Internal morphology of human facet joints: comparing cervical and lumbar spine with regard to age, gender and the vertebral core

Development of a Cranial Suture Traction Therapy Program for Facial Asymmetry Correction Using the New Delphi Technique

Background and Objectives: We aimed to develop a cranial suture traction therapy program, a non-surgical therapeutic method for facial asymmetry correction. Materials and Methods: Six experts, including rehabilitation medicine specialists, oriental medical doctors, dentistry specialists, five experts, including Master’s or doctoral degree holders in skin care and cosmetology with more than 10 years of experience in the field, 4 experts including educators in the field of skin care, a total of 15 people participated in the validation of the development of the cranial suture traction therapy program in stages 1 to 3. Open questions were used in the primary survey. In the second survey, the results of the first survey were summarized and the degree of agreement regarding the questions in each category was presented. In the third survey, the degree of agreement for each item in the questionnaire was analyzed statistically. Results: Most of the questions attained a certain level of consensus by the experts (average of ≥ 4.0). The difference between the mean values was the highest for the third survey at 0.33 and was the lowest between the second and third surveys at 0.47. The results regarding the perceived degree of importance for each point of the evaluation in both the second and third stages of the cranial suture traction therapy program were verified using the content validity ratio. The ratio for the 13 evaluation points was within the range of 0.40−1.00; thus, the Delphi program for cranial suture traction therapy verified that the content was valid. Conclusions: As most questions attained a certain level of consensus by the experts, it can be concluded that these questions are suitable, relevant, and important. The commercialization of the cranial suture traction treatment program will contribute to the correction and prevention of facial dislocations or asymmetry, and the developed treatment will be referred to as cranial suture traction therapy (CSTT).

The biomechanical effect of the relevant segments after facet-disectomy in different diameters under posterior lumbar percutaneous endoscopes: a three-dimensional finite element analysis

OBJECTIVE

To evaluate the biomechanical influence after percutaneous endoscopic lumbar facetectomy in different diameters on segmental range of motion (ROM) and intradiscal pressure (IDP) of the relevant segments by establishing three dimensional finite element (FE) model.

METHODS

An intact L3-5 model was successfully constructed from the CT of a healthy volunteer as Model A (MA). The Model B (MB), Model C (MC) and Model D (MD) were obtained through facetectomy on L4 inferior facet in diameters 7.5 mm, 10 mm and 15 mm on MA for simulation. The ROM and IDP of L3/4 and L4/5 of four models were all compared in forward flexion, backward extension, left and right bending, left and right rotation.

RESULTS

Compared with MA, the ROM of L4/5 of MB, MC and MD all increased. MD changed more significantly than MB and MC in backward extension, right bending and right rotation. But that of MB and MC on L3/4 had no prominent change, while MD had a slight increase in backward extension. The IDP of MB and MC on L4/5 in six states was similar to MA, yet MD increased obviously in backward extension, right bending, left and right rotation. The IDP on L3/4 of MB and MC was resemble to MA in six conditions, nevertheless MD increased slightly only in backward extension.

CONCLUSION

Compared with the facetectomy in diameters 7.5 mm and 10 mm, the mechanical effect brought by facetectomy in diameter 15 mm on the operating segment changed more significantly, and had a corresponding effect on the adjacent segments.

Micro-architecture study of the normal odontoid with micro-computed tomography

Introduction: Odontoid fractures easily lead to instability, causing spinal cord injury. The aim of this study was to measure and analyze the micro-architecture and morphometric parameters of the normal odontoid with high-resolution three-dimensional (3D) micro-computed tomography (micro-CT).Methods: Micro-CT scans were obtained from five normal odontoid processes. The scanned data were reconstructed with micro-CT software, and the nutrient foramina and the ossification center of the base of the odontoid were revealed. The trabeculae of the odontoid were measured and divided into four parts to obtain the volume fraction of regions of interest.Results: High-resolution 3D images of the micro-structures' parameters were obtained from the odontoid using micro-CT software. The images demonstrated sponge-like trabecular bone, with the trabeculae showing a complex, net-like micro-construction. The subchondral bone plate was of lamella-like, compact construction and extended and transformed into a net-like structure with rod-shaped trabeculae arranged radially in all directions. There was a statistically significant difference in the volume fraction compared with the region of interest in the fourth part of the trabeculae and the first part of the odontoid (P < 0.05). The nutrient foramina and the ossification center of the odontoid were also observed.Conclusions: It is feasible to use high-resolution 3D micro-CT to evaluate the micro-architecture of the normal odontoid. Other studies can benefit from use of the micro-CT images, such as finite element evaluations.

