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 Oxford phase 3 unicompartmental knee replacement in Korean patients. Unicompartmental knee arthroplasty compares favorably to total knee arthroplasty in the same patient. Total or partial knee replacement? Cost-utility analysis in patients with knee osteoarthritis based on a 2-year observational study Superior femoral component alignment can be achieved with Oxford microplasty instrumentation after minimally invasive unicompartmental knee arthroplasty Unicondylar knee arthroplasty in the UK National Health Service: an analysis of candidacy, outcome and cost efficacy. A comparison of fixed-bearing and mobile-bearing total knee arthroplasty at a minimum follow-up of 4.5 years. Outcome of Unicondylar Knee Arthroplasty vs Total Knee Arthroplasty for Early Medial Compartment Arthritis: A Randomized Study. Mobile bearing UKA compared to fixed bearing TKA: a randomized prospective study. High tibial osteotomy versus unicompartmental joint replacement in unicompartmental knee joint osteoarthritis: 7-10-year follow-up prospective randomised study. Fixed or mobile bearing unicompartmental knee replacement? A comparative cohort study. Evidence-Based Indications for Mobile-Bearing Unicompartmental Knee Arthroplasty in a Consecutive Cohort of Thousand Knees. No difference in quality-of-life outcomes after mobile and fixed-bearing medial unicompartmental knee replacement. Does a high-flexion design affect early outcome of medial unicondylar knee arthroplasty? Clinical comparison at 2 years. Comparison of Outcome and Survival After Unicompartmental Knee Arthroplasty Between Navigation and Conventional Techniques With an Average 9-Year Follow-Up.
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 Medium-term survivorship of the Oxford phase 3 unicompartmental knee replacement ( UKR ) has not yet been established in an Asian population . We prospect ively evaluated the outcome of 400 phase 3 Oxford UKRs in 320 Korean patients with a mean age at the time of operation of 69 years ( 48 to 82 ) . The mean follow-up was 5.2 years ( 1 to 10 ) . Clinical and radiological assessment was carried out pre- and post-operatively . At five years , the mean Knee Society knee and functional scores had increased significantly from 56.2 ( 30 to 91 ) pre-operatively to 87.2 ( 59 to 98 ) ( p = 0.034 ) and from 59.2 ( 30 to 93 ) to 88.3 ( 50 to 100 ) ( p = 0.021 ) , respectively . The Oxford knee score increased from a mean of 25.8 ( 12 to 39 ) pre-operatively to 39.8 ( 25 to 58 ) at five years ( p = 0.038 ) . The ten-year survival rate was 94 % ( 95 % confidence interval 90.1 to 98.0 ) . A total of 14 UKRs ( 3.5 % ) required revision . The most common reason for revision was dislocation of the bearing in 12 ( 3 % ) . Conversion to a total knee replacement was required in two patients who developed osteoarthritis of the lateral compartment . This is the largest published series of UKR in Korean patients . It shows that the mid-term results after a minimally invasive Oxford phase 3 UKR can yield satisfactory clinical and functional results in this group of patients There are several surgical management options for medial knee arthritis , and it is often difficult to decide whether a unicompartmental knee arthroplasty ( UKA ) or total knee arthroplasty ( TKA ) is appropriate . Few studies have compared UKAs and TKAs in the same patient . We identified 23 patients with osteoarthritis who had a TKA on one side and a UKA on the other . The preoperative values of the 2 knees were not statistically different . Strict criteria were used to determine whether a UKA could be performed ( functional anterior cruciate ligament , minimal deformity , and minimum changes in other compartments ) . Preoperative radiographs were review ed to confirm that the knee undergoing TKA had medial compartment disease only . Knee Society scores , radiographic analysis , and patient preferences were recorded for all patients . Average follow-up was 46 months ( range , 7.2 - 148 months ) and 42 months ( range , 11.5 - 59.8 months ) for TKA and UKA , respectively . We found little or no difference in outcomes between the 2 procedures , except for an improved range of motion with the UKA compared with the TKA ( 123 degrees + /-9 degrees vs 119.8 degrees + /-7 degrees , respectively ) . Knee Society scores improved from 45.9 to 89.7 in UKA and from 42.4 to 90.3 in TKA . Of the 23 patients , 11 expressed no preference between either knee and 12 preferred the unicompartmental knee ; no patient preferred the total knee . With appropriate patient selection , UKAs are a successful option for patients with osteoarthritis The objective of this study was to evaluate incremental cost-utility of total knee replacement ( TKR ) versus unicompartmental knee arthroplasty ( UKA ) in patients with knee osteoarthritis ( OA ) of the medial compartment . A 2-year non-r and omised prospect i ve observational cohort study was conducted in unicompartmental knee osteoarthritis patients scheduled for TKR ( n = 431 ) or UKA ( n = 102 ) .  