The Subscapularis-Sparing Approach in Humeral Head Replacement

Failure of the subscapularis repair can be detrimental to patient outcome and shoulder function in shoulder replacement surgery. This report details an approach to resurfacing the humeral head that preserves the majority of the subscapularis attachment to the humerus, allowing a more rapid rehabilitation and minimizing post-operative subscapularis insufficiency.

In this approach, only the inferior 30% to 50% of the subscapularis tendon is detached from the humerus, leaving the critical superior aspect of the tendon attached to the lesser tuberosity. In a previous study, we evaluated this approach in 43 patients. Nineteen had postoperative magnetic resonance imaging (MRI), and 24 patients had ultrasound (US) evaluation. Physical examination included belly press and lift-off tests; follow-up included visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES), Constant, UCLA, Rowe, and SF-12 scores.

All patients had a minimum 2-year follow-up (range 2 to 6, average 4). All patients had subscapularis strength equal to the opposite side as measured by lift-off, belly press, and bear hug tests. Average postoperative scores included ASES, 74.4; Constant, 78.3; UCLA, 27; Rowe, 81.7; and VAS, 2.2; SF-12 averages all showed statistically significant improvement except for general health, which showed improvement approaching significance. All had an intact subscapularis tendon attachment as evaluated by either MRI or US imaging. None had atrophy in the muscle belly.

The subscapularis-sparing, minimally-invasive approach to the glenohumeral joint provides adequate exposure for shoulder replacement surgery and provides a decreased risk of postoperative failure (rupture or atrophy) of the subscapularis tendon.