Sunday, November 30, 2014

The subscapularis - does it ever recover after shoulder arthropllasty - peel vs LTO?

The return of subscapularis strength after shoulder arthroplasty.

These authors compared the strength of the subscapularis at baseline (preoperatively) and at follow-up after unilateral shoulder arthroplasty to that of the contralateral normal side in sixty-four patients.

Two different means of managing the subscapularis were used, subscapularis peel (34 patients; 53%) and osteotomy of the lesser tuberosity (30 patients; 47%). After arthroplasty and subscapularis repair, a shoulder sling was worn for the first 6 weeks. On the first postoperative day, patients were instructed to initiate self-assisted, passive forward elevation to 90 in the supine position and to limit external rotation to neutral for 6 weeks. Active elevation was allowed at 6 weeks, and gentle strengthening was begun 12 weeks postoperatively.

The primary outcome measure was subscapularis strength in both the operative and contralateral (normal) arms as measured by a hand-held dynamometer in the belly-press position preoperatively
and at 3, 6, 12, and 24 months after surgery. The dynamometer was strapped to the patient’s hand; the hand was placed on the lower sternum with the elbow in line with but not posterior to the hand. The patient was asked to press the dynamometer into his or her sternum with a maximum force for a 5-second duration. The mean strength was calculated on the basis of 2 separate trials.

At 24 months the mean subscapularis strength on the operative side was 19% greater than preoperatively. On average, the operative side improved from 54% of the normal side at before surgery to 70% of the normal side at two years. 

Subscapularis strength recovery was significantly less than supraspinatus recovery, suggesting that the surgical release and repair of the subscapularis may account in part for the poorer recovery.

Multivariable regression analysis did not demonstrate any correlation between the independent variables studied and final subscapularis strength - including whether a lesser tuberosity osteotomy or  subscapularis peel was performed.  Specifically, no associations were identified among factors including sex, age, surgery on the dominant arm, baseline strength, baseline external rotation, subscapularis management technique, and fatty infiltration.

Comment: This is a well done and interesting study in that it indicates that the subscapularis function is compromised before surgery and never fully recovers.

Readers may wish to review a prior article on this topic by these authors. Our preferred method for caring for the subscapularis in shoulder arthroplasty is shown here.


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