Neurovascular variations in the proximal plantar metatarsal region of the horse.

Abstract

Neurovascular variation may be relevant when performing surgical techniques to the proximal plantar metatarsal region. To document variations in the neurovascular anatomy of the proximal plantar metatarsal region and study the relationship of the neurovascular components to each other and other structures located in this area. Descriptive anatomical study. Paired cadaver hind limbs from 15 horses were dissected from the distal tibia to the metatarsophalangeal joint. Deep branch of the lateral plantar nerve (DBLPN) length, location of its origin from the lateral plantar nerve (LPN), individual DBLPN ramifications into the suspensory ligament (SL) and relationship of the DBLPN to the plantar arch and accessory ligament of the deep digital flexor tendon (ALDDFT) were recorded. Mean DBLPN length was 5.8±1.7cm with the nerve arising 3.7±1.5cm proximal to the head of the fourth metatarsal bone (MTIV). There was a median of three individual DBLPN ramifications (range 2-6) entering the SL. There were no significant left/right differences. In 57% (CI 39%-74%; n=17) limbs, the deep plantar arch was superficial to the DBLPN, whereas in 33% (CI 16%-50%; n=10) limbs, the DBLPN passed between the venous and arterial components of the arch. In 10% (CI 1%-20%; n=3) limbs, the deep plantar arch was deep to the DBLPN. In 67% (CI 50%-84%; n=20) limbs, the DBLPN was superficial to the ALDDFT, whereas in 33% (CI 16%-50%; n=10) limbs, the nerve ran deep to the ALDDFT. An additional branch from the LPN was noted in one limb. Limbs were used from horses with unknown clinical history. Anatomical variation, in particular the relationship of the DBLPN and deep metatarsal fascia to the deep plantar arch and the ALDDFT is an important consideration when undertaking surgical approaches to the proximal plantar metatarsal region.