DIGITAL NERVES OF THE FOOT - ANATOMIC VARIATIONS AND IMPLICATIONS REGARDING THE PATHOGENESIS OF INTERDIGITAL NEUROMA

Seventy-one cadaveric feet were dissected, with attention to communica ting branches of the digital nerves, the diameters of the digital nerv es, the distance between the metatarsal heads, and the presence or abs ence of interdigital neuromas. A communicating branch was absent in 52 feet (73.2%) and present in 19 specimens (26.8%). The communication w as from the fourth to the third web space common digital nerve (i.e., from the lateral to the medial plantar nerve) in 11 specimens. A rever se communication, from the third to the fourth web space common digita l nerve (i.e., from the medial to the lateral plantar nerve), was pres ent in eight specimens. Neuromas were identified in the second web spa ce in 26 specimens and in the third web space in 32 feet. The common d igital nerve to the third web space was not thicker in feet with a con tribution from the fourth to the third web space nerve. Additionally, the incidence of third web space neuroma in feet with this type of com munication was not significantly greater than in those feet without an internervous communication. However, the intermetatarsal head distanc es and the ratios of the intermetatarsal head distance to the digital nerve diameter in web spaces 2 and 3 were significantly smaller in com parison to spaces 1 and 4 (P < .05). The morphometric data lend suppor t to theories that explain the propensity for neuroma formation in bot h the second and third web spaces on a mechanical basis. The data do n ot support those theories that explain an increased incidence of third web space neuroma formation based on a communication from the fourth to the third web space digital nerve.