Hallux Valgus

Abstract

Category: Bunion Introduction/Purpose: Abnormal motion of the first tarsometatarsal (TMT) joint disrupts the anatomic alignment of the metatarsal head, sesamoid complex and proximal first phalanx. This anatomic disruption combined with the deforming forces of the extensor hallucis longus, adductor tendons, and extensor hallucis brevis result in a hallux valgus deformity. First TMT arthrodesis or the Lapidus procedure has been described as treatment for moderate to severe hallux valgus deformities by correcting hypermobility and restoring anatomic alignment of the first ray. The aim of this study was to evaluate the safety of a percutaneous approach to the Lapidus procedure and its relation to anatomic structures. Methods: A percutaneous, modified Lapidus procedure was performed on 19 embalmed cadaveric feet under fluoroscopic guidance. The specimens were then dissected to identify the extensor hallucis longus (EHL), extensor hallucis brevis (EHB), tibialis anterior (TA), median branch of the superficial peroneal nerve (MBSPN), intermediate branch of the superficial peroneal nerve (IBSPN), deep peroneal neurovascular bundle (DPNVB) and saphenous vein (SV). The structures were localized with reference to percutaneous burr and screw placement during the procedure. Results: The tibialis anterior and intermediate branch of the superficial peroneal nerve were a mean of 3.75 millimeters (mm) and 5.08 mm from the closest burr or screw placement. The extensor hallucis longus and extensor hallucis brevis were at greatest risk under the new approach with mean distances of .92 to 4.08 mm to nearby instrumentation. The extensor hallucis longus or extensor hallucis brevis were either directly pierced or <2 mm from instrumentation on 26 occasions. A terminal branch of the saphenous vein was also either pierced or within 2 mm of instrumentation on 4 occasions. The deep peroneal neurovascular bundle and median branch of superficial peroneal nerve were relatively safe, coming within 2 mm of percutaneous burr or screw placement on only 2 occasions each. Conclusion: The minimally invasive percutaneous Lapidus arthrodesis provides a safe alternative to the traditional, open approach for patients with moderate to severe hallux valgus deformities. This may be a beneficial alternative to conventional open Lapidus procedures by minimizing soft tissue dissection. Further clinical studies must be performed to compare deformity correction, fusion rate, and complications with the modified percutaneous Lapidus procedure.