Anatomy of the portal tract for endoscopic decompression of the first branch of the lateral plantar nerve.

PURPOSE: Our purpose is to study the anatomy of the portal tract for endoscopic decompression of the first branch of the lateral plantar nerve.

METHODS

The anatomy of the portals and portal tract with endoscopic release of the first branch of the lateral plantar nerve was studied in 12 feet in 6 cadaveric bodies.

RESULTS

The proximal portal is located at the fascial opening for the first branch of the lateral plantar nerve and is about 16 mm inferior and 23 mm posterior to the tip of the medial malleolus. The distal portal is located at the inferior edge of the deep fascia of the abductor hallucis muscle and just distal to the medial calcaneal tubercle. The portal tract is deep to the deep surface of the whole width of the deep abductor fascia. In 1 of 12 specimens, the nerve lay superficial to a rod placed between the portals, whereas the nerve was deep to the rod in the remaining 11 specimens. In all specimens the first branch of the lateral plantar nerve, after it pierced the deep fascia of the abductor hallucis at the fascial defect, ran anteriorly and distally, approximately parallel to the direction of the rod.

CONCLUSIONS

The proximal portal for endoscopic decompression of the first branch of the lateral plantar nerve is located at the fascial opening for the first branch of the lateral plantar nerve. This can be consistently located with the Wissinger rod technique. The portal tract thus created is effective for deep abductor fascia release. However, percutaneous release without endoscopic visualization of the first branch of the lateral plantar nerve is not safe because of the potential risk of nerve injury, because the nerve can be sandwiched between the instrument and the deep abductor fascia without being noticed.

CLINICAL RELEVANCE: The study confirmed the first branch of the lateral plantar nerve can be effectively released endoscopically.