Costs were identified using administrative data bases and health outcomes were measured using the SF-36 and the Oxford knee score ( OKS ) 1 week before , 6 months after , and 2 years after surgery . The incremental cost-utility ratio ( ICUR ) for TKR versus UKA was calculated and its 95 % confidence interval estimated using a nonparametric bootstrapping technique . Cost-effectiveness acceptability curves were constructed from different perspectives . On average , from the societal perspective , the ICUR was US $ 65,245 per quality -adjusted life-year ( QALY ) . In the scenario with costs calculated from the perspective of patients , the ICUR was $ 60,382/QALY . This value decreased to $ 4,860/QALY in the scenario with costs calculated from the governmental perspective . However , the 95 % confidence interval of ICURs can not be defined because more than 5 % bootstrapped sample s fell into the upper left quadrant of the cost-effectiveness plane from all three perspectives . Based on the 2-year data , TKR gained more QALYs at higher costs compared to UKA . A long-term prospect i ve study is necessary to determine cost-effectiveness of TKR and UKA Abstract Purpose Oxford microplasty ( MP ) instrumentation has been developed to facilitate the reproducible and consistent performance of minimally invasive unicompartmental knee arthroplasty ( MI-UKA ) operation . The aim of this study was to compare the clinical and radiographic results of two groups of patients implanted using either a conventional instrumentation technique or an MP technique .  Methods A prospect i ve cohort study of 108 knees in 108 patients who underwent an MI-UKA procedure using either conventionally instrumented UKA ( CI-UKA ) ( 52 knees of 52 patients ) or MP-assisted UKA ( MP-UKA ) ( 56 knees of 56 patients ) . The clinical assessment included the Oxford Knee Score ( OKS ) , the Knee Society Score ( KSS ) , a visual analogue scale ( VAS ) for pain , and range of motion ( ROM ) . Complications were also recorded . Results No significant differences were observed between the two groups regarding OKS , KSS , VAS , and ROM . There were also no significant differences in terms of mechanical limb alignment and tibia implant alignment . However , the MP-UKA group showed significantly more accurate positioning of the femoral component than the CI-UKA group . Additionally , the MP-UKA group had more femoral prostheses implanted in the “ satisfactory ” range and fewer “ outliers ” than the CI-UKA group . No significant difference in complications was noted between the two groups . Conclusion This study suggested that compared with CI-UKA , MP-UKA provides significant improvements in increasing the accuracy of sagittal and coronal implantation of the femoral component and in reducing the numbers of outliers for femoral prosthetic alignment . It is advocated that the MP system should be considered when MI-UKA is performed . Level of evidence Therapeutic study , Level IV The viability of  unicondylar knee arthroplasty ( UKA )  as a st and -alone or temporising option for the management of  gonarthrosis  is a topic of considerable contention . Despite recent advances in prosthesis design and surgical technique , as well as mounting evidence of long-term survivorship , UKA remains infrequently used , accounting for just 8 - 15 % of all knee arthroplasties . Instead this group is more typically managed using total knee arthroplasty ( TKA ) . For UKA to warrant increased usage the c and idacy for UKA must be prevalent , the outcome must be equivalent or superior to that of TKA , and the costs should be comparatively low . Here we address three issues regarding UKA : 1 ) a prospect i ve assessment of the proportion of knees needing arthroplasty that are c and i date s for UKA ; 2 ) retrospective outcome measures comparing TKA , UKA and controls ; and 3 ) an estimation of the difference in costs between TKA and UKA from a hospital perspective . We show in a series of 200 knees that c and idacy for UKA is widespread ; representing 47.6 % of knees . Furthermore , we also show for the first time , that not only is UKA functionally superior to TKA ( based on Total Knee Question naire ( TKQ ) scores ) , but scores in medial and lateral UKA knees do not differ significantly from normal , non-operative age- and sex-matched knees ( t=1.14 [ 38 ] , p=0.163 ; and t=1.16 [ 38 ] , p=0.255 respectively ) . Finally , we report that UKA offers a substantial cost saving over TKA ( pound 1761 per knee ) indicating that UKA should be considered the primary treatment option for unicompartmental knee arthritis BACKGROUND Durable long-term independent results with the Low Contact Stress rotating-platform ( mobile-bearing ) and the Insall Burstein-II ( fixed-bearing ) total knee prostheses have been reported , but no studies describing either the mid-term or long-term results and comparing the two prostheses are available , to our knowledge . METHODS Thirty-two patients who had bilateral arthritis of the knee with similar deformity and preoperative range of motion on both sides and who agreed to have one knee replaced with a mobile-bearing total knee design and the other with a fixed-bearing design were prospect ively evaluated . Comparative analysis of both design s was done at a mean follow-up period of six years , minimizing patient , surgeon , and observer-related bias . Clinical and radiographic outcome , survival , and complication rates were compared . RESULTS Patients with osteoarthritis had better function scores and range of motion compared with patients with rheumatoid arthritis . However , with the numbers available , no benefit of mobile-bearing over fixed-bearing design s could be demonstrated with respect to Knee Society scores , range of flexion , subject preference , or patellofemoral complication rates . Radiographs showed no difference in prosthetic alignment . Two knees with a mobile-bearing prosthesis required a reoperation : one had an early revision because of bearing dislocation and another required conversion to an arthrodesis to treat a deep infection . CONCLUSIONS We found no advantage of the mobile-bearing arthroplasty over the fixed-bearing arthroplasty with regard to the clinical results at mid-term follow-up . The risk of bearing subluxation and dislocation in knees with the mobile-bearing prosthesis is a cause for concern and may necessitate early revision . LEVEL OF EVIDENCE Therapeutic Level II BACKGROUND With increasing number of patients with early osteoarthritis of knee opting for total knee arthroplasty ( TKA ) , there has been increase in patients dissatisfied with surgical outcomes . It is being presumed that offering unicondylar knee arthroplasty ( UKA ) to them would improve outcomes . METHODS Primary objective of our study was to look for any difference in patient-reported outcome and function at 2-year follow-up in patients undergoing UKA as compared to TKA .  Our study was a r and omized study with parallel assignment conducted at a high-volume specialized arthroplasty center . Eighty patients with bilateral isolated medial compartment knee arthritis were r and omized into simultaneous 2-team bilateral TKA ( n = 40 ) and UKA ( n = 40 ) group . We finally analyzed 36 patients in each group . Main outcome measure was improvement in Knee Outcome Survey-Activities of Daily Living Scale ( KOS-ADLS ) and High Activity Arthroplasty Score ( HAAS ) obtained at 2-year follow-up . RESULTS Improvement in KOS-ADLS and HAAS at 2 years was similar ( P = .2143 and .2010 ) in both groups . Performance as assessed with Delaware index was also similar . Length of hospital stay was less in UKA group ( 6.6 days as against 5.4 days ) . Complications and readmission rates were more in TKA group ( nil in UKA group ; 08 in TKA group ) . CONCLUSION At 2-year follow-up , UKA provides similar improvement in patient-reported outcomes , function , and performance as compared to TKA when performed in patients with early arthritis . However , UKA patients have shorter hospital stay and fewer complications We prospect ively evaluated a consecutive series of 56 patients with unicompartmental knee arthritis who underwent unicompartmental knee replacement or total knee arthroplasty and received an average of 52months of follow-up . These patients were enrolled in a prospect i ve r and omized clinical trial . There were no significant differences in the pre-operative parameters of both groups . All the patients were followed up and evaluated preoperatively and yearly , the data was collected and statistical