Alignment outcomes in navigated total knee arthroplasty: a meta-analysis

Whether navigated total knee arthroplasty can improve the limb and component alignment is a matter of debate. This systematic literature review analyzed the differences on alignment outcomes between navigated total knee arthroplasty and conventional total knee arthroplasty. Multiple databases, online registers of randomized controlled trials were searched. Published and unpublished randomized controlled trials were included, and data on methodological quality, population, intervention, and outcomes were abstracted in duplicate. Data were pooled across studies, and odds ratios for categorical outcomes were calculated according to study sample size. Twenty-one randomized controlled trials of varying methodological quality involving 2,414 patients were included. Statistically significant differences were observed between navigated group and conventional group in mechanical axis malalignment of > 3A degrees (odds ratio, 0.26; 95% confidence interval, 0.17-0.38) and mechanical axis malalignment of > 2A degrees (odds ratio, 0.33; 95% confidence interval, 0.26-0.42). Navigated group had a lower risk of malalignment for both coronal femoral component and coronal tibial component of > 3A degrees and > 2A degrees. Both sagittal femoral component alignment and tibial slope showed statistical significance in favor of navigated arthroplasty at > 2A degrees and 3A degrees malalignment. Meta-analysis indicates significant improvement in alignment of the limb and the component position with use of computer navigation system. Its clinical benefits are unclear and remain to be defined on a larger scale randomized controlled trials with long-term follow-up. Therapeutic study (Systematic review of Level-I studies with inconsistent results), Level II.