Gender and laterality differences on measurements of acromiohumeral distance (AHD) at rest and at shoulder abduction using musculoskeletal ultrasound in asymptomatic Filipino adults

Abstract

Musculoskeletal ultrasound is increasingly becoming a popular tool in the diagnosis of musculoskeletal disorders with the shoulder as one of the most routinely scanned joints. Common causes of shoulder pain, such as subacromial impingement syndrome and rotator cuff tendinopathy, have been shown to be associated with reduced acromiohumeral distance. This study aimed to determine mean ultrasonographic acromiohumeral distance and compare measurements between male and female Filipino adults, dominant and non-dominant side, at neutral shoulder position and at 60° abduction. Secondarily, it aimed to determine interrater reliabiliy of ultrasonographic measurements. This study employed a cross-sectional observational study design. AHD was measured on both shoulders of forty-one volunteers, 15 males and 26 females with mean age 22.1 and 22.3 respectively, at neutral shoulder position and at 60° of passive abduction by two different raters. For the dominant side, mean AHD at neutral was 11.40 mm (SD 1.16 mm) for males and 10.65 mm (SD 1.22 mm) for females ( P -value < 0.05). At 60° passive abduction, AHD decreased to 9.96 mm (SD 1.10 mm) for males and 9.49 mm (SD 1.43 mm) for females. For the non-dominant side, the mean AHD at neutral was 11.15 mm (SD 1.13 mm) for males and 10.70 mm (1.20 mm) for females. At 60° abduction, mean AHD was 9.86 mm (1.13 mm) for males and 9.36 mm (1.54 mm) for females ( P -value > 0.05). Comparison of the dominant and non-dominant sides showed no significant difference at both shoulder positions. ICC values for the all the measurements ranged from 0.848 to 0.913. Results of this study suggest that measurement of AHD may have gender differences, but is similar between the dominant and non-dominant side. Musculoskeletal ultrasound was found to have excellent interrater reliability to measure AHD at both neutral position and at 60° of passive abduction.