The relationship between postoperative limb alignment and clinical outcomes in primary total knee arthroplasty (TKA) is well reported, but the instruments used to evaluate clinical outcomes of TKA are mainly scoring systems from the physician's viewpoint, not patient-reported outcomes. The purpose of this study was to investigate retrospectively the relationship between postoperative limb alignment and patient-reported clinical outcomes using the 2011 Knee Society Knee Scoring System (2011 KSS).
The present study included 155 knees of patients (median age, 74 years) who underwent primary TKA for varus osteoarthritis, with a mean follow-up period of 46 months. The subjects were divided into three groups based on postoperative limb alignment and femoral and tibial component positioning angle (varus, neutral, and valgus). The 2011 KSS scores were compared among the groups.
For limb alignment, the postoperative objective knee indicator score was significantly lower in the valgus group than in the varus and neutral groups, whereas no significant differences were observed in any subjective categories of the 2011 KSS. However, for the femoral component angle, functional activity scores were significantly lower in the valgus group than in the varus and neutral groups.
The subjective patient-reported score was not affected by the postoperative limb alignment. However, the valgus femoral component angle resulted in lower subjective functional scores. For clinical relevance, postoperative valgus positioning of femoral component should be avoided from patient-reported functional aspects during TKA.