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Yang Li,1,&ast; Yuling Sun,1,&ast; Ji Wu,1,&ast; Zhongya Gao,1 Youcai Qiu,1 Lin Han,2 Xuhua Lu1 1Department of Orthopaedics, Shanghai Changzheng Hospital, Naval Medical University, Shanghai, People’s Republic of China; 2Department of Orthopaedics, Third Affiliated Hospital of Naval Medical University, Shanghai, 200433, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xuhua Lu, Department of Orthopaedics, Shanghai Changzheng Hospital, Naval Medical University, No. 415 Fengyang Road, Shanghai, 200003, People’s Republic of China, Tel +86-21-81885793, Email xuhualu415@163.com Lin Han, Department of Orthopaedics, Third Affiliated Hospital of Naval Medical University, Shanghai, 200433, People’s Republic of China, Email hanlin1018@163.comBackground and Aim: Cervical hyperextension injury is very frequent with anterior longitudinal ligament (ALL) injury, and the ligament damage has a remarkable effect on whether and what type of operation should be performed. This study aims to establish a new scoring system for the accurate diagnosis of ALL damage.Methods: The imaging data of the consecutive patients was measured and scored by four radiologists. Intraoperative exploration was performed by three surgeons. The crude and adjusted odds ratios (cOR and aOR) and receiver operating characteristic curve (ROC) were constructed to assess the diagnostic accuracy of the scoring system.Results: A total of 255 patients with cervical spine trauma were included in this study. There was no statistical difference in the relationship between demographics and ALL injuries (P > 0.05). Thickness of prevertebral soft tissue (aOR = 11.922, P = 0.004), intervertebral disk angle (aOR = 13.21, P = 0.002), avulsion fracture of the anterior edge of the vertebral body (aOR = 13.844, P = 0.029), ALL disrupted in T1-weighted sequence (aOR = 18.349, P < 0.001), and high signal area in T2-weighted sequence (aOR = 20.898, P = 0.002) h

Objective: Pedicle screw fixation is a common technique used in posterior lumbar interbody fusion (PLIF) surgery for lumbar disorders. During operation, rod contouring is often subjective and not satisfactory, but only few studies focused on the rod-contouring issue previously. The aim of the study was to explore the effect of the rod contouring on the single-segment PLIF by the finite element (FE) method and retrospective study. Methods: A FE model of the lumbosacral vertebrae was first reconstructed, and subsequently single-segmental (L4/5) PLIF surgeries with four rod curvatures (RCs) were simulated. Herein, three RCs were designed by referring to centroid, Cobb, and posterior tangent methods applied in the lumbar lordosis measurement, and zero RC indicating straight rods was included as well. Clinical data of patients subjected to L4/5 segmental PLIF were also analyzed to verify the correlation between RCs and clinical outcome. Results: No difference was observed among the four RC models in the range of motion (ROM), intersegmental rotation angle (IRA), and intradiscal pressure (IDP) under four actions. The posterior tangent model had less maximum stress in fixation (MSF) in flexion, extension, and axial rotation than the other RC models. Patients with favorable prognosis had larger RC and positive RC minus posterior tangent angle (RC-PTA) of fused segments with respect to those who had poor prognosis and received revision surgery. Conclusion: All RC models had similar biomechanical behaviors under four actions. The posterior tangent-based RC model was superior in fixation stress distribution compared to centroid, Cobb, and straight models. The retrospective study demonstrated that moderate RC and positive RC-PTA were associated with better postoperative results.

Objective To develop modified finite element models to simulate degenerative lumbar scoliosis (DLS) based on the normal lumbar spine model and to investigate the facet joint force of the DLS. Methods A 3-dimensional finite element model of a normal lumbar spine was modified to simulate 3 different Cobb angles conditions (12.3°, 22.2°, and 31.8°). The stresses on the facet joint were calculated on both sides (right and left) of the each vertebra. Changes of stress and asymmetry in contact forces between facet joints in the development of DLS were quantitatively analyzed to better understand the development of DLS and the biomechanical forming mechanism. Results The results show that asymmetric responses of the facet joint forces exist in various postures and that such effect is amplified with larger curve. When the Cobb angle was smaller, the convex side of the facet joints suffered larger force. When the Cobb angle was larger than 20°, the concave side of the facet joints suffered larger force. In the axial-rotation cases, the facet joint compression is less often located on the ipsilateral side than the contralateral side at the same level. Conclusions With the asymmetric loading, facet joints compressive deformation appears on the concave side, and it decreases in the effect of the facet joints to limit the vertebral rotation and listhesis. Asymmetric loading on facet joint contact forces accelerates asymmetry in the lumbar spine.

Adult degenerative lumbar scoliosis usually occurs in people aged over 45 years. Although its etiology is still unknown, it is well-accepted that the spinal disorder starts with the degeneration of the intervertebral disc. In this study, the influence of the disc degeneration on the facet joint contact force was investigated in four loading cases, i.e., straight-standing, flex/extension, lateral-bending and axial-rotation cases. First, a 3D finite element model of normal lumbar spine was validated, and further it was modified to simulate the degenerative scoliosis of lumbar spine by decreasing the disc height on one side and simultaneously altering its material properties. For all loading cases, the facet joint forces in the degenerated segment are much greater than the others. The present study can be helpful to understand the hyperostosis of the facet joints and pain in the lower back, and further to clinical application

The purpose of this study was to evaluate the association between lumbar spine facet joint orientation and tropism, sagittal spinopelvic alignment, and rotational deformity, identified by radiographic and computed tomography (CT) measurements, in degenerative lumbar scoliosis (DLS). Standing whole-spine sagittal radiographs and CT scans, including the pelvis, were performed and analyzed in 60 DLS patients (16 males, 44 females; mean age 65 years). Cobb angle, pelvic incidence (PI) and lumbar lordosis (LL) were measured on standing lumbar radiographs. Facet joint orientation on both sides at L3/4, L4/5, and L5/S1 was determined from transverse-plane CT. Facet joint tropism was defined as a difference in symmetry of more than 10 degrees between the orientations of the facet joints. There were significant differences in the incidence of facet joint tropism between the two groups at L3/4, L4/5, and L5/S1 (P = 0.011, P = 0.043, and P = 0.004, respectively). LL was significantly smaller in type II DLS (P = 0.049). Facet joint orientation, pelvic incidence, and Cobb angle did not differ between groups. No significant correlation between LL and PI was observed in either group. This study provides a reliability analysis of rotational deformity in patients with DLS. In conclusion, we observed a significant relationship between facet joint tropism and rotational deformity in patients with DLS. Furthermore, the different types of DLS demonstrated significant differences in LL that may induce spinal symptoms.