Multivariate analysis of pedicle screw invasion of the proximal facet joint after lumbar surgery

Background To analyze the risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery. Methods From January 2019 to January 2021, 1794 patients with lumbar degenerative disease, such as lumbar disc herniation, lumbar spinal stenosis and lumbar spondylolisthesis, were treated at our hospital. In all, 1221 cases were included. General data (sex, age, BMI), bone mineral density, proximal facet joint angle, degenerative lumbar spondylolisthesis, isthmic lumbar spondylolisthesis and fixed segment in the two groups were recorded. After the operation, vertebral CT of the corresponding surgical segments was performed for three-dimensional reconstruction and evaluation of whether the vertebral arch root screw interfered with the proximal facet joint. The included cases were divided into an invasion group and a noninvasion group. Univariate analysis was used to screen the risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery, and the selected risk factors were included in the logistic model for multivariate analysis. Results The single-factor analysis showed a significant difference in age, BMI, proximal facet joint angle, degenerative lumbar spondylolisthesis, and fixed segment (P < 0.1). Multifactor analysis of the logistic model showed a significant difference for age ≥ 50 years (P < 0.001, OR = 2.291), BMI > 28 kg/m2 (P < 0.001, OR = 2.548), degenerative lumbar spondylolisthesis (P < 0.001, OR = 2.187), gorge cleft lumbar relaxation (P < 0.001, OR = 2.410), proximal facet joint angle (35 ~ 45°: P < 0.001, OR = 3.151; > 45°: P < 0.001, OR = 3.578), and fixed segment (lower lumbar spine: P < 0.001, OR = 2.912). Conclusion Age (≥ 50 years old), BMI (> 28 kg/m2), proximal facet joint angle (35 ~ 45°, > 45°), degenerative lumbar spondylolisthesis, isthmic lumbar spondylolisthesis and fixed segment (lower lumbar spine) are independent risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery. Compared with degenerative lumbar spondylolisthesis, facet joint intrusion is more likely in isthmic lumbar spondylolisthesis.

A morphological characterization of the lumbar neural arch in females and males with degenerative spondylolisthesis

Background Although Degenerative Spondylolisthesis (DS) is a common osseous dysfunction, very few studies have examined the bony morphology of lumbar the neural arch in the population afflicted with DS. Therefore, this study aimed to characterize the neural arch (NA) morphology along the entire lumbar spine in individuals with degenerative spondylolisthesis (DS) and compare them to healthy controls. Methods One hundred CTs from a database of 500 lumbar CTs of spondylolisthesis were selected. We excluded vertebral fractures, non-L4-L5 slips, previous surgeries, vertebral spondyloarthropathies, and scoliosis. Scans were divided into a study group of 50 individuals with single-level DS (grades 1–2) at L4–5 (25 males and 25 females), and an age-sex matched control group of 50 individuals. Linear and angular measurements from all lumbar segments included: vertebral canals, intervertebral foramens, pedicles, and articular facets. Results Compared with the controls, all individuals with DS had greater pedicle dimensions in the lower lumbar segments (∆ = 1 mm–2.14 mm) and shorter intervertebral foramens in all the lumbar segments (∆range:1.85 mm–3.94 mm). In DS females, the lower lumbar facets were mostly wider (∆ = 1.73–2.86 mm) and more sagittally-oriented (∆10°) than the controls. Greater prevalence of grade-3 facet arthrosis was found only in the DS population (DS = 40–90%,controls = 16.7–66.7%). In DS males, degenerated facets were observed along the entire lumbar spine (L1-S1), whereas, in DS females, the facets were observed mainly in the lower lumbar segments (L4-S1). Individuals with DS have shorter intervertebral foramens and greater pedicle dimensions compared with controls. Conclusions Females with DS have wider articular facets, more sagittally-oriented facets, and excessively degenerated facets than the controls. This unique NA shape may further clarify DS’s pathophysiology and explain its greater prevalence in females compared to males.

