Anatomic Structures at Risk When Utilizing an Intramedullary Nail for Distal Fibular Fractures: A Cadaveric Study

Background: Retrograde intramedullary fibular nail fixation is being utilized with increasing frequency, particularly in patients at higher risk of wound complications. The purpose of this anatomic study was to assess the relative risk to nearby anatomic structures when implanting a contemporary retrograde locked intramedullary fibular nail. Methods: Ten human cadaveric lower extremities were instrumented with a fibular nail. The cadavers were dissected. The shortest distance, in millimeters (mm), between the site of procedural steps and nearby named structures of interest (ie, sural nerve, superficial peroneal nerve, and the peroneal tendons) was measured and recorded. Levels of risk were assigned based on observed distances as high (0 to 5 mm), moderate (5.1-10 mm), and low (greater than 10 mm). Results: The peroneus brevis (PB) tendon was found to be less than 5.0 mm from the distal skin incision in all specimens. When reaming and inserting the nail through the distal fibula aperture, the PB was less than 5.0 mm in 6 specimens. The peroneus longus tendon was at moderate to high risk when inserting both the proximal and distal syndesmotic screws in 9 specimens. The superficial peroneal nerve was at high risk when inserting an anterior to posterior distal locking screw in 7 specimens. The sural nerve was at low risk for all procedural steps. No structures were violated or damaged during any portion of the fibular nail instrumentation. Conclusion: The peroneal tendons and superficial peroneal nerve were at the highest risk; however, no structures were injured during instrumentation. Clinical relevance: The current findings indicate that strict adherence to sound percutaneous technique is needed in order to minimize iatrogenic damage to neighboring structures when performing retrograde locked intramedullary fibular nail insertion. This includes making skin-only incisions, blunt dissection down to bone, and maintaining close approximation between tissue protection sleeves and bone at all times.