Limited Forearm Motion Compensated by Thoracohumeral Kinematics When Performing Tasks Requiring Pronation and Supination

作者：Pereira Barry P^*; Thambyah Ashvin; Lee Taeyong

来源：Journal of Applied Biomechanics, 2012, 28(2): 127-138.

DOI：10.1123/jab.28.2.127

• activities of daily living
• compensatory mechanisms
• forearm biomechanics
• limited forearm rotation
• shoulder kinematics

This study investigates the altered thoracohumeral kinematics when forearm rotation is restricted while performing five activities requiring pronation and supination. Two splints simulated both a fixed-supinated or fixed-neutral forearm in six healthy subjects; the three-dimensional coupled relationship among motion about the forearm, elbow, and shoulder were analyzed. In using a screwdriver, the normal range of forearm rotation of 77.6 degrees (SD = 30.8 degrees) was reduced in the fixed-supinated to 11.3 degrees (SD = 2.9 degrees) and fixed-neutral to 18.2 degrees (SD = 6.2 degrees). This restriction from the fixed-supinated and fixed-neutral forearms was compensated at the shoulder by a significant increase in the total range of (1) ad/abduction by 57.3 degrees and 62.8 degrees respectively (p %26lt; .001), (2) forward-reverse flexion (24.3 degrees and 18.2 degrees respectively; p %26lt; .05) and (3) internal-external rotation (37.1 degrees and 44.2 degrees respectively; p %26lt; .001). A similar result was demonstrated for the doorknob activity. The elbow did not significantly contribute to forearm rotation (p = .14), and is believed to be due to the elbow axis being orthogonal and oblique to the forearm axis. For open kinetic-chain activities, with a fixed-supinated forearm performing there was a significant coupled increase in ad/abduction (p %26lt; .05) and it/external rotation (p %26lt; .05) for the phone and feeding tasks, with the phone task also having a significantly increased forward shoulder flexion (p %26lt; .05). For the fixed-neutral forearm, significant compensatory movement was only seen in the feeding task with increased ad/abduction and internal-external shoulder rotation (p %26lt; .05) and the card inserting task with increased ad/abduction and forward-reverse shoulder flexion. Limited forearm function requires compensatory motion from adjacent joints to perform activities that require pronation and supination. This study quantifies the compensatory mechanism about the shoulder in a forearm limited in prosupination.

• 出版日期2012-5