BACKGROUND: Decreased scapulothoracic upward rotation has been theorized to increase an individual's risk for rotator cuff compression by reducing the clearance for the tendons in the subacromial space (ie, subacromial proximities). However, the impact of decreased scapulothoracic upward rotation on subacromial proximities has not been tested during dynamic in vivo shoulder motion. OBJECTIVE: To determine the impact of decreased scapulothoracic upward rotation on subacromial proximities. METHODS: Shoulder kinematics were quantified in 40 participants, classified as having high or low scapulothoracic upward rotation, during scapular plane abduction using single-plane fluoroscopy and 2-D/3-D shape-matching. Subacromial proximities were calculated as (1) the normalized minimum distance between the coracoacromial arch and humeral rotator cuff insertion, and (2) the surface area of the humeral rotator cuff insertion in immediate proximity to the coracoacromial arch. The effect of decreased scapulothoracic upward rotation on subacromial proximities was assessed using 2-factor mixed-model analyses of variance. The prevalence of contact between the coracoacromial arch and rotator cuff was also quantified. RESULTS: Subacromial distances were generally smallest below 70° of humerothoracic elevation. With the arm at the side, the normalized minimum distance for participants in the low scapulothoracic upward rotation group was 34.8% smaller compared to those in the high upward rotation group (P = .049). Contact between the coracoacromial arch and rotator cuff tendon occurred in 45% of participants. CONCLUSION: Decreased scapulothoracic upward rotation shifts the range of risk for sub-acromial rotator cuff compression to lower angles. However, the low prevalence of contact suggests that subacromial rotator cuff compression may be less common than traditionally presumed.
|Original language||English (US)|
|Number of pages||12|
|Journal||Journal of Orthopaedic and Sports Physical Therapy|
|State||Published - Mar 2019|
Bibliographical noteFunding Information:
1Division of Rehabilitation Science, Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN. 2Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN. 3Division of Physical Therapy, Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN. The Institutional Review Board and the All-University Radiation Protection Advisory Committee at the University of Minnesota approved the study protocol. Research reported in this publication was supported by the National Institutes of Health’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (F31-HD087069 and L30-HD089226), National Institute of Arthritis and Musculoskeletal and Skin Diseases (T32-AR050938), National Center for Advancing Translational Sciences (UL1-TR002494), and National Institute of Biomedical Imaging and Bioengineering (P41-EB015894). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported in part by Promotion of Doctoral Studies II scholarships from the Foundation for Physical Therapy Research, the Minnesota Partnership for Biotechnology and Medical Genomics, and the University of Minnesota’s Department of Orthopaedic Surgery and Clinical and Translational Science Institute. The authors certify that they have no affiliations with or financial involvement in any organization or entity with a direct financial interest in the subject matter or materials discussed in the article. Address correspondence to Dr Rebekah Lawrence, Bone and Joint Center, Henry Ford Health System, 6135 Woodward Avenue, Detroit, MI 48202. E-mail: firstname.lastname@example.org U Copyright ©2019 Journal of Orthopaedic & Sports Physical Therapy®
Copyright © 2019 Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.
- Rotator cuff