Objective: Gap planning in navigated total knee arthroplasty (TKA) is a critical concern. Osteophytes are normally removed prior to gap planning, with the exception of posterior condylar osteophytes of the femur, which are removed after posterior condylar resection. This study investigated how posterior condylar osteophytes affect gap balancing during surgery.
Methods: This prospective study was conducted on 40 primary varus osteoarthritic knees with a posterior condylar osteophyte that underwent TKA navigation. For all knees, computed tomography (CT) was performed to evaluate osteophyte position. The extension gap and flexion gap were determined under navigation using a tension device with a distraction force of 44 lb. The extension gap and flexion gap were measured before and after osteophyte removal.
Results: This study revealed that the average osteophyte thickness after removal was 7.75 ± 5.34 mm. The average extension gap change was 0.64 ± 0.80 mm, and the average flexion gap change was 0.85 ± 1.12 mm. With respect to increases in the medial extension gap, lateral extension gap, medial flexion gap and lateral flexion gap, the average effects of posterior condylar osteophyte removal were 0.74 ± 0.81 mm, 0.53 ± 0.96 mm, 0.71 ± 0.97 mm and 1.00 ± 1.41 mm, respectively. Posterior condylar osteophyte thickness was also significantly associated with increases in the lateral extension gap (R2 = 0.107, p = 0.03), medial flexion gap (R2 = 0.101, p = 0.04) and lateral flexion gap (R2 = 0.107, p = 0.04).
Conclusion: These results indicated that posterior condylar osteophytes of the femur affect gap balancing during TKA navigation.
Keywords: Computer-assisted surgery; Gap balancing; Posterior condylar osteophyte; Total knee arthroplasty.