Osteolysis

Osteolysis is the active resorption of bone tissue, resulting in localized loss of bone mass. It can occur as part of normal bone remodeling, but in clinical practice it most often refers to pathological bone destruction seen on imaging as radiolucent or expanding areas within bone or around an implant.

Several contexts are common. Periprosthetic osteolysis is a well‑recognized complication of joint replacement, caused by reaction to wear debris from polyethylene, metal, or other implant components. Particles activate macrophages and promote osteoclast activity, leading to bone resorption and possible loosening of the prosthesis. Osteolysis can also reflect other processes that cause bone destruction, including malignant lesions (such as metastases or multiple myeloma), infection (osteomyelitis), and inflammatory or other systemic conditions. In radiology reports, osteolysis denotes focal bone loss that may have various etiologies.

Pathophysiology involves osteoclast-mediated resorption enhanced by inflammatory mediators. Cytokines such as interleukin-1 and tumor necrosis factor‑alpha, along with the RANK/RANKL/osteoprotegerin axis, promote osteoclast formation and activity. Debris, tumor cells, or inflammatory cells can amplify this resorptive process, while osteoblast-driven bone formation may be insufficient to restore lost bone.

Diagnosis and management rely on imaging and clinical context. Plain radiographs identify areas of lucency that may progress over time; CT provides detailed bony anatomy, MRI assesses adjacent soft tissue, and bone scintigraphy or PET can gauge activity. Biopsy is indicated when malignancy cannot be excluded. Treatment is cause-specific: in periprosthetic osteolysis, options range from observation to surgical revision and infection control; in osteoporosis or metastatic disease, systemic therapies to reduce resorption and address the underlying condition are used. Prevention focuses on reducing debris generation and optimizing implant materials and technique.