Anatomic Considerations Regarding the Placement of a Retrograde Intramedullary Fibular Screw

The purpose of this study was to identify the ideal start site for a retrograde intramedullary fibular cortical screw based on its relationship to the surrounding soft tissue structures and to assess for damage to the surrounding soft tissue structures caused during placement of the screw. Four fresh frozen cadavers underwent fluoroscopic placement of a 3.5 mm cortical screw utilizing a standardized protocol. No damage to the peroneal tendons were noted in any cadaver with the foot in an inverted and plantarflexed position. The closest structure to the center of the screw head was the anterior talofibular ligament anteriorly (3.33 mm range: 3-4 mm) and the calcaneofibular ligament posteriorly (2.66 mm, range: 2-3 mm). Two screws violated the malleolar fossa medially and were noted to impinge on the lateral process of the talus. The ideal start site for a 3.5 mm intramedullary fibular screw is at the midline on the lateral radiograph and 3.0 mm lateral to the malleolar fossa on the AP radiograph. This avoids damage to the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) and prevents impingement on the lateral process of the talus. (Journal of Surgical Orthopaedic Advances 30(2):078-081, 2021).