[Thickness of A1 Pulley Measured by High-frequency Ultrasound and Its Influence Factors in Healthy Volunteers].

Objective: To investigate A1 pulley thickness of flexor tendon in healthy volunteers and to analyze its influence factors.

Methods: The study included 90 healthy volunteers and the A1 pulley thickness at bilateral fingers was measured using high frequency ultrasound. The following parameters were recorded for each participant: age, gender, weight, height, body mass index (BMI).

Results: High-frequency ultrasound can clearly show A1 pulley. There was no significant difference in A1 pulley thickness between the bilateral fingers ( P>0.05). A1 pulley thickness was significantly different in different fingers ( P<0.05). Further comparison showed that A1 pulley thickness could be divided into two subsets: thumb and little finger ((0.196±0.051) mm), index, middle and ring fingers ((0.230±0.055) mm). A1 pulley thickness was positively correlated with age ( r=0.468, P<0.001). The normal reference ranges for thumb and little finger were 0.09-0.23 mm, 0.12-0.30 mm and 0.12-0.32 mm, respectively. The normal reference ranges for index, middle and ring fingers were 0.11-0.27 mm, 0.15-0.35 mm and 0.17-0.35 mm in volunteers aged 3-19 yr., 20-49 yr., and ≥50 yr., respectively. Gender and BMI had negligible impact on A1 pulley thickness ( P>0.05).

Conclusion: High-frequency ultrasound can clearly show and measure A1 pulley. Site and age should be taken into account when determining the reference range of normal A1 pulley thickness. High-frequency ultrasound can be a quantitative evaluation method for A1 pulley lesions.