青少年腰椎间盘突出症患者的髓核形态特征及生物力学有限元分析

Morphological characteristics of the nucleus pulposus and biomechanical finite element analysis in patients with adolescent lumbar disc herniation

中文关键词:  腰椎间盘突出症  青少年  髓核  形态特征  有限元分析

英文关键词:Lumbar disc herniation  Adolescent  Nucleus pulposus  Morphological characteristics  Finite element analysis

中文摘要:

  【摘要】 目的：分析青少年腰椎间盘突出症（adolescent lumbar disc herniation，ALDH）患者的髓核形态学特征，通过有限元模型分析其生物力学改变，探讨ALDH的潜在风险因素。方法：选取2020年1月1日~2025年3月1日于徐州医科大学附属医院就诊的98例ALDH患者，男60例，女38例，年龄13~21岁，纳入病例组；其中L4/5突出52例，L5/S1突出46例。选取同期因腰痛就诊、腰椎MRI结果为阴性或仅伴腰背部肌筋膜炎的42例青少年作为对照组。所有患者均行腰椎MRI检查，利用Mimics软件测量L2~S1各节段髓核的形态学参数，包括髓核的面积占比及髓核重心位置，通过R软件分别比较病例组的突出节段、非突出节段与对照组的髓核形态学参数差异。基于临床参数建立9个L4~L5节段模型（M0~M8），髓核面积占比为20%~60%，髓核重心位置偏移为-2mm~+2mm，并模拟生理载荷下椎间盘等效应力分布，分析髓核形态学参数的改变对椎间盘生物力学的影响。另构建同条件下的L5~S1节段模型，以验证跨节段一致性。结果：（1）病例组突出节段髓核面积占比均显著性高于对照组（P＜0.05），髓核重心位置较对照组显著性后移（P＜0.05）。除L2/3节段的髓核位置参数外，病例组中其他非突出节段的髓核面积占比及髓核重心位置也呈现出同样的变化，差异具有统计学意义（P<0.05）。（2）有限元分析L4~5、L5~S1节段模型所得结论一致，髓核面积占比增大使后伸、侧屈、旋转工况下椎间盘应力极值增加；髓核重心位置后移时，前屈工况下的椎间盘应力极值减小，后伸工况下椎间盘的应力极值增大。结论：ALDH患者存在髓核相对面积较大、重心位置后移的形态学特征；髓核面积占比增大会导致后伸、侧屈、旋转工况下椎间盘应力极值升高，而重心位置后移则在后伸工况下加剧应力集中。上述形态学改变可能通过改变椎间盘力学环境增加ALDH的发生风险。

英文摘要:

  【Abstract】 Objectives: To analyze the morphological characteristics of the nucleus pulposus in patients with adolescent lumbar disc herniation(ALDH) and to investigate the biomechanical changes via finite element models, thereby exploring potential risk factors for ALDH. Methods: From January 1, 2023, to March 1, 2025, 98 ALDH patients treated at the Affiliated Hospital of Xuzhou Medical University, were enrolled as the case group, including 60 males and 38 females, aged 13-21 years, with herniation at L4/5 level in 52 cases and at L5/S1 level in 46 cases. 42 adolescents who presented with low back pain during the same period but had negative lumbar MRI findings or only lumbar myofasciitis were selected as the control group. All subjects underwent lumbar MRI examination. The area ratio and centroid position of the nucleus pulposus at L2-S1 levels were measured using Mimics software. R software was used to compare the morphological parameters of the nucleus pulposus between the herniated levels and non-herniated levels in the case group and those in the control group. Based on clinical parameters, nine L4-5 level models(M0-M8) were established, with nucleus pulposus area ratios ranging from 20% to 60% and centroid position offsets from -2mm to +2mm. The equivalent stress distribution of the intervertebral disc under physiological loading was simulated to analyze the biomechanical effects of changes in morphological parameters. Additional L5-S1 level models were constructed under the same conditions to verify consistency across levels. Results: (1)The nucleus pulposus area ratio in herniated levels of the case group was significantly higher than that in the control group(P<0.05), and the centroid position was significantly more posterior(P<0.05). Except for the centroid position at L2-3, the nucleus pulposus area ratio and centroid position in other non-herniated levels of the case group also showed similar changes, with statistically significant differences(P<0.05). (2)Finite element analysis revealed consistent findings between the L4-5 and L5-S1 models: an increased nucleus pulposus area ratio raised the peak disc stress under extension, lateral bending, and rotation conditions. When the centroid shifted posteriorly, the peak disc stress decreased under flexion but increased under extension. Conclusions: ALDH patients exhibit morphological characteristics of a relatively larger nucleus pulposus area and a more posterior centroid position. An increased nucleus pulposus area ratio elevates the peak disc stress under extension, lateral bending, and rotation, while posterior displacement exacerbates stress concentration under extension. These morphological alterations may increase the risk of ALDH by altering the mechanical environment of the intervertebral disc.