UW Shoulder and Elbow Academy: What does it take to repair the subscapularis after a TSA?

Healing and functional outcome of a subscapularis peel repair with a stem-based repair after total shoulder arthroplasty

These authors point out that the post total shoulder (TSA) integrity and function of the subscapularis is dependent on surgical technique. While some authors have advocated a lesser tuberosity osteotomy, they point out that this method violates the proximal humeral bone integrity, this technique may be of concern during placement of the humeral stem. They report the results with a prosthesis-specific approach to reattaching the subscapularis after TSA using holes in the implant.

They present minimum one year followup outcomes in 60 cases treated with a subscapularis peel which is repaired to the stem after total shoulder arthroplasty (TSA). The long head biceps tendon was routinely sacrificed and tenodesed.

The clinical outcomes of these arthroplasties were good: the Simple Shoulder Test scores showed significant improvement from 4.3 to 10.2, (P < .001).

On ultrasound examination, the subscapularis was healed intact in 55 cases (91.7%), attenuated in 3 cases (5%), and torn in 2 cases (3.3%).

Comment: The integrity of the subscapularis depends on four key elements:

(1) the pre-incision quality of the tendon

(2) the technique with which it is incised from the humerus - important to preserve the integrity of the subjacent capsule to offer a robust tendon edge for reattachment

(3) the security of the reattachment to bone, and

(4) the rehabilitation of the shoulder in a way that protects the subscapularis repair from external rotation stretching or active internal rotation loads.

Our surgical approach to subscapularis management can be used with any prosthesis. It involves a careful peel of the subscapularis tendon from the lesser tuberosity with attention to preserving the integrity of the biceps tendon and a 360 degree release of the capsule from the glenoid to resolve limitation of external rotation. By retaining the capsule on the deep surface of the tendon, the strength of the repair is enhanced.

At the conclusion of the case, drill holes are placed through good bone at the margin of the neck cut and six sutures of #2 non-absorbable suture are passed through these holes. The security each suture is verified to make sure it does not pull through the bone.

These sutures are then passed through the tendon edge, including the capsule retained on its deep surface, and tied securely.

A principal cause of post operative subscapularis failure is the overzealous and premature stretching of external rotation or premature initiation of internal rotation strengthening as explained in this post:
Rehabilitation after shoulder arthroplasty - cautions!

Our approach is to limit external rotation stretching to zero degrees (the hand shake position) and avoid internal rotation strengthening exercises for at least 3 months after surgery. We also caution patients about the risk of events that may suddenly externally rotate the shoulder such as a fall or a sudden pull on the arm from a leashed dog.