Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer

Study design: Cross-sectional study. Objectives: To quantify three-dimensional (3D) reachable workspace in different groups of tetraplegic participants and to assess their reaching performance within this workspace. Setting: Northwest Regional Spinal Injuries Centre, UK. Methods: The 3D reachable workspace of three groups of tetraplegics (NON-OP, operated group (OP) and tetraplegic control group (CON(Tetraplegic)) with varying levels of triceps function together with a healthy control group (CON(Healthy))) was defined by reaching to five target positions (anterior, medial, lateral, superior and inferior) located on the periphery of their workspace. Joint angles and inter-joint coordination were analysed after a 3D reconstruction of the thorax, humerus and forearm. The performance related variables of movement time, peak velocity, time-to-peak velocity and curvature index were also examined. Results: The reachable volumes covered were consistent with the level of triceps function as CON(Healthy) covered a significantly greater volume than the tetraplegic groups and in turn the OP covered a larger workspace volume than NON-OP. The reduced workspace of tetraplegics was identified as being due to restrictions in workspace above shoulder height and across the body. Coordination data identified some differences in movement patterns but when reaching to targets on the workspace there were no significant differences between the OP and NON-OP groups. Conclusion: This study provided a detailed assessment of reachable workspace and target reaching. Tetraplegic participants found the superior and medial parts of the workspace were the most challenging directions. Standardised biomechanical analysis of tetraplegic upper-limb function is required for objective assessment. Spinal Cord (2010) 48, 619-627; doi:10.1038/sc.2009.193; published online 12 January 2010