgeons involved with the design of the prosthesis to treat anteromedial osteoarthritis and spontaneous osteonecrosis of the knee , which are recommended indications . Patients were prospect ively identified and followed up independently for a mean of 10.3 years ( 5.3 to 16.6 ) . At ten years , the mean Oxford Knee Score was 40 ( st and ard deviation ( sd ) 9 ; 2 to 48 ) : 79 % of knees ( 349 ) had an excellent or good outcome . There were 52 implant-related re-operations at a mean of 5.5 years ( 0.2 to 14.7 ) . The most common reasons for re-operation were arthritis in the lateral compartment ( 2.5 % , 25 knees ) , bearing dislocation ( 0.7 % , seven knees ) and unexplained pain ( 0.7 % , seven knees ) . When all implant-related re-operations were considered as failures , the ten-year rate of survival was 94 % ( 95 % confidence interval ( CI ) 92 to 96 ) and the 15-year survival rate 91 % ( CI 83 to 98 ) . When failure of the implant was the endpoint the 15-year survival was 99 % ( CI 96 to 100 ) . This is the only large series of minimally invasive UKAs with 15-year survival data . The results support the continued use of minimally invasive UKA for the recommended indications The literature contains limited yet controversial information regarding whether a fixed or a mobile bearing implant should be used in unicompartmental knee arthroplasty ( UKA ) . This r and omized study was to further document the performance and comparison of the two design s. Fifty-six knees in 48 patients ( mean age of 72 years ) undergoing medial UKA were r and omized into a fixed bearing ( Miller/Galante ) or a mobile bearing ( Oxford ) UKA . The 2 year clinical outcomes ( clinical scores ) , radiographic findings , and weight bearing knee kinematics ( assessed using RSA ) were compared between the two groups . The mobile bearing knees displayed a larger and an incrementally increased tibial internal rotation ( 4.3 degrees , 7.6 degrees , 9.5 degrees vs. 3.0 degrees , 3.0 degrees , 4.2 degrees respectively at 30 degrees , 60 degrees , 90 degrees of knee flexion ) compared to the fixed ones . The medial femoral condyle in the mobile bearing knees remained 2 mm from the initial position vs. a 4.2 mm anterior translation in the fixed bearing knees during knee flexion . The contact point in the mobile bearing implant moved 2 mm posteriorly vs. a 6 mm anterior movement in the other group . The mobile bearing knees had a lower incidence of radiolucency at the bone implant interface ( 8 % vs. 37 % , p < 0.05 ) . The incidence of lateral compartment OA and progression of OA at patello-femoral joint were equal . No differences were found regarding Knee Society Scores , WOMAC , and SF-36 scores ( p > 0.05 ) . This study indicates that mobile bearing knees had a better kinematics , a lower incidence of radiolucency but not yet a better knee function at 2 years The Oxford mobile-bearing unicompartmental knee replacement ( UKR )  is an effective and safe treatment for  osteoarthritis of the medial compartment . The results in the lateral compartment have been disappointing due to a high early rate of dislocation of the bearing . A series using a newly design ed domed tibial component is reported . The first 50 consecutive domed lateral Oxford UKRs in 50 patients with a mean follow-up of three years ( 2.0 to 4.3 ) were included .  Clinical scores were obtained prospect ively and Kaplan-Meier survival analysis was performed for different endpoints . Radiological variables related to the position and alignment of the components were measured . One patient died and none was lost to follow-up . The cumulative incidence of dislocation was 6.2 % ( 95 % confidence interval ( CI ) 2.0 to 17.9 ) at three years . Survival using revision for any reason and aseptic revision was 94 % ( 95 % CI 82 to 98 ) and 96 % ( 95 % CI 85 to 99 ) at three years , respectively . Outcome scores , visual analogue scale for pain and maximum knee flexion showed a significant improvement ( p < 0.001 ) . The mean Oxford knee score was 43 ( SD 5.3 ) , the mean Objective American Knee Society score was 91 ( SD 13.9 ) and the mean Functional American Knee Society score was 90 ( SD 17.5 ) . The mean maximum flexion was 127 ° ( 90 ° to 145 ° ) . Significant elevation of the lateral joint