An Anatomical Study to Ensure Precise Percutaneous Release of the Annular Pulley in the Trigger Finger.

BACKGROUND

The exact cause of trigger finger remains unknown; however, symptoms suggest that it occurs when the tendon becomes inflamed or thickened, leading to entrapment within the A1 pulley of the metacarpophalangeal joint. This study aims to establish an anatomical foundation for achieving successful outcomes in percutaneous A1 pulley release procedures.

METHODS

Specifically, easily identifiable skin creases were used as reference points to locate the A1 and A2 pulleys during surgery. A total of 156 fingers from 39 Korean adult cadavers were examined. Before dissection, surface landmarks such as the palmar crease (PC) and palmar digital crease (PDC) were identified, and the distances between nearby creases were measured. Following meticulous dissection, 9 distances, including the lengths of the A1 and A2 pulleys and the distance between the pulley edge and nearby crease, were recorded.

RESULTS

The results varied according to the fingers, with the A1 pulley averaging 7.2 mm (range, 6.9-7.4 mm) and the A2 pulley averaging 17.1 mm (range, 15.5-18.6 mm) in fingers 2 to 4. The gap between the A1 and A2 pulleys was relatively narrow (average, 3.4 mm). The A1 pulley was located distal to the PC in all cases. Additionally, the distance from the PC to the proximal margin of the A1 pulley averaged 4.2 mm (range, 3.1-4.9 mm). Furthermore, in some fingers, the entire A2 pulley was located proximal to the PDC, emphasizing anatomical variability.

CONCLUSIONS

The findings of this study provide practical anatomical references for identifying the A1 and A2 pulleys using palmar skin creases, which may improve the safety and precision of percutaneous A1 pulley release while minimizing the risk of A2 pulley injury.