Mylène Jansen

MRI cartilage thickness after KJD and HTO 285 14 Prediction of cartilage thickness changes Kellgren-Lawrence grade and treatment were the strongest statistically significant predictors of MAC cartilage thickness change. A higher Kellgren-Lawrence grade was associated with in a greater increase in cartilage thickness during treatment ( B =0.174; R 2 =0.255; p= 0.002). Detailed results can be found in the supplementary data. A Kruskal-Wallis test confirmed that, for KJD patients, the distribution of the MAC cartilage thickness change was not the same across the different Kellgren-Lawrence grades ( p= 0.009). Post-hoc tests identified statistically significant differences between grade 1 – 3, grade 1 – 4, grade 2 – 3 and grade 2 – 4. Separating KJD patients in those with mild OA (Kellgren-Lawrence grade ≤2; KJD mild ) and with severe knee OA (Kellgren-Lawrence grade ≥3; KJD severe ) resulted in the best fit of the univariable regression model ( B =0.209; R 2 =0.317; p< 0.001): KJD patients with severe OA showed a significantly greater increase in cartilage thickness than those with mild OA. Longitudinal changes by baseline severity Since baseline OA severity was the strongest predictor for cartilage tissue changes over time, and had a stronger influence than the trial in which patients were included, the main MRI and JSW outcome parameters are presented here comparing mild and severe OA groups irrespective of the trial the patients originated from. Additionally, severe KJD patients are compared with severe HTO patients, and mild KJD patients with mild HTO patients. The changes over time for the different groups are shown in Table 3; the differences between the groups are shown in Table 4. Table 3 : Two-year changes for mild and severe knee joint distraction and high tibial osteotomy patients KJD mild KJD severe HTO mild HTO severe MAC ThCtAB (mm) -0.19 (-0.36 to -0.02) 0.23 (0.10 to 0.35) -0.10 (-0.20 to -0.01) -0.13 (-0.31 to -0.05) MAC dABp (%) 2.3 (-1.1 to 5.6) -6.1 (-10.1 to -2.2) 1.2 (-0.2 to 2.6) 5.3 (0.0 to 10.5) Mean MAC JSW (mm) 0.04 (-0.38 to 0.47) 0.78 (0.32 to 1.24) 0.46 (0.14 to 0.79) 0.47 (-0.09 to 1.03) Mean changes and 95% confidence interval are shown. dABp: percentage of denuded subchondral bone area; HTO mild : high tibial osteotomy patients with mild osteoarthritis (OA); HTO severe : HTO patients with severe OA; JSW: joint space width; KJD mild : knee joint distraction (KJD) patients with mild OA; KJD severe : KJD patients with severe OA; MAC: most affected compartment; ThCtAB: mean cartilage thickness over the total subchondral bone area.