Longitudinal monitoring of bone remodelling activity around the acetabular cup after total hip arthroplasty using 18F-fluoride PET/CT scans

Aims Aseptic loosening of the acetabular cup is one of the main causes of implant failure after total hip arthroplasty (THA). Insight in bone remodelling activity around implants could enable early assessment of implant fixation as a predictor for long-term implant stability. In this study, 18F-fluoride positron emission tomography/CT (PET/CT) is used to quantify longitudinal bone remodelling activity around two different acetabular cup designs. Methods A prospective cohort of 14 patients undergoing THA was enrolled. These patients received an uncemented hydroxyapatite-coated cup (n = 6) or an uncemented cup with a porous titanium surface (n = 8). PET/CT scanning was performed postoperatively at three, six, and 12 months. Custom-made software was developed to analyze the longitudinal bone remodelling activity around acetabular cup. A set of points surrounding the cup was semiautomatically defined in the CT scan. For each of these points, the standardized uptake value (SUV) was calculated using the corresponding PET data. These points were used for 3D visualization and quantification of bone remodelling activity by averaging SUVs into segments. Results For both acetabular cup designs, the highest SUVs were found in the superolateral region after three months' follow-up, and a significant decrease of SUVs over time was observed. For the titanium cup, the higher SUV in the superolateral region compared to other regions was still apparent after 12 months' follow-up. Conclusion A semiautomatic method to evaluate 18F-fluoride PET/CT scans of patients after THA was designed. The technique can be used to analyze and compare longitudinal bone remodel ling activity around different acetabular cup designs.-