From the unstable painful shoulder to multidirectional instability in the young athlete.

In conclusion, instability as a cause of shoulder pain in the young athlete is a difficult and often missed diagnosis. These young patients often seek treatment of shoulder pain but do not recall any episodes of shoulder instability. As a result, these uncommon, poorly described forms of instability are often misdiagnosed. A heightened clinical suspicion and an accurate, prompt diagnosis of instability is of paramount importance in this athletic group. It dictates appropriate treatment of the condition, avoids treatment delays and failure, provides better outcomes, and ensures timely return to play. UPS and MDI are two forms of this diagnosis. In UPS, patients at risk are young hyperlax athletes with a history of direct trauma or forceful overextension of the shoulder. They have shoulder pain that is described as deep anterior, reproduced with an anterior apprehension test and relieved with a relocation test. Soft tissue and/or bony lesions consistent with instability (observed on imaging or at arthroscopy) are necessary to confirm the diagnosis of UPS. Once the diagnosis is made, standard arthroscopic techniques with labrum reinsertion and/or anteroinferior capsule plication can lead to predictable good results and return to sport. In MDI, patients at risk are also young hyperlax athletes. However, these patients often do not have a history of trauma. They have shoulder pain that is often somewhat vague in location and is reproduced with a sulcus and/or hyper abduction test. Soft tissue and/or bony lesions consistent with instability are uncommon, with the exception of capsular laxity. The mainstay of treatment is physiotherapy rehabilitation. When surgery is necessary, open capsular shift and arthroscopic capsular plication are effective.