Lateralizing Calcaneal Osteotomy Performed with a Percutaneous Burr Results in a Significantly Lower Increase in Tarsal Tunnel Pressure

Category: Hindfoot; Basic Sciences/Biologics Introduction/Purpose: Single-plane calcaneal osteotomies are used to manage hindfoot deformity. Neurological complications, such as tarsal tunnel syndrome, are well-documented following lateralizing calcaneal osteotomy. Traditionally, calcaneal osteotomy is performed using an oscillating saw. No studies have investigated the effect of alternative surgical techniques on postoperative tarsal tunnel pressure. The purpose of this study was to investigate the difference in tarsal tunnel pressures following lateralizing calcaneal osteotomy performed using a high-torque, low-speed “minimally invasive surgery” (MIS) Shannon burr versus an oscillating saw. Methods: Lateral-to-medial lateralizing calcaneal osteotomy via a lateral approach was performed on 10 below-knee cadaveric specimens. This was conducted on 5 specimens using an oscillating saw (Saw group) and 5 specimens using the MIS burr (Burr group). The calcaneal tuberosity was translated 1 centimeter laterally in all specimens and transfixed using 2 Kirschner wires. Tarsal tunnel pressure measurements were collected before and after osteotomy under ultrasound guidance using a percutaneous needle barometer. Mean pre- and post-osteotomy tarsal tunnel pressures were compared between groups. Differences were analyzed using Student’s t-test. Results: The mean pre-procedure tarsal tunnel pressure in the Saw group was 25.8 ± 5.1 mm Hg and 26.4 ± 4.3 mm Hg in the Burr group (p = 0.85). The mean post-procedure tarsal tunnel pressure was 63.4 ± 5.1 mm Hg in the Saw group and 47.8 ± 4.3 mm Hg in the Burr group (p = 0.01). The change in tarsal tunnel pressure after lateralizing calcaneal osteotomy was significantly lower in the Burr group (21.4 ± 4.5) compared to the Saw group (37.6 ± 12.5) (p = 0.03). The increase in tarsal tunnel pressure was 43% lower in the Burr group compared to the Saw group. Conclusion: In this cadaveric study, the increase in tarsal tunnel pressure following lateralizing calcaneal osteotomy was significantly lower when using a burr versus an oscillating saw. This is likely due to the increased width (“kerf”) of the 3mm MIS burr relative to the submillimeter saw blade width causing increased shortening of the calcaneus. This smaller magnitude of tarsal tunnel pressure increase suggests that use of the MIS burr for lateralizing calcaneal osteotomy may decrease the risk of postoperative tarsal tunnel syndrome. Future research in vivo should be aimed at investigating this.