Midterm outcomes of TKA: Conventional vs. Navigation

Computer navigation in Total Knee Arthroplasty (TKA) has shown promise for enhancing patient outcomes by improving post-operative alignment however the long term benefits are unclear. This case-control study aimed to investigate whether poor alignment was a risk factor for revision in both conventional and navigated TKA and therefore whether better alignment following navigated surgery can predict improved long-term outcomes. The population was TKAs from our institution with hip-knee-ankle (HKA) radiographs and minimum five-year follow-up. Cases were patients who had been revised. Four controls, matched for operative technique, were selected for each case. Pre-operative and six-week post-operative HKA radiographs were measured to give mechanical alignment. Poor alignment was defined as outwith ±3° or ±5°. Odds- ratios were calculated to estimate the relative risk (RR) of poor alignment on revision. There were five conventional and eight navigated cases (conventional cohort=25, navigated cohort=40). For navigated TKAs poor alignment was a risk factor (±3°: RR=6.3, p=0.028; ±5°: RR=4.05, p=0.106). For conventional TKAs poor alignment did not appear to be a risk factor (±3°: RR=0.580, p=0.659; ±5°: RR=1.41, p=0.786). Whilst these results indicate that poor alignment is a risk factor for revision in navigated knees, no definitive conclusions can be drawn. Further investigation is required