间歇性低剂量全身应用甲状旁腺激素对兔下颌快速骨牵张的作用

The effects of PTH administration on rapid mandibular distraction osteogenesis in rabbits

目的研究甲状旁腺激素(parathyroid hormone,PTH)间歇性低剂量全身应用对兔下颌快速骨牵张的作用。方法对24只成年新西兰白兔进行单侧下颌骨快速骨牵张,实验动物随机均分为2组:牵张开始后实验组每日皮下注射PTH(10μg/kg)生理盐水溶液,为期30 d;对照组同期注射等量生理盐水。牵张结束6周后取出下颌骨对牵张区骨痂进行micro-CT、组织学及生物力学检测,并对牵张旁钉孔区进行双能X线吸收实验(dual energy X-Ray absorptiometry,DEXA)检测其骨密度(bone mineral density,BMD)。结果 micro CT图像显示实验组新生骨小梁密集而粗大,骨皮质连续,而对照组新生骨小梁稀疏而细小,未见明显骨皮质形成,定量分析结果实验组牵张区的骨体积分数((48.30±3.46)%),骨连接密度((9.77±1.81)mm-3),骨小梁厚度((0.25±0.01)mm)和骨小梁数((2.25±0.26)mm-1)均显著高于对照组(分别为(37.55±3.72)%,(7.89±1.73)mm-3,(0.12±0.03)mm,(1.27±0.27)mm-1)(P<0.01),而骨小梁间隙((0.22±0.03)mm)则显著低于对照组((0.30±0.04)mm)(P<0.01)。组织学观察证实实验组新生骨质更为丰富而成熟,实验组三点弯曲试验最大载荷((378.30±29.10)N),与牵张旁钉孔区BMD((0.26±0.01)g/cm2)也均显著高于对照组(分别为(196.60±14.50)N,(0.17±0.01)g/cm2)(P<0.01)。结论间歇性低剂量全身应用甲状旁腺激素有助于促进兔下颌骨快速骨牵张的新骨生成,同时还有助于减少牵张旁区的骨量丢失。

Objective To assess the effect of parathyroid hormone（PTH） intermittent administration on bone regeneration after rapid mandibular distraction osteogenesis（DO） in rabbits. Methods Unilateral mandibular rapid DO was performed on 24 adult New Zeal- and white rabbits and they were randomly divided into two groups. At the＇ beginning of the distraction, the experimental group was subcu- taneously administered PTH daily for 30 days while the control group was injected with physiological saline. Rabbits sacrificed 6 weeks after the completion of DO. The distracted mandibular bones were collected and the calluses were processed with micro-CT, histology and biomechanical testing. Bone mineral density （BMD） in surrounding segments of the distraction gap was evaluated by dual energy xray absorptiometry （ DEXA）. Results The figures of micro-CT showed better growth and remodeling of regeneration of the experimental group than the control group. The result of the micro CT analysis showed greater parameters of the experimental group in bone volume fraction （ （48.30 ± 3.46 ） % ） , bone connectivity density （ （ 9.77 ± 1.81 ） mm -3 ） , trabecular thickness （ （ 0.25 ± 0.01 ） mm ） and number （ （ 2.25 ± 0. 26 ） mm - 1 ） than the control group （ which were respectively （ 37.55 ± 3.72 ） %, （ 7.89 ± 1.73 ） mm - 3, （ 0.12 ± 0.03 ） mm, （ 1.27 ± 0.27 ） mm -1） （ P 〈 0.01 ）, yet the trabecular spacing of the experimental group （ （ 0.26 ± 0.03 ） mm） was less than that of the control group （ （0.30 ± 0.04）mm） （P 〈 0.01 ）. Histological Examination showed a more mature newly formed bone in experimental group. PTH treated animals showed greater mechanical properties（ （378.30 ± 29.10） N） and higher BMD（0. 26 ± 0. 01 ） g/cm2 ） than the control group（which respectively were（196.60 ±14.50）N,（0.17 ±0.01）g/cm2） （P〈0.01）. Conclusions PTH enhances new bone formation and meanwhile prevents disuse osteopenia of surrounding segments of distraction gap in a rapid mandibular DO model.