Anterior Structures at Risk During Antegrade Subtalar Fusion: A Cadaver Study

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Category: Hindfoot Introduction/Purpose: Talocalcaneal arthrodesis is the gold standard treatment for severe arthritis and has a wide range of techniques that have been described to achieve fusion. However, there is a lack of the complications associated with guide wire placement for the screw construct described in the literature. The aim of this study was to assess the proximity and structural damage to the various structures of the anterior foot resulting from guide wire placement in a top down subtalar arthrodesis procedure. Methods: Seven fresh-frozen below-the-knee cadaver specimens were randomly assigned to receive either a percutaneous or mini open approach for an antegrade subtalar screw placement. Blunt dissection was performed after each screw placement to determine the proximity of the anatomical structures of interest [superficial peroneal nerve (SPN), deep peroneal nerve (DPN), dorsalis pedis artery (DPA), dorsalis pedis vein (DPV), extensor hallucis longus (EHL), and the tibialis anterior (TA)] to the inserted hardware. The mean, standard deviation, and range for distances were calculated for all structures. Analysis of variance (ANOVA) was used to determine statistical significance. Results: Antegrade subtalar screw placement was performed percutaneously in four specimens and via a mini-open approach in three specimens. The guidewire was touching an anatomic structure of interest in the three specimens in the percutaneous groups and one specimen in the mini-open group. For the mini-open approach, the DPN, DPA, DPV, and EHL were uninjured but touching the guidewire on one cadaver. For the percutaneous approach, the DPN was uninjured but touching the guidewire on two cadavers, the DPA was uninjured but touching the guidewire on one cadaver and penetrated on a different cadaver, the DPV was uninjured but touching the guidewire on two cadavers and penetrated on a different cadaver, and the EHL was uninjured but touching the guidewire on one cadaver and penetrated on a different cadaver. Distance from each structure of interest to the screw head can be found in Table 1. Conclusion: This study shows the potential risks to anterior structures when placing an antegrade subtalar screw during fusion. We suggest that orthopedic surgeons exercise caution when performing critical steps of the procedure to minimize avoidable injury to structures of importance that may increase the morbidity of the patient.