Abstract
Objective
To explore whether good postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur.
Methods
Data of 46 TKAs with lateral bowing femur were collected prospectively, the center of the femoral intercondylar notch was the fixed drilling hole whether preoperative planning or intraoperative implementing. The intramedullary rod was put into the femur as deep as possible, until completely entrance or the distal point of the rod contact with the lateral cortical bone of the femur, which prevent the further entrance of the rod. Individual valgus resection angle ranging from 7°to 9°was performed according to preoperative planning, followed by meticulous assessment of matching between cutting surface and valgus resection angle. Postoperative hip-knee-ankle (HKA) angle?medial tibial plate angle and position of lower extremity alignment passing through the tibial plate were measured.
Results
The preoperative measurement valgus resection angle include 14 cases of 8°, 13 cases of 9°, 5 cases of 10°, 2 case of 11°. The postoperative mean medial tibial plate angle was 89.5°±0.5°, mean HKA angle was 179.3°±0.8°. 27(79.4%), 23(67.6%) and 16 (47.1%) cases had restoration of mechanical axis to ±3°, ±2°and ±1°of neutral respectively, and there were 7 (15.2%) outlier (±3°). Excluding 3 cases of actual performed 9°valgus resection angle while preoperative measurement larger than 9°, both components were aligned within 3° of neutral in 88.2% of the knees. 27 (79.4%) cases had lower extremity alignment passing through the middle third of tibial plate, 7 (20.6%) cases pass through the medial third of the tibial plate.
Conclusions
Excellent postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur.
