Evaluation of Upper Extremity Reachable Workspace in Children With Brachial Plexus Birth Injury

Purpose: Brachial plexus birth injury (BPBI) results in upper extremity (UE) movement limitations. Current assessments of UE function used to inform clinical decision-making only evaluate a limited set of static postures and/or movements and have been criticized for being insensitive to certain meaningful differences in function. Reachable workspace provides a numeric and visual assessment of global UE movement ability by quantifying the regions in space that patients can reach with their hands, and it can be collected using real-time feedback to elicit a best-effort acquisition of function. This study evaluated the ability of a real-time feedback reachable workspace tool to assess UE movement in BPBI. Methods: Twenty-two children with BPBI participated. Reachable workspace data were collected with three-dimensional motion capture using real-time visual feedback to measure UE reaching ability in all regions surrounding the body. All outer, far-from-body points reached by the hand were recorded and analyzed by region. A two-way, within-subjects analysis of variance was used to assess interlimb differences in percentage workspace reached and median reach distance for each of the six regions. Results: The affected limb had significantly less percentage workspace reached than the unaffected limb for all six regions (mean interlimb differences by region, 5.7%–38.6%). The affected limb had significantly less median reach distance than the unaffected limb for all six regions (mean interlimb differences by region, 3.1%–36.8%). Conclusions: The workspace approach was capable of detecting UE movement impairments of the BPBI-affected limb. The reported deficits in workspace on the affected limb correspond to common movement impairments in BPBI, such as limitations in shoulder elevation, external rotation, extension, and elbow extension. Clinical relevance: The real-time feedback reachable workspace tool is sufficiently robust for assessing UE movement impairments in children with BPBI.