A new method of fixation in osteoporotic bone. A preliminary report

Over-tightening of cortical bone screws in osteoporotic bone results in weak fixation. Once a screw is over-tightened and the bone thread form is stripped, there are limited means at the surgeon's disposal to rescue the situation, none of them entirely satisfactory. We describe a simple device that is specifically designed to resolve this problem. It consists of a nylon cavity plug and applicator. The plug is inserted into the stripped hole and the screw re-applied and tightened in the normal manner. The plug expands and forms a load-bearing region on the inner face of the bone. Tests on osteoporotic cadavaric bone have shown that the plug effectively re-establishes screw fixation. When compared to an over-tightened screw, the plug is at least twice as resistant to loads acting to pull the screw out of the surrounding bone.