Role Of Facet Joints Research Articles

Coupled motions in human and porcine thoracic and lumbar spines

Coupled motions, i.e., motions along axes other than the loaded axis, have been reported to occur in the human spine, and are likely to be influenced by inclined local axes due to the sagittal plane spine curvature. Furthermore, the role of facet joints in such motions is as yet unclear. Therefore, this study aimed at assessing coupled motions in multiple spine sections in vitro, before and after removal of posterior elements. Six elderly human and 6 young porcine spines were sectioned in four segments (high thoracic, mid thoracic, low thoracic and lumbar), each consisting of four vertebrae and three intervertebral discs. Segments were loaded along each of the three axes, and three-dimensional rotations of the middle segment were quantified. Subsequently, posterior elements were removed and the protocol was repeated. To avoid mixed loading between Axial Rotation (AR) and Lateral Bending (LB), in contrast to other studies, local axes at the vertebrae were defined as aligned with the loading device prior to each load application.Expressed as a percentage of motion in the loaded direction, coupled motions were on average larger in human (22.7%, SD = 2.2%) than in porcine (11.9%, SD = 1.2%) spines (p < .001). Largest coupled motions were obtained in AR loading of the lumbar spine segments, with mean magnitudes averaged over coupling axes for human L2-L3 joints of 48.9% (SD = 13.2%), including somewhat more LB (56.4%, SD = 18.6) than FE (41.4%, SD = 14.1%) coupling. For porcine L3-L4 joints average coupling in AR loading was 29.3% (SD = 8.2%). In human segments removal of posterior elements only had substantial effects in the lumbar spine segments, where posterior element removal decreased coupled motion during AR loading, averaged over LB and FE coupling, from 48.9% (SD = 13.2%) to 27.7% (SD = 6.1%), mainly through increased motion in the loaded direction.The present results indicate that coupled motions were largest in the lumbar spine. In human spines, posterior elements only contributed to coupled motions in lumbar axial rotation loading.

Role of facet joints in spine pain and image-guided treatment: a review.

Chronic low back and neck pain remain prevalent medical concerns, with much debate regarding the effective evaluation and treatment. Facet disease has been implicated as a source of axial nonradiating low back pain. We discuss patient evaluation, the role of imaging, current and emerging image-guided therapies for facet-related pain, and the increasing importance of outcome-related research in this arena.

Detailed pathological changes of human lumbar facet joints L1–L5 in elderly individuals

Facet joints play an important role in intervertebral load transmission and are crucial for rotational kinematics. Clinically, the role of facet joints as a possible source of low back pain is seen as controversial and at present is not sufficiently investigated. In this study, human lumbar facet (zygapopyhysial) joints from donors with advanced age were analyzed macroscopically, for degenerative changes. The aim was to determine the extent and morphology of degenerative changes in these joints. Lumbar facet joints (L1-L5) of 32 donors were studied (mean age 80.1+/-11.2 years). Joint capsules were carefully removed and joint surfaces (5 zones) examined using magnifying glasses and probes. In the result, the majority of facet joints showed cartilage defects of varying extent. Defects were located mostly at the margins of the articular surface, the central zone being relatively well preserved. Defect localization was different between superior (most cartilage defects in superior zone) and inferior (most defects inferiorly) facets. Further, defects were more severe caudal (level of L5) and in older persons. Osteophytes were present in up to 30%, located mostly at the latero-dorsal enthesis of the joint capsule on the superior facet. In conclusion, most margins of the articular facets are subject to degenerative changes in the lumbar spine of elderly persons, the topographical pattern being different in superior and inferior facets. This observation can be explained by the segmental motion patterns during extension/flexion movements of the facets. Sometimes, due to the marginal extension, it is obvious that not all changes can be assessed by CT or MRI.

Poroelastic analysis of lumbar spinal stability in combined compression and anterior shear.

A three-dimensional poroelastic finite element (FE) L2-L3 model was developed to study lumbar spinal instability and intrinsic parameters in the intervertebral disc (IVD). The FE model took into consideration poroelasticity of the IVD and viscoelasticity of the annulus fibers and ligaments to predict the time-dependent behavior. To simulate a holding task, the motion segment was subjected to a combined loading of constant compressive load (1600 N) and anterior shear (200 N) for 2 hours, and the role of facet joints and ligaments in the biomechanical response was investigated by removal of unilateral/bilateral facets, posterior ligaments (supraspinous and interspinous), and facets and ligaments. The results show the stabilizing role of the facets and ligaments in resisting anterior shear and sagittal rotation under combined loading over time. The main pathway of fluid movement was found to permeate through the central region of the endplate, and the fluid diffusion occurred earlier at the posterior nucleus than the anterior nucleus. The fluid loss from the nucleus dictated the time-dependent motion under the sustained loading, whereas the intrinsic properties of ligaments/annulus fibers played a role only in the early stage of the loading. The predicted results using poroelastic elements provide new insight into the IVD in providing the spinal stiffness under combined loading.

