Facet Joint Angle Research Articles

Association of facet tropism with lumbar disc herniation

Facet tropism is defined as asymmetry between left and right facet joints and is postulated as a possible cause of disc herniation. In the present study, the authors used a 3-T MRI to investigate the association between facet tropism and lumbar disc herniation at a particular motion segment. They also examined whether the disc herniated towards the side of the more coronally oriented facet joint. Sixty patients (18-40years) with single level disc herniation (L3-L4, L4-L5, or L5-S1) were included in the study. Facet angles were measured using MRI of 3-T using the method described by Karacan et al. Facet tropism was defined as difference of 10° in facet joint angles between right and left sides. Normal disc adjacent to the herniated level was used as control. We also examined if disc herniated towards the side of more coronally oriented facet. Twenty-five herniations were at L4-L5 level and 35 at L5-S1. Statistical analysis was performed using the Fischer Exact Test. At L4-L5 level, 6/25 cases had tropism compared to 3/35 controls (p=0.145). At L5-S1 level, 13/35 cases had tropism as compared to 1/21 controls (p=0.0094). Of 19 cases having tropism, the disc had herniated towards the coronally oriented facet in six (p=0.11). The findings of the study suggest that facet tropism is associated with lumbar disc herniation at the L5-S1 motion segment but not at the L4-L5 level.

Association of Facet Tropism with Lumbar Disk Herniation

Introduction Study Design Analytical cross-sectional hospital-based cohort study. Objective (1) To determine whether there is an association between facet tropism and the occurrence of lumbar disk herniation at that level. (2) In patients with facet tropism at the herniated disk level, to determine whether there is an association between facet tropism and the side of disk herniation (sagittal or coronal). Background Facet tropism is defined as asymmetry between left and right facet joint angles and is postulated as a possible etiological cause in occurrence of disk herniation. A correlation in literature is still being debated. Materials and Methods Total 60 patients (18 to 40 years) with single disk herniation (L3-L4, L4-L5, or L5-S1) were selected. Exclusion criteria included multiple/recurrent disk herniation, spondylolisthesis, transitional vertebra, scoliosis, previous surgery/trauma/infection, and significant facetal arthropathy. Facet angles were measured using 3 Tesla MRI by two surgeons and mean taken to minimize bias. Facet tropism was defined as difference of 10 degrees in facet joint angles between right and left sides. Normal adjacent disk was used as control. We also examined if disk herniated towards the side of more coronally oriented facet. Results Overall we found a statistically significant association of facet tropism with lumbar disk herniation ( p = 0.0009). However, analyzing each level separately, an association of facet tropism with lumbar disk herniation was found to be statistically significant at the L5S1 level ( p = 0.0094) but not at L4L5 level ( p = 0.145). Of 19 cases having tropism at the herniated disk level, the disk had herniated towards the sagittally oriented facet in 13 ( p = 0.11). Conclusion Statistically significant association exists between facet tropism and lumbar disk herniation at L5-S1. Same does not hold true at L4-5. There is no statistically significant association between facet tropism and the side of the disk herniation (sagittal or coronal) but the numbers were small. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared

Orientation and Osteoarthritis of Lumbar Facet Joints: Association with Degenerative Disk Disease

