Controversy exists regarding the ability of unicompartmental knee arthroplasty (UKA) to restore native knee kinematics, with some studies suggesting native kinematics are restored in most or all patients after UKA1–3, while others indicate UKA fails to restore native knee kinematics4,5. Previous analysis of UKA articular contact kinematics focused on the replaced compartment2,5, neglecting to assess the effects of the arthroplasty on the contralateral compartment which may provide insight to future pathology such as accelerated degeneration due to overload6 or a change in the location of cartilage contact7. The purpose of this study was to assess the ability of medial UKA to restore native knee kinematics, contact patterns, and lateral compartment dynamic joint space. We hypothesized that medial UKA restores knee kinematics, compartmental contact patterns, and lateral compartment dynamic joint space. Six patients who received fixed-bearing medial UKA consented to participate in this IRB-approved study. All patients (4 M, 2 F; average age 62 ± 6 years) completed pre-surgical (3 weeks before) and post-surgical (7±2 months) testing. Synchronized biplane radiographs were collected at 100 images per second during three repetitions of a chair rise movement (Figure 1). Motion of the femur, tibia, and implants were tracked using an automated volumetric model-based tracking process that matches subject-specific 3D models of the bones and prostheses to the biplane radiographs with sub-millimeter accuracy8. Anatomic coordinate systems were created within the femur and tibia9 and used to calculate tibiofemoral kinematics10. Additional outcome measures included the center of contact in the medial and lateral compartments, and the lateral compartment dynamic joint space (INTRODUCTION
METHODS
There have been increased concerns with trunnion fretting and corrosion and adverse local tissue reactions (ALTR) in total hip arthroplasty. We report on 11 catastrophic trunnion failures associated with severe ALTR requiring urgent revision arthroplasty. We retrospectively reviewed 10 patients with gross trunnion failure (n=11) and an additional 3 patients with impending trunnion failure.Introduction
Methods
