title: Use of high resolution dual-energy x-ray absorptiometry-region free analysis (DXA-RFA) to detect local periprosthetic bone remodeling events.
abstract: Dual-energy x-ray absorptiometry (DXA) is the gold standard method for measuring periprosthetic bone remodeling, but relies on a region of interest (ROI) analysis approach. While this addresses issues of anatomic variability, it is insensitive to bone remodeling events at the sub-ROI level. We have validated a high-spatial resolution tool, termed DXA-region free analysis (DXA-RFA) that uses advanced image processing approaches to allow quantitation of bone mineral density (BMD) at the individual pixel (data-point) level. Here we compared the resolution of bone remodeling measurements made around a stemless femoral prosthesis in 18 subjects over 24 months using ROI-based analysis versus that made using DXA-RFA. Using the ROI approach the regional pattern of BMD change varied by region, with greatest loss in ROI5 (20%, p < 0.001), and largest gain in ROI4 (6%, p < 0.05). Analysis using DXA-RFA showed a focal zone of increased BMD localized to the prosthesis-bone interface (30-40%, p < 0.001) that was not resolved using conventional DXA analysis. The 20% bone loss observed in ROI5 with conventional DXA was resolved to a focal area adjacent to the cut surface of the infero-medial femoral neck (up to 40%, p < 0.0001). DXA-RFA enables high resolution analysis of DXA datasets without the limitations incurred using ROI-based approaches.
authors: Academic Unit of Bone Metabolism, Northern General Hospital, University of Sheffield, Sheffield, United Kingdom.
authors: J Mark
authors: JM
authors: Wilkinson
authors: Richard M
authors: RM
authors: Morris
authors: Miguel A
authors: MA
authors: Martin-Fernandez
authors: Jose M
authors: JM
authors: Pozo
authors: Alejandro F
authors: AF
authors: Frangi
authors: Marci
authors: M
authors: Maheson
authors: Lang
authors: L
authors: Yang
mesh_terms: D015502:Absorptiometry, Photon; D019644:Arthroplasty, Replacement, Hip; D016723:Bone Remodeling; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
keywords: bone mineral density; dual-energy x-ray absorptiometry region free analysis; femur; total hip arthroplasty