DISTAL ANATOMICAL RELATIONSHIP BETWEEN THE FLEXOR HALLUCIS LONGUS AND THE FLEXOR DIGITORUM LONGUS

Abstract

Anatomical variations in the attachment between the tendon of the flexor hallucis longus (FHL) and of the flexor digitorum longus (FDL) are not clearly detailled in the medical literature. Twenty-four cadaver specimens were dissected and the distal anatomical relationship between the FHL and the FDL were analyzed and measured. There are three configurations of the attachment between the tendon of the FHL and of the FDL. The absence of a tendon link seems to be more common than has been published to date in the medical literature. We have also shown that the same patient may have a different configuration on each foot.

Anatomical variations in the links between the tendon of the flexor hallucis longus (FHL) and of the flexor digitorum longus (FDL) are not clearly detailled in the medical literature.

There are three configurations of links between the tendon of the FHL and of the FDL. The absence of a tendon link seems to be more common than has been published to date in the medical literature.

A surgeon who wants to preserve the distal function of the FDL after transferring the proximal portion of the latter should perform surgical tenodesis initially or explore the FHL-FDL attachment and perform tenodesis when a type-3 configuration is discovered.

We distinguish three different configurations of the distal link between the FHL and the FDL. In type 1, a tendinous band from the FHL is attached to the FDL (42%, 10/24). In type 2, a tendinous band from the FHL is attached to the FDL and another one from the FDL is attached to the FHL (42%, 10/24). In type 3, there is no attachment (17%, 4/24). In no case is there only an attachment from the FDL to the FHL. In four cadavers a different configuration was present on each foot. The diameter of the attachment compared with the “donor” tendon varied between 37 and 53%.

Twenty-four intact cadaver specimens were dissected and the distal anatomical relationship between the FHL and the FDL were analyzed. The width of the tendons and their attachments were measured to the nearest half-millimetre.