Gait assessment of osteosarcoma patients undergoing total knee arthroplasty: Influence of abduction-adduction angles in knee prostheses.

Abstract

Bone tumors often affect the knee, necessitating total knee arthroplasty for functional restoration. While rotating hinge prostheses enable biaxial movement, an ideal design should replicate natural multi-axis motion. A proposed ball-axis prosthesis with an open coronal plane has undergone in vitro finite element validation but lacks in vivo assessment. This study aims to deeply explore the influence of abduction-adduction freedom of the open prosthesis knee joint on the gait function of patients in vivo. We recruited 8 patients with ball-axis prostheses, 8 with rotating hinge knee prostheses, and 8 healthy controls to collect three-dimensional motion data and ground reaction forces during normal gait. The joint angles and moments of the lower extremities were calculated using the musculoskeletal model. The characteristic parameters of the joint angle and moment curves were calculated, and one-way analysis of variance was used to evaluate the mean differences between groups. Compared to the rotating hinge prosthesis, the ball-axis prosthesis exhibited significantly lower gait speed, peak knee flexion during the swing phase, and peak anterior ground reaction force (p = 0.030, p = 0.010, p = 0.018). Despite the opened coronal plane freedom, there was no significant difference in gait abduction-adduction range compared to the rotating hinge prosthesis or healthy controls. This study indicates the patients with ball-axis prosthesis had weaker propulsion and did not expand the abduction-adduction range as expected. The in vivo gait analysis of ball-axis prostheses provides a valuable reference for future prosthetic design improvements.