Case 20

Discussion:

Small particle disease (SPD) was first recognized by Charney in the 1960s and was initially believed to be related to the cement used to anchor the prostheses. Originally this was called cement disease or aggressive granulomatosus. Small particle disease is a frequent complication in total hip arthroplasty and a frequent reason for revisions. Today it is mostly seen in non-cemented hips as a reaction to small polyethylene wear particle, although any small particles (metal, cement, or polyethylene) can play a role in initiating osteolysis. Micro-particles produced by polyethylene wear in prostheses readily phagocytosed by macrophages but not easily digested which in turn results in production of numerous mediators and cytokines by stimulated macrophages such as prostaglandin E2, IL-1, and osteoclast activating factors that destroy bone and form focal granulomatous lesions composed of multinucleated giant cells and monocytes. Small particle disease can virtually take place with any joint arthroplasty.

Radiographically, the lesions are typically well-defined focal areas of bone resorption that do not conform to the shape of the prosthesis. They can be expansile, resulting in areas of cortical breaks.

References:

• Anthony PP, Gie GA, Howie CR, Ling RS. Localized endosteal bone lysis in relation to the femoral components of cemented total hip arthroplasties. J Bone Joint Surg Br 1990; 72:971-979.
• Mihra S. Taljanovic, Marci D. Jones, Tim B. Hunter, James B. Benjamin, John T. Ruth,  Andrew W. Brown, and Joseph E. Sheppard,  Joint Arthroplasties and Prostheses. Radiographics. 2003;23:1295-1314.