line as measured by the proximal tibial varus angle ( p = 0.04 ) was evident in the dislocation group when compared with the non-dislocation group . Clinical results are excellent and short-term survival has improved when compared with earlier series . The risk of dislocation remains higher using a mobile-bearing UKR in the lateral compartment when compared with the medial compartment . Patients should be informed about this complication . To avoid dislocations , care must be taken not to elevate the lateral joint line Aims The interest in unicompartmental knee arthroplasty ( UKA ) for medial osteoarthritis has increased rapidly but the long-term follow-up of the Oxford UKAs has yet to be analysed in non- design er centres . We have examined our ten- to 15-year clinical and radiological follow-up data for the Oxford Phase III UKAs . Patients and Methods Between January 1999 and January 2005 a total of 138 consecutive Oxford Phase III arthroplasties were performed by a single surgeon in 129 patients for medial compartment osteoarthritis ( 71 right and 67 left knees , mean age 72.0 years ( 47 to 91 ) , mean body mass index 28.2 ( 20.7 to 52.2 ) ) . Both clinical data and radiographs were prospect ively recorded and obtained at intervals . Of the 129 patients , 32 patients ( 32 knees ) died , ten patients ( 12 knees ) were not able to take part in the final clinical and radiological assessment due to physical and mental conditions , but via telephone interview it was confirmed that none of these ten patients ( 12 knees ) had a revision of the knee arthroplasty . One patient ( two knees ) was lost to follow-up . Results The mean follow-up was 11.7 years ( 10 to 15 ) . A total of 11 knees ( 8 % ) were revised . The survival at 15 years with revision for any reason as the endpoint was 90.6 % ( 95 % confidence interval ( CI ) 85.2 to 96.0 ) and revision related to the prosthesis was 99.3 % ( 95 % CI 97.9 to 100 ) . The mean total Knee Society Score was 47 ( 0 to 80 ) pre-operatively and 81 ( 30 to 100 ) at latest follow-up . The mean Oxford Knee Score was 19 ( 12 to 40 ) pre-operatively and 42 ( 28 to 55 ) at final follow-up . Radiolucency beneath the tibial component occurred in 22 of 81 prostheses ( 27.2 % ) without evidence of loosening . Conclusion This study supports the use of UKA in medial compartment osteoarthritis with excellent long-term functional and radiological outcomes with an excellent 15-year survival rate . Cite this article : Bone Joint J 2016;98-B(10 Suppl B):41–7 The purpose of this study was to evaluate the mid‐term results of an Oxford phase‐3 unicompartmental knee arthroplasty ( UKA ) for medial arthritis in Chinese patients This prospect i ve study describes the outcome of the first 1000 phase 3 Oxford medial unicompartmental knee replacements ( UKRs ) implanted using a minimally invasive surgical approach for the recommended indications by two surgeons and followed up independently . The mean follow-up was 5.6 years ( 1 to 11 ) with 547 knees having a minimum follow-up of five years . At five years their mean Oxford knee score was 41.3 ( sd 7.2 ) , the mean American Knee Society Objective Score 86.4 ( sd 13.4 ) , mean American Knee Society Functional Score 86.1 ( sd 16.6 ) , mean Tegner activity score 2.8 ( sd 1.1 ) . For the entire cohort , the mean maximum flexion was 130 ° at the time of final review . The incidence of implant-related re-operations was 2.9 % ; of these 29 re-operations two were revisions requiring revision knee replacement components with stems and wedges , 17 were conversions to a primary total knee replacement , six were open reductions for dislocation of the bearing , three were secondary lateral UKRs and one was revision of a tibial component . The most common reason for further surgical intervention was progression of arthritis in the lateral compartment ( 0.9 % ) , followed by dislocation of the bearing ( 0.6 % ) and revision for unexplained pain ( 0.6 % ) . If all implant-related re-operations are considered failures , the ten-year survival rate was 96 % ( 95 % confidence interval , 92.5 to 99.5 ) . If only revisions requiring revision components are considered failures the ten-year survival rate is 99.8 % ( confidence interval 99 to 100 ) . This is the largest