The Journal of Arthroplasty, Volume 34, Issue 7, 1538 - 1545

Improving Estimates of Annual Survival Rates for Medial Unicompartmental Knee Arthroplasty, a Meta-Analysis

Braiden M. Heaps, Jason L. Blevins, Yu-Fen Chiu, Joseph F. Konopka, Shaun P. Patel, Alexander S. McLawhorn


Medial unicompartmental knee arthroplasty (mUKA) is an increasingly popular treatment option for medial compartment knee osteoarthritis. Published mUKA survival rates have varied. The purpose of this meta-analysis was to provide pooled estimates of mUKA survival 5 and 10 years postoperatively.


We included studies in English within the last 15 years with a clear description of mUKA failure. Random-effects models were used to pool complementary log-log transformed implant survival estimates at 5 and 10 years postoperatively. Between-study variance was estimated using the restricted maximum likelihood method. Between-study heterogeneity was tested using the χ2 test and quantified using the I 2 statistic. I 2 values <25%, 25%-75%, and >75% were considered low, moderate, and high, respectively. Multivariable meta-regression was used to assess the potential association of mean patient age and study start year with survival estimates at 5 and 10 years. All analyses were performed using the metafor and meta packages implemented in R software version 3.3.4 (R Foundation for Statistical Computing, Vienna, Austria).


Twenty-six studies met inclusion criteria, representing 42,791 knees. Study-level and pooled 5- and 10-year mUKA survival estimates were 95.3% (95% confidence interval, 93.6-96.6) and 91.3% (88.9-93.3), respectively. Between-study heterogeneity was high (>88%) for all years. Mean patient age and study start year explained only 12.3% and 30.7% of between-study heterogeneity at 5 and 10 years, respectively.


Five- and 10-year pooled mUKA survival estimates were 95.3% and 91.3%, respectively. These data establish better estimates of mUKA survivorship and can help when counseling patients considering mUKA.

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