Trunk and upper extremity kinematics during sitting pivot transfers performed by individuals with spinal cord injury.

BACKGROUND: Although reaching an optimal level of independence during sitting pivot transfer is crucial for individuals with spinal cord injury, little is known regarding the kinematic requirements of this functional task.
METHODS: Ten males with spinal cord injury performed independent sitting pivot transfers between an initial seat and a target one placed at same (50 cm), lower (40 cm), and higher heights (60 cm) than the initial one, using their usual movement strategies. Three-dimensional trunk, shoulder, elbow and wrist kinematics were collected bilaterally during sitting pivot transfers. Each sitting pivot transfer was divided into three phases for analysis: pre-lift, lift-pivot and post-lift. Temporal parameters were also documented.
FINDINGS: Peak shoulder extension displacement and velocities were always higher at the leading shoulder compared to the trailing one (P<0.004), and almost coincided with peak trunk velocities early during the lift phase. With increasing target seat height, shoulder flexion (P<0.011) and elbow extension (P<0.013) displacements and velocities of the trailing upper extremity augmented and reached higher values at this upper extremity compared to the leading upper extremity, with one exception at the shoulder. Elbows generally remained flexed (min=28-56 degrees ) during the lift phase of all transfers whereas extreme wrist extension positions (max=84-88 degrees ) were documented across all transfers. Total durations of transfers (2.6-2.8s) and lift-pivot phases (1.0-1.3s) were not affected by target seat heights.
INTERPRETATION: Sitting pivot transfers are characterized by substantial angular displacements and velocities at the trunk and upper extremities. Some kinematic parameters documented during sitting pivot transfers may increase the risk of developing secondary musculoskeletal impairments in this population.