Nine studies (1,565 knees) assessed UKA in comparison with TKA: 1 randomised controlled trial (RCT, 102 knees), 6 concurrent non-randomised trials (459 knees) and 2 retrospective comparative studies (1,004 knees).
Six studies (334 knees) assessed UKA in comparison with HTO: 2 RCTs (102 knees), 2 concurrent non-randomised trials (60 knees) and 2 retrospective comparative studies (172 knees).
Safety.
No significant differences in the overall rates of complications could be found between UKA and TKA, although deep vein thrombosis appeared to be reported more frequently after TKA than UKA. When UKA and HTO were compared, it appeared that complications (mainly deep vein thrombosis and wound complications) were reported more often with HTO.
Efficacy.
Knee function and post-operative pain were difficult to compare across the studies because of the various scoring systems used. UKA appeared to be equivalent to TKA and HTO. The range of motion was generally greater with UKA than TKA and HTO.
There was a trend towards higher survival of prostheses (based on revision rates) for TKA than UKA in the follow-up between 3 and 10 years after implantation, but this was not statistically significant. When UKA was compared with HTO, 1 RCT found significantly more revisions at 4.5 years' follow-up in the HTO patients (relative risk 0.64, 95% confidence interval: 0.27, 1.54).
The evidence base was rated average according to the ASERNIP-S classification system.