Risk factors for anterior shoulder instability: a matched case-control study

Area of Science:

• Orthopedics
• Biomechanics
• Radiology

Background:

• Anterior shoulder dislocation is influenced by skeletal anatomy.
• Limited research exists on the impact of humeral structure on shoulder instability.
• This study investigates glenoid and humeral factors contributing to anterior shoulder instability.

Purpose of the Study:

• To identify and analyze risk factors for anterior shoulder instability.
• To examine the association between glenoid and humeral morphometrics and shoulder instability.
• To determine cutoff points for significant structural parameters.

Main Methods:

• Case-control study involving 64 individuals with anterior shoulder instability out of 10,035 MRI scans.
• Propensity score matching used for age, sex, height, and weight-matched controls.
• Conditional logistic regression and ROC curve analysis applied to glenoid and humeral structural data.

Main Results:

• Significant differences observed in depth-to-width ratio, height-to-width ratio, humeral head diameter-to-glenoid fossa diameter ratio, and humeral containing angle between groups.
• Humeral containing angle (OR, 0.95; P=.024) and glenoid height-to-width ratio (OR, 7.88; P=.002) were significant risk factors.
• Identified cutoff points: humeral containing angle of 64° and height-to-width ratio of 1.60.

Conclusions:

• The humeral containing angle and glenoid height-to-width ratio are significant risk factors for anterior shoulder instability.
• Findings provide insights into the anatomical basis of shoulder instability in the Chinese Han population.
• Highlights the importance of specific humeral and glenoid dimensions in predicting shoulder instability.