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Studying Edema Formation After Release of the Infraspinatus Tendon as an Experimental Model of Rotator Cuff Tears in Sheep: A Preliminary Imaging and Morphological Analysis


Lädermann, Alexandre; Gehrke, Rieke; Klein, Karina; Karol, Agnieszka; Darwiche, Salim; Schwarzenberg, Peter; Steffen, Thomas; Wieser, Karl; Kronen, Peter; von Rechenberg, Brigitte (2022). Studying Edema Formation After Release of the Infraspinatus Tendon as an Experimental Model of Rotator Cuff Tears in Sheep: A Preliminary Imaging and Morphological Analysis. American Journal of Sports Medicine, 50(14):3934-3940.

Abstract

BACKGROUND

The cause, extent, and role of muscle edema for muscle degeneration are unknown and not considered in the current literature. In vivo experiments were designed to prove muscle edema formation in the early period in a sheep model of acute rotator cuff tears.

HYPOTHESIS

Muscle edema occurs after tendon release with or without additional stretching trauma and may be associated with muscle retraction and subsequent muscle degeneration.

STUDY DESIGN

Controlled laboratory study.

METHODS

A sheep model with acute release of the infraspinatus tendon was used. An osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed in 14 sheep. To demonstrate presence of edema, magnetic resonance imaging scans were performed at 0, 2, and 4 weeks using T1-weighted, T2-weighted, proton density-weighted, and Dixon sequences. Excisional biopsy specimens were taken at 0, 3, and 4 weeks (histological results will be reported in a later publication). Two injury models were created: a nontrauma group that consisted of muscle release alone and a trauma group that included additional standardized traction to the musculotendinous unit. Evaluation of T1- and T2-weighted images included calculation of pennation angle, muscle fiber length, signal intensity (edema), and muscle volume. Muscle wet weight and volume were measured at sacrifice.

RESULTS

Edema formation was shown in all sheep and slightly more pronounced in the trauma group, where muscle intensity increased significantly between time point 0 (200 Grey Value (GV)) and weeks 2, 3, and 4 (300 GV). Edema formation started early after tendon release with a plateau between 3 and 4 weeks. Deterioration of muscle fiber bundles began also after tendon release with a peak at 4 weeks. Muscle volume decreased steadily over time.

CONCLUSION

Muscle edema appeared early after rotator cuff tendon release, was more pronounced in the trauma group, and reached a plateau after 3 to 4 weeks. Muscle fatty content decreased within the short period of 4 weeks owing to a dilution effect. Muscle edema seems to be an essential factor in cuff tears and subsequent muscle retraction and degeneration.

CLINICAL RELEVANCE

This study demonstrates a new type of muscle edema of retraction and describes the characteristics of edema associated with a retracted rotator cuff tear.

Abstract

BACKGROUND

The cause, extent, and role of muscle edema for muscle degeneration are unknown and not considered in the current literature. In vivo experiments were designed to prove muscle edema formation in the early period in a sheep model of acute rotator cuff tears.

HYPOTHESIS

Muscle edema occurs after tendon release with or without additional stretching trauma and may be associated with muscle retraction and subsequent muscle degeneration.

STUDY DESIGN

Controlled laboratory study.

METHODS

A sheep model with acute release of the infraspinatus tendon was used. An osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed in 14 sheep. To demonstrate presence of edema, magnetic resonance imaging scans were performed at 0, 2, and 4 weeks using T1-weighted, T2-weighted, proton density-weighted, and Dixon sequences. Excisional biopsy specimens were taken at 0, 3, and 4 weeks (histological results will be reported in a later publication). Two injury models were created: a nontrauma group that consisted of muscle release alone and a trauma group that included additional standardized traction to the musculotendinous unit. Evaluation of T1- and T2-weighted images included calculation of pennation angle, muscle fiber length, signal intensity (edema), and muscle volume. Muscle wet weight and volume were measured at sacrifice.

RESULTS

Edema formation was shown in all sheep and slightly more pronounced in the trauma group, where muscle intensity increased significantly between time point 0 (200 Grey Value (GV)) and weeks 2, 3, and 4 (300 GV). Edema formation started early after tendon release with a plateau between 3 and 4 weeks. Deterioration of muscle fiber bundles began also after tendon release with a peak at 4 weeks. Muscle volume decreased steadily over time.

CONCLUSION

Muscle edema appeared early after rotator cuff tendon release, was more pronounced in the trauma group, and reached a plateau after 3 to 4 weeks. Muscle fatty content decreased within the short period of 4 weeks owing to a dilution effect. Muscle edema seems to be an essential factor in cuff tears and subsequent muscle retraction and degeneration.

CLINICAL RELEVANCE

This study demonstrates a new type of muscle edema of retraction and describes the characteristics of edema associated with a retracted rotator cuff tear.

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4 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Balgrist University Hospital, Swiss Spinal Cord Injury Center
05 Vetsuisse Faculty > Veterinärwissenschaftliches Institut > Department of Molecular Mechanisms of Disease
07 Faculty of Science > Department of Molecular Mechanisms of Disease
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Health Sciences > Orthopedics and Sports Medicine
Health Sciences > Physical Therapy, Sports Therapy and Rehabilitation
Language:English
Date:December 2022
Deposited On:16 Jan 2023 16:04
Last Modified:28 Jun 2024 01:38
Publisher:Sage Publications
ISSN:0363-5465
OA Status:Closed
Publisher DOI:https://doi.org/10.1177/03635465221130446
PubMed ID:36341735