Sonographic evaluation of the axillary artery during simulated overhead throwing arm positions.

Objectives: The aim of this study was to determine changes in axillary artery diameter and peak systolic velocity in asymptomatic individuals during upper limb positioning commonly used to assess vascular pathology in athletes.

Design: Repeated measures observational study.

Setting: Physiology laboratory.

Participants: Subjective and objective screening excluded individuals with past, or present, conditions related to neurovascular compression syndromes. Thirty-one subjects (21 females, 10 males; mean age: 25+/-4 years) were included in the final analysis.

Main Outcome Measures: Sonographically determined axillary artery diameter and peak systolic velocity, as well as symptom production, were recorded for a series of 12 randomised arm positions, incorporating varying degrees of abduction, external rotation, and horizontal flexion/extension.

Results: The majority of arm positions revealed no change in artery diameter and peak systolic velocity. However, at the extreme of abduction, and arm positions incorporating 120 degrees abduction, significant (p<0.0005) reductions in axillary artery diameter were noted. All mean results masked wide heterogeneity: 13% demonstrating a greater than 50% reduction in diameter, 10%, a doubling of peak systolic velocity, and 42%, reporting symptoms.

Conclusions: The number of individual clinically "positive" responses questions the specificity of individual diagnostic tests, such as the hyperabduction manoeuvre, and highlights the need to interpret test results in conjunction with the subjective assessment and other physical findings from the objective assessment.