Improved kinematics of unrestrained arm raising in C5-C6 tetraplegic subjects after deltoid-to-triceps transfer

Abstract

Study design: Prospective comparative study. Objective: To determine whether control of upper limb joint synergy during unrestrained arm raising involving shoulder and elbow flexion is modified by deltoid-to-triceps transfer. Setting: Rehabilitation unit for spinal cord injury patients, France. Methods: Five C6 subjects with C5-C6 tetraplegia sustained posterior deltoid-to-triceps transfer and were compared to a control group of 11 subjects. Kinematics of shoulder and elbow joints before, 6 month and 1 year after surgery, during straight-arm raising (SAR) in the plane of the scapula and hand-to-nape-of-neck movements (HNNMs) were explored. Motion was recorded with a six-camera Vicon motion analysis system and the data used to assess the coupling of elbow and shoulder flexion velocities (EFVs and SFVs) and extension velocities. Results: All subjects were initially assessed at 6.9 months (mean) postsurgery. Three of the upper limbs were assessed a second time (mean 17.9 months). The first assessment showed an increase in shoulder flexion amplitudes in tetraplegic subjects with presurgery shoulder flexion deficits. Peak SFVs and EFVs and extension velocities were slightly modified at the first postsurgery assessment and dramatically improved at the second assessment during both SAR and HNNM. Despite these increased velocities, joint coordination was only partially restored. Conclusion: A restored elbow active extension improves the speed of elbow flexion. The additional improvement of shoulder motion emphasises the relation between joints in the control of arm movement.