Ultrasonographic evaluation of the anterior axillary recess in the normal shoulder

Abstract

OBJECTIVES: The objectives of the study were to demonstrate the usefulness of ultrasound to estimate the thickness of the anterior axillary recess (AAR) in the shoulder, determine if the thickness of the anterior axillary recess is altered with the patient's position, the degree of arm abduction, gender and laterality; compare the thickness of the anterior axillary recess obtained with the normal value reported in current scientific literature. MATERIAL AND METHODS: Descriptive, longitudinal, prospective study, carried out in 32 normal volunteers aged between 18-60 years, excluding people who had a history of inflammatory and traumatic pathology of the rotator cuff, rheumatic diseases, diabetics and hypothyroid patients. An ultrasound evaluation protocol was designed considering the variables patient position, arm position in abduction of 90º, 60º and 45º, laterality and gender. The descriptive statistical analysis of the quantitative variables was carried out by calculating the mean, standard deviation, error of the mean and confidence intervals; The variation of AAR according to position, laterality and gender was analyzed with one-way ANOVA. The thickness AAR by ultrasound and MRI was compared with the t-student test for a single sample; after determining normality with the Shapiro-Wilk test. RESULTS: Of 32 normal volunteers, 20 (62.5%) women and 12 (38.5%) men, obtaining 64 cases. The thickness of the anterior axillary recess without discriminating the patient's position or the degree of abduction was 2.07 mm, (SD ± 0.34mm), 95% CI [2.03 – 2.11 mm]. No statistically significant difference was found in the anterior axillary recess according to the patient's position, arm abduction (p=0.055) or laterality (p=0.085). According to gender, the ARR is thicker in men, 2.38mm, 95% CI [2.16 – 2.58 mm], the difference was significant (p=0.00). When comparing the thickness of the anterior axillary recess obtained with the normal value reported in current scientific literature, a statistically significant difference was found (p=0.00). CONCLUSIONS: Ultrasound allows the evaluation of the anterior axillary recess of the shoulder, the thickness is not altered with the patient's position or the degree of arm abduction, but it is thicker in men than in women and the average thickness obtained differs from the normal reference value.