Dyson School of Design Engineering, Imperial College, London, UK.
Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Hammersmith Hospital, Imperial College London, London, UK.
Ann Biomed Eng. 2021 Oct;49(10):2716-2733. doi: 10.1007/s10439-021-02785-0. Epub 2021 May 10.
New helmet technologies have been developed to improve the mitigation of traumatic brain injury (TBI) in bicycle accidents. However, their effectiveness under oblique impacts, which produce more strains in the brain in comparison with vertical impacts adopted by helmet standards, is still unclear. Here we used a new method to assess the brain injury prevention effects of 27 bicycle helmets in oblique impacts, including helmets fitted with a friction-reducing layer (MIPS), a shearing pad (SPIN), a wavy cellular liner (WaveCel), an airbag helmet (Hövding) and a number of conventional helmets. We tested whether helmets fitted with the new technologies can provide better brain protection than conventional helmets. Each helmeted headform was dropped onto a 45° inclined anvil at 6.3 m/s at three locations, with each impact location producing a dominant head rotation about one anatomical axes of the head. A detailed computational model of TBI was used to determine strain distribution across the brain and in key anatomical regions, the corpus callosum and sulci. Our results show that, in comparison with conventional helmets, the majority of helmets incorporating new technologies significantly reduced peak rotational acceleration and velocity and maximal strain in corpus callosum and sulci. Only one helmet with MIPS significantly increased strain in the corpus collosum. The helmets fitted with MIPS and WaveCel were more effective in reducing strain in impacts producing sagittal rotations and a helmet fitted with SPIN in coronal rotations. The airbag helmet was effective in reducing brain strain in all impacts, however, peak rotational velocity and brain strain heavily depended on the analysis time. These results suggest that incorporating different impact locations in future oblique impact test methods and designing helmet technologies for the mitigation of head rotation in different planes are key to reducing brain injuries in bicycle accidents.
新的头盔技术已经被开发出来，以改善自行车事故中创伤性脑损伤（TBI）的缓解。然而，它们在斜向冲击下的效果，与头盔标准采用的垂直冲击相比，会在大脑中产生更多的应变，这仍然不清楚。在这里，我们使用一种新的方法来评估 27 种自行车头盔在斜向冲击下的脑损伤预防效果，包括带有摩擦减少层（MIPS）、剪切垫（SPIN）、波浪状蜂窝衬垫（WaveCel）、气囊头盔（Hövding）和许多传统头盔的头盔。我们测试了带有新技术的头盔是否能比传统头盔提供更好的脑保护。每个戴头盔的头模以 6.3 米/秒的速度从三个位置下降到一个 45°倾斜的砧座上，每个冲击位置都会使头部围绕头部的一个解剖轴产生主导旋转。我们使用 TBI 的详细计算模型来确定大脑和关键解剖区域（胼胝体和脑沟）的应变分布。我们的结果表明，与传统头盔相比，大多数采用新技术的头盔显著降低了峰值旋转加速度和速度以及胼胝体和脑沟的最大应变。只有一个带有 MIPS 的头盔显著增加了胼胝体的应变。带有 MIPS 和 WaveCel 的头盔在产生矢状旋转的冲击中减少应变更有效，而带有 SPIN 的头盔在冠状旋转中更有效。气囊头盔在所有冲击中都能有效地减少大脑的应变，然而，峰值旋转速度和大脑应变严重依赖于分析时间。这些结果表明，在未来的斜向冲击测试方法中纳入不同的冲击位置，并设计用于减轻不同平面头部旋转的头盔技术，是减少自行车事故中脑损伤的关键。
