TECHNIQUES FOR SUBSCAPSULARIS LENGTHENING

Abstract

Internal rotation contracture/tightness presents a functional problem for the patient and a technical challenge for the surgeon performing total shoulder arthroplasty most commonly occurring in cases of osteoarthritis. Internal rotation contractures result from a number of physiologic and biomechanical conditions. Osteophytes, which form around the head and neck of the humerus and glenoid provide a mechanical block to external rotation, which occurs over time. The inability to pass through a full excursion of external rotation tightens the anterior capsular structures over time and causes a contracture of the musculotendinous units (subscapularis and pectoralis major), responsible for internal rotation. The osteophytes themselves also change the vector of pull of the internal rotators and cause them to be “tented” anteriorly. Hence the issues causing an internal rotation contracture and inhibiting external rotation following total shoulder arthroplasty include a mechanical bone block, diminished tissue compliance and abnormal tendon excursion. Management of this problem has frequently been focused predominantly on fractional lengthening the subscapularis tendon, but all components must be addressed at the time of surgery to make sure that a functional range of motion in external rotation can be achieved following reconstruction. This video details the assessment of each of these components and their management.

Surgical technique includes: resection of all obstructive osteophytes which block rotation and which cause abnormal tendon excursion; adequate head removal and shaping to provide restoration of an anatomical arc of curvature of the humeral head in continuity with the metaphyseal support base, adequate release of upper pectoralis major tendon tightness, release of capsular contractures and adhesions about the subscapularis muscle and tendon; and fractional lengthening of the subscapularis muscle-tendon itself to allow adequate healthy reattachment of the subscapularis tendon to the more superior aspects of the rotator cuff without allowing anterior instability to occur. Attention to the myotendinous junction rather than thinning the tendon itself has proven to be important in achieving a healthy tendon attachment without significant attenuation. Appropriate seating of the humeral head in anatomic version is also important to prevent unnatural distention of the anterior structures. These surgical techniques should help the surgeon provide an anatomic restoration of motion and function.