Mechanical evaluation of the KneeReviver device under axial loading in knee joint distraction therapy for tibiofemoral osteoarthritis treatment – a cadaver study

Objective: Knee joint distraction is a treatment for younger patients (ages 45–65) with tibiofemoral osteoarthritis, aimed at unloading cartilage through separation of the femur and tibia. The KneeReviver is a device specifically developed for this kind of treatment. While the KneeReviver has proven successful for some, the results vary among patients, highlighting the need for a deeper understanding of its mechanical behavior. This study aims to investigate the mechanical working principle of the KneeReviver under varying axial loads. Design: An experimental study using five cadaveric knees measured tibiofemoral contact pressures, joint space width narrowing, and spring compression under axial loads of 0, 1.2, 1.5, and 3 times body weight, with and without the KneeReviver. Results: It was found that the KneeReviver effectively reduced contact parameters (peak pressure, mean pressure, contact area, and load on cartilage) across all loads in all five cadavers. However, at physiological loading while walking with crutches (1.2 times body weight), the joint space was not fully maintained. Spring compression increased with loading up to 1.2 times body weight but remained constant at higher loads. Conclusions: This study confirmed the unloading effect of the KneeReviver. However, it also showed that the joint gap is not fully maintained during the treatment. Furthermore, this study also showed that elastic deformation of bone pins plays a more significant role in joint gap narrowing than the compression of internal device springs.