Anatomic and Histological Features of the Extensor Digitorum Longus Tendon Insertion in the Proximal Nail Matrix of the Second Toe

Abstract

Background: Anatomic and histological landmarks of the extensor digitorum longus (EDL) tendon insertion in the proximal nail matrix may be key aspects during surgery exposure in order to avoid permanent nail deformities. Objective: The main purpose was to determine the anatomic and histological features of the EDL’s insertion to the proximal nail matrix of the second toe. Methods: A sample of fifty second toes from fresh-frozen human cadavers was included in this study. Using X25-magnification, the proximal nail matrix limits and distal EDL tendon bony insertions were anatomically and histologically detailed. Results: The second toes’ EDLs were deeply located with respect to the nail matrix and extended superficially and dorsally to the distal phalanx in all human cadavers. The second toe distal nail matrix was not attached to the dorsal part of the distal phalanx base periosteum. Conclusions: The EDL is located plantar and directly underneath to the proximal nail matrix as well as dorsally to the bone. The proximal edge of the nail matrix and bed in human cadaver second toes are placed dorsally and overlap the distal EDL insertion. These anatomic and histological features should be used as reference landmarks during digital surgery and invasive procedures.

Accessory extensor pollicis longus tendon in emergency surgery

“…In a cadaveric study, tendon bony insertions can be anatomically and histologically examined in detail. 2 They can then be used as reference landmarks during digital surgery and invasive procedures. Variations of a true supernumerary long extensor tendon of the thumb has six subtypes: Type 1a (double EPL tendons traveling through different compartments), Type 1b (double EPL tendons traveling through the same compartment), Type 1c (tendon attaching onto the distal portion of the original EPL tendon and traveling through different compartments), Type 1d (supernumerary tendon originating immediately proximal to the origin of the extensor indicis proprius (EIP)), Type 1e (extensor pollicis et indicis communis: one attaching to the radial side of the extensor hood of the index finger and the other to the thumb), and Type 1f (extra-compartmental two-slip extensor pollicis tendons, with the radial side passing between the first and second compartments and the ulnar side traveling through the extensor retinaculum).…”

“…Together with the extensor pollicis brevis, the EPL allows for extension of the thumb in the first metacarpophalangeal joint. 2 , 3 Variations of the extensor tendons in the hand are common. 4 However, a true accessory extensor tendon of the thumb—with its own origin, insertion, and separate muscle belly—seems to be rare.…”

Anatomical Variation and Clinical Diagnosis

“…Other studies presented implications for surgical and other invasive interventions of the pelvis and extremities. Palomo-Lopez and colleagues documented the anatomic and histological features of the insertion of the extensor digitorum longus tendon on the proximal phalanx of the second toe [ 4 ]. They described for the first time the relationship between the tendon, distal nail matrix, and bone, which they explain should be used as reference landmarks during surgical procedures.…”