| Background:Fractures often occur in the spine.Osteoporotic vertebral fractures are characterized by a decrease in bone strength,resulting in fractures of the vertebral body under slight external forces.The incidence of osteoporotic vertebral fractures has increased significantly in recent years.During the fracture healing process,bone histomorphological parameters are commonly used as indicators to reflect the microstructural characteristics of bone tissue,and bone turnover markers can indirectly reflect the bone formation ability as well as bone resorption ability during fracture healing process.However,few studies have reported differences in histomorphometric characteristics as well as serum concentration levels of bone turnover markers after osteoporotic vertebral fractures under different bone mineral densities.Objective:The aim of this study was to compare the differences after osteoporotic vertebral fractures under different bone mineral densities by measuring bone morphometric parameters and serum concentrations of bone turnover markers.Method:A total of 209 patients diagnosed with osteoporotic vertebral compression fractures received percutaneous vertebroplasty surgery in the department of spine between September 2013 and September 2019 were included in the study.All patients were divided into two groups according to the T-score of bone mineral density:Group A(T-score<-2.5)and Group B(T-score>-2.5).103 patients with bone mineral density<-2.5 were included in the group A and 106 patients with bone mineral density>-2.5 were included in the group B.All patients were treated with vertebroplasty.Bone biopsy specimens were obtained from the areas of fractured vertebrae during vertebroplasty by transpedicular bone biopsy method.All tissue samples were stained with HE to make tissue sections.Images were observed and recorded under a light microscope and analyzed for bone histomorphological parameters using Image Pro Plus measurement software(Image Pro Plus,Media Cybernetics,Inc.).Bone histomorphometry parameters include:cancellous bone volume/tissue volume%(BV/TV%),fibrous tissue volume/tissue volume%(FV/TV%),endochondral bone volume/tissue volume%(EBV/TV%),necrotic bone volume/tissue volume%(NBV/TV%),woven bone volume/tissue volume%(WBV/TV%),lamellar bone volume/tissue volume%(LBV/TV%).Fasting blood samples were obtained before vertebroplasty to determine serum concentrations of bone turnover markers.Bone turnover markers included N-terminal propeptide of type Ⅰ collagen(PINP)and β-isomerized C-terminal telopeptide of type I collagen(β-CTX).According to the period of bone tissue appearance during fracture healing process,we divided the clinical healing process into six stages:stage Ⅰ(1-3 days),stage Ⅱ(4-10 days),stage Ⅲ(11-20 days),stage Ⅳ(21-30 days),stage Ⅴ(1-3 months),and stage Ⅵ(3-6 months).The T-test was used for difference analysis at the same period.Results:There was no statistically significant difference in gender and age distribution between the group A and the group B.Necrotic bone tissue was observed in the group A within the first 3 days after fracture(5.13 ± 2.61%),which was significantly higher than that in the group B(3.52±1.88%,P=0.023).The serum concentrations ofβ-CTX,reflecting the bone resorption ability,reached the first peak(0.71±0.23 ng/ml)at 4-10 days after fracture in the group B.The serum concentrations ofβ-CTX in the group A was significantly higher than that in the previous period(0.68±0.25 ng/ml),but did not reach the peak value in this period.Endochondral bone was gradually formed at 11-20 days after fracture,and the content of endochondral bone in the group A(10.71 ± 3.97%)was significantly lower than that in the group B(15.22 ±4.19%,P=0.001).At the same time,the concentration levels of PINP,reflecting the bone formation ability,was significantly lower in the group A(56.81±23.67 ng/mL)than in the group B(66.35±26.08 ng/mL,P=0.016).Endochondral bone was gradually mineralized to woven bone in both groups at 21-30 days after fracture.The woven bone content in the group A(17.63±1.67%)was significantly lower than that in the group B(20.39±1.97%,P=0.009).In addition,PINP serum concentrations in the group B increased significantly during 1 to 3 months after fracture compared with the previous period,and the only one peak after fracture was reached in this period(81.51 ± 26.76 ng/mL,P=0.039).At 3-6 months after fracture,lamellar bone gradually appeared through the synergistic effect of osteoblasts and osteoclasts,and the content of lamellar bone in the group A(14.96±5.07%)was significantly lower than that in the group B(19.96±2.87%,P=0.019).At the same time,a large amount of necrotic bone appeared in the group A(12.92±3.66%),which was significantly higher than that in the group B(5.78±3.1%,P=0.001).Conclusion:There are significant differences after osteoporotic vertebral compression fractures with different bone mineral densities.Osteoporotic vertebral fractures with T-score<-2.5 are often associated with histomorphological characteristics of new fractures during the healing process.At the same time,the serum concentration levels of bone turnover markers reflecting osteoblast activities during the healing process in such patients with T-score<-2.5 were lower than those patients with T-score>-2.5 during the same period. |
PDF Full Text Request