The 2011 Knee Society Knee Scoring System (KSS) was developed as a new patient-derived outcome measure to better characterize satisfaction, expectations, and physical activities after total knee arthroplasty. The rotational alignment of the femoral and tibial components was assessed with computed tomography in 75 patients (92 knees), and its effect on the scores of the KSS was evaluated. Internal rotation of the femoral component relative to the surgical epicondylar axis significantly decreased the score of functional activities and slightly decreased the score of satisfaction. Femoral component malrotation did not affect the scores of symptoms and expectations. Tibial component malrotation did not affect any of the scores of the 2011 KSS. Surgeons should avoid internal rotation of the femoral component to preserve functional activities.
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