Diagnostic Ultrasound in the Evaluation of Stiff Shoulder: Association of Axillary Recess Thickness with Standard Clinical Measures.

Abstract

Stiff shoulder, including primary and secondary types, poses diagnostic challenges due to vague definitions and criteria. This study evaluates the diagnostic potential of ultrasound-measured axillary recess (AR) thickness in shoulder stiffness. In this cross-sectional study, 35 patients with unilateral shoulder stiffness were assessed. AR thickness was measured using high-resolution ultrasound. Parameters like passive range of motion (PROM), Numerical Rating Scale (NRS), and Constant-Murley (CM) score were evaluated to find correlations with AR thickness. The average age was 50.7 years, and mean BMI was 22.7. AR thickness in stiff shoulders (average 3.19 mm) was significantly higher than in unaffected shoulders (average 1.93 mm, p < 0.001). A cutoff of 3.0 mm for AR thickness yielded 73.3% sensitivity and 84.6% specificity for primary stiffness; 2.6 mm cutoff resulted in 57.9% sensitivity and 88.2% specificity for secondary stiffness. Significant correlations were found between AR thickness and PROM, especially in shoulder external rotation and extension. AR thickness measured by ultrasound might serve as a valuable diagnostic and evaluation parameter in shoulder stiffness.