Patterns of 18 F-FDG PET images in patients with uncomplicated total hip arthroplasty

Objective: This retrospective study was carried out to determine the typical patterns of 18 F-FDG uptake in uncomplicated total hip arthroplasty (THA). Subjects and Methods: 18 F-FDG PET images of 62 asymp-tomatic THA patients who had undergone whole body scanning were evaluated for this retrospective study. The uptake was assessed qualitatively as positive or negative in the head/neck and the stem of the prosthesis. There were 76 hip prosthesis scans (34 left side and 42 right) and the average time following surgery was 75 months (range from 40 days to 372 months). Furthermore, the time course after surgery was subdivided into 3 time interval groups: Group I less than 2 years, Group II between 2 to 5 years, Group III more than 5 years. The regions of assessment were: head region including acetabulum and femoral head, femoral neck, trochanter, and femoral shaft. Results: In patients who demonstrated increased peri-prosthetic 18 F-FDG uptake (59 of the 76 hip scans), the activity was confined to the femoral neck and prox-imal femoral shaft with the majority in the neck regions alone: 68% (40 of 59). Majority of the uptake was noted in the femoral neck, proximal shaft and trochanteric regions. Conclusions: Uptake of 18 F-FDG in the asymptomatic patients with THA is commonly visualized and appears to be confined to the proximal segment of the prosthesis with minimal or no activity in its femoral segment.