analysis was performed . At an average of 52months after surgery the mean Knee Society score was 80.5 ( range : 70 - 100 ) and 78.9 ( range : 70 - 87 ) for Unicompartmental knee replacement and total knee arthroplasty , mean range of postoperative motion for TKA is 115(0)±4(0 ) and 117(0)±7(0 ) for the group of UKA , with the numbers available , the difference between the two groups could not be shown to be significant . The average operation time of UKA and TKA is 68.8min and 81.5min(p<0.01 ) . Blood drainage after operation had a significant difference between the two groups ( p<0.01 ) . Seven cases of UKA were converted to total knee arthroplasty - all of them within the first 2years of starting the procedure and all of them in relatively young patients . From the study we concluded that mobile bearing UKA can obtain similar clinical effect with TKA by surgeons who have the adequate training and experience . After the learning curve UKA should be considered the primary treatment option for unicompartmental knee arthritis The  clinical outcome of patients treated either by high tibial osteotomy or unicompartmental arthroplasty for medial unicompartmental osteoarthritis of the knee was compared in a prospect i ve r and omised study . In total , 32 patients received a high tibial osteotomy ( HTO ) and 28 patients a unicompartmental arthroplasty ( UKA ) .  More intra- and postoperative complications were observed after HTO . Patients were assessed at an average of 2.5 ( 1.6 - 5 ) , 4.5 ( 3.6 - 7 ) , and 7.5 years ( 6.6 - 10 ) after the operation . Using the Knee Society Score , 71 % ( 15 ) of patients after osteotomy and 65 % ( 13 ) after replacement had a knee score of excellent or good 7 - 10 years postoperatively . The Kaplan-Meier survival analysis 7 - 10 years postoperatively showed a survivorship of 77 % for UKA and 60 % for HTO . Although the unicompartmental prosthesis used in this series has not shown promising results , we conclude that with the advanced design of unicompartmental prosthesis today , UKA offers better long-term success Unicompartmental knee replacement ( UKR ) for anteromedial osteoarthritis is a well-established technique . Numerous clinical outcome studies demonstrate good medium and long-term results . The aim of this prospect i ve study was to compare the complications and short-term clinical outcome of the St. Georg Sled , a fixed bearing UKR , with the Oxford mobile bearing UKR . Outcome at 2 years was assessed using the Bristol knee score and the Oxford knee score ; in addition , complications occurring since formal scoring at 2-year follow-up were recorded . A total of 47 Oxford UKRs and 57 St. Georg Sled UKRs were performed in 91 patients , none of whom were lost to follow-up . At 2 years , both outcome measures were better for the St. Georg Sled Group . The pain component of the Bristol knee score was significantly better for this group ( p-value = 0.013 ) . Three patients in the Oxford group had bearing dislocations and a further four patients required revision ( mean time to revision 3.0 years ) . In the St. Georg Sled group , three patients required revisions ( mean time to revision 3.4 years ) . These results demonstrate that in the short-term , the Oxford mobile bearing prosthesis has a higher re-operation rate and that the St. Georg Sled achieves better pain relief . The functional scores of the two groups were similar BACKGROUND The indications for unicompartmental knee arthroplasty remain controversial . Previously recommended contraindications include the following : age under 60 years , weight 180 lb ( 82 kg ) or over , patients undertaking heavy labor , chondrocalcinosis , and exposed bone in the patellofemoral joint . This study explores whether these contraindications are valid in mobile-bearing unicompartmental knee arthroplasty . METHODS Using a prospect i ve series of 1000 consecutive medial unicompartmental knee arthroplasties in which the reported contraindications were not applied , the functional outcome and survival in patients with or without contraindications were compared . RESULTS Of the 1000 consecutive unicompartmental knee arthroplasties ( 818 patients ) , 68 % ( 678 knees ) would be considered contraindicated based on published contraindications . At a mean follow-up of 10 years ( 5 - 17 ) , there was no difference in American Knee Society ( AKS ) Objective Scores ( P = .05 ) or Oxford Knee Score ( P = .08 ) between groups . However , knees with contraindications had significantly ( P = .02 ) fewer poor outcomes and significantly