Knee joint distraction in tibiofemoral osteoarthritis: evaluating the impact of bone pins and springs on the mechanical performance of the KneeReviver device

Knee joint distraction is a joint-preserving treatment for younger patients (45-65 years) with tibiofemoral osteoarthritis, aiming to unload cartilage by temporarily separating the femur and tibia. The KneeReviver (KR) is a distraction device specifically developed for this purpose. Despite clinical successes, inter-patient variability in outcomes indicate a limited understanding of its mechanical behavior. This study evaluates the mechanical contribution of KR's bone pins and springs using finite element (FE) modeling. Variations in bone pin length, diameter, and the inclusion of KR's springs were assessed in terms of contact mechanics, initial joint gap creation, and gap narrowing under axial load. Results showed that smaller pin diameters, longer pin lengths, and the inclusion of springs increased cartilage contact pressures, reduced initial joint gaps, and led to earlier joint gap closure. These findings identify critical mechanical factors that may inform future device design, patient-specific configurations, and surgical application strategies.