Effect of posterior condylar offset on early results after posterior-stabilized total knee arthroplasty

Abstract

Objective To explore the effect of the posterior condylar offset (PCO) on clinical results after total knee arthroplasty (TKA) using a high-flex posterior-stabilized (PS) fixed-bearing prosthesis. Methods Clinical and radiographic materials of 107 consecutive female patients (107 knees), who had undergone primary TKAs for end-stage osteoarthritis was prospectively analyzed. All operations were performed by using the same operative technique. Based on the corrected PCO change, all cases were divided into two groups: 66 knees in which the corrected PCO change ≥0 mm (aged 48-73 years, with an average of 61.4 years) and 41 knees in which the corrected PCO change < 0 mm (aged 52-75 years, with an average of 62.2 years). One-year post-operatively, clinical and radiographic variables from the two groups were compared by independent t-test. The associations between the corrected PCO changes and the improvements of clinical variables in all patients were analyzed by Pearson linear correlation. Results The corrected PCO change was 2.49±1.71 mm in the PCO change ≥0 mm group and -1.28±1.41 mm in the PCO change < 0 mm group. One-year postoperatively, the Knee Society scores, the Western Ontario and McMaster Universities Osteoarthritis Index, non-weight-bearing active and passive range of knee flexion, flexion contracture, and their improvements had no statistical differences between the two groups. The corrected PCO change was not significantly correlated with the improvement of any clinical variable. While the PCO change ≥0 mm group (130.40°±11.63°) demonstrated greater flexion than the PCO change < 0 mm group (123.80°±13.12°) during active weight-bearing one year after TKA, which was significantly different between the two groups (t=2.11 , P=0.0401). Conclusion Restoration of PCO plays an important role in the optimization of active knee flexion during weight-bearing conditions after posterior-stabilized TKA, while it had no benefit to non-weight-bearing knee flexion and any other clinical result. Key words: Arthroplasty, replacement, knee; Range of motion, articular; Treatment outcome