A modified lateral skin incision reduces wound complications and hospital stay in morbidly obese patients undergoing total knee arthroplasty: a propensity-matched cohort study.

BACKGROUND: This prospective cohort study, with post-hoc 1:1 propensity score matching investigates whether a modified curved lateral skin incision in total knee arthroplasty (TKA) for morbidly obese patients reduces complications. We hypothesized that preserving the medial angiosomal blood supply would decrease wound issues, and a lateralized skin incision would decrease hypesthesia, and kneeling difficulties without impacting operative time or function. METHODS: The study evaluated 124 morbidly obese patients undergoing primary TKA, comparing a modified curved lateral skin incision (n = 62) to a standard midline incision (n = 62). Following 1:1 propensity score matching for demographics and preoperative status, a single surgeon performed all procedures using curved lateral skin incision and then medial parapatellar arthrotomies. Patients were followed for 1 year postoperatively. Primary endpoints were wound complication rates and hospital stay length; secondary outcomes included hypesthesia, kneeling ability (VAS), Knee Society Scores (KSS), and operative metrics. RESULTS: Both groups were well-balanced at baseline (SMD < 0.20). The lateral group showed a significantly lower overall wound complication rate (3.2% vs. 19.4%, p = 0.016), exclusively minor, with no major complications. Additionally, this cohort had shorter hospital stays (3.02 vs. 3.48 days, p = 0.021) and a markedly smaller area of hypesthesia. On multivariable logistic regression, the lateral incision was an independent protective factor against wound complications (OR 0.094; 95% CI 0.014-0.643; p = 0.016), while smoking was the strongest independent risk factor (OR 48.95; 95% CI 4.958-483.4; p < 0.001). CONCLUSION: In morbidly obese patients undergoing TKA, a modified curved lateral skin incision significantly reduces wound complications, hospital stay, and anterior knee hypesthesia compared to the standard midline approach. While the lateral technique improves early kneeling ability, long-term functional outcomes remain equivalent. The study concludes that the lateral incision is an effective strategy for this high-risk population.