Rezaee Taraneh, Bouxsein Mary L, Karim Lamya
Department of Bioengineering, University of Massachusetts Dartmouth, 285 Old Westport Road, Dartmouth, MA 02747, USA.
Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02115, USA.
Bone. 2020 Jul;136:115369. doi: 10.1016/j.bone.2020.115369. Epub 2020 Apr 19.
Elevation of bone fluoride levels due to drinking beverages with high fluoride content or other means such as inhalation can result in skeletal fluorosis and lead to increased joint pain, skeletal deformities, and fracture. Because skeletal fluorosis alters bone's mineral composition, it is likely to affect bone's tissue-level mechanical properties with consequent effects on whole bone mechanical behavior. To investigate this, we determined whether incubation with in vitro sodium fluoride (NaF) altered bone's mechanical behavior at both the tissue- and whole bone-levels using cyclic reference point indentation (cRPI) and traditional 3-point bending, respectively. Forty-two ulnas from female adult rats (5-6 months) were randomly divided into 5 groups (vehicle, 0.05 M NaF, 0.25 M NaF, 0.75 M NaF, and 1.5 M NaF). Bones were washed in a detergent solution to remove organic barriers to ion exchange and incubated in respective treatment solutions (12 h, 23 °C). Cortical tissue mineral density (TMD) and geometry at the mid-diaphysis were determined by microCT. cRPI was performed on the distal diaphysis (9 N, 2 Hz, 10 cycles), and then bones were tested in 3-point bending to assess whole bone mechanical properties. The incubations in vehicle (0 M) up to 1.5 M in vitro NaF concentrations achieved bone fluoride levels ranging from approximately 0.70 to 15.8 ppm. NaF-incubated bones had significantly greater indentation distances, higher displacement-to-maximum force, and lower estimated elastic modulus, ultimate stress, and bending rigidity with increasing NaF concentration compared to vehicle-incubated bones. cRPI variables were moderately correlated to whole bone mechanical properties such that higher indentation distances were associated with lower estimated elastic modulus, ultimate stress, and bending rigidity. In conclusion, in vitro NaF incubation mostly has a deleterious effect on bone mechanical behavior with increasing NaF levels that is independent of bone turnover and reflected, in part, by less resistance of the tissue to cRPI-based indentation.
饮用高氟含量饮料或通过吸入等其他方式导致骨氟水平升高，可引发氟骨症，导致关节疼痛加剧、骨骼畸形和骨折。由于氟骨症会改变骨骼的矿物质组成，很可能会影响骨骼的组织水平力学性能，进而影响整个骨骼的力学行为。为了对此进行研究，我们分别使用循环参考点压痕法（cRPI）和传统三点弯曲试验，来确定体外氟化钠（NaF）孵育是否会在组织和全骨水平上改变骨骼的力学行为。将42只成年雌性大鼠（5 - 6个月）的尺骨随机分为5组（赋形剂组、0.05 M NaF组、0.25 M NaF组、0.75 M NaF组和1.5 M NaF组）。将骨骼在洗涤剂溶液中清洗以去除离子交换的有机屏障，然后在各自的处理溶液中孵育（12小时，23°C）。通过显微CT测定骨干中部的皮质骨组织矿物质密度（TMD）和几何形状。在骨干远端进行cRPI试验（9 N，2 Hz，10个循环），然后对骨骼进行三点弯曲试验以评估全骨力学性能。在赋形剂（0 M）至1.5 M体外NaF浓度下孵育，骨骼的氟含量范围约为0.70至15.8 ppm。与赋形剂孵育的骨骼相比，随着NaF浓度增加，经NaF孵育的骨骼具有明显更大的压痕距离、更高的位移 - 最大力，以及更低的估计弹性模量、极限应力和弯曲刚度。cRPI变量与全骨力学性能呈中度相关，即压痕距离越大，估计弹性模量、极限应力和弯曲刚度越低。总之，体外NaF孵育大多会对骨骼力学行为产生有害影响，随着NaF水平升高，这种影响与骨转换无关，部分表现为组织对基于cRPI的压痕的抵抗力降低。
