Review Question - QID 217657

The radiograph demonstrates an osteolytic lesions behind the acetabular component and eccentric wear of the polyethylene. Of the options listed, revision surgery with head and liner exchange is the best treatment option.

Polyethylene wear is one of the primary limiting factors in the functional behavior and longevity of a THA. Radiographs shown in Figure A show superior migration of the femoral head with eccentric polyethylene wear. Despite the obvious radiographic changes, an infectious process should always be ruled out by obtaining inflammatory markers. In the setting of well fixed implants, head liner exchange with retroacetabular bone grafting (if needed) is the treatment of choice in a symptomatic active patient. However, it is also crucial to have components available if the any implants are found to be loose intraoperatively.

Maloney et al review the treatment of pelvic osteolysis in the setting of well fixed implants. They report a case series of 35 patients who underwent femoral head and polyethylene exchange with retroacetabular bone grafting of osteolytic lesions. All 35 cups remained stable and had not been revised at 2 years following surgery. They conclude that this is a viable treatment options for this cohort of patients.

Maloney et al discusses the treatment of osteolytic defects following hip and knee arthroplasty at the 2007 Implant Wear Symposium. They emphasize that surgical intervention must address the wear particle generator (usually, but not always, the bearing surface), the osteolytic defects, and implant-related issues, primarily fixation and alignment.

Figure A is an AP radiograph showing significant polyethylene wear as evidence by superior migration of the femoral head in the acetabular component.

Incorrect Answers:
Answer 1: While patients should be monitored radiographically, this patient has an issue that should be addressed given her drop in ambulatory status, pain and radiographic findings of eccentric polyethylene wear.
Answer 2: MRI of the hip is not necessary in this scenario as it wouldn't change your treatment plan.
Answer 3: Aspiration is not warranted in the setting of normal inflammatory markers.
Answer 5: The femoral stem appears to be well fixed on radiographs and thus does not need to be revised.