A modified technique for the fixation of pathologic fractures in the lower femur

Intramedullary nail fixation augmented by the pressure injection of methylmethacrylate was investigated by use of bovine femora. In this technique, the nail is first placed in its final desired position; cement is then injected with a conical-tipped syringe through a distal drill hole into the medullary canal around the nail. This method was compared with the conventional technique of first placing the cement into the medullary canal and then driving the nail into position. Calf femora were used to compare the cement pressures generated, the shear resistance at the bone/cement interface, and the contour of the endosteal cement surface produced by the two cementing techniques. Significantly higher bone/cement interface pressures were generated by the injection of cement. Shear resistance at the bone/cement interface, investigated by push-out tests, revealed no significant difference between the two techniques. Dissolution of the specimens in nitric acid produced a methylmethacrylate cast of the endosteal surface, thus revealing the pattern of cement penetration into endosteal bone. The cement surfaces made by the injection of cement revealed characteristics of superior fixation and penetration compared to those made by the conventional method. The injection of cement for pathologic long-bone fractures is safer than the conventional method, is less susceptible to intraoperative complications, and offers satisfactory fixation.