Increased Lateral Calcaneal Body and Subtalar Joint Visualization Utilizing a Modified Sinus Tarsi Approach

The traditional sinus tarsi approach (TST) for open reduction and internal fixation (ORIF) of calcaneus fractures has gained popularity because of adequate fracture exposure with lower wound complication rates. Visualization, as compared with more extensile approaches, can be limited, however. This study introduces a modified sinus tarsi approach (MST) that extends the TST incision approximately 2 cm posterodorsally as well as 2 cm anteroplantarly, 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.

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 dorsal surface 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.

The MST provided significantly greater exposure of the lateral calcaneal wall, posterior facet and dorsal surface compared to the TST (865 ± 77.8 mm², 39% of total lateral wall area, vs 322 ± 71.9 mm², 14.9% of total lateral wall area; 204 ± 69.8 mm², 43.3% of posterior facet area, vs 66.9 ± 27.9 mm², 13.7% of posterior facet area; and 549 ± 124 mm², 45.1% of dorsal surface area, vs 199 ± 61.8 mm², 16.3% of dorsal surface area, all P < .0001). The sural nerve was found an average of 1.8 ± 6.1 mm dorsal to the plantar extent of the MST incision.

In noninjured cadaver specimens, the modified sinus tarsi approach, which extends the incision by 4 cm, was found to substantially increase visualization of calcaneal surfaces compared with the traditional sinus tarsi approach. Care must be taken with the sural nerve, which is often in or near the MST distal extension. This enhanced exposure may allow for improved fracture reduction and fixation while retaining the soft tissue and angiosomal benefits of the traditional sinus tarsi approach.