The Effect of Chilled vs Room Temperature Irrigation on Thermal Energy Dissipation During MIS Calcaneal Osteotomy

Abstract

Category: Hindfoot; Basic Sciences/Biologics; Other Introduction/Purpose: Minimally Invasive (MIS) calcaneal osteotomy has grown in popularity in recent years to address hindfoot deformity. A potential complication is thermal bone necrosis secondary to heat generation from the burr, leading to nonunion of the osteotomy. Irrigation is commonly employed to reduce this risk. The effect of irrigation on reducing this risk remains an understudied area. The purpose of this study was to evaluate the effect of cooled versus room-temperature irrigation on thermal energy dissipation on a temperature curve during calcaneal osteotomy using a Shannon burr. Methods: Ten cadaveric limbs (5 pairs) at room temperature (68 0F) were randomized to receive either cooled saline or room temperature irrigation during MIS calcaneal osteotomy. Two thermocouple probes (EL-USB-TC-LCD, Lascar Electronics) were inserted 5mm away from the plane of the osteotomy, on proximal and distal sides respectively (Fig. 1). The probes were inserted to a depth of 2cm. A 3 x 30mm Shannon burr was used to perform the osteotomy. The burr was run continuously under continuous irrigation using either room temperature (680F) and chilled (370F) irrigation, until the osteotomy was completed. All osteotomies were performed in approximately 60 seconds. Temperature was recorded at 15sec, 30sec, 45 sec and 60 sec for the two groups and used as a measure of thermal energy generation. Results: Both room temperature and chilled irrigation were effective in minimizing temperature change. On the proximal side, an overall mean increase of 2.60F (70.60F) with room temperature irrigation and a mean increase of 0.70F (68.70F) with chilled irrigation were observed at the 60 sec interval (p=0.09). On the distal side both irrigation methods were more effective in heat control (70.20F vs 67.10F; p=0.17). Conclusion: For the duration of a MIS calcaneal osteotomy, both continuous room temperature and chilled irrigation can reduce thermal energy generation. Use of chilled irrigation can be considered for osteotomies of denser bone that may take longer to perform and generate higher temperatures.