Evaluation of Medial-Lateral Stability and Functional Outcome Following Total Knee Arthroplasty: Results of a Single Hospital Joint Registry

A precept of a successful total knee arthroplasty (TKA) would be a well balanced, stable knee. We analyzed the effects of medial-lateral (ML) stability on functional outcome at 2 years post-operatively. Prospectively collected Joint Registry data of all unilateral primary TKAs between 2004 and March 2008 were used. ML stability (Group 1: <5°, Group 2: 6°–9°, Group 3: ≥10°) was assessed by 3 independent researchers. 1500 patients undergoing 1507 arthroplasties were divided into their various groups. Outcome assessment involved range of motion (ROM) and functional outcome, using the Knee Society Function Score (KSS), Oxford Knee Score (OKS) and SF-36 score. At 2 years, Group 1 patients reported significantly higher KSS (P < 0.001) and SF-36 scores. All groups had good post-operative ROM. A stable knee (ML stability <5°) post TKA is likely associated with significantly better functional outcome.