Strength evaluation of lateral calcaneal wall with circular external fixation application in cadaveric specimens

Circular external fixation is a useful treatment option for the correction of complex trauma, extremity deformity, osteomyelitis, and reconstruction of the foot and ankle. The goal of the present study was to determine the degrees of bolt rotation required to create enough wire tension to cause structural failure of the lateral calcaneal wall when stressed with both olive and smooth wires in a cadaveric model. Ten fresh, thawed, below-the-knee specimens were tested at the San Diego Cadaveric Academic Research Symposium. The mean bolt rotation required to pull an olive wire through the lateral wall of the calcaneus was 79.8° ± 32.81°, and the mean bolt rotation required to "walk" a skinny wire (narrow diameter) and create 1 mm of cortical bone failure was 50.5° ± 30.91°. The results of the present investigation further define and elucidate the appropriate "Russian tensioning" technique applicable for external fixation of the calcaneus using olive or skinny wires in the case of fracture repair or compression arthrodesis.