Congenital subacromial stenosis.

Congenital subacromial stenosis is a previously undescribed entity that causes narrowing of the height of the subacromial space without proximal migration of the humerus. This study comprised 25 shoulders with congenital subacromial stenosis. All patients had either an impingement syndrome or rotator cuff tear. The average acromiohumeral interval was 4.7 mm. Fifteen of the 25 shoulders (60%) had rotator cuff tears. Patients requiring surgery comprised a bimodal age distribution: those with an impingement syndrome requiring decompression had an average age of 42, whereas those with rotator cuff tears requiring surgical treatment had an average age of 66. Study of a separate standard asymptomatic population of 84 patients showed that some younger individuals with congenital subacromial stenosis may be asymptomatic. However, the natural history seems to be a relentless progression to impingement and eventually to complete rotator cuff tear. Therefore, subacromial decompression is recommended in younger symptomatic individuals to prevent later rotator cuff tear.