Mapping of Posterior Talar Dome Access Through Posteromedial Versus Posterolateral Approaches

Abstract

Objective: To evaluate the accessible area of the talar dome through 2 standard posterior approaches [posteromedial (PM) and posterolateral (PL)] with and without distraction.

Methods: A standard PM or PL approach was performed with and without external fixator distraction on 12 through-knee cadaveric legs (6 matched pairs). The accessible area of the talar dome was outlined and imaged in a microcomputed tomography scanner to achieve 3D reconstructions of the accessible surface area. The study outcomes were accessible surface area of the talar dome in (1) total surface area and (2) sagittal plane distance of the talar dome at predetermined intervals.

Results: The PM approach provided significantly more access to the talar dome than did the PL approach both with and without distraction (P < 0.001). The PM approach allowed access to 15.8% (SD = 4.7) of the talar dome without distraction and 26.4% (SD = 8.0, P < 0.001) of the talar dome with distraction. The PL approach provided access to 6.69% (SD = 2.69, P = 0.006 compared with PM) and 14.6% (SD = 6.24, P = 0.006 compared with PM) of the talar dome surface area without and with distraction. At the difficult to access posterocentral region (L50) of the talus, the PM approach without and with distraction allowed 26.7% (SD = 4.1) and 38.6% (SD = 5.6, P < 0.001) sagittal plane access compared with 18.7% (SD = 5.61, P = 0.03) and 27.5% (SD = 7.11, P = 0.003) through a PL approach.

Conclusion: The PM approach provides greater access to the posterocentral and PM talus. Using an external fixator for distraction can improve intraoperative visualization by at least 40%. This study provides a roadmap that can help guide talar dome surgical access for treatment of posterior talus fractures and help determine when an approach that includes an osteotomy can be avoided.