Comparison of Efficiency and Effectiveness Between a Slap Hammer and Rigid C-Frame Device for Extraction of an Intramedullary Nail.

Abstract

Removal of orthopaedic intramedullary implants can be difficult and time-consuming. Instrumentation for implant removal is frequently deficient for effective removal. The purpose of this study is to compare the efficiency of a C-type jig with a standard slap hammer attachment. We hypothesize that a C-type jig will be a more energy efficient method of implant removal. An IM nail removal was simulated in a series of 10 tests using 40 PCF Sawbones bone blocks with drilled holes and custom-made IM nails. Each attachment was secured to a Shukla Medical threaded connector from their IM nail revision product. A camera recorded each hammer swing, and a caliper recorded the distance the nail traveled out of the bone block. The data was then analyzed to determine extraction rate, and efficiency. The c-frame hammer exerted a greater force, had a greater extraction efficiency and required 37.4% less energy expenditure than the slap hammer to extract the nail the same distance. The C-frame hammer also removed the nail 38.1% faster with the same energy expenditure and possessed greater usable kinetic energy, whereas the slap hammer had more "lost" energy. The c-frame hammer attachment was found to have a considerably higher extraction rate and efficiency than the slap hammer. It will be a more useful method of implant extraction, especially for cases involving larger bones or larger implants. However, the slap hammer may be more suitable for smaller tools or bones for which larger impact loading would be detrimental.