Isolated rupture of the tendon of the subscapularis muscle. Clinical features in 16 cases

TLDR

The subscapularis tendon rupture is caused by forceful hyperextension or external rotation of the adducted arm. Diagnosis is made by the lift‑off test and confirmed with ultrasound or MRI, while surgical repair requires careful exposure to protect the axillary nerve. In 16 men, isolated subscapularis tendon ruptures produced anterior shoulder pain, weakness, increased external rotation, and decreased internal rotation strength, and surgical exploration confirmed the diagnosis in all cases.

Abstract

Traumatic rupture of the tendon of the subscapularis muscle was documented as an isolated lesion in the shoulders of 16 men. The injury was caused either by forceful hyperextension or external rotation of the adducted arm. The patients complained of anterior shoulder pain and weakness of the arm when it was used above and below the shoulder level. They did not experience shoulder instability. The injured shoulders exhibited increased external rotation and decreased strength of internal rotation. A simple clinical manoeuvre called the 'lift-off test', reliably diagnosed or excluded clinically relevant rupture of the subscapularis tendon. Confirmation of the clinical diagnosis was best achieved by ultrasonography or MRI, but arthrography or CT arthrography were also useful. Surgical exploration confirmed the diagnosis in every case. Repair of the ruptured tendon was technically demanding and required good exposure to identify and protect the axillary nerve.