Osteolysis

Osteolysis was originally described in 1976 by Harris et al6 about the femoral stem of hip arthroplasties. They described focal endosteal scalloping and periprosthetic bone erosion. This term, also know as particle disease and aggressive granulomatosis, now refers to both focal and linear periprosthetic bone loss adjacent to any joint replacement.

Osteolysis results from a foreign body response to particulate debris from the wear of arthroplasty components and cement. The most common inciter is polyethylene debris.7 Large particles are sequestered in fibrous tissue, but small particles are taken up by macrophages and multinucleated giant cells, which may release cytokines that initiate a cascade reaction ultimately resulting in osteolysis.8 Osteolysis is usually asymptomatic. Follow-up radiographs are used to identify the process early on, before progressive, catastrophic bone loss occurs.

Radiographs demonstrate focal areas of lytic bone. Large areas can occur, but do not necessarily indicate prosthesis loosening. Thinned cortex and weakened bone places patients at risk of pathologic fracture, prosthesis subsidence and loosening. Osteolysis occurs adjacent to tibial, femoral or patellar components. Large amounts of particulate may dissolve in joint fluid, staining the fluid and synovium a dark metal color. This is called metallosis.

Osteolysis about hemiarthroplasty stem with progressive bone-cement interface widening. Note endosteal scalloping on close-up view (arrow).

 



Osteolysis of the scapula with resultant loosening and posterior dislocation of the polyethylene component and its cement mantle (red arrow). note fragmented bone (white arrow) and cement (blue arrow).

Osteolysis high power: methylmethacralate debris (arrows) surrounded by giant cells (arrowheads).

Osteolysis high power polarized microscopy: polyethylene flakes (arrow) surrounded by foreign body giant cell reaction (arrowhead).

Osteolysis low power: polyethylene flakes (arrows) surrounded by foreign body giant cell reaction and histiocytes.

Synovial fluid aspirated from total joint replacement with metallosis. Note dark metallic tint to fluid.

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