Wang Gang, Qu Xinhua, Yu Zhifeng
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Department of Orthopedic Surgery, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
PLoS One. 2014 Oct 14;9(10):e108324. doi: 10.1371/journal.pone.0108324. eCollection 2014.
Under normal conditions, loading activities result in microdamage in the living skeleton, which is repaired by bone remodeling. However, microdamage accumulation can affect the mechanical properties of bone and increase the risk of fracture. This study aimed to determine the effect of microdamage on the mechanical properties and composition of bone. Fourteen male goats aged 28 months were used in the present study. Cortical bone screws were placed in the tibiae to induce microdamage around the implant. The goats were euthanized, and 3 bone segments with the screws in each goat were removed at 0 days, 21 days, 4 months, and 8 months after implantation. The bone segments were used for observing microdamage and bone remodeling, as well as nanoindentation and bone composition, separately. Two regions were measured: the first region (R1), located 1.5 mm from the interface between the screw hole and bone; and the second region (R2), located>1.5 mm from the bone-screw interface. Both diffuse and linear microdamage decreased significantly with increasing time after surgery, with the diffuse microdamage disappearing after 8 months. Thus, screw implantation results in increased bone remodeling either in the proximal or distal cortical bone, which repairs the microdamage. Moreover, bone hardness and elastic modulus decreased with microdamage repair, especially in the proximal bone tissue. Bone composition changed greatly during the production and repair of microdamage, especially for the C (Carbon) and Ca (Calcium) in the R1 region. In conclusion, the presence of mechanical microdamage accelerates bone remodeling either in the proximal or distal cortical bone. The bone hardness and elastic modulus decreased with microdamage repair, with the micromechanical properties being restored on complete repair of the microdamage. Changes in bone composition may contribute to changes in bone mechanical properties.
在正常情况下，负荷活动会导致活体骨骼出现微损伤，而这种微损伤会通过骨重塑进行修复。然而，微损伤的积累会影响骨骼的力学性能并增加骨折风险。本研究旨在确定微损伤对骨骼力学性能和成分的影响。本研究使用了14只28月龄的雄性山羊。将皮质骨螺钉植入胫骨，以在植入物周围诱导微损伤。对山羊实施安乐死后，在植入后0天、21天、4个月和8个月分别从每只山羊身上取出3个带有螺钉的骨段。这些骨段分别用于观察微损伤和骨重塑，以及纳米压痕和骨成分。测量了两个区域：第一个区域（R1），距离螺钉孔与骨的界面1.5毫米；第二个区域（R2），距离骨-螺钉界面大于1.5毫米。随着术后时间的增加，弥漫性和线性微损伤均显著减少，弥漫性微损伤在8个月后消失。因此，螺钉植入会导致近端或远端皮质骨的骨重塑增加，从而修复微损伤。此外，随着微损伤的修复，骨硬度和弹性模量降低，尤其是在近端骨组织中。在微损伤的产生和修复过程中，骨成分发生了很大变化，尤其是R1区域的碳（C）和钙（Ca）。总之，机械性微损伤的存在会加速近端或远端皮质骨的骨重塑。随着微损伤的修复，骨硬度和弹性模量降低，微损伤完全修复后微观力学性能得以恢复。骨成分的变化可能导致骨力学性能的改变。
