Imaging and histological evaluation of the long head of the biceps tendon in the presence of different types of rotator cuff tears

• Published in: BMC musculoskeletal disorders Vol. 24; no. 1; p. 230
• Main Authors: Kajiwara, Daisuke, Ochiai, Nobuyasu, Hashimoto, Eiko, Hirosawa, Naoya, Akimoto, Koji, Nojima, Daisuke, Shimada, Yohei, Ise, Shohei, Ohtori, Seiji
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 27.03.2023; BioMed Central; BMC
• Subjects: Animals; Care and treatment; Causes of; Computed tomography; Degeneration; Extracellular matrix; Histologic evaluation; Imaging evaluation; Injuries; Laboratory animals; Long head of biceps tendon; Musculoskeletal diseases; Patient outcomes; Prevention; Rat model; Rats; Rats, Sprague-Dawley; Risk factors; Rotator cuff; Rotator Cuff - diagnostic imaging; Rotator Cuff - pathology; Rotator Cuff Injuries - diagnostic imaging; Rotator Cuff Injuries - pathology; Rotator Cuff Injuries - surgery; Rotator cuff repair; Rotator cuff tear; Shoulder; Shoulder injuries; Shoulder pain; Tendons; Tendons - diagnostic imaging; Tendons - pathology; X-Ray Microtomography; Japan; Rat model; Rotator cuff tear; Histologic evaluation; Imaging evaluation; Long head of biceps tendon
• ISSN: 1471-2474; 1471-2474
• DOI: 10.1186/s12891-023-06338-5

A comparison of changes in the long head of the biceps tendon for different types of rotator cuff tears has not been previously performed. Furthermore, the correlation between the thickening and degeneration of the long head of the biceps tendon and the cause of these changes have not been fully clarified. We evaluated the relationship between degenerative changes in the long head of the biceps tendon and rotator cuff tears in a rat model using imaging and histology. Ninety-six 12-week-old Sprague-Dawley rats were divided into anterior (subscapularis tear), anterosuperior (subscapularis, supraspinatus, and infraspinatus tears), superior (supraspinatus and infraspinatus tears), and control groups. The long head of the biceps tendon was harvested at 4 or 12 weeks postoperatively. The cross-sectional areas of the intra- and extra-capsular components of the tendon were measured using micro-computed tomography, and the affected/normal ratio of the cross-sectional area was calculated. Masson's trichrome staining and Alcian blue staining were performed for histologic analysis, with degenerative changes described using the modified Bonar scale. The correlation between the affected/normal ratio and Bonar scores was evaluated. The affected/normal ratio was higher for the anterior and anterosuperior groups than for the control group at 4 and 12 weeks. The ratio increased for the intra-articular portion in the superior group and for both the intra- and extra-articular portions in the anterior and anterosuperior groups. Degeneration considerably progressed in the anterior and anterosuperior groups compared with the control group from weeks 4 to 12 and was greater in the intra- than in the extra-articular portion. The ratio correlated with extracellular matrix score. Subscapularis tears were associated with progressive thickening and degeneration of the long head of the biceps tendon at 4 and 12 weeks postoperatively, which was more significant in the intra- than in the extra-articular portion. Histologic evaluation indicated that the extracellular matrix likely caused these degenerative changes.