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. 2016 Mar 25:10:36-40.
doi: 10.2174/1874325001610010036. eCollection 2016.

Comparison of the Thickness of Pulley and Flexor Tendon Between in Neutral and in Flexed Positions of Trigger Finger

Junko Sato  1 , Yoshinori Ishii  1 , Hideo Noguchi  1
Affiliations

Comparison of the Thickness of Pulley and Flexor Tendon Between in Neutral and in Flexed Positions of Trigger Finger

Junko Sato et al. Open Orthop J. .

Abstract

Objective: This study aims to compare the morphology of the A1 pulley and flexor tendons in idiopathic trigger finger of digits other than the thumb between in neutral position and in the position with the interphalangeal joints full flexed and with the metacarpophalangeal (MP) joint 0° extended (hook grip position).

Method: A total of 48 affected digits and 48 contralateral normal digits from 48 patients who initially diagnosed with idiopathic trigger finger were studied sonographically. Sonographic analysis was focused on the A1 pulley and flexor tendons at the level of the MP joint in the transverse plane. We measured the anterior-posterior thickness of A1 pulley and the sum of the flexor digitorum superficialis and profundus tendons, and also measured the maximum radialulnar width of the flexor tendon in neutral and hook grip positions, respectively. Each measurement was compared between in neutral and in hook grip positions, and also between the affected and contralateral normal digits in each position.

Results: In all the digits, the anterior-posterior thickness of flexor tendons significantly increased in hook grip position as compared with in neutral position, whereas radial-ulnar width significantly decreased. Both the A1 pulley and flexor tendons were thicker in the affected digits as compared with contralateral normal digits.

Conclusion: The thickness of flexor tendons was significantly increased anteroposteriorly in hook grip position as compared with in neutral position. In trigger finger, A1 pulley and flexor tendon were thickened, and mismatch between the volume of the flexor tendon sheath and the tendons, especially in anterior-posterior direction, might be a cause of repetitive triggering.

Keywords: A1 pulley; flexor tendon; hook grip; metacarpophalangeal joint; trigger finger; ultrasonography.

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Figures

Fig. (1)
Fig. (1)
Position of the probe in the sonographic study. Left and right images present the neutral position and hook grip position of transverse plane study, respectively. Sonographic evaluation was focused on the MP joint.
Fig. (2)
Fig. (2)
The comparison of sonographic images between unaffected left ring finger (left image) and affected right ring finger (right image) of 69 years old woman including anatomical reference. The upper and lower images exhibit the transverse image at the MP joint in the neutral and hook grip positions, respectively. The flexor tendon was measured on the longitudinal and transverse axes: anterior–posterior thickness and radial-ulnar width. The hypoechogenic bundle including the A1 pulley at the rim of the flexor tendon, which is delineated by two dotted lines, was also measured on the top of the tendon. The A1 pulley thickness was defined as the longitudinal axis of this area, including the centralized hyperechogenic area. The black arrows indicate these measurements. The Dopplar flow around the A1 pulley was also recognized. FL: flexor tendon, VP: volar plate, MH: metacarpal head.
See this image and copyright information in PMC

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