Comparison of Postoperative Alignment Using Fixed vs Individual Valgus Correction Angle in Primary Total Knee Arthroplasty With Lateral Bowing Femur.

BACKGROUND: Lateral bowing of the femur, commonly observed among Asian populations, may cause malalignment after primary total knee arthroplasty (TKA). Therefore, in this study, a fixed valgus correction angle (VCA) technique for TKA was compared with individual VCA to determine which surgical technique leads to better limb and component alignment.

METHODS: Patients with primary TKAs with lateral bowing femurs (n = 133) were randomized to 2 groups: individual VCA (group A) and fixed VCA (group B). Full-length standing hip-knee-ankle radiographs were used to measure the VCA and limb alignment. The postoperative mechanical axis, femoral component, and tibial component alignment were measured and compared between the 2 groups.

RESULTS: The mean postoperative mechanical axis and femoral component alignment were 178.1° and 88.3°, respectively, in group A, compared with 175.9° and 86.4°, respectively, in group B (P < .05). There were 52 (77.6%) knees with ±3° mechanical axis deviation from the neutral axis in group A, compared with 19 (28.8%) in group B (P < .001). There were 56 (83.6%) knees with femoral component alignment deviation within ±3° in group A, compared with 26 (39.4%) in group B (P < .001).

CONCLUSION: The individual VCA achieves a better radiographic limb and femoral component alignment than fixed VCA in our study patients. Preoperative hip-knee-ankle radiographs are imperative for distinguishing a bowing femur and performing accurate planning of the distal femoral resection.