Mylène Jansen

378 Chapter 18 Abstract Background: Increased subchondral cortical bone plate thickness and trabecular bone density are characteristic of knee osteoarthritis (OA). Knee joint distraction (KJD) is a joint-preserving knee OA treatment where the joint is temporarily unloaded. It has previously shown clinical improvement and cartilage regeneration, indicating reversal of OA-related changes. The purpose of this research was to explore 3D subchondral bone changes after KJD treatment using computed tomography (CT) imaging. Methods: Twenty patients were treated with KJD and included to undergo knee CT imaging before, 1, and 2 years after treatment. Tibia and femur segmentation and registration to canonical surfaces were performed semi-automatically. Cortical bone thickness and trabecular bone density were determined using an automated algorithm. Statistical parametric mapping (SPM) with 2-tailed F -tests was used to analyze whole-joint changes. Bone shape changes were explored visually. Results : Data was available of 16 patients. Subchondral cortical bone plate thickness and trabecular bone density were higher in the weight-bearing region of the affected compartment (MAC; mostly medial). Especially the MAC showed a decrease in thickness and density in the first year after treatment, which was sustained towards the second year. Shape changes showed the femoral condyles became more convex while the tibial condyles became less concave, especially during the second year after treatment. Conclusion: KJD treatment results in bone changes that include thinning of the subchondral cortical bone plate, decrease of subchondral trabecular bone density, and improved bone shape in the first 2 years after treatment, potentially indicating a partial normalization of subchondral bone.