New fossils of Australopithecus sediba reveal a nearly complete lower back

Adaptations of the lower back to bipedalism are frequently discussed but infrequently demonstrated in early fossil hominins. Newly discovered lumbar vertebrae contribute to a near-complete lower back of Malapa Hominin 2 (MH2), offering additional insights into posture and locomotion in Australopithecus sediba. We show that MH2 possessed a lower back consistent with lumbar lordosis and other adaptations to bipedalism, including an increase in the width of intervertebral articular facets from the upper to lower lumbar column (‘pyramidal configuration’). These results contrast with some recent work on lordosis in fossil hominins, where MH2 was argued to demonstrate no appreciable lordosis (‘hypolordosis’) similar to Neandertals. Our three-dimensional geometric morphometric (3D GM) analyses show that MH2’s nearly complete middle lumbar vertebra is human-like in overall shape but its vertebral body is somewhat intermediate in shape between modern humans and great apes. Additionally, it bears long, cranially and ventrally oriented costal (transverse) processes, implying powerful trunk musculature. We interpret this combination of features to indicate that A. sediba used its lower back in both bipedal and arboreal positional behaviors, as previously suggested based on multiple lines of evidence from other parts of the skeleton and reconstructed paleobiology of A. sediba.

Stress Analysis of the Lower Lumbar Spine Three-joint Complex According to Different Pelvic Incidences

Background: Pelvic incidence is closely related to degeneration of the facet joint and intervertebral disc and is related to the orientation of the facet joints. Currently, very few studies have been conducted on the force analysis of the three-joint complex in patients with different pelvic incidence measurements under different sports postures. We designed this study to better assess the influence of pelvic incidence on the stress of the lumbar three-joint complex. Finite element analysis can provide a biomechanical basis for the relationship between different pelvic incidences and degenerative diseases of the lower lumbar spine.Methods: We developed three nonlinear finite element models of the lumbar spine (L1-S1) with different pelvic incidences (27.44°, 47.05°, and 62.28°) and validated them to study the biomechanical response of facet joints and intervertebral discs with a follower preload of 400 N, under different torques (5 Nm, 10 Nm, and 15 Nm), and compared the stress of the three-joint complex of the lower lumbar spine (L3-S1) in different positions (flexion-extension, left-right bending, and left-right torsion).Results: In the flexion position, the stress of the disc in the low pelvic incidence model was the largest among the three models; the stress of the facet joint in the high pelvic incidence model was the largest among the three groups during the extension position. During torsion, the intradiscal pressure of the high pelvic incidence model was higher than that of the other two models in the L3/4 segment, and the maximum von Mises stress of the annulus fibrosus in the L5/S1 segment with a large pelvic incidence was greater than that of the other two models.Conclusions: Pelvic incidence is related to the occurrence and development of degenerative lumbar diseases. The stress of the lower lumbar facet joints and fibrous annulus of individuals with a high pelvic incidence is greater than that of individuals with a low pelvic incidence or a normal pelvic incidence. Although this condition only occurs in individual segments, to a certain extent, it can also reflect the influence of pelvic incidence on the force of the three-joint complex of the lower lumbar spine.

Analysis of Measurement Changes in the Pelvic Incidence According to Pelvic Rotation using a 3-dimensional Model

