The development of polymethylmethacrylate bone cement with an open spongelike structure resulted as a spin-off from efforts to dampen the high exothermal peak during hardening of the cement. A cement formulation in which an aqueous gel was mixed through the organic dough showed the desired signifi cantly reduced temperature peak and improved biocompatibility but also ingrowth of bone into the pores that had been formed by the resorbing aqueous gel in the polymerized matrix. The expectation that such a cement would provide a better fi xation of total hip prostheses did not come true because of the diminished mechanical strength due to the same porosity. Better applicability of the cement was found for bony areas that were not subjected to heavy stresses such as bone defect fi lling and augmentation of cranio-facial and sternal deformities. In spite of successful clinical trials and positive fi ndings after long term evaluations a commercial development of the cement was not undertaken because of a market that was estimated too small to be profi table.