Microstructure and the regional distribution characteristics of osteoblast and osteoclast activity in the sample of the osteonecrosis femoral heads / 中华骨科杂志

ABSTRACT

Objective To compare the bone microstructure and osteoblast and osteoclast activity in different regions of osteonecrosis of the femoral head.Methods The osteonecrosis femoral heads were collected from 10 patients (Ficat Ⅳ) who had undergone total hip arthroplasty from March 2011 to May 2013.There were 6 males and 4 females.Their average age was 47.7 years old (range,40-57 years).The samples were divided into subchondral bone region,necrotic region,sclerosis region and healthy region according to radiographic results,then the bone microstructure,micro mechanism and osteoblasts/osteoclasts activity were analyzed byMicro-CT,RT-PCR,Nanoindentation,immunohistochemistry and Trap staining.Results According to the micro-CT results,the continuity of trabecular bone in necrotic region was damaged.The number of trabecular was increased and the gap was narrowed in sclerosis region.The shape and number of trabecular bone were normal in the healthy region.The elasticity moduli in different regions weresubchondral bone region 13.808±4.22 GPa,necrotic region 13.999±3.816 GPa,sclerosis region 17.266±3.533 GPa and healthy region 11.927±1.743 GPa.The hardness were subchondral bone region 0.425±0.173 GPa,necrotic region 0.331±0.173 GPa,sclerosis region 0.661±0.208 GPa,and healthy region 0.423±0.088 GPa.The trap staining of subchondral bone in healthy region and necrotic region were positive while other regions were negative.Immunohistochemistry staining showed that compared with necrotic region,the RANK and RANKL staining level increased significantly in subchondral bone and necrotic region,while Runx2 and BMP2 staining level increased significantly in sclerosis region.Conclusion The mechanical properties of trabecular have no significant difference between necrotic region and healthy region in the progress of the osteonecrosis,while the bone structure has obvious changes.An active bone resorption is observed in subchondral bone and necrotic region,while a higher bone formation activity is found in sclerosis region.