The Swimmer's Shoulder: Multi-directional Instability

Swimmer's shoulder is the term used to describe the problem of shoulder pain in swimmers. Originally described as supraspinatus tendon impingement under the coracoacromial arch, it is now understood that several different pathologies can cause shoulder pain in competitive swimmers, including subacromial impingement syndrome, overuse and subsequent muscle fatigue, scapular dyskinesis, and laxity and instability.

Swimmers may develop increased shoulder laxity over time due to repetitive use. Such excessive laxity can decrease passive shoulder stability and lead to rotator cuff muscle overload, fatigue, and subsequent injury in order to properly control the translation of the humeral head. Generalized laxity can be present up to 62% of swimmers, while a moderate degree of multi-directional instability can be present in the majority. Laxity in swimmers can be due to a combination of underlying inherent anatomical factors as well as from repetitive overhead activity. The role of excessive laxity and muscle imbalance are crucial in the swimmer's shoulder and should be well understood since they are the primary target of the training and rehabilitation program.