Fingerprint pattern of bone mineralisation on cemented and uncemented femoral stems: analysis by [18F]-fluoride-PET in a randomised clinical trial

Abstract

Purpose: We present a randomised clinical study using 18F-fluoride positron emission tomography/computed tomography (F-PET/CT) to analyse the osteoblastic part of bone metabolism (new bone mineralisation) in periprosthetic bone adjacent to femoral stems following total hip arthoplasty (THA) surgery. Patients with hip osteoarthritis were randomly assigned to THA surgery with cemented or uncemented femoral components. Patients and methods: THA was performed on 26 patients (26 cases) with hip osteoarthritis. The patients received either an uncemented HA-coated femoral stem or a cemented one. The contralateral healthy femur was used as referent for normal bone metabolism. The patients were analysed with clinical score, radiography and F-PET/CT preoperatively, and postoperatively at 6 weeks and 6 months. After 2 years, clinical score and radiography was analysed again. We used the Polar Map system for analysing and presenting the PET results in 13 regions of interest adjacent to the whole stem. Results: The clinical results were good in all patients; there were no major complications. Radiographically, all stems were stable. PET analyses after 6 weeks showed that bone mineralising activity was significantly higher around the uncemented stems, both compared to the cemented group and to the contralateral healthy reference femur group. The cemented group also had elevated activity but only at a barely significant level. Interpretation: Mineralising activity analysed with F-PET/CT was significantly higher for the uncemented group and also decreased at a slower rate. F-PET/CT is a useful new tool for analysing secondary stabilisation of femoral stems after THA. The study was registered at ClinicalTrials.gov (identifier NCT01623687).