Monitoring and risk of progression of osteolysis after total hip arthroplasty.

Osteolysis after total hip arthroplasty (THA) develops in response to particulate wear debris and may not be associated with clinical symptoms. Osteolysis is associated with greater wear volume. Wear increases with the increased use and activity of the joint, so longer in vivo use of a THA implant increases the risk of osteolysis. Patients with non-cross-linked, ultra-high-molecular weight polyethylene implants and younger more active patients are at greater risk for the development of osteolysis. Routine monitoring for osteolysis 5 years after THA, with radiographic imaging every 2 to 3 years thereafter, is recommended. Patients at greater risk for osteolysis should be monitored more closely. If a lesion is seen radiographically, serial radiographs are helpful to determine the relative rate of progression of the lesion. CT with metal artifact reduction can be used to effectively quantitate the lesion size and location. MRI is useful in visualizing osteolytic areas and soft-tissue pathology. Both MRI and CT with metal artifact reduction protocols have been developed to effectively visualize osteolytic lesions in proximity to THA implants and provide supplemental information to plain radiography.