Mylène Jansen

352 Chapter 17 Abstract Background : Knee joint distraction (KJD) treatment has shown cartilage repair and clinical improvement in patients with osteoarthritis, as has high tibial osteotomy (HTO). Following KJD, in synovial fluid (SF) an increase was shown in transforming growth factor- β 1 (TGF β - 1) and interleukin-6 (IL-6), factors related to cartilage regeneration, but also to osteophyte formation. As such, osteophyte formation resulting of both joint-preserving treatments was studied. Methods : Radiographic osteophyte size was measured before treatment and 1 and 2 years after treatment. Changes were compared with natural progression in patients from the CHECK cohort just before undergoing total knee arthroplasty. An additional KJD cohort underwent SF aspiration, and 1-year Altman osteophyte score changes were compared to SF-marker changes during treatment. Results : After 2 years, both KJD (n=58) and HTO (n=38) patients showed a significant increase in osteophyte size (+6.2 mm 2 and +7.0 mm 2 respectively; both p< 0.004), with no significant differences between the treatments ( p= 0.592). Untreated CHECK patients (n=44) did not show significant 2-year changes (+2.1 mm 2 ; p= 0.207) and showed significant differences with KJD and HTO (both p< 0.044). In SF aspiration patients (n=17), there were significant differences in TGF β -1 changes ( p= 0.044), but not IL-6 ( p= 0.898), between patients with a decrease, no change, or increase in osteophyte Altman score. Conclusion : After KJD treatment, joint space widening and clinical improvement are accompanied by osteophyte formation, observed similarly after HTO. Increased osteophytosis after joint-preserving treatments may be a bystander effect of cartilage repair activity related to intra-articular factors like TGF β -1 and questions osteophyte formation as solely characteristic of the joint degenerative process.