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

Objectives 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 thickness in shoulder stiffness. Designs In this cross-sectional study, 35 patients with unilateral shoulder stiffness were assessed. Axillary recess thickness was measured using high-resolution ultrasound. Parameters like passive range of motion, Numerical Rating Scale, and Constant-Murley score were evaluated to find correlations with axillary recess thickness. Results The average age was 50.7 yrs, and mean body mass index was 22.7. Axillary recess 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 axillary recess 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 axillary recess thickness and passive range of motion, especially in shoulder external rotation and extension. Conclusions Axillary recess thickness measured by ultrasound might serve as a valuable diagnostic and evaluation parameter in shoulder stiffness.