published series of  UKRs  implanted through a minimally invasive surgical approach and with ten-year survival data . The survival rates are similar to those obtained with a st and ard open approach whereas the function is better . This demonstrates the effectiveness and safety of a minimally invasive surgical approach for implanting the Oxford UKR We present the peak outcome results of the Oxford medial unicompartmental arthroplasty through a minimally invasive surgical incision . This prospect i ve study included 78 Oxford medial unicompartmental knee replacements in 68 patients . At the 2 year review the patients achieved a mean Oxford Knee Score of 38.3 . This was not significantly different to the 2 year results of the phase 2 Oxford knee carried out using a st and ard parapatellar approach when patients achieved a mean OKS of 36.0 . Four unicompartmental knee replacements required revision for unexplained pain , deep infection , aseptic loosening and bearing dislocation .  Minimally invasive joint replacement is attractive to both patients and surgeons , but is technically dem and ing with complications inherent to limited access Purpose In a mobile-bearing unicompartmental knee arthroplasty ( UKA ) , stability is of utmost importance to promote knee function and to prevent dislocation of the insert . Gap balancing can be guided by the use of spacers or a tensioner . The goal of this study is to compare laxity of a tension-guided implantation technique versus a spacer-guided technique for medial UKA with a mobile bearing . Also clinical function was compared between the groups . Methods The tension-guided UKA system ( BalanSys ™ , Mathys Ltd , Bettlach , Switzerl and ) was compared with a retrospective group with a  spacer-guided system  ( Oxford , Biomet Ltd , Bridgend , UK ) . A total of 30 tension-guided medial UKAs were implanted and compared with 35 spacer-guided medial prostheses .  In both groups , valgus laxity was measured at least 4 months postoperatively in extension and 70 ° flexion using stress radiographs . Knee Society Scores ( KSS ) were obtained at the 6-month follow-up . Results Valgus laxity in flexion was significantly higher in the tension-guided group compared with the spacer-guided group : 3.9 ° ( SD 1.8 ° ) versus 2.4 ° ( SD 1.2 ° ) , respectively , P < 0.001 ) . In extension , valgus laxity was significantly different : 1.8 ° ( SD 1.0 ° ) in the tension-guided group compared with 2.7 ° ( SD 0.9 ° ) in the spacer-guided group ( P < 0.001 ) . There was no significant difference between the KSS for the two groups ( n.s . ) . Conclusions The tensor-guided system result ed in significantly more valgus laxity in flexion compared with the spacer-guided system . However , in extension , the situation was reversed : the tension-guided system result ed in less valgus laxity than the spacer-guided system . Clinical ly , there were no differences between the groups . The valgus laxity found with the spacer-guided system better approximates the valgus laxity values of the healthy elderly . Level of evidence Lower quality prospect i ve cohort study ( < 80 % follow-up , patients enrolled at different time points in disease ) , Level II
Conclusions Although total reoperation rates did not differ in the two population s , reoperation for bearing dislocation was more likely to occur in Asian than in Western patients , whereas reoperation for lateral knee OA progression was more likely to occur in Western than in Asian patients after Oxford Phase III UKA .
Background Implant survivorship is reported to be lower and complications , particularly bearing dislocation , are reported to be more frequent in Asian than in Western patients with medial knee osteoarthritis ( OA ) undergoing Oxford ® Phase III unicompartmental knee arthroplasty ( UKA ) .
To date , however , these complications have not been compared between these groups of patients .
Questions / purpose s The purpose of this study was to perform a meta- analysis comparing the st and ardized incidence rates of ( 1 ) all-cause reoperation ; ( 2 ) reoperation related to bearing dislocation ; and ( 3 ) reoperation related to progression of lateral compartment arthritis in Asian and Western patients with medial knee OA who underwent Oxford Phase III UKA .