Posterior Osteophyte Resection from the Medial Femoral Condyle Increases Medial Gap of Extension and Mid-Flexion in Total Knee Arthroplasty

Abstract

Background The present study aimed to determine the effect of posterior osteophyte resection from the medial femoral condyle on the medial gap increase in varus osteoarthritis during posterior-stabilized total knee arthroplasty (TKA). Methods One hundred and eight cases of primary posterior-stabilized TKA for varus knee osteoarthritis were reviewed retrospectively. In a preoperative lateral view of the knee radiograph, 39 cases had the largest size osteophyte of the posterior femoral condyle > 5 mm (large osteophyte group) and 69 cases had 0 to 5 mm (small osteophyte group). After femoral component trial insertion, the posterior osteophyte of the medial femoral condyle was removed using a curved osteotome. Medial and lateral joint gaps at 0 degrees, 45 degrees, and 90 degrees of flexion were measured intraoperatively before and after the posterior osteophyte resection from the medial femoral condyle. Results The large osteophyte group showed a significantly larger increase in medial gap change at 0 degrees and 45 degrees of flexion than the small osteophyte group (medial gap increase at 0 degrees: 0.2 +/- 0.4 mm in the small osteophyte group and 2.9 +/- 1.4 mm in the large osteophyte group, p < 0.001; medial gap increase at 45 degrees: 0.3 +/- 0.5 mm in the small osteophyte group and 1.7 +/- 0.8 mm in the large osteophyte group, p < 0.001). At 0 degrees and 45 degrees of flexion, medial gap values after osteophyte resection were significantly larger than before osteophyte resection in both groups (p < 0.001). In linear regression analysis, posterior osteophyte size was also significantly associated with medial gap change at 0 degrees and 45 degrees of flexion (p < 0.001). Conclusions Resection of large posterior osteophytes > 5 mm from the medial femoral condyle can be expected to result in a larger increase in the medial gap than resection of osteophytes <= 5 mm. Surgeons need to pay close attention to these intraoperative changes in the medial gap after posterior osteophyte resection to achieve appropriate mediolateral balance during TKA.