背景:尽管胫骨骨折治疗期间外固定器的应力变化与骨愈合过程之间的具体关系尚不清楚,据信,外固定器支架中的应力变化可以,在某种程度上,反映胫骨愈合的进展。
目的:本研究旨在提出一种通过监测应力传递的变化来评估骨折愈合程度的非侵入性方法,应力敏感点的位置,胫骨骨折愈合过程中外固定器-胫骨系统的位移。
方法:在本研究中,建立了胫骨骨折不同愈合阶段的有限元模型。生理条件,包括轴向,扭转,胫骨上的弯曲载荷,进行了模拟,以评估在正常生理负荷条件下外部支架-胫骨系统内的应力和应变。
结果:结果表明,在愈合的不同阶段,外固定器和胫骨之间的应力分布存在差异。在骨折愈合的早期阶段,在所有三种载荷条件下,外固定器作为主要的承重单元起着至关重要的作用。随着骨折愈合的进展,胫骨上的应力逐渐增加,集中在轴向和扭转载荷下的胫骨内侧部分,在上端和下端,以及弯曲载荷时胫骨前后的中央部分。愈伤组织的应力逐渐增加,而微运动减少。外支架内的应力逐渐减小,连杆倾向于向螺钉传递应力。在整个骨折愈合过程中,外固定器中最大应力的位置保持不变。在轴向和扭转载荷下,最大应力位于最低螺钉和骨皮质的交点处,在弯曲载荷下,它位于第二螺钉和连杆的相交处。
结论:在骨愈合过程中,应力在外固定架和骨之间传递。随着骨骼愈合的进展,外固定架的连杆和螺钉上的应力减小,应力变化的幅度减小。当实现完整和鲁棒的融合时,应力变化稳定,外固定架最大受力位置不变。最低的螺钉和骨皮质的交叉点,以及第二个螺钉和连杆,可用作监测骨愈合程度的敏感点。
BACKGROUND: Although the specific relationship between the stress changes in the external fixator during tibial fracture treatment and the bone healing process remains unclear, it is believed that stress variations in the external fixator scaffold can, to a certain extent, reflect the progress of tibial healing.
OBJECTIVE: This study aims to propose a non-invasive method for assessing the degree of fracture healing by monitoring the changes in stress transmission, the locations of stress-sensitive points, and displacement in the external fixator-tibia system during the healing process of tibial fractures.
METHODS: In this study, finite element models of tibial fractures at various healing stages were developed. Physiological conditions, including axial, torsional, and bending loads on the tibia, were simulated to evaluate stress and strain within the external scaffold-tibia system under normal physiological loading conditions.
RESULTS: The results indicate variations in the stress distribution between the external fixator and the tibia during different stages of healing. In the early phase of fracture healing, the external fixator plays a crucial role as the primary load-bearing unit under all three loading conditions. As the fracture healing progresses, the stress on the tibia gradually increases, concentrating on the medial part of the tibia under axial and torsional loading, and at the upper and lower ends, as well as the central part of the anterior and posterior tibia during bending loading. The stress at the callus gradually increases, while micro-movements decrease. The stress within the external bracket gradually decreases, with a tendency for the connecting rod to transfer stress towards the screws. Throughout the fracture healing process, the location of maximum stress in the external fixator remains unchanged. Under axial and torsional loading, the maximum stress is located at the intersection of the lowest screw and the bone cortex, while under bending loading, it is at the intersection of the second screw and the connecting rod.
CONCLUSIONS: During the bone healing process, stress is transferred between the external fixation frame and the bone. As bone healing advances, the stress on the connecting rods and screws of the external fixation frame decreases, and the amplitude of stress changes diminishes. When complete and robust fusion is achieved, stress variations stabilize, and the location of maximum stress on the external fixation frame remains unchanged. The intersections of the lowest screw and the bone cortex, as well as the second screw and the connecting rod, can serve as sensitive points for monitoring the degree of bone healing.