Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study
Background: Location of small- to medium-sized (<30 mm) rotator cuff tears can predict (supraspinatus [SS]) muscle fatty degeneration. It has been hypothesized that SS fatty degeneration occurs because of loss of force transfer by either the coracohumeral ligament (CHL) or the SS cord. The CHL is...
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Elsevier
2025-07-01
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| author | Omar E. Rodriguez-Alejandro, MD Bethany G. Ricci, BS Christopher C. Schmidt, MD Sean P. Cooke, BS Austin J. Cook, MS Justin G. Buce, MS Joshua D. Dworkin, MD Mark C. Miller, PhD Patrick J. Smolinski, PhD |
| author_facet | Omar E. Rodriguez-Alejandro, MD Bethany G. Ricci, BS Christopher C. Schmidt, MD Sean P. Cooke, BS Austin J. Cook, MS Justin G. Buce, MS Joshua D. Dworkin, MD Mark C. Miller, PhD Patrick J. Smolinski, PhD |
| author_sort | Omar E. Rodriguez-Alejandro, MD |
| collection | DOAJ |
| description | Background: Location of small- to medium-sized (<30 mm) rotator cuff tears can predict (supraspinatus [SS]) muscle fatty degeneration. It has been hypothesized that SS fatty degeneration occurs because of loss of force transfer by either the coracohumeral ligament (CHL) or the SS cord. The CHL is the anterior insertion of the rotator cable theorized to carry rotator muscle force to the humerus. In this study, we aimed to map the anatomic insertions of the CHL and superior rotator cuff onto the humeral head and then sequentially release the footprint to determine which structures are the most critical for force transmission. Methods: Twenty fresh-frozen cadaveric specimens (average age 69 ± 10 years, 9 males) were tested in a shoulder simulator under physiological conditions at 0° and 30° of shoulder abduction. After cyclic loading, shoulder abduction force and glenohumeral translation were measured for the native condition and after each humeral footprint release. Ten specimens were assigned randomly to a CHL-first footprint release with sequential release of the SS cord, SS strap, and infraspinatus tendons. The other 10 specimens underwent an SS cord-first footprint release, with sequential release of remaining insertions. Following mechanical testing, soft tissue cross-sectional dimensions and footprint widths, lengths, and areas were scanned for three-dimensional modeling and dimensionally quantified. Results: An SS cord-first release decreased abduction force by 10% at 0° of abduction and 22% at 30° (P = .047); further, releasing the CHL did not influence the abduction force values (P ≥ .091). A CHL first-release or a CHL release after an SS cord release did not result in a decrease in abduction force (P ≥ .081). However, the abduction force with a subsequent SS cord release did significantly decrease (P ≤ .047). The average anterior-to-posterior humeral footprint widths of the CHL, SS cord, SS strap, and infraspinatus tendons were 0 mm-3 mm, 3 mm-11 mm, 11 mm-20 mm, and 20 mm-40 mm behind the bicipital groove, respectively. Conclusion: The SS cord, and not the CHL, is the key structure responsible for the transmission of anterior shoulder abduction force. Relating the clinical tear location with the study’s humeral footprint results indicates the SS cord is intact in small- to medium-sized rotator cuff tears without SS fatty degeneration. Repairing the SS cord in small to medium rotator cuff tears could be efficacious in improving abduction strength and preventing SS muscle fatty degeneration. |
| format | Article |
| id | doaj-art-b0fbdf00f2cd43ac9b2f20e5909e7c34 |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
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| spelling | doaj-art-b0fbdf00f2cd43ac9b2f20e5909e7c342025-08-20T03:50:21ZengElsevierJSES International2666-63832025-07-01941098110610.1016/j.jseint.2024.12.024Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical studyOmar E. Rodriguez-Alejandro, MD0Bethany G. Ricci, BS1Christopher C. Schmidt, MD2Sean P. Cooke, BS3Austin J. Cook, MS4Justin G. Buce, MS5Joshua D. Dworkin, MD6Mark C. Miller, PhD7Patrick J. Smolinski, PhD8Shoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, Sports Medicine, Cleveland Clinic, Cleveland, OH, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Corresponding author: Bethany G. Ricci, BS, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, 9104 Babcock Blvd, Suite 5113, Pittsburgh, PA 15237, USA.Shoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Mechanical