The cementless femoral component in failed prosthetic hip joints: Periprosthetic uptake patterns on bone scintigraphy

Abstract

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Objectives: This retrospective investigation was undertaken to determine the significance and patterns of periprosthetic uptake around the cementless femoral component on bone scans of failed hip arthroplasties. Methods: Bone scans of 25 failed hip arthroplasties with cementless femoral components, ranging in age from 2 weeks to 15 years, were included. Images were reviewed by one experienced nuclear physician without knowledge of other test results or final diagnoses. Periprosthetic activity that was indistinguishable from normal nonarticular bone activity was interpreted as normal. Increased periprosthetic activity was classified as abnormal and further characterized as focal at the distal tip or diffuse around the shaft. Imaging results were compared with final diagnoses which were based on surgical, histopathological, and microbiological results in all cases. Results: There were 8 infected hip prostheses. Final diagnoses in the remaining 17 included aseptic loosening (femoral component (n=7), acetabular component (n=5)), failed acetabular liner (n=2), component malposition (n=2), and periprosthetic scar formation (n=1). Periprosthetic femoral component uptake was normal in 11 patients. In 9, including 5 with infection, the femoral component was fixed. Periprosthetic femoral component uptake was abnormal in 14 prostheses. In 7, the femoral component was loose and in 7, it was fixed. In 11 cases, the periprosthetic activity was diffuse: 3 prostheses were infected, 4 were aseptically loosened, and 4 were neither loose nor infected. In 3 prostheses, the uptake was focal, all uninfected, 2 were fixed, and 1 was loose. Conclusions: In this investigation, there was no correlation between the presence or absence of periprosthetic uptake around the cementless femoral component of a failed hip arthroplasty and the presence or absence of infection or loosening. These data suggest that the role of the bone scan in the evaluation of hip arthroplasties with a cementless femoral component merits renewed investigation.