ABSTRACT
BACKGROUND: A2 pulley release is often needed for exposure of the lacerated tendon, retrieval of retracted tendons, placement of core sutures, or to permit full motion and gliding of the repaired and edematous tendon. However, there is no agreement in the literature on the specific quantity of pulley venting that can be performed and recommendations are limited to an undefined "judicious release" of the pulleys when necessary. METHODS: Following a previously developed testing protocols, finger kinematics, tendon excursion, and bowstringing were evaluated on cadaveric hands for venting in increments of 20% of the pulley length. RESULTS: In our study, we found a statistically significant influence of venting on bowstringing, although no difference was found between fingers, and a significant difference in tendon slack, which was variable depending on the finger. Bowstringing started increasing at 20% of A2 venting and peaked at full release. Tendon slack did not start until 40% of A2 venting on the index finger, but started at 20% on the middle, ring, and small fingers. CONCLUSIONS: Venting of the A2 pulley leads to an incremental increase in tendon bowstringing and tendon slack. However, differences in metacarpophalangeal flexion angle were not observed until full A2 pulley release, and only observed in the index finger, and no differences were observed in proximal interphalangeal flexion angles. Therefore, the benefit of releasing the A2 pulley when clinically necessary will likely outweigh the risks of loss of motion or strength.
ABSTRACT
Purpose: The purpose of this article is to explore the amount of work, quantitated by flexion and extension cycles, that is needed to obtain a positive Elson test following a central slip injury. Methods: Thirteen frozen cadaveric fingers from individuals with an average age of 79.6 years were used. Testing was performed by imposing sinusoidal displacement of the 2 tendons, with loads ranging from 30 N to 2 N at 1 Hz. Following transection to the central slip, each finger was cycled 1,000 times using the same protocol adopted for the control. Following 100, 200, 300, and 1,000 cycles, we measured the extension angles of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints from the flexed position and the distance between landmarks of the extensor apparatus and simulated an Elson test. Results: In both the fingers, the range of motion of the metacarpophalangeal and distal interphalangeal joints measured in the controls remained unchanged, whereas the range of motion of the proximal interphalangeal joint was significantly reduced immediately after central slip transection. Combining both ring and middle fingers, for a displacement of 5 mm, the force measured in the control (1.05 ± 0.69 N) increased to the value of 2.36 ± 0.97 N at the 1,000th cycle. Although the middle finger has shown a significant difference in force at 100 cycles following central slip transection, 200 cycles were needed to observe a difference on the ring finger. Conclusions: In controlled conditions, there is a variation in resistance to flexion of the distal interphalangeal joint. However, the amplitude of the forces is so small that they are likely imperceptible clinically. Delayed testing should be considered to increase the sensitivity of the test or in patients experiencing pain. Type of study/level of evidence: Diagnostic V.
