抄録
Objective: In total knee arthroplasty (TKA), if osteotomy is performed to remove an equal amount of the thickness of the distal femoral component in patients who exhibit severe abrasion in the distal femoral condyle, a large degree of osteotomy is required, which can result in an increase of overhang in the proximity of the posterior femoral condyle. We simulated the position of the components by using the preoperative planning software Athena® (Soft Cube, Osaka, Japan), and measured the distance of overhang of the posterior femoral component.
Methods: The subjects were 202 knees from 137 consecutive patients with varus osteoarthritis who were scheduled to undergo TKA. Computed tomography (CT) scans of each lower extremity were obtained preoperatively for each patient. The thickness of the distal and posterior condyle was 9 mm in this component of the investigation. Overhang in the posteromedial and posterolateral condylar areas was measured following three distal femoral osteotomy procedures as follows; 1) 9 mm was removed from the distal medial condyle, 2) 9 mm was removed from the distal lateral condyle, and 3) measurement was performed at the level of the femoral intercondylar notch.
Results: The 9 mm distal medial condylar osteotomy value for the posteromedial condyle was 1.6 ± 1.3 mm and for the posterolateral condyle was 2.8 ± 2.3 mm, respectively. The 9 mm distal lateral condylar osteotomy value for the posteromedial condyle was 3.0 ± 1.7 mm and for the posterolateral condyle was 4.1 ± 2.0 mm, respectively. Osteotomy at the level of the femoral intercondylar notch on the medial side was −0.1 ± 1.2 mm and on the lateral side was 1.0 ± 1.9 mm, respectively.
Conclusion: When osteotomy was performed at the level of the femoral intercondylar notch, it seemed to have less of an abrasive effect on the joint surface. As a result, the posteromedial condyle was able to maintain its original form, and overhang in the posterolateral condyle was the smallest in the three procedures. It suggests that this procedure may be able to restore the original form of the femoral condyle.
