Fig. 2From: Evaluation of the first annular pulley stretch effect under isometric contraction of the flexor tendon in healthy volunteers and trigger finger patients using ultrasonographyA hockey stick type of probe was used in this study. The examiner applied an ultrasonic probe onto the first annular (A1) tendon sheath and instructed the participants to perform active flexion of the proximal interphalangeal (PIP) joint of the middle finger isometrically to resist the passive extension load for the PIP joint applied by the examiner while keeping the metacarpophalangeal joint flexed at 45° with a custom-made fixing blockBack to article page