Kinematics and electromyographic analysis of three types of internal rotation in the shoulder
Bentham Science PublishersInternal rotation of the shoulder—the inward rotation of the arm—is essential for many everyday tasks. Reaching behind the back to tuck in a shirt, fastening a bra strap, retrieving a wallet from a back pocket, all depend on a specific form of internal rotation in which the hand moves upward behind the back toward the spine. Clinicians commonly assess this capacity in patients with adhesive capsulitis, rotator cuff tears, and after shoulder arthroplasty using three clinical tests: internal rotation at the side (IRs), with the elbow at the side and the forearm swinging inward; internal rotation at 90°, abduction (IRa) with the arm abducted and rotated downward; and internal rotation to the posterior (IRp), in which the hand reaches upward behind the back. These tests are often used together in clinical practice, yet little research has examined whether they measure the same underlying motion or different ones. This distinction matters when clinicians encounter patients whose IRp is severely limited while IRs appears near normal, or when IRp deficits prove resistant to rehabilitation.
- Journal
- The Open Orthopaedics Journal