Trigger Finger Release with Hand Surface Landmark Ratios: An Anatomic and Clinical Study

The purpose of this study was to identify surface landmark ratios to locate the Al pulley and clarify the controversy of differing anatomic descriptions of the Al, CO, and A2 pulleys. Minimally invasive and percutaneous approaches to Al pulley release may be facilitated with surface landmark ratios, which identify and predict the proximal and distal margins of the Al pulley. Two-hundred fifty-sixty fingers were dissected in 64 preserved cadaver hands. Measurements of Al pulley lengths and pulley margins in relation to surface landmarks were obtained. We found that the distance from the palmar digital crease to the proximal interphalangeal crease (mean, 2.42 ± 0.03 cm) corresponds to the distance of the proximal edge of the Al pulley from the palmar digital crease (mean, 2.45 ± 0.03 cm). The mean absolute difference between these two measured distances in each finger was 0.13 cm, with a 95 percent confidence interval of 0.11 to 0.14 cm. Thus, the distance between the palmar digital crease and the proximal interphalangeal crease can be used to predict the distance between the palmar digital crease and the Al pulley proximal edge with reasonable accuracy. Al pulley length averaged 0.98 ± 0.02 cm for the small finger and 1.17 ± 0.02 cm for the index, middle, and ring fingers. The length of the Al pulley was significantly shorter (p < 0.001) for the small finger than for the index, middle, and ring fingers. Additionally, a cruciate (C0) pulley was consistently located between the Al and A2 pulleys, an average of 0.46 cm proximal to the palmar digital crease, which can serve as guide for concluding the release of the Al pulley. Clinically, hand surface landmark ratios were used to release 32 trigger fingers with a minimally invasive technique, without a complication during 4- to 30-week follow-up. We conclude that hand surface landmark ratios can serve to locate the proximal Al pulley edge, thus facilitating complete trigger finger release by either open or minimally invasive techniques. Additionally, our study clarifies the discrepancy of prior smaller reports of the pulley system anatomy regarding the existence of the CO pulley between the Al and A2 pulleys. The cruciate fibers of this CO pulley can serve as the distal boundary for release of trigger finger. (Plast. Reconstr. Surg. 108908, 2001.)