Comparative Analysis of Bone Structural Parameters Reveals Subchondral Cortical Plate Resorption and Increased Trabecular Bone Remodeling in Human Facet Joint Osteoarthritis

Facet joint osteoarthritis is a prominent feature of degenerative spine disorders, highly prevalent in ageing populations, and considered a major cause for chronic lower back pain. Since there is no targeted pharmacological therapy, clinical management of disease includes analgesic or surgical treatment. The specific cellular, molecular, and structural changes underpinning facet joint osteoarthritis remain largely elusive. The aim of this study was to determine osteoarthritis-related structural alterations in cortical and trabecular subchondral bone compartments. To this end, we conducted comparative micro computed tomography analysis in healthy (n = 15) and osteoarthritic (n = 22) lumbar facet joints. In osteoarthritic joints, subchondral cortical plate thickness and porosity were significantly reduced. The trabecular compartment displayed a 42 percent increase in bone volume fraction due to an increase in trabecular number, but not trabecular thickness. Bone structural alterations were associated with radiological osteoarthritis severity, mildly age-dependent but not gender-dependent. There was a lack of association between structural parameters of cortical and trabecular compartments in healthy and osteoarthritic specimens. The specific structural alterations suggest elevated subchondral bone resorption and turnover as a potential treatment target in facet joint osteoarthritis.

Characterization of subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis

Facet joint osteoarthritis may be a cause of low back pain in degenerative spine diseases including lumbar spinal stenosis. Subchondral bone is regarded as a potential therapeutic target for osteoarthritis treatment. The goal of this study was to characterize subchondral bone histopathology in osteoarthritic facet joints from lumbar spinal stenosis patients. Fifteen patients with degenerative spinal stenosis scheduled for transforaminal lumbar interbody fusion surgery were recruited for this study. Osteoarthritis severity was graded on T1- and T2-weighted MRI images using Weishaupt scoring system. Dissected osteoarthritic facet joints were subjected to histological and immunohistochemistry analyses to study relative abundance of osteoblast, osteoclasts, and macrophages using van Gieson's, tartrate-resistant acid phosphatase and CD68-antibody staining, respectively. Presence of nerve fibers was evaluated by PGP9.5-antibody staining. Differential bone histopathology, independent from radiological osteoarthritis grade, was observed in facet joints. Extensive de novo bone formation was found in subchondral bone tissues of eight of fifteen specimens. Regions of bone formation showed high abundance of blood vessels and CD68-positive macrophages, but were devoid of multinucleated osteoclasts. Additional pathological changes in subchondral marrow spaces, including inflammatory infiltration and enhanced osteoclast activity, were characterized by macrophage-rich tissues. PGP9.5-positive nerve fibers were detected near arterioles, but not in regions displaying bone pathology. Individual histopathological parameters did not associate with clinical features or radiological osteoarthritis severity. Subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis is characterized by marrow infiltration by macrophage-rich tissues and enhanced de novo bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1475-1480, 2016.

The role of obesity in the biomechanics and radiological changes of the spine: an in vitro study

OBJECT

The effects of obesity on lumbar biomechanics are not fully understood. The aims of this study were to analyze the biomechanical differences between cadaveric L4–5 lumbar spine segments from a large group of nonobese (body mass index [BMI] < 30 kg/m2) and obese (BMI ≥ 30 kg/m2) donors and to determine if there were any radiological differences between spines from nonobese and obese donors using MR imaging.

METHODS

A total of 168 intact L4–5 spinal segments (87 males and 81 females) were tested using pure-moment loading, simulating flexion-extension, lateral bending, and axial rotation. Axial compression tests were performed on 38 of the specimens. Sex, age, and BMI were analyzed with biomechanical parameters using 1-way ANOVA, Pearson correlation, and multiple regression analyses. MR images were obtained in 12 specimens (8 from obese and 4 from nonobese donors) using a 3-T MR scanner.

