Experimental studies of the biological response to a new bone cement: II Soft tissue reactions in the rat.

The biological response to a new bone cement (London Hospital cement), which contains polyethylmethacrylate/n-butylmethacrylate, has been examined experimentally and compared with polymethylmethacrylate. The cellular reaction was identical when the polymer powders of the cements were inserted subcutaneously in rats, there being a macrophage response to the polymer beads of both materials. Experimental implantation of the two cements into the paraspinal musculature of rats showed that there was less tissue damage adjacent to the new material than to polyethylmethacrylate. There was a significantly smaller macrophage and giant cell reaction in relation to the polyethylmethacrylate/n-butylmethacrylate cement. These differences may be related to the lower heat of polymerisation of the new cement and to its smoother surface contour, as demonstrated by scanning electron microscopy.