Is limb overcorrection following total knee arthroplasty compromising functional outcome?

Abstract

Purpose: Many patients remain unsatisfied after total knee arthroplasty (TKA). Personalized alignment strategies have gained popularity in the search to improve patient satisfaction and function. This study aimed to examine the impact of limb overcorrection in the coronal plane on patient satisfaction and functional outcome. The secondary aim was to investigate how a change in knee phenotype following TKA affects clinical outcome. Methods: A retrospective matched case-control study was designed between patients with limb overcorrection (N = 37) and a control group (N = 104). Mean follow-up was 68 months. Satisfaction and function were compared by means of the new 2011 Knee Society Score (KSS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Radiological evaluation was performed on weight-bearing full-leg radiographs. Overcorrection was defined as a mechanical HKA (mHKA) angle of 2 degrees or more and opposite to the preoperative alignment. The control group consisted of TKAs that were corrected to neutral or left in slight undercorrection. Finally, component alignment (lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA)) and Coronal Plane Alignment of the knee (CPAK) phenotypes were evaluated. Results: The overcorrection group performed better than the control group in terms of KSS subscores satisfaction and functional activities, total KSS score, all KOOS subcategories, and total KOOS score. Subdivision of the control group into a neutral and undercorrection group, and the overcorrection group into mild and severe overcorrection, revealed similar findings. A chance in knee phenotype as per aHKA, JLO or CPAK did not result in worse clinical outcomes. Conclusion: Accidental limb overcorrection after TKA does not result in inferior clinical outcomes or patient satisfaction at midterm follow-up. The present study could not identify an optimal coronal alignment target. This suggests that coronal alignment as a predictor of patient satisfaction and function is likely less important than previously believed. Level of evidence: Level III, retrospective case-control study.