Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Subscapularis Tears

Rupture of the subscapularis in association with primary anterior shoulder instability is more common after a prior open instability repair and should be suspected in those who have had prior anterior stabilization procedures in which the subscapularis was released for exposure.

Failure to recognize and treat a subscapularis tear in a proper and timely fashion can result in a poor outcome. A careful physical examination to assess the subscapularis is necessary. Individuals with subscapularis deficiency will have increased passive external rotation and positive belly press and lift off signs.

A CT-arthrogram or MRI-arthrogram can also be helpful when evaluating the structural integrity of the subscapularis tendon. Three-dimensional imaging allows for the quantification of muscle atrophy, best observed on the axial and sagittal oblique views.

On rare occasions, individuals who have had prior surgery may have subscapularis dysfunction due to denervation of the muscle, and in such settings an EMG may be helpful.

There are several published studies on rupture of the subscapularis tendon in association with instability. Hauser was the first to describe an isolated tear of the subscapularis tendon in association with anterior instability. Neviaser et al. It have emphasized that a rupture of the subscapularis tendon should be suspected in all cases of recurrent instability and in older patients after an initial anterior dislocation of their shoulder.

Results of surgical treatment for subscapularis tendon tears are less successful than those reported for supraspinatus tears. Gerber and Krushell have emphasized the importance of timely diagnosis and early surgical management.

Results are significantly better if the duration between the traumatic event and the repair is short. Delay in diagnosis leads to retraction of the tendon and atrophy of the muscle such that tendon mobilization becomes difficult. Results of surgical repair are usually good for pain and instability, but many patients continue to have mild to moderate internal rotation weakness.

When the subscapularis tendon is deficient or irreparable, a pectoralis major muscle transfer may be used to augment or substitute for the subscapularis. Gerber et al.It originally described the surgical technique for the mobilization and repair of the subscapularis tendon and recommended that the inferior portion of the subscapularis tendon be repaired so that the pectoralis major transfer can be used simply to augment the function of the deficient upper part of the tendon.

There are several reports of transfer of the pectoralis major tendon for anterior shoulder instability in the literature. Decreased pain and restored stability are the main benefits of this surgery. Usually functional gains in term of mobility are variable and unfortunately more limited.

Even when motion is improved in flexion and abduction, many individuals remain limited in overhead activities. In the majority of instances, the lift off test and the belly-press test remain positive post-operatively.

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