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 (CONTetraplegic) with varying levels of triceps function together with a healthy control group (CONHealthy)) 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 co-ordination 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 CONHealthy 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. Co-ordination 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.