Structures at Risk During Percutaneous Extra-Articular Chevron Osteotomy of the Distal First Metatarsal.

Abstract

Background. Minimally invasive surgery of the forefoot has regained popularity as an alternative to traditional open procedures. Minimally invasive hallux valgus surgery has been shown to be effective and reproducible for the treatment of mild to moderate hallux valgus. The aim of this study is to identify vital structures that are at risk for iatrogenic damage while performing a minimally invasive distal chevron osteotomy due to limited direct visualization. Methods. Ten fresh-frozen below knee cadavers were used for this study. A minimally invasive distal chevron osteotomy and medial eminence resection with a 2.2 mm × 22 mm Shannon burr was performed on each cadaver. Each specimen was dissected to expose the potential structures at risk for injury during the procedure. Structures evaluated included the medial neurovascular bundle, first metatarsophalangeal joint capsule, extensor hallucis longus tendon, flexor hallucis longus tendon, abductor hallucis tendon, and the sesamoid apparatus. Results. Ten specimens were evaluated. The dorsal medial cutaneous nerve was directly injured in 5 of the 10 cadaver specimens and intact/uninjured in the remaining 5 specimens. The flexor hallucis longus, extensor hallucis longus, adductor tendon, sesamoid apparatus, and first metatarsophalangeal joint capsule were uninjured in all specimens. Conclusion. Minimally invasive chevron distal osteotomy and medial eminence resection has a high learning curve. The resection of the medial eminence may iatrogenically injure the dorsal medial cutaneous nerve. The incidence is higher in this study than prior reported cadaveric studies and may warrant extra care to protect vital structures.Level of Evidence: Level IV: Cadaver study.