Sterba Manon, Arnoux Pierre-Jean, Labelle Hubert, Warner William C, Aubin Carl-Éric
Department of Mechanical Engineering, Polytechnique Montreal, Montreal, QC, Canada.
Laboratoire de Biomécanique Appliquée, Aix-Marseille Université, IFSTTAR, LBA UMR T24, Marseille, France.
Eur Spine J. 2018 Aug;27(8):2044-2052. doi: 10.1007/s00586-018-5667-0. Epub 2018 Jun 20.
To study the risks of spondylolysis due to extrinsic loading conditions related to sports activities and intrinsic spino-pelvic postural parameters [pelvic incidence (PI) and sacral slope (SS)].
A comprehensive osseo-disco-ligamentous L4-S1 finite element model was built for three cases with spondylolysis representing three different spino-pelvic angular configurations (SS = 32°, 47°, 59° and PI = 49°, 58°, 72°, respectively). After simulating the standing posture, 16 dynamic loading conditions were computationally tested for each configuration by combining four sport-related loads (compression, sagittal and lateral bending and axial torque). For each simulation, the Von Mises stress, L5-S1 facet contact force and resultant internal loads at the sacral endplate were computed. Significant effects were determined with an ANOVA.
The maximal stress and volume of cancellous bone in the pars with stress higher than 75% of the ultimate stress were higher with 900 N simulated compression (2.2 MPa and 145 mm) compared to only the body weight (1.36 MPa and 20.9 mm) (p < 0.001). Combined compression with 10 Nm of flexion and an axial torque of 6 Nm generated the highest stress conditions (up to 2.7 MPa), and L5-S1 facet contact force (up to 430 N). The maximal stress was on average 17% higher for the case with the highest SS compared to the one with lowest SS for the 16 tested conditions (p = 0.0028).
Combined flexion and axial rotation with compression generated the highest stress conditions related to risks of spondylolysis. The stress conditions intensify in patients with higher PI and SS. These slides can be retrieved under Electronic Supplementary Material.
研究与体育活动相关的外在负荷条件以及内在脊柱 - 骨盆姿势参数[骨盆入射角（PI）和骶骨坡度（SS）]导致椎弓根峡部裂的风险。
构建了一个综合的L4 - S1节段的骨 - 椎间盘 - 韧带有限元模型，用于模拟三例椎弓根峡部裂病例，分别代表三种不同的脊柱 - 骨盆角度构型（SS分别为32°、47°、59°，PI分别为49°、58°、72°）。在模拟站立姿势后，通过组合四种与运动相关的负荷（压缩、矢状面和侧面弯曲以及轴向扭矩），对每种构型进行16种动态负荷条件的计算测试。对于每次模拟，计算L5 - S1小关节接触力、骶骨终板处的冯·米塞斯应力和合成内部负荷。采用方差分析确定显著影响。
与仅考虑体重相比，模拟900 N压缩时，椎弓根峡部松质骨的最大应力和应力高于极限应力75%的骨体积更高（分别为2.2 MPa和145 mm，而仅体重时为1.36 MPa和20.9 mm）（p < 0.001）。压缩与10 Nm的屈曲和6 Nm的轴向扭矩相结合产生了最高应力条件（高达2.7 MPa）和L5 - S1小关节接触力（高达430 N）。在16种测试条件下，SS最高的病例的最大应力平均比SS最低的病例高17%（p = 0.0028）。
屈曲、轴向旋转与压缩相结合产生了与椎弓根峡部裂风险相关的最高应力条件。在PI和SS较高的患者中，应力条件会加剧。这些幻灯片可在电子补充材料中获取。
