Sixty-six UKAs from 58 consecutive patients (36 male [62.1%], age 63.7 ± 9.2 years, body mass index 28.2 ± 4.9 kg/m2, and mean follow-up time 49.2 months) were imaged in weight-bearing standing position using biplanar radiography. We performed multiple comparisons to analyze the relationship between 3D UKA component alignment and European Quality of Life - 5 Dimensions (EQ-5D), UCLA activity score, and Knee Injury and Osteoarthritis Outcome Scores.
Significant improvements in EQ-5D, EQ-5D (United States adjusted), and Knee Injury and Osteoarthritis Outcome Scores (Sport/Rec) scores were noted postoperatively. However, high variability in 3D UKA femoral (6.2° ± 6.5°) and tibial (4.6° ± 6.4°) component positioning was observed. A trend toward better outcome scores in lower angles of femoral (<2.7° external rotation [ER]) and tibial (2.7° ER to 2.4° internal rotation [IR]) component rotation was noted, with better functional scores observed at mean femoral and tibial rotation angles of 3° ER to 3° IR.
Patients with UKA femoral and/or tibial component rotation angles within 3° ER to 3° IR of neutral component alignment reported better functional outcomes. Surgeons should be cognizant of the high variability noted in UKA component axial rotation and its potential correlation with functional scores.