Orthopaedic cement. Freshly mixed orthopaedic cement (bone cement) being applied to a prosthetic component in total knee replacement surgery. Orthopaedic cement is a type of acrylic glass, a thermoplastic, that is used to bond joint replacements to existing bone in orthopaedic surgery. It is formed by mixing two components together, a powder and a liquid. On mixing, they form a dough-like cement that gradually hardens whilst giving off a large amount of heat. See clips K004 6229 - K004 6255 for entire sequence.