Background: Pelvic incidence (PI) is used as a key parameter in surgical correction of adult spinal deformity (ASD) patients. However, there is a limitation to reflecting the exact center or inclination of 3-dimentional anatomical structures in a 2-dimensional (2D) sagittal radiographs, and these can lead to the measurement errors. Therefore, we evaluated whether there is a change in PI measurement according to the actual rotation of the pelvis, and conducted a study on a more accurate method of measuring PI in a 2D sagittal radiograph.Methods: From 2014 to 2015, 30 patients who visited our outpatient clinic were analyzed retrospectively. CT scan images including the lower lumbar spine, pelvis, and both femurs in DICOM format were imported to Mimics Research 17.0 (Materialise NV, Belgium), Solidworks (Dassault systems, France), and AutoCAD 2014 (AUTODESK, US), and the changes in PI according to vertical and horizontal pelvic rotations were evaluated.Results: The average PI according to the horizontal pelvic rotations measured on AutoCAD with 0º, 5º, 10º, 15º, 20º, 25º, 30º, 35º, and 40º was 48.8º, 48.7º, 48.3º, 47.8º, 46.9º, 45.6º, 44.0º, 42.2º, and 39.9º, respectively. The PI of an acceptable error of 6º on radiographs was 35º in the horizontal pelvic rotation. The average PI according to the vertical pelvic rotations measured on AutoCAD with 0º, 5º, 10º, 15º, 20º, 25º, 30º, 35º, and 40º was 48.8º, 49.0º, 49.5º, 50.2º, 51.3º, 52.7º, 54.4º, 56.6º, and 59.4º, respectively. The PI of an acceptable error of 6º on radiographs was 30º in the vertical pelvic rotation. Conclusions: This study revealed that the PI value could differ from the actual anatomical value due to the horizontal and vertical rotation of the pelvis while acquiring the radiograph. In whole-spine lateral radiographs, errors in PI measurement may occur due to rotation of the pelvis or nonvertical projection of X-rays. In the standing pelvic lateral radiographs, placing the overlapping femoral heads at the center and obtaining the straight sacral endplate as much as possible by referring to CT or magnetic resonance imaging would be a more accurate measurement method to define the PI.

Intramuscular Properties of Resting Lumbar Muscles in Patients with Unilateral Lower Limb Amputation

Lower limb amputees (LLAs) have a high incidence of low back pain (LBP), and identifying the potential risk factors in this group is key for LBP prevention. This study analyzed the intramuscular properties of the resting lumbar muscle in thirteen unilateral LLAs and age-matched controls to predict the onset of LBP. To measure the lumbar intramuscular properties, resting erector spinae muscles located in the upper and lower lumbar regions were examined using a handheld myotonometer. The dynamic stiffness, oscillation frequency, and logarithmic decrement were measured. In our results, the stiffness and frequency of the upper lumbar region were greater in the amputee group than in the control, whereas the decrement did not differ between the two groups. Additionally, the measured values in the lower lumbar region showed no significant difference. Within each group, all three factors increased at the upper lumbar region. In the LLAs, the frequency and stiffness values of the upper lumbar on the non-amputated side were significantly higher than those on the amputated side. These results indicate that the upper lumbar muscles of the amputees were less flexible than that of the control. This study can help in providing therapeutic strategies treating LBP in amputees.

3D printed composite model of pelvic osteochondroma and nerve roots

Background 3D-printing has become increasingly utilized in the preoperative planning of clinical orthopaedics. Surgical treatment of bone tumours within the pelvis is challenging due to the complex 3D bone structure geometry, as well as the proximity of vital structures. We present a unique case where a composite bone and nerve model of the lower lumbar spine, pelvis and accompanying nerve roots was created using 3D-printing. The 3D-printed model created an accurate reconstruction of the pelvic tumour and traversing nerves for preoperative planning and allowed for efficient and safe surgery. Case presentation We present a unique case where a composite bone and nerve model of the lower lumbar spine, pelvis and accompanying nerve roots was created using 3D-printing. The bony pelvis and spine model was created using the CT, whereas the nerve roots were derived from the MRI and printed in an elastic material. 3D-printed model created an accurate reconstruction of the pelvic tumour and traversing nerves for preoperative planning and allowed for efficient and safe surgery. Pelvic tumour surgery is inherently dangerous due to the delicate nature of the surrounding anatomy. The composite model enabled the surgeon to very carefully navigate the anatomy with a focused resection and extreme care knowing the exact proximity of the L3 and L4 nerve roots. Conclusion The patient had complete resection of this tumour, no neurological complication and full resolution of his symptoms due to careful, preoperative planning with the use of the composite 3D model.