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. 2024 Dec 11:15589447241302356.
doi: 10.1177/15589447241302356. Online ahead of print.

Back to the Anatomy Lab to Redefine the Pulley System of the Thumb: Is There an A0 Pulley?

John M Sullivan 3rd  1 , Shelley Edwards  1 , Eric Waetjen  1 , Shireen Dogar  1 , Marc E Walker  1
Affiliations

Back to the Anatomy Lab to Redefine the Pulley System of the Thumb: Is There an A0 Pulley?

John M Sullivan 3rd et al. Hand (N Y). .

Abstract

Background: There are various anatomical descriptions of the pulley system of the fingers and thumb. The A0 pulley, often referred to as palmar aponeurosis of the fingers, is of keen interest, especially regarding surgical release of the A1 pulley for trigger finger; however, there has been no anatomical description of the A0 pulley in the thumb.

Methods: Twenty-four cadaveric thumbs were dissected to expose the entire pulley system. Each structure, including the A2, Aob, Av, A1 pulleys, and any proximal transverse elements, were cataloged.

Results: Three distinct transverse elements were identified proximal to the A1 pulley including: (1) the named ligament of Grapow; (2) the proximal commissural ligament and associated transverse fascial tissues; and (3) a definable A0, identified in 10/12 (83.3%) cadavers and 15/24 (62.5%) thumbs. Ten A0 pulleys occurred bilaterally, while 5 occurred unilaterally.

Conclusions: The presence of an A0 pulley in greater than 80% of the studied thumbs serves as an important anatomic finding that should be considered in surgical treatment. An additional finding of importance is that the pulley system anatomy demonstrated variability in laterality. Based on these anatomic findings, not only can the A0 pulley be defined as a unique anatomic structure of the thumb, but its repair also has implications for successful surgical treatment of thumb pulley system pathologies.

Keywords: hand; ligament; thumb.

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Conflict of interest statement

Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Anatomical dissection of the right hand of cadaver 5058. On the left, the pulleys are seen as distinct bands of tan-colored (left) transverse fibers with a clear separation illustrated by the visible brown tendon running underneath the pulleys. On the right, is the same specimen after having the tan-colored pulleys dyed with methylene blue.
Figure 2.
Figure 2.
Anatomical dissection of the right thumb of cadaver 5058. On the left is an anatomical dissection, and on the right is the same dissection generated using the Figure 1 image with an anatomical illustration made with biorender.com.
See this image and copyright information in PMC

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