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Background: Clinical diagnosis and classification of trigger fingers is traditionally based on physical examinations and certain obvious symptoms. However, it might lack quantitative evidence to describe the different graded trigger digits. This study provides quantitative evidence of kinematics and functional differences among different graded trigger fingers based on Froimson's classification., Methods: Forty-seven patients with fifty-five trigger fingers and graded twenty-three, eleven, and twenty-one fingers as grades II, III, and IV, respectively. The QuickDASH questionnaire evaluated the subject's self-perception of hand symptoms and functions. The study measured maximal workspace of the fingertip motion and range of motion of the finger joints during an assigned tendon-gliding task using an electromagnetic tracking device. In addition, R(alpha), defined as the ratio range of angular acceleration during finger extension to the range during finger flexion of each joint, quantified the triggering effect., Findings: The QuickDASH score results show that functional performances have significant differences among three grades (P<0.05). Workspace, range of motion of proximal interphalangeal joint and R(alpha) of proximal interphalangeal and distal interphalangeal joint of trigger fingers also significantly differ among three grades (P<0.05). These findings quantitatively show that trigger fingers in different impairment levels have different kinematics and functional performances., Interpretation: The results serve as evidence-based knowledge for clinics. The more practical and immediate application of this study would be to facilitate the assessment, design and execution of rehabilitation for patients with trigger fingers., (Crown Copyright (c) 2010. Published by Elsevier Ltd. All rights reserved.)

Background: Trigger finger is most common in the ring finger, but the reason for this is not known. We hypothesized that the compliance of the A1 pulley might be one of the factors responsible for this phenomenon. The purpose of this study was therefore to compare the compliance of the normal A1 pulley of the thumb, index, middle, ring and little fingers using human cadavers., Methods: Eight normal thumbs, index, middle, ring and little fingers from eight fresh frozen human hand cadavers were used in this experiment. The compliance of the A1 pulley was measured by the resistance when passing a tapered metal rod through the A1 pulley. The slopes of the linear region of radial force/increasing area ratio curve were calculated and analyzed., Findings: The mean slope of the linear region of the radial force/increasing area ratio curve was significantly different among the five digits (p<0.05). Post hoc analysis indicated that the mean slope for the middle finger A1 pulleys was larger than the thumb and little finger A1 pulleys (p<0.05)., Interpretation: The findings did not support our clinical hypothesis that A1 pulley stiffness would parallel the relative frequency of trigger finger by digit., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)