Mylène Jansen

302 Chapter 15 Abstract Background : High tibial osteotomy (HTO) and knee joint distraction (KJD) are joint- preserving knee osteoarthritis (OA) treatments that have previously shown good clinical results and cartilage thickness increase. The objective of this exploratory study was to evaluate the change in cartilage T2 relaxation times, as a measure of collagen structure, after treatment with HTO or KJD, and compare this to natural OA progression. Methods : Ten patients indicated for total knee arthroplasty (TKA) were treated with KJD (KJD TKA ). Thirty patients indicated for HTO were treated with KJD (KJD HTO ; n=10) or HTO (n=20). 3T T2-mapping MRI scans were performed before and 1 (KJD groups only) and 2 years after treatment, from which cartilage was segmented and the volume and T2 relaxation times were calculated. Patients were matched with untreated patients from the Osteoarthritis Initiative (OAI) to compare the change in T2 values over time. Results: KJD HTO (n=8) and HTO (n=17) patients both showed statistically significant increases in T2 values but no volume changes. KJD TKA patients (n=8) only showed a tendency for (first- year) T2 value increase, and a significant volume increase in the most affected compartment (MAC). There were no significant differences between the 3 groups. All treated patients combined showed a significantly higher increase in T2 times than untreated patients from the OAI for both femur and tibia. Conclusion: KJD and HTO treatment result in a significant T2 value increase. In TKA- indicated KJD patients, this goes paired with volume increase, indicating it may be the result of maturation of newly formed cartilage.