Classification of glenohumeral joint instability

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanics

Background:

• Shoulder instability is complex, with existing classifications based on etiology or direction.
• A need exists for a clearer system to differentiate various forms of shoulder instability.

Purpose of the Study:

• To present a novel classification system for shoulder instability.
• To distinguish between static, dynamic, and voluntary shoulder dislocations.

Main Methods:

• The authors propose a classification distinguishing static, dynamic, and voluntary shoulder instabilities.
• Static instabilities are diagnosed radiologically, linked to rotator cuff issues or joint degeneration.
• Dynamic instabilities result from trauma, potentially involving capsulolabral or glenoid rim lesions, or hyperlaxity, and can be uni- or multidirectional.

Main Results:

• The proposed system categorizes shoulder instability into three distinct types: static, dynamic, and voluntary.
• Static instabilities present without typical symptoms, diagnosed via imaging, and associated with degenerative conditions.
• Dynamic instabilities are trauma-induced, with specific lesion associations, and voluntary dislocations are controlled by the patient.

Conclusions:

• The new classification provides a framework for understanding shoulder instability based on distinct mechanisms.
• Differentiating static, dynamic, and voluntary dislocations improves diagnostic accuracy and treatment planning.
• This system offers a clearer approach to managing patients with various shoulder instability presentations.