Influence of Posterior Condylar Offset on Maximal Flexion and Outcome Scales Following TKA in Asian Patients

Abstract

Background: Infection complicates traditional joint reconstruction prostheses in up to 7% of cases, witBackground: Alteration in femoral posterior condylar offset (PCO) after total knee arthroplasty (TKA) has been reported to influence maximal flexion angle after TKA. However, there are contradictory reports about its influence on clinical outcome, and the effects of PCO alterations may vary with implant type. Question / purposes: The purpose of this study was to determine whether PCO alterations affect maximal flexion after TKA and other functional outcomes, and whether the effects of PCO alterations differ by implant type. Patients and Methods: Fifty consecutive cases of TKAs in each of four implant types, namely, fixed bearing (FB) cruciate retaining (CR) or posterior stabilized (PS), mobile bearing (MB) CR or PS were included in the study. Patients were evaluated for maximal flexion and clinical outcome scales. The PCO alteration was measured using pre- and postoperative true lateral knee radiographs. Correlations between PCO alterations and functional outcomes including maximal flexion were compared among the four implant types. Results: No significant correlation was found between PCO alterations and maximal flexion achieved in any of the four implant groups (Correlation Coefficient [CC]=-0.03, 0.14, -0.14, 0.04; p> 0.05). The mean maximal postoperative flexion was greater in PS implants than in CR implants (p <0.05). In MB-CR implanted knees, a greater PCO alteration was correlated with worse anterior knee pain score as measured by the PF scoring system (CC=-0.44, p=0.003) and worse WOMAC pain score (CC=-0.41, p=0.007). Conclusions: Our findings indicate that PCO alterations have no effect on maximal postoperative flexion after TKA regardless of the implant type. Whether the implant is of PS or CR type is a better predictor of the final flexion achieved. However, increased PCO is correlated with worse pain score in MB-CR implants.