Role of Facet Joints in Chronic Low Back Pain in the Elderly: A Controlled Comparative Prevalence Study

Evaluation of the age related prevalence of persistent low back pain has been estimated to be consistently higher in the elderly compared to the younger population. Facet joints have been shown to be the cause of chronic low back pain in 15% to 45% of the patients in controlled studies. Prevalence of facet joint mediated pain has not been studied in the elderly. The study population consisted of 100 patients. Group I consisted of 50 patients that were 64 years of age or younger. Group II consisted of 50 patients 65 years of age or older. The patients were randomly allocated into 1 of the 2 groups. Facet joints were investigated with diagnostic blocks initially using lidocaine 1% followed by bupivacaine 0.25%, usually 2 weeks apart. The prevalence of facet joint mediated pain was determined to be 30% in the adults and 52% in the elderly, which was significantly higher with a false positive rate of 26% in adults and 33% in the elderly. In conclusion, the results of this study show that facet joint mediated pain is a significant problem in all patients suffering with chronic low back pain with the prevalence of 52% in the elderly and 30% in adults.

Facet Joint Pain and the Role of Neural Blockade in Its Management.

Chronic spinal pain is a common medical problem with serious financial and social consequences. Among the various structures with potential for producing pain in the spine, facet joints as sources of chronic spinal pain have attracted considerable attention and controversy. Significant progress has been made in precision diagnosis of spinal pain with neural blockade, in the face of less than optimal diagnostic information offered by imaging and neurophysiologic studies. Research into the role of facet joints in spinal pain has shown that cervical facet joints are the cause of chronic neck pain in 54% to 60% of patients, whereas lumbar facet joints cause pain in 15% to 40% of patients with chronic low back pain. Local anesthetic blocks of medial branches have proven to be a reliable diagnostic test; they are target-specific when used appropriately with control blocks, either with two local anesthetics with different durations of action or with the addition of an inactive placebo injection. The literature is replete with reports on uncontrolled studies, case reports, and documentation from a few controlled studies, all of which offer supporting information on the rationale and effectiveness of facet blocks and neurotomy. Facet joint injections and medial branch blocks are considered to be of equal value. Lumbar intra-articular steroid injections have been proven effective to a certain extent, but evidence indicates that cervical intra-articular steroids are ineffective. The role of repeat medial branch blocks is not known. Radiofrequency neurotomy remains the only practical and validated treatment for cervical facet joint pain; however, its role in management of either lumbar or thoracic facet joint pain awaits validation.

Poroelastic creep response analysis of a lumbar motion segment in compression

The nonlinear three-dimensional poroelastic creep response of a lumbar motion segment under a constant axial compression (400, 1200, or 2000 N) is investigated for a period of 2 h. The role of facet joints, strain-dependent variable permeability, boundary pore pressure, and coupled sagittal rotation on response is studied. Biomechanics of annulus excision, nucleotomy, and facetectomy are also investigated. Both material and geometric nonlinearities are considered. The annulus bulk is modelled as a nonhomogeneous composite of collagenous fibers and annulus bulk. As time progresses, axial displacement increases, pore pressure decreases, annulus bulk undergoes larger compressive stresses, fiber layers become slack, and facets carry larger loads. Surgical alterations markedly soften the temporal response and increase facet forces. In contrast, the strain-dependent variable permeability and boundary pore pressure stiffen the response and decrease forces on the facets. Changes in the nucleus fluid content, facet joints, boundary pore pressure, and disc permeability markedly influence the lumbar biomechanics.

The Role of the Lumbar Facet Joints in Spinal Stability

The role of the facet joints in spinal stability was analyzed using long-segment cadaver spines. To establish the existence of alternate paths of loading when the facet joints and anulus are compromised. It has been reported that facet arthrosis and degeneration never occur without the presence of adjacent disc degeneration. This suggests that intact discs protect the facets from severe loading and degeneration. Based on these studies of spinal mechanics, the authors devised an experiment to further explain the relationship of the disc and the facet in sharing compressive loads. Ten human cadaver spines were placed unsupported in an Instron Model 4206 Tensile Testing Machine. Compressive loads of 1000 N then were applied to the specimens at a rate of 20 N per minute. The facet joints, anterior anulus, and lateral anulus then were destroyed sequentially at L3 and the loading cycles were repeated. The load-deflection curves for each cycle were evaluated and compared with the intact specimen. Unilateral and bilateral facetectomies had little affect on the ability of the specimen to support a physiologic load. Facetectomies in combination with anterior anulus destruction showed a significant change in the ability of the specimen to support a load with an extension moment applied. The facet joints of the lumbar spine are not the principle support structures in extension. With destruction of the facets, an alternate path of loading is established. The alternate path of loading transfers axial loads to the anulus and anterior longitudinal ligament to support the spine. Although facet joint destruction will not produce acute instability, it will transfer the loads to the adjacent disc and conceivably accelerate its degeneration.

Back Pain: The History and Physical Examination-Reply

In Reply. —I thank Drs Abromovitz, Frazier, Kelleher, Rothschild, and Weintraub for their interest and comments. Their letters offer an opportunity to reemphasize several points, and my colleagues and I invite them all to join us in seeking better evidence regarding the accuracy and usefulness of the history and physical examination. There are several parallel but different ways to think about test accuracy, and different ones are being adopted by different generations of clinicians. None is inherently better than any other and some of the writers call attention to the advantages and disadvantages of various statistics. These points are discussed in greater detail by Sackett in his introductory article to the series on the rational clinical examination. 1 We are unaware of data on the reproducibility or validity of the tests proposed by Dr Abromovitz. Some recent studies challenge the role of facet joints as a common cause of back