Liu Da, Zhao Chang-Qing, Li Hai, Jiang Sheng-Dan, Jiang Lei-Sheng, Dai Li-Yang
Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University, Shanghai, China.
Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University, Shanghai, China.
Bone. 2008 Jul;43(1):119-125. doi: 10.1016/j.bone.2008.03.015. Epub 2008 Apr 8.
Both spinal cord injury (SCI) and hindlimb cast immobilization (HCI) cause reduction in maturation-related bone gain in young rats, but the effects of the two interventions on bone pathophysiology may be different. The objective of this study was to compare the effects of SCI and HCI on the sublesional/supralesional bones and bone turnover indicators in young rats. Forty male Sprague-Dawley rats (six-week-old) were randomized into four groups, with ten rats in each group. The groups were classified as follows: base-line control, age-matched intact control, HCI, and SCI groups. Bone tissues, blood, and urine samples were studied at 4 weeks after treatments. The tibial dry weights and ash weights in SCI were remarkably reduced by 7.5% (dry weights) and 8.2% (ash weights) compared with HCI. SCI rats showed lower areal bone mineral density in the proximal tibiae compared with HCI rats (- 14%). Cortical thickness and cortical area of the tibial midshaft in SCI were lower than HCI (- 23%, - 33% respectively). The bone surface/bone volume, trabecular separation, trabecular number, connectivity of the trabecular network, and structure model index of the proximal tibiae were remarkably different between SCI and HCI groups. In SCI tibiae, the mineralizing surface, mineral apposition rate, and surface-based bone formation rate were significantly higher than HCI groups (12%, 47%, and 29% respectively). In the compression test, the ultimate load, the energy of ultimate load, and Young's modulus of the proximal tibiae in SCI rats were significantly lower than HCI rats. The serum levels of osteocalcin and the urinary levels of deoxypyridinoline in SCI were higher than those in HCI. There were no significant changes in supralesional bones between SCI and HCI rats. SCI results in a rapid bone loss with more deterioration of trabecular microstructure and cortical bone geometric structure in sublesional bones. High bone turnover rate and low biomechanics strength were found in tibiae in SCI rats. This might be the result of the imbalance of bone resorption and bone formation induced by the impaired neuronal function.
脊髓损伤（SCI）和后肢石膏固定（HCI）均会导致幼鼠成熟相关骨量增加减少，但这两种干预措施对骨病理生理学的影响可能不同。本研究的目的是比较SCI和HCI对幼鼠损伤节段以下/以上骨骼及骨转换指标的影响。40只雄性Sprague-Dawley大鼠（6周龄）随机分为四组，每组10只。分组如下：基线对照组、年龄匹配的完整对照组、HCI组和SCI组。在治疗4周后对骨组织、血液和尿液样本进行研究。与HCI组相比，SCI组胫骨干重和灰重显著降低，分别降低了7.5%（干重）和8.2%（灰重）。与HCI大鼠相比，SCI大鼠胫骨近端的骨面积密度较低（-14%）。SCI组胫骨中轴的皮质厚度和皮质面积低于HCI组（分别为-23%、-33%）。SCI组和HCI组胫骨近端的骨表面/骨体积、小梁间距、小梁数量、小梁网络连通性和结构模型指数存在显著差异。在SCI胫骨中，矿化表面、矿化沉积率和基于表面的骨形成率显著高于HCI组（分别为12%、47%和29%）。在压缩试验中，SCI大鼠胫骨近端的极限载荷、极限载荷能量和杨氏模量显著低于HCI大鼠。SCI组血清骨钙素水平和尿脱氧吡啶啉水平高于HCI组。SCI组和HCI组大鼠损伤节段以上骨骼无显著变化。SCI导致骨快速丢失，损伤节段以下骨骼的小梁微结构和皮质骨几何结构恶化更严重。SCI大鼠胫骨出现高骨转换率和低生物力学强度。这可能是神经功能受损导致骨吸收和骨形成失衡的结果。
