MINIMAL FEMORAL CORTICAL THICKNESS NECESSARY TO PREVENT PERFORATION BY ULTRASONIC TOOLS IN JOINT REVISION SURGERY

Ultrasonic tools are effective in removing cement in revision surgery and almost eliminate perforation of the femoral shaft, a dangerous com plication associated with cement removal using drills, chisels, osteot omes, and other tools. Clinically, the ultrasonic tool used to remove cement could not be passed through a relatively normal femoral cortex; however, a perforation occurred in a patient with a femoral cortex le ss than 1 mm thick. The purpose of this study was to determine how thi n the femoral cortex can be and yet allow the safe use of ultrasonic t ools to remove cement without the risk of perforation. A cement mantle was constructed in the intramedullary canal of human cadaver femurs. Each specimen was mounted on a jig, which was then fastened to a Mater ials Testing System (Minneapolis, MN). The average load generated acro ss the cortex by the ultrasonic tools while removing cement was measur ed. Loads of varying magnitudes were then applied by the ultrasonic to ols to femoral cortices of varying thickness. When the cortex measured 3 mm thick, perforation did not occur. When the cortex measured 2 mm, perforation was possible but required loads three to six times greate r than those normally used to remove cement.