title: Bone apatite composition of necrotic trabecular bone in the femoral head of immature piglets.
abstract: Ischemic osteonecrosis of the femoral head (IOFH) can lead to excessive resorption of the trabecular bone and collapse of the femoral head as a structure. A well-known mineral component to trabecular bone is hydroxyapatite, which can be present in many forms due to ionic substitution, thus altering chemical composition. Unfortunately, very little is known about the chemical changes to bone apatite following IOFH. We hypothesized that the apatite composition changes in necrotic bone possibly contribute to increased osteoclast resorption and structural collapse of the femoral head. The purpose of this study was to assess the macroscopic and local phosphate composition of actively resorbed necrotic trabecular bone to isolate differences between areas of increased osteoclast resorption and normal bone formation. A piglet model of IOFH was used. Scanning electron microscopy (SEM), histology, X-ray absorbance near edge structure (XANES), and Raman spectroscopy were performed on femoral heads to characterize normal and necrotic trabecular bone. Backscattered SEM, micro-computed tomography and histology showed deformity and active resorption of necrotic bone compared to normal. XANES and Raman spectroscopy obtained from actively resorbed necrotic bone and normal bone showed increased carbonate-to-phosphate content in the necrotic bone. The changes in the apatite composition due to carbonate substitution may play a role in the increased resorption of necrotic bone due to its increase in solubility. Indeed, a better understanding of the apatite composition of necrotic bone could shed light on osteoclast activity and potentially improve therapeutic treatments that target excessive resorption of bone.
authors: Materials Science and Engineering Department, University of Texas at Arlington, 501 West First Street, Arlington, TX, 76019, USA.
authors: Olumide O
authors: OO
authors: Aruwajoye
authors: Harry K W
authors: HK
authors: Kim
authors: Pranesh B
authors: PB
authors: Aswath
mesh_terms: D000818:Animals; D001031:Apatites / Q000737:chemistry*; D015519:Bone Density; D001862:Bone Resorption; D001842:Bone and Bones / Q000378:metabolism*; D002254:Carbonates / Q000737:chemistry; D005270:Femur Head / Q000473:pathology*; D005271:Femur Head Necrosis / Q000473:pathology*; D008855:Microscopy, Electron, Scanning; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism; D010020:Osteonecrosis / Q000503:physiopathology; D010710:Phosphates / Q000737:chemistry; D012542:Scattering, Radiation; D012995:Solubility; D013059:Spectrum Analysis, Raman; D013552:Swine; D055114:X-Ray Microtomography
chemical_list: D001031:Apatites; D002254:Carbonates; D010710:Phosphates