Laura Peeters

The trunk in Duchenne Muscular Dystrophy | 81 4 Active range of motion and joint torque The maximum trunk angles were significantly lower (p<0.05) in all movement directions for DMD patients compared to HC (Figure 1). Only trunk axial rotation showed a significant relation (p=0.014) with Brooke scale, where smaller angles were seen with a higher Brooke scale (Additional file 1). DMD patients had significantly (p<0.01) lower joint torques compared to HC in all muscle groups and tasks both with and without normalization to body weight (Table 2). However, a significant (p<0.05) effect of Brooke scale was only found when correcting the joint torques for body weight, except for the trunk extension torque (Table 2, Additional file 2). Both with and without correction for body weight, trunk torque was already approximately two times smaller in DMD patients with Brooke scale 1 compared to HC. Performing daily activities Trunk ROM in one or more movement directions was significantly higher in DMD patients compared to HC in all of the reaching and daily tasks (Figure 2, Additional file 3). Increased lateral bending was seen for all tasks, except for reaching laterally at nearby distance, and increased trunk flexion-extension was seenfor most of the nearby reaching tasks, i.e. reaching at arm length distance. However, the change in trunk ROM with task difficulty (e.g. object weight), was not significantly different Healthy DMD p-value HC vs DMD p-value Brooke scale n median IQR n median IQR Joint torque [Nm] Trunk (flexion) 25 47.5[24.5-58.2] 17 20.3 [14.8-25.0] 0.001 0.120 Trunk (extension) 25 43.9[19.8-78.6] 16 21.4 [14.3-30.8] 0.003 0.673 Trunk (lateral bending) 25 44.4[27.5-65.2] 17 23.6 [17.0-33.1] 0.001 0.355 Shoulder elevation 25 50.0[30.1-95.8] 17 18.2 [12.6-24.4] <0.001 0.244 Shoulder abduction 25 30.6[20.0-46.9] 17 11.9 [4.4-14.8] <0.001 0.019 Joint torque [Nm/kg] Trunk (flexion) 25 0.94[0.73-1.09] 15 0.43 [0.34-0.52] <0.001 0.009 Trunk (extension) 25 0.81[0.72-1.25] 14 0.41 [0.31-0.52] <0.001 0.585 Trunk (lateral bending) 25 0.99[0.88-1.14] 15 0.45 [0.39-0.64] <0.001 0.014 Shoulder elevation 25 1.10[0.9-1.76] 15 0.34 [0.26-0.56] <0.001 0.027 Shoulder abduction 25 0.69[0.61-0.8] 15 0.2 [0.08-0.28] <0.001 0.012 Table 2 Maximum joint torques (in Nm and Nm/kg) of trunk and shoulder.