Glenoid Track Assessment at Imaging in Anterior Shoulder Instability: Rationale and Step-by-Step Guide.

Area of Science:

• Orthopedics
• Radiology
• Biomechanics

Background:

• Anterior shoulder dislocation is the most common joint instability, often involving soft-tissue and bone lesions like anterior glenoid rim and humeral head fractures.
• These bone lesions can lead to recurrent dislocations and are integral to understanding anterior shoulder instability.
• The glenoid track concept integrates the biomechanics of shoulder motion and bone lesion interaction into managing instability.

Purpose of the Study:

• To explain the rationale and stepwise assessment of the glenoid track concept using CT or MRI.
• To highlight the significance of glenoid track assessment in prognostication, treatment planning, and outcome evaluation for anterior shoulder dislocation.
• To emphasize the importance of radiologists recognizing and reporting on glenoid track assessment for improved patient care.

Main Methods:

• The study focuses on the glenoid track concept, defining it as the humeral head-glenoid contact zone during motion.
• Key determinants of Hill-Sachs lesion (HSL) status (on-track or off-track) are the glenoid track width (GTW) and Hill-Sachs interval (HSI).
• Stepwise CT or MRI assessment protocols for the glenoid track are explained.

Main Results:

• An HSL is 'off track' if GTW < HSI, and 'on track' if GTW > HSI.
• Converting an 'off-track' HSL to an 'on-track' state is a primary goal in surgical stabilization for anterior instability.
• Accurate imaging assessment of the glenoid track is vital for surgical planning and achieving stability.

Conclusions:

• Glenoid track assessment is a critical, evolving concept in managing anterior shoulder instability and associated bone lesions.
• Radiologists must understand glenoid track assessment, its challenges, and pitfalls to provide actionable reports for orthopedic surgeons.
• Effective glenoid track assessment and reporting ultimately benefit patient outcomes in anterior shoulder dislocation management.