Increased lateral calcaneal body and subtalar joint visualization utilizing a modified sinus tarsi approach

Introduction: Surgical fixation of calcaneus fractures have a high incidence of wound healing complications. The traditional sinus tarsi approach (TST) for open reduction and internal fixation has gained popularity due to adequate fracture exposure with lower wound complication rates. Visualization, as compared to more extensile approaches, can be limited however. This study introduces a modified sinus tarsi approach (MST) which extends the TST incision approximately 2cm postero-dorsally as well as 2cm antero-plantarly, to enhance exposure. The aim of this study is to quantify the amount of exposure obtained with the traditional sinus tarsi approach and the modified sinus tarsi approach.

Methods: Twelve unpaired fresh-frozen cadaveric specimens underwent sequential dissection starting with the TST followed by the MST. Standardized tension was applied to the incisions during both surgical exposures. Exposed surface areas, including the lateral calcaneal wall, posterior facet, and intraarticular surfaces were marked. Digital images of the exposed calcaneal surfaces were analyzed using digital imaging software. The distance of the sural nerve from the incision was recorded for the MST.

Results: The MST provided greater exposure of the lateral calcaneal wall (865.8 ±77.8mm², 39% of total wall area) compared to the TST (322.3 ±71.9mm², 14.9%) (P < .0001). Similarly, the MST exposed more of the posterior facet (204.4 ±69.8mm², 43.3%) and intraarticular area (548.8 ±124.2mm², 45.1%) compared to the TST (P < .0001). The sural nerve was found an average of 1.8 ± 6.1mm proximal to the distal extent of the MST incision.

Conclusion: The modified sinus tarsi approach increases visualization of calcaneal surfaces compared to the traditional sinus tarsi approach. Care must be taken to avoid the sural nerve distally. This enhanced exposure may improve fracture reduction and fixation while retaining the soft tissue and angiosomal benefits of the traditional sinus tarsi approach.

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