Department of Trauma and Orthopedic Surgery, University Hospital of Cologne, Cologne, Germany.
Department of Trauma and Orthopedic Surgery, University Hospital of Cologne, Cologne, Germany.
Clin Biomech (Bristol). 2021 Apr;84:105329. doi: 10.1016/j.clinbiomech.2021.105329. Epub 2021 Mar 20.
Biomechanical functionality as well as trauma mechanisms of the atlantoaxial complex are still an issue of controversy. The transverse atlantal ligament is the strongest stabilizator. The present study aimed to analyze the bending forces of the transverse atlantal ligament and of the base of the odontoid in elderly specimens.
In this biomechanical study five cadaveric specimen with a mean age of 72 at death and bone mineral density measuring for 555.3 Hounsfield units on average were used. To analyze the strain of the transverse atlantal ligament and the dense base, strain gauges were used. A custom biomechanical setup was used to test each specimen at C1/2 flexion and the strain of the transverse atlantal ligament and the dens base (μm/m) were measured.
In four out of five, a rupture of the transverse atlantal ligament was observed, the mean force required for the ligament to fall was 175 N (min. 99.8 N; 249.2 N; SD 64.7) by a mean strain of 2102.9 μm/m (min. 1953.5 μm/m; max. 2272.3 μm/m; SD 189.7). In one specimen with the lowest Hounsfield units (155), the dens base fractured before the transverse atlantal ligament ruptured and no strain could be measured at the transversal ligament during movement afterwards.
The transverse atlantal ligament fails at an average of 175 N in the elderly, which is less than the value reported previously. In osteoporotic specimen the generated force to rupture the transverse atlantal ligament can fracture the dens itself.
寰枢复合体的生物力学功能和创伤机制仍然存在争议。横韧带是最强的稳定器。本研究旨在分析老年人标本中横韧带和齿状突基底部的弯曲力。
在这项生物力学研究中，使用了五个平均死亡年龄为 72 岁且骨密度平均为 555.3 亨氏单位的尸体标本。为了分析横韧带和致密基底部的应变，使用了应变片。使用定制的生物力学装置在 C1/2 屈曲时测试每个标本，并测量横韧带和致密基底部的应变（μm/m）。
在五个标本中的四个中，观察到横韧带断裂，韧带断裂所需的平均力为 175N（最小 99.8N；最大 249.2N；SD 64.7），平均应变 2102.9μm/m（最小 1953.5μm/m；最大 2272.3μm/m；SD 189.7）。在一个 Hounsfield 单位最低（155）的标本中，齿状突基底部在横韧带断裂之前断裂，并且在随后的运动中无法在横韧带上测量到应变。
老年人的横韧带平均在 175N 处断裂，低于先前报道的值。在骨质疏松标本中，断裂横韧带所需的产生的力可使齿状突本身断裂。
