Biceps Detachment Decreases Joint Damage in a Rotator Cuff Tear Rat Model

Abstract

Background Pathology in the long head of the biceps tendon often occurs in patients with rotator cuff tears. Arthroscopic tenotomy is the most common treatment. However, the role of the long head of the biceps at the shoulder and the consequences of surgical detachment on the remaining shoulder structures remain unknown. Questions/purposes We hypothesized that detachment of the long head of the biceps, in the presence of supraspinatus and infraspinatus tears, would decrease shoulder function and decrease mechanical and histologic properties of both the subscapularis tendon and the glenoid articular cartilage. Methods We detached the supraspinatus and infraspinatus or the supraspinatus, infraspinatus, and long head of the biceps after 4 weeks of overuse in a rat model. Animals were gradually returned to overuse activity after detachment. At 8 weeks, the subscapularis and glenoid cartilage biomechanical and histologic properties were evaluated and compared. Results The group with the supraspinatus, infraspinatus, and long head of the biceps detached had greater medial force and decreased change in propulsion, braking, and vertical force. This group also had an increased upper and lower subscapularis modulus but without any differences in glenoid cartilage modulus. Finally, this group had a significantly lower cell density in both the upper and lower subscapularis tendons, although cartilage histology was not different. Conclusions Detachment of the long head of the biceps tendon in the presence of a posterior-superior cuff tear resulted in improved shoulder function and less joint damage in this animal model. Clinical Relevance This study provides evidence in an animal model that supports the use of tenotomy for the management of long head of the biceps pathology in the presence of a two-tendon cuff tear. However, long-term clinical trials are required.

Biceps tenotomy in the presence of a supraspinatus tear alters the adjacent intact tendons and glenoid cartilage

“…After surgery, animals were allowed 1 week of cage activity before gradually returning to the overuse training over 2 weeks. After treadmill training, all animals underwent an additional 5 weeks of overuse activity (Reuther et al, 2014, 2013a, 2013b; Thomas et al, 2014). The treadmill training protocol, including overuse, was constant across both groups.…”

“…If a rotator cuff tear is present, this can cause force imbalances, which have negative implications for the surrounding tissues if left untreated (Peltz et al, 2009; Perry et al, 2009; Reuther et al, 2013b). While past studies have determined the mechanical mechanisms by which rotator cuff tears lead to further joint damage (Reuther et al, 2014, 2013a, 2013b; Thomas et al, 2014), the implications of associated surgical procedures, such as full detachment of the long head of the biceps (LHB) via tenotomy, have yet to be fully examined.…”

“…Past studies using our rotator cuff rat model have shown that different variants of rotator cuff tendon injury and overuse results in varying amounts of damage to the glenohumeral joint (Peltz et al, 2011, 2010, 2009, Reuther et al, 2014, 2013a, 2013b, 2012; Thomas et al, 2014). For example, concurrent detachment of the supraspinatus and infraspinatus (SI) tendons resulted in decreased glenohumeral cartilage thickness after 4 weeks of cage activity (Reuther et al, 2012).…”

“…This concurrent SI tear also showed decreased properties in the surrounding joint when compared to an SO tear in the presence of overuse (Reuther et al, 2014). Additionally, an LHB tenotomy in the presence of an SI rotator cuff tear resulted in improvements in subscapularis tendon properties, but minimal changes in shoulder function (Thomas et al, 2014). However, the effect of an LHB tenotomy, in the presence of an SO tear and overuse activity, on shoulder function, intact rotator cuff properties, and cartilage properties is currently unknown.…”

Ground reaction forces are more sensitive gait measures than temporal parameters in rodents following rotator cuff injury

“…Data from two other studies were used to test the regression model created from the SO and SI data. In study #2 (Thomas et al, 2014), animals underwent unilateral detachment of the supraspinatus, infraspinatus, and biceps (SIB) tendons and ambulatory measures were collected identically to the SO and SI groups. In study #3 (Caro et al, 2014), animals underwent unilateral detachment and repair of the supraspinatus tendon and repair with (RW) or without (RWO) post-operative analgesics.…”