Ruptures of the supraspinatus tendon. Cadaver dissection.

Ninety-nine shoulders from 50 decreased with an average age of 73 years were dissected. There was a significant decrease in the thickness of the supraspinatus tendons with full thickness ruptures but not in partial ruptures. A highly significant increase in the length of the extramuscular supraspinatus tendon in shoulders with partial or full thickness supraspinatus ruptures was found. However, the total length of the supraspinatus aponeurosis was the same in shoulders with ruptures as in normal shoulders of the same age. This might indicate that the increase in length of the extramuscular portion of the tendon in ruptures is not caused by elongation of the tendon but is the result of muscular decay.