RESULTS

The segments from the obese male group allowed significantly greater range of motion (ROM) than those from the nonobese male group during axial rotation (p = 0.018), while there was no difference between segments from obese and nonobese females (p = 0.687). There were no differences in ROM between spines from obese and nonobese donors during flexion-extension or lateral bending for either sex. In the nonobese population, the ROM during axial rotation was significantly greater for females than for males (p = 0.009). There was no significant difference between sexes in the obese population (p = 0.892). Axial compressive stiffness was significantly greater for the obese than the nonobese population for both the female-only group and the entire study group (p < 0.01); however, the difference was nonsignificant in the male population (p = 0.304). Correlation analysis confirmed a significant negative correlation between BMI and resistance to deformation during axial compression in the female group (R = −0.65, p = 0.004), with no relationship in the male group (R = 0.03, p = 0.9). There was also a significant negative correlation between ROM during flexion-extension and BMI for the female group (R = −0.38, p = 0.001), with no relationship for the male group (R = 0.06, p = 0.58). Qualitative analysis using MR imaging indicated greater facet degeneration and a greater incidence of disc herniations in the obese group than in the control group.

CONCLUSIONS

Based on flexibility and compression tests, lumbar spinal segments from obese versus nonobese donors seem to behave differently, biomechanically, during axial rotation and compression. The differences are more pronounced in women. MR imaging suggests that these differences may be due to greater facet degeneration and an increased amount of disc herniation in the spines from obese individuals.

An over-nonlocal implicit gradient-enhanced damage-plastic model for trabecular bone under large compressive strains

PURPOSE

Investigation of trabecular bone strength and compaction is important for fracture risk prediction. At 1-2% compressive strain, trabecular bone undergoes strain softening, which may lead to numerical instabilities and mesh dependency in classical local damage-plastic models. The aim of this work is to improve our continuum damage-plastic model of bone by reducing the influence of finite element mesh size under large compression.

METHODOLOGY

This spurious numerical phenomenon may be circumvented by incorporating the nonlocal effect of cumulated plastic strain into the constitutive law. To this end, an over-nonlocal implicit gradient model of bone is developed and implemented into the finite element software ABAQUS using a user element subroutine. The ability of the model to detect the regions of bone failure is tested against experimental stepwise loading data of 16 human trabecular bone biopsies.

FINDINGS

The numerical outcomes of the nonlocal model revealed reduction of finite element mesh dependency compared with the local damage-plastic model. Furthermore, it helped reduce the computational costs of large-strain compression simulations.

ORIGINALITY

To the best of our knowledge, the proposed model is the first to predict the failure and densification of trabecular bone up to large compression independently of finite element mesh size. The current development enables the analysis of trabecular bone compaction as in osteoporotic fractures and implant migration, where large deformation of bone plays a key role.

One-stage removal of a giant thoracic paraspinal shamrock-shaped schwannoma via modified hemilaminectomy and posterolateral thoracotomy

BACKGROUND CONTEXT

Paraspinal neurogenic tumors in the thoracic region are not a rare clinical entity in neurosurgical practice. They usually consist of intrathoracic and intraspinal parts, namely dumb-bell type. However, in some rare cases, they might display a bidirectional extraspinal growing pattern, compromising three components with intraspinal, intrathoracic, and subcutaneous parts, thus appearing to be shamrock-like. Despite its benign nature, the removal of this type of tumor could be challenging for both neurosurgeons and thoracic surgeons, especially when the tumor has grown to an enormous size.

PURPOSE

We present a case of a giant paraspinal shamrock-shaped schwannoma in the T9-T12 level resected completely by one-stage combined surgery of hemilaminectomy and posterolateral thoracotomy performed by an interdisciplinary team of neurosurgeons and thoracic surgeons.

STUDY DESIGN/SETTING

Operating room of a large tertiary medical center where expertise and equipment of neurosurgery, thoracic surgery, and neuroanesthesia are readily available.

METHODS

Under generalized anesthesia, the patient was intubated with a double-lumen endotracheal tube to allow one-lung ventilation during the thoracotomy, and he was then placed in the left lateral position. Because of the giant subcutaneous mass, the normal hemilaminectomy could not be carried out like it usually would be. Thus, we did slight modification to the standard hemilaminectomy; first, by elevation of a skin flap to allow in situ excision of the subcutaneous portion of the tumor, then followed by a standard unilateral laminectomy to remove the intraspinal portion, done by neurosurgeons, and finally, posterolateral thoracotomy to remove the intrathoracic part, performed by a thoracic team.

RESULTS

The postoperative magnetic resonance imaging scan showed complete removal of the tumor, and the patient experienced an improvement in lower extremity muscle weakness with no new neurological deficits.

CONCLUSIONS

This is the first case to demonstrate the removal of giant paraspinal shamrock-shaped schwannoma in the thoracic level. The combined approach of modified hemilaminectomy and posterolateral thoracotomy was proven to be appropriate in managing such cases, making this procedure a potential addition to present methods.