In vitro evaluation of a single injection technique for diagnostic analgesia of the proximal suspensory ligament of the equine pelvic limb.

OBJECTIVE

To examine the anatomic relationship of the deep branch of the lateral plantar nerve (DBLPN) with structures of the proximal metatarsal region, and to define the anatomic location of a solution injected using a single injection technique for diagnostic analgesia of the proximal suspensory ligament (PSL).

STUDY DESIGN

Descriptive study.

ANIMALS

Cadaveric equine pelvic limbs (n=29).

METHODS

The proximal metatarsal region of both pelvic limbs (n=5 horses, 10 limbs) was dissected and measurements were made of anatomic structures relative to the head of the 4th metatarsal bone (HMT4). A single injection technique was used to inject dye 15 mm distal to the HMT4, axial to the MT4 at a depth of 25 mm in each limb from 10 equine cadavers (19 limbs). Hindlimbs were dissected and the position of the dye was recorded.

RESULTS

DBLPN branched from the lateral plantar nerve (LPN) at a mean distance of 30 mm proximal to the HMT4 and entered the PSL at a mean distance of 17 mm distal to the HMT4. A 2nd DBLPN was observed in 1 of 10 dissected limbs. Blue dye surrounded the DBLPN in 18 limbs (95%).

CONCLUSIONS

A single injection technique was likely to have resulted in desensitization of the DBLPN in 18 of 19 limbs (95%).

CLINICAL RELEVANCE

This technique provides a reliable method using a single needle puncture for perineural analgesia of the DBLPN for diagnosis of proximal suspensory desmitis of the pelvic limb with a minimal risk of inadvertently desensitizing structures within the tarsal sheath and the tarsometatarsal joint.