Mechanically aligned total knee arthroplasty demonstrates acceptable outcomes in obese patients, with insufficient evidence for alternative alignment strategies: A systematic review.

Purpose: Obesity (body mass index [BMI] ≥ 30 kg/m Methods: Eligible studies (1) included patients who underwent primary TKA with defined alignment, (2) reported BMI ≥ 30 kg/m Results: Thirty studies were included. 8468 obese patients (14,662 knees) underwent mechanically aligned TKA, with mean follow-up of 91.1 ± 45.3 months (range, 0.5-110.5 months). Mechanically aligned TKA in obese patients was associated with post-operative improvements in PROMs, including Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis Index and Oxford Knee Score. Short-term cumulative aseptic revision incidence was low, ranging from 0.5% to 1.3%, while revision-free survivorship commonly exceeded 95% at short-term and >90% at long-term follow-up. Radiographic outcomes demonstrated reliable restoration of near-neutral limb alignment across BMI strata. One study evaluated a kinematically-designed bicruciate-stabilized implant with an unspecified alignment strategy in obese patients, and another study evaluated functional alignment in obese patients, limiting comparisons. Conclusion: Evidence evaluating the influence of alignment on outcomes in obese patients undergoing TKA remains insufficient to determine whether alignment philosophy meaningfully affects clinical or radiographic outcomes. Although mechanically aligned TKA demonstrated generally acceptable post-operative outcomes in obese cohorts, the available literature was overwhelmingly dominated by mechanically aligned studies, with only limited evaluation of alternative approaches. Level of Evidence: Level IV.