Mechanical subacromial rotator cuff compression is one theoretical mechanism in the pathogenesis of rotator cuff disease. However, the relationship between shoulder kinematics and mechanical subacromial rotator cuff compression across the range of humeral elevation motion is not well understood. The purpose of this study was to investigate the effect of humeral elevation on subacromial compression risk of the supraspinatus during a simulated functional reaching task. Three-dimensional anatomical models were reconstructed from shoulder magnetic resonance images acquired from 20 subjects (10 asymptomatic, 10 symptomatic). Standardized glenohumeral kinematics from a simulated reaching task were imposed on the anatomic models and analyzed at 0, 30, 60, and 90° humerothoracic elevation. Five magnitudes of humeral retroversion were also imposed on the models at each angle of humerothoracic elevation to investigate the impact of retroversion on subacromial proximities. The minimum distance between the coracoacromial arch and supraspinatus tendon and footprint were quantified. When contact occurred, the magnitude of the intersecting volume between the supraspinatus tendon and coracoacromial arch was also quantified. The smallest minimum distance from the coracoacromial arch to the supraspinatus footprint occurred between 30 and 90°, while the smallest minimum distance to the supraspinatus tendon occurred between 0 and 60°. The magnitude of humeral retroversion did not significantly affect minimum distance to the supraspinatus tendon except at 60 or 90° humerothoracic elevation. The results of this study provide support for mechanical rotator cuff compression as a potential mechanism for the development of rotator cuff disease.
Bibliographical noteFunding Information:
Grant sponsor: Eunice Kennedy Shriver National Institute of Child Health and Human Development; Grant number: R03-HD070871; Grant sponsor: National Institute of Arthritis and Musculoskeletal and Skin Diseases; Grant number: T32-AR050938; Grant sponsor: National Institute of Child Health and Human Development; Grant number: F31-HD087069; Grant sponsor: Foundation for Physical Therapy. Correspondence to: Paula M. Ludewig (T: 612-626-0420; F: 612-625-4274; E-mail: firstname.lastname@example.org)
This project was supported by Award Number R03-HD070871 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (P.M.L.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the Eunice Kennedy Shriver National Institute of Child Health and Human Development or the National Institutes of Health. This project was also supported by a pre-doctoral training grant (T32-AR050938) through the National Institute of Arthritis and Musculoskeletal and Skin Diseases (R.L.L.), a pre-doctoral fellowship (F31-HD087069) through the National Institute of Child Health and Human Development (R.L.L.), and pre-doctoral scholarships through the Foundation for Physical Therapy (R.L.L. and J.L.S.). One author (J.P.B.) receives research funding from Stryker Corporation. No funds received from Stryker were used for this project.
- subacromial impingement