Structures at Risk From an Intermetatarsal Screw for Lapidus Bunionectomy: A Cadaveric Study

Abstract

The Lapidus bunionectomy is performed to treat hallux valgus. Recurrence of the deformity remains a concern. A transverse intermetatarsal screw spanning the base of the first metatarsal to the base of the second can increase stability. The neurovascular bundle is located within the proximity of this screw. In this study, we assessed the structures at risks with the use of this technique. In 10 specimens, a guide wire was placed, and a 4.0-mm cannulated screw was inserted. The neurovascular bundle was dissected and inspected for direct trauma to the neurovascular bundle, and the proximity of the screw was measured using a digital caliper. Ten cadaveric specimens were used. The dorsalis pedis artery and deep peroneal nerve were free from injury in 9 of 10 specimens. In those 9 specimens, the neurovascular bundle was located dorsal in relation to the screw. The mean distance of the screw to the neurovascular bundle was 7.1 ± 3.3 mm. The mean distance from the screw to the first tarsometatarsal joint (TMTJ) was 14.7 ± 4.3 mm. The mean distance from the screw as it entered the second metatarsal to the second TMTJ was 18.0 ± 7.2 mm. In 1 specimen, the screw was found to be traversing through the neurovascular bundle. The distance from the screw to the first TMTJ was 15.0 mm. The distance of the screw from where it entered the second metatarsal to the second TMTJ was 24.0 mm. Although the intermetatarsal screw avoided the neurovascular cases in most instances, there is some anatomic risk to the neurovascular bundle. Further study is warranted to evaluate clinical results using the intermetatarsal screw for the modified Lapidus procedure.