D.P.26 3D kinematic and EMG study of the arm function in boys with DMD: A pilot study

Abstract

Duchenne muscle dystrophy (DMD) is a muscular disorder characterized by progressive muscle weakness, resulting in loss of functions. With increasing life expectancy, the preservation of functional abilities becomes increasingly important. Good assistive arm supports however are rare and do not support the full range of arm functional abilities. For designing new functional arm support a good knowledge of the pattern of arm function loss is needed. Therefore a new measurement protocol, using 3D kinematics and surface electromyography (sEMG), was developed. Five boys with DMD (12.03years, sd 2.52, range 8–15, Brooke 1–4) and 6 age matched controls participated in this pilot study. Standardized (StM) and non standardized (NStM) single joint movements and ADL activities were examined by means of 3D-Vicon motion analysis in combination with sEMG. Outcome measures were: normalized EMG amplitude, passive range of motion (pROM), active range of motion (aROM) and the absolute difference between pROM and aROM. Patients used significantly more of their maximal muscle capacity to conduct StM and NStM compared to controls, also seen in compensatory muscles. pROM was significantly lower in patients in 4 out of 10 movements. aROM of StM was significantly lower in patients in 5 out of 10 movements and aROM of NStM was significantly lower in 7 out of 10 movements. The difference between pROM and aROM was larger in patients than controls for all shoulder movements. A strong relation between age of patients and muscle capacity as well as aROM was seen. The protocol was found feasible for measuring arm function in boys with DMD. The tool was able to discriminate between patients and controls and also between different stages of the disease. Patients used relatively more muscle capacity to conduct arm movements and have a decreased pROM and aROM with increasing age.