The effects of implanted ionomeric and acrylic bone cements on peripheral nerve function

The effects of two experimental ionomeric and one commercial acrylic bone cement and set ionomeric microimplant bone substitute (lonogran®) on peripheral nerve conduction, 1 and 3 weeks after implantation, have been compared. In 44 experiments the rat saphenous nerve was exposed midway between the ankle and thigh and bone cement placed into a pocket created in the connective tissue adjacent to the nerve. In terminal experiments, 1 and 3 weeks later, stimulating electrodes were placed on the saphenous nerve at the ankle, and the amplitude and conduction velocity of the compound action potential (CAP) evoked was recorded through another pair of electrodes positioned on the nerve proximal to the implant, in the thigh. One week after placing an ionomeric bone cement (HVA or V-4), no neural activity could be recorded. Three weeks, after HVA implantation apparently normal CAPs were recorded indicating a recovery from a temporary nerve conduction block, but 3 weeks after V-4 implantation only small CAPs were recorded and these could be attributed to axonal regeneration. After implantation of acrylic bone cement, small CAPs were recorded after 1 week, and within 3 weeks nerve conduction appeared to have completely recovered. Three weeks after placing set ionomeric microimplant particles the amplitude and conduction velocity of the CAP was similar to the controls.