Heat Generation and Risk of Thermal Necrosis during Minimally Invasive Hallux Valgus Correction Utilizing a Shannon Burr: A Cadaveric Study

Abstract

Category: Midfoot/Forefoot; Other Introduction/Purpose: Minimally invasive (MIS) bunion correction is growing in popularity as a treatment option of hallux valgus deformities. This technique has been shown to help with post-operative pain and improve functional outcomes. Despite these benefits there are concerns that the Shannon burr may lead to excess heat generation, thermal necrosis of bone and potentially increase the risk of nonunion. The purpose of our study was to assess the heat generation while using a Shannon burr during MIS first metatarsal osteotomies. Methods: Four below knee cadavers were utilized and osteotomies of the distal and proximal aspects of each of the first metatarsal were performed utilizing a 2mm x 20mm Shannon burr under fluoroscopic guidance. 3 K-type thermocouples were placed in each metatarsal, one distal, one in between and one proximal to the osteotomy sites. Temperatures were evaluated during the entire burring process and after to assess heat dissipation and total heat generated. Three different techniques of burring were utilized, 1. Continuous without irrigation, 2. Continuous with irrigation and 3. Pulse burring technique with irrigation (20 seconds on, 10 seconds off). Results: The pulse burring technique with irrigation showed the overall lowest max temperature and change in temperature compared to the other techniques. Average burr time, maximum heat generation and overall change in heat was 86.2 seconds, 102.4 °F and 78.9 °F for all trials. Conclusion: The pulse burr technique with irrigation generated less heat than both continuous burring with and without irrigation. There was an overall trend toward higher heat generation with longer burr times regardless of irrigation and burring technique. Utilizing a Shannon burr with pulse burring and irrigation can minimize heat generation and potentially decrease the risk of thermal necrosis of bone.