Engineering and Material Science, University of Pittsburgh, Pittsburgh, PA, USA; Corresponding author: Christopher C. Schmidt, MD, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, 9104 Babcock Blvd, Suite 5113, Pittsburgh, PA 15237, USA.Shoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; University of Illinois, College of Medicine, Chicago, IL, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Benton Franklin Orthopedic Associates, Kennewick, WA, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Mechanical Engineering and Material Science, University of Pittsburgh, Pittsburgh, PA, USAShoulder and Elbow Mechanical Research Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Mechanical Engineering and Material Science, University of Pittsburgh, Pittsburgh, PA, USABackground: Location of small- to medium-sized (<30 mm) rotator cuff tears can predict (supraspinatus [SS]) muscle fatty degeneration. It has been hypothesized that SS fatty degeneration occurs because of loss of force transfer by either the coracohumeral ligament (CHL) or the SS cord. The CHL is the anterior insertion of the rotator cable theorized to carry rotator muscle force to the humerus. In this study, we aimed to map the anatomic insertions of the CHL and superior rotator cuff onto the humeral head and then sequentially release the footprint to determine which structures are the most critical for force transmission. Methods: Twenty fresh-frozen cadaveric specimens (average age 69 ± 10 years, 9 males) were tested in a shoulder simulator under physiological conditions at 0° and 30° of shoulder abduction. After cyclic loading, shoulder abduction force and glenohumeral translation were measured for the native condition and after each humeral footprint release. Ten specimens were assigned randomly to a CHL-first footprint release with sequential release of the SS cord, SS strap, and infraspinatus tendons. The other 10 specimens underwent an SS cord-first footprint release, with sequential release of remaining insertions. Following mechanical testing, soft tissue cross-sectional dimensions and footprint widths, lengths, and areas were scanned for three-dimensional modeling and dimensionally quantified. Results: An SS cord-first release decreased abduction force by 10% at 0° of abduction and 22% at 30° (P = .047); further, releasing the CHL did not influence the abduction force values (P ≥ .091). A CHL first-release or a CHL release after an SS cord release did not result in a decrease in abduction force (P ≥ .081). However, the abduction force with a subsequent SS cord release did significantly decrease (P ≤ .047). The average anterior-to-posterior humeral footprint widths of the CHL, SS cord, SS strap, and infraspinatus tendons were 0 mm-3 mm, 3 mm-11 mm, 11 mm-20 mm, and 20 mm-40 mm behind the bicipital groove, respectively. Conclusion: The SS cord, and not the CHL, is the key structure responsible for the transmission of anterior shoulder abduction force. Relating the clinical tear location with the study’s humeral footprint results indicates the SS cord is intact in small- to medium-sized rotator cuff tears without SS fatty degeneration. Repairing the SS cord in small to medium rotator cuff tears could be efficacious in improving abduction strength and preventing SS muscle fatty degeneration.http://www.sciencedirect.com/science/article/pii/S2666638325000465Basic Science StudyBiomechanics |
| spellingShingle | Omar E. Rodriguez-Alejandro, MD Bethany G. Ricci, BS Christopher C. Schmidt, MD Sean P. Cooke, BS Austin J. Cook, MS Justin G. Buce, MS Joshua D. Dworkin, MD Mark C. Miller, PhD Patrick J. Smolinski, PhD Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study JSES International Basic Science Study Biomechanics |
| title | Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study |
| title_full | Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study |
| title_fullStr | Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study |
| title_full_unstemmed | Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study |
| title_short | Load transmission via the supraspinatus cord prevents muscle fatty degeneration, a biomechanical study |
| title_sort | load transmission via the supraspinatus cord prevents muscle fatty degeneration a biomechanical study |
| topic | Basic Science Study Biomechanics |
| url | http://www.sciencedirect.com/science/article/pii/S2666638325000465 |
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