Irreducible superolateral dislocation of the glenohumeral joint.

The overwhelming majority of glenohumeral dislocations are anterior dislocations that either spontaneously reduce or are reduced at the point of care without significant complications. Posterior dislocations are uncommon, and superior and inferior dislocations are even rarer. We present a case of "superolateral" shoulder dislocation in which the entire rotator cuff was torn either off its insertion or at the musculotendinous junction in combination with a large longitudinal split tear of the deltoid muscle. This allowed the humeral head to dislocate both superiorly and laterally into a subcutaneous position through the tear of the anterolateral deltoid muscle with an associated de-gloving soft tissue lesion. Buttonholing of the humeral head through the deltoid and interposition of the dislocated long head of the biceps tendon and macerated rotator cuff prevented closed reduction of the glenohumeral joint. The resultant radiographic appearance and treatment of this dislocation is unique. To our knowledge, this is the first reported case of this dislocation in the literature.