To investigate whether postoperative lower extremity mild varus alignment can generate better outcomes than postoperative lower extremity mechanical alignment (MA) in patients with structural varus of lower extremity who had received total knee arthroplasty (TKA).

PubMed, Excerpta Medica Database (Embase), Web of Science, the Cochrane Library, China Online Journals (Wanfang), China Science and Technology Journal Database (VIP) and China National Knowledge Infrastructure (CNKI) were retrieved to compare the efficacy of postoperative lower extremity MA and postoperative lower extremity mild varus alignment. The retrieval time ends by October 5, 2022. Articles screening and data extraction were completed by two researchers according to the inclusion and exclusion criteria. The quality of the cohort study was evaluated by the Newcastle-Ottawa Scale (NOS). The quality of the randomized controlled study (RCT) was evaluated using the modified Jadad scale. Meta-analysis was performed using Revman 5.3 software.

Fourteen articles were included in this analysis, all of which were high-quality cohort studies. The analysis results showed that the forgotten joint score of postoperative lower extremity mild varus alignment [mean difference (MD)=8.05, 95% confidence interval (CI) (5.53, 10.58), P< 0.01] was better than that in the MA group, and the difference was statistically significant.As for the Western Ontario and McMaster University osteoarthritis index (WOMAC) [MD=-1.34, 95%CI (-2.95, 0.26), P=0.10], Oxford knee score (OKS) [MD=0.18, 95%CI (-0.37, 0.73), P=0.52], revision rate [odds ratio (OR) =0.55, 95%CI (0.22, 1.35), P=0.19], range of motion (ROM) of knee joint [MD=-0.84, 95%CI (-2.24, 0.55), P=0.24], Knee Society knee score (KSKS) of American Knee Society score (KSS) [MD=0.05, 95%CI (-0.59, 0.69), P=0.87] and Knee Society function score (KSFS) [MD=-0.44, 95%CI (-2.13, 1.25), P=0.61], the prognosis of postoperative lower extremity mild varus alignment group was similar to that of the MA group, and the difference was not statistically significant.

For patients with knee arthritis and structural varus of lower extremity, the effect of postoperative lower extremity mild varus alignment after TKA is not inferior to that of MA.