FATTY INFILTRATION OF DISRUPTED ROTATOR CUFF MUSCLES

The extent of fatty infiltration of rotator cuff muscles was evaluated on computed tomography displays using a five-point scoring system in 63 shoulders before surgery for a rotator cuff tear and in 57 of these shoulders after surgical repair of the tear (the quality of cuff repa ir was evaluated in these 57 shoulders by arthrography, usually couple d with computed tomography, after a mean time interval of 8 months sin ce the procedure). Preoperatively, significant fatty infiltration of t he supraspinatus muscle was uncommon. Severe fatty infiltration of the infraspinatus and subscapularis muscles was seen in some patients. In most instances, fat accumulated in those muscles whose tendons were t orn; however, tendon cleavage was associated with mild fatty infiltrat ion of the corresponding muscle in some instances, and wide tears of t he supraspinatus and subscapularis muscles were sometimes accompanied with severe fatty infiltration of the infraspinatus muscle. In half th e cases, fatty degenerescence of the infraspinatus muscle occurred wit hin six months of the tendon rupture. After surgery, in most shoulders without evidence of rotator cuff leakage on the postoperative arthrog ram, no further accumulation of fat occurred. However, a decrease in t he amount of existing fat was rarely documented and occurred only in t he supraspinatus muscle. Before and after surgery, increasing severity of the fatty infiltration of the infraspinatus muscle was associated with increasing functional impairment of the same muscle. Recurrent ro tator cuff tears, which involved only the supraspinatus muscle, were c onsiderably more common when there was severe preoperative fatty infil tration of the infraspinatus muscle. Since fatty infiltration of muscl es, in particular of the infraspinatus muscle, has an adverse impact o n anatomic and functional results of tendon repair, it seems preferabl e to recommend early surgery to patients with wide rotator cuff tears involving the infraspinatus muscle and, probably, the subscapularis mu scle.