Reachable workspace and performance of upper limb (PUL) in Duchenne muscular dystrophy

Introduction: The Kinect-based reachable work-space relative surface area (RSA) is compared with the performance of upper limb (PUL) assessment in Duchenne muscular dystrophy (DMD). Methods: 29 individuals with DMD (ages: 7-23; Brooke: 1-5) underwent both Kinect-based reachable workspace RSA and PUL assessments. RSAs were also collected from 24 age-matched controls. Total and quadrant RSAs were compared with the PUL total, shoulder-, middle-, and distal-dimension scores. Results: The total reachable workspace RSA correlated well with the total PUL score (Spearman rho = -0.602; P < 0.001), and with each of the PUL dimensional scores: shoulder (rho = -0.624; P < 0.001), middle (rho = -0.564; P = 0.001), and distal (rho = -0.630; P < 0.001). With quadrant RSA, reachability in a particular quadrant was closely associated with respective PUL dimensional-level function (lateral-upper quadrant for shoulder-, lateral-upper/lower quadrants for middle-, and lateral-lower quadrant for distal-level function). Conclusions: This study demonstrates concurrent validity of the reachable workspace outcome measure (RSA) with the DMD-specific upper extremity outcome measure (PUL).