Knee joint distraction is an experimental treatment for knee OA, aimed at temporarily unloading the joint cartilage and subchondral bone by use of an external fixation frame. The technique proved to be clinically long-term effective for end-stage ankle OA. This clinical improvement was supported by structural tissue changes significant improvement of the joint space width and normalization of bone sclerosis as evaluated by digital X-ray analysis. Since knee OA occurs more often and has a greater socio-economical impact than ankle OA, joint distraction as a therapy was applied for the knee. So far two years follow-up results of the first study on knee joint distraction are available demonstrating significant cartilage repair, as analyzed by quantitative MRI analysis. Additionally, X-rays were taken under full weight bearing, demonstrating the mechanical competence of the formed tissue. Collagen type II biomarkers showed a significant increase in synthesis, suggesting the newly formed cartilaginous tissue is hyaline cartilage. Importantly, this structural cartilage repair is accompanied by significant clinical improvement in pain and function, sustaining for at least two years.
These clinical data are supported by several OA animal studies also demonstrating both structural changes and clinical improvement.
As this cartilage repair activity is unique, this provides for the first time the opportunity to study the unknown mechanism required for cartilage repair. Acquiring this knowledge will open new frontiers to establish actual treatment of a still incurable joint disease.
The cartilage repair activity as observed by joint distraction cannot be solely the result of the matrix synthesis by the resident chondrocytes. It is anticipated that intrinsic mesenchymal stem cells (MSCs) activity plays a crucial role in the observed cartilage repair activity. MSCs can originate from (peri-articular) bone marrow, cartilage, synovium, synovial fluid, and infrapatellar/sub-synovial fat pad. Apparently, joint distraction provides the appropriate biomechanical intra-articular milieu, facilitating MSCs in their cartilage repair activity.
Disclosure of Interest None Declared
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