better AKS Functional Scores ( P < .001 ) and Tegner Activity Scores ( P < .001 ) . At 15 years , no difference in implant survival ( P = .33 ) was observed . The 3 % of unicompartmental knee arthroplasties performed in young men ( age < 60 ) weighing 180 lb or over with high activity levels , who have been reported to have poor outcomes after fixed-bearing unicompartmental knee arthroplasty , had significantly better AKS Functional Scores ( P < .001 ) , Oxford Knee Score ( P = .01 ) , and Tegner Activity Score ( P < .001 ) at 10 years . No difference in AKS Objective Scores ( P = .54 ) at 10 years or implant survival at 15 years ( P = .75 ) was seen . CONCLUSION This large case series provides evidence that patients with the previously reported contraindications do as well as , or even better than , those without contraindications . Therefore these contraindications should not apply to mobile-bearing unicompartmental knee arthroplasty This is a retrospective study comparing the clinical outcomes of mobile vs fixed medial unicompartmental knee replacements . Patients were identified from a prospect ively collected data base .  Demographic data and pre- and postoperative outcomes ( Oxford , Western Ontario and McMaster Universities Osteoarthritis Index , Short Form Health Survey-12 , and satisfaction ) were collected-104 knees ( 90 patients ) with minimum 2-years of follow-up : 37 mobile and 67 fixed-bearing .  At baseline , the median age was 60 years ( mobile ) and 66 ( fixed ) ; body mass index  was significantly higher ( 32 ) for the mobile group than for the fixed ( 28 ) . At follow-up , the groups differed only in the Oxford score : median 83 ( mobile ) and 90 ( fixed ) . There is no difference in outcomes between mobile and fixed unicompartmental knee replacements Recently , implant companies have sought to target a more active segment of the population with high-flex implants . Our aim was to compare a successful medial UKA implant with its newer high-flex version . Sixty-one patients ( nonflex , 33 ; high-flex [ HF ] , 28 ) were prospect ively followed after medial UKA  with a minimum of 2-year follow-up . Patients were evaluated using Short Form 12 , Western Ontario and McMaster Osteoarthritis ( WOMAC ) , Knee Society Scores , and range of motion ( ROM ) . The HF group exhibited significantly higher WOMAC Physical Function scores at 3-month follow-up and higher WOMAC Pain and SF-12 Mental Component scores at 2-year follow-up ; all other comparisons were not statistically different , including ROM . The HF cohort had significantly higher improvements in Knee Society Function and Knee score at 1- and 2-year follow-up , respectively ; all other comparisons yielded no significant differences in mean improvement from baseline , including ROM or survivorship BACKGROUND Unicompartmental knee arthroplasty(UKA ) has become a treatment of choice for many patients with isolated unicomparmental arthritis due to its specific advantages over total knee arthroplasty , but few studies have compared conventional and navigational UKA with similar instrumentation on mid- to long-term results . We investigated whether the use of imageless navigation can improve implant positioning and clinical outcomes of UKA at a long-term follow-up compared to the conventional technique . METHODS We prospect ively studied clinical and radiological results in 68 patients with an average age of 64.0 years ( range , 50 to 81 years ) who received UKA between January 2003 and December 2005 using the conventional or navigational technique .  Clinical evaluations were performed preoperatively and the last follow-up included knee range of motion , Hospital for Special Surgery ( HSS ) scores , Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) scores and Visual Analogue Scale ( VAS ) pain score . For radiologic evaluation , the mechanical alignment of the lower limb was measured using mechanical femoro-tibial angle ( mFTA ) and Kennedy protocol . RESULTS After an average 9-year follow-up ( range , 7.4 to 10.8 years ) , the navigation group showed better coronal alignments of the components , fewer radiological outliers and better clinical scores , but similar estimated 10-year prosthesis survival rates . CONCLUSION This study indicates that the use of navigation significantly contributes to the desired mechanical axis and improved component placement as compared to the conventional technique . LEVEL OF EVIDENCE Prospect i ve comparative study , Level III
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 .