Lawrence RL, Richardson LB, Bilodeau HL, Bonath DJ, Dahn DJ, Em MA, Sarkar S, Braman JP, Ludewig PM. Effects of Scapular Angular Deviations on Potential for Rotator Cuff Tendon Mechanical Compression.
Orthop J Sports Med 2024;
12:23259671231219023. [PMID:
38435717 PMCID:
PMC10906059 DOI:
10.1177/23259671231219023]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 07/14/2023] [Indexed: 03/05/2024] Open
Abstract
Background
One proposed mechanism of rotator cuff disease is scapular motion impairments contributing to rotator cuff compression and subsequent degeneration.
Purpose
To model the effects of scapular angular deviations on rotator cuff tendon proximity for subacromial and internal mechanical impingement risk during scapular plane abduction.
Study Design
Descriptive laboratory study.
Methods
Three-dimensional bone models were reconstructed from computed tomography scans obtained from 10 asymptomatic subjects and 9 symptomatic subjects with a clinical presentation of impingement syndrome. Models were rotated to average scapular orientations from a healthy dataset at higher (120°) and lower (subject-specific) humeral elevation angles to investigate internal and subacromial impingement risks, respectively. Incremental deviations in scapular upward/downward rotation, internal/external rotation, and anterior/posterior tilt were imposed on the models to simulate scapular movement impairments. The minimum distance between the rotator cuff insertions and potential impinging structures (eg, glenoid, acromion) was calculated. Two-way mixed-model analyses of variance assessed for effects of scapular deviation and group.
Results
At 120° of humerothoracic elevation, minimum distances from the supraspinatus and infraspinatus insertions to the glenoid increased with ≥5° changes in upward rotation (1.6-9.8 mm, P < .001) or external rotation (0.9-5.0 mm, P≤ .048), or with ≥10° changes in anterior tilt (1.1-3.2 mm, P < .001). At lower angles, ≥20° changes in most scapular orientations significantly increased the distance between the supraspinatus and infraspinatus insertions and the acromion or coracoacromial ligament.
Conclusion
A reduction in scapular upward rotation decreases the distance between the rotator cuff tendon insertions and glenoid at 120° humerothoracic elevation. Interpretation is complicated for lower angles because the humeral elevation angle was defined by the minimum distance.
Clinical Relevance
These results may assist clinical decision making regarding the effects of scapular movement deviations in patients with rotator cuff pathology and scapular dyskinesia and may help inform the selection of clinical interventions.
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