Lee T C, Taylor D
Department of Anatomy, Royal College of Surgeons in Ireland, Dublin, Ireland.
Eur J Morphol. 2003 Jul-Oct;41(3-4):117-25.
Mechanical loading in the sheep proximal radius was increased by ulnar osteotomy (Group O), decreased by Steinmann pinning (Group P) and unaltered in sham operated controls (Group C). A series of intravenous fluochromes was given to label bone formation and the adaptive response was measured at intervals up to 24 weeks. Surface strains, measured in an in vitro rig, were reduced in Group P and increased significantly in Group O. Cross-sectional area (CSA) peaked in all groups at 6 weeks consistent with a regional acceleratory phenomenon (RAP) and the formation of fibrolamellar bone of low density. In Groups C and P the extent of the RAP was related to the degree of operative trauma and the newly-formed bone was subsequently resorbed. In Group P, CSA fell below control levels suggesting negative adaptation. The increase in area was sustained in Group O and bone density increased due to mineralisation and infilling. Periosteal labelling of the scaffold of parallel-fibred bone peaked at 10 weeks, followed by labelling of lamellar bone filling the gaps in the structure. This adaptive response reduced surface strains to near normal levels by 24 weeks in Group O. Positive adaptation was distinguished from the non-specific RAP due to surgical trauma. The adaptive response is both 'intelligent', in that it utilises and adds to the RAP, and accurate, as no further increase in cross-sectional area was required after 6 weeks.
通过尺骨截骨术增加绵羊桡骨近端的机械负荷（O组），通过斯氏针固定降低机械负荷（P组），假手术对照组（C组）的机械负荷保持不变。给予一系列静脉荧光染料标记骨形成，并在长达24周的时间间隔内测量适应性反应。在体外装置中测量的表面应变，P组降低，O组显著增加。所有组的横截面积（CSA）在6周时达到峰值，这与局部加速现象（RAP）和低密度纤维层状骨的形成一致。在C组和P组中，RAP的程度与手术创伤程度相关，随后新形成的骨被吸收。在P组中，CSA降至对照水平以下，表明出现负适应性。O组的面积增加得以维持，并且由于矿化和填充，骨密度增加。平行纤维骨支架的骨膜标记在10周时达到峰值，随后是填充结构间隙的板层骨标记。在O组中，这种适应性反应在24周时将表面应变降低至接近正常水平。积极适应性与手术创伤引起的非特异性RAP不同。适应性反应既“智能”，因为它利用并增加了RAP，又准确，因为6周后横截面积无需进一步增加。