Introduction Several studies have shown relationship between sagittal orientation of lumbar facet joint and degenerative spondylolisthesis1,2,3; however, there is no current information on how much the facet orientation and osteoarthritis associate with different grades and morphologies of lumbar disk degeneration on MRI. We hypothesize that sagittally oriented facet joints promote a degenerated intervertebral disk (IVD) to develop spondylolisthesis rather than a collapsed disk. Aim of this study is to evaluate the association between lumbar facet joint orientation, facet osteoarthritis, IVD herniation, and different grades of disk degeneration. Materials and Methods A total of 550 patients who underwent lumbar spine MRI for low back pain or radicular leg pain were reviewed. Patients with previous back surgery, congenital anomalies, spondylolysis, infection, tumor, or fracture were excluded. Total 153 patients were included and assessed for IVD degeneration according to Modified Pfirrmann (MP) grading4 at L3-S1 lumbar segments. Facet joint angles on axial scan and Fujiwara osteoarthritic grading5 were assessed at spinal segments of the following six groups: “Bright disk” (MP grade 1 or 2), “Black disk” (MP grade 4 or 5), “Collapse disk” (MP grade 6 to 8), “Herniated disk” (bulging or prolpase), spondylolisthesis and “nonslip level” of spondylolisthesis. The mean facet angles and the percentages of the mild (Fujiwara grade 1 or 2) and advanced (Fujiwara grade 3 or 4) facet osteoarthritis were compared between six groups using independent sample t test and Pearson Chi Square test, respectively. The association of facet joint orientation and osteoarthritis was also examined by linear regression analysis. Results The mean facet angles relative to the coronal plane in patients who had “Black disk” (right L3/4: 55.70, L4/5: 47.50, L5/S1: 39.70), “Collapse disk” (right L3/4: 54.10, L4/5: 470, L5/S1: 380) and “Herniated disk” (right L3/4: 560, L4/5: 46.10, L5/S1: 38.10) were significantly more sagittal at all levels (p0, L4/5: 41.10, L5/S1: 35.80). There was no statistical difference of mean facet angles at all levels between “Black disk”, “Collapse disk,” and “Herniated disk” (Table 1). Facet joint osteoarthritis were more advanced in “Black disk”, “Collapse disk”, “Herniated disk” than “Bright disk”, but there was no difference in percentage of mild and advanced facet osteoarthritis among three groups. Degenerative spondylolisthesis segments demonstrated significantly more sagittal mean facet angle (right L3/4: 72.60, L4/5: 67.20, L5/S1: 490, p0, L4/5: 540, L5/S1: 420, p0, which is the mean facet angle of patient without spondylolisthesis + SD, was 25 times more likely to have degenerative spondylolisthesis. Advanced degenerative “Collapse disk” had no significant difference in mean facet angle from that of early degenerative “Black disk.” A positive association between sagittal orientation and osteoarthritis of facet joints was demonstrated. Only degenerative spondylolisthesis demonstrated the significant correlation between facet joint osteoarthritis and disk degeneration (Fig. 1). Conclusion Sagittal facet orientation relates to facet joint osteoarthritis and IVD degeneration. Degenerative spondylolisthesis had more advanced facet osteoarthrosis and disk degeneration. The increase in facet angles at “nonslip” levels other than that of the spondylolisthesis suggests that increased facet angles represent variations in developmental anatomy and contribute to instability of a functional spine unit when degenerative disk loses its anterior vertebral column support. I confirm having declared any potential conflict of interest for all authors listed on this abstract No Disclosure of Interest None declared Kalichman, et al. Facet orientation and tropism associations with facet joint osteoarthritis and degeneratives. Spine 2009; 34(16):E579-E585 Boden, et al. Orientation of the lumbar facet joints: association with degenerative disc disease. Journal of Joint and Bone surgery 1996;78A(3):403–411 Fujiwara, et al. Orientation and osteoarthritis of the lumbar facet joint. CORR 2001;385:88–94 Griffith, et al. Modified Pfirrmann grading system for lumbar intervertebral disc degeneration. Spine 2007; 32(24):708–712 Fujiwara, et al. The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study. European Spine Journal 1999; 8:396–401

Risk factors for degenerative spondylolisthesis: a systematic review.

Study design: Systematic literature review.Rationale: Many authors have postulated on various risk factors associated with the pathogenesis of degenerative spondylolisthesis (DS), yet controversies regarding those risk factors still exist.Objective: To critically appraise and summarize evidence on risk factors for DS.Methods: Articles published before October 15, 2011, were systematically reviewed using PubMed and bibliographies of key articles. Each article was subject to quality rating and was analyzed by two independent reviewers.Results: From 382 citations, 30 underwent full-text review. Fourteen studies met inclusion criteria. All but two were considered poor quality. Female gender and higher facet joint angle were consistently associated with an increased risk of DS across multiple studies. Multiple studies also consistently reported no association between back pain and prolonged occupational sitting. Associations between age, parity, lumbosacral angle, lumbar lordosis, facet joint tropism, and pelvic inclination angles were inconsistent.Conclusions: There appears to be consistent evidence to suggest that the risk of DS increases with increasing age and is greater for females and people with a greater facet joint angle.

Incidencia y factores de riesgo de degeneración de los discos límites a una fusión lumbar

Objective The aim of this retrospective study is to determine the incidence, the rate of adjacent disc degeneration (ADD) and to analyse the major risk factors after instrumented lumbar fusion. Materials and methods Retrospective consecutive study of 230 patients, with lumbar degenerative disease, who underwent lumbar or lumbosacral instrumented spine fusion between 1990 and 2000. We used radiographic criteria (X-RAY and MRI) in order to determine ADD, and we analysed the following risk factors: age, gender, number of levels fused, adjacent disc status before surgery, segmental lordosis and lumbosacral lordosis, and finally, the facet joint angle of adjacent disc. Results ADD was found in 41 (17.82%) patients, the mean follow-up period was 8.5 years. The average age was 59 years with female predominance. L5-S1 fusion showed a significant ( P < .05) lower risk for developing degenerative changes at the adjacent segments than any other fusions. The cranial level of the fused segment was mainly affected in 36 (87.8%) patients and 19 (46%) patients required surgery. The average interval from surgery to the development of ADD was 6.1 years. Conclusions There is a risk of 17.82% (41 patients) of being affected by radiographic ADD in an average of 6 years after the first surgery, with a risk of 6.26% (19 patients) of having surgery. The gender, number of levels fused and fusion to the sacrum were the main risk factors.

Incidence and risk factors of adjacent disc degeneration after lumbar fusion

Objective The aim of this retrospective study is to determine the incidence, the rate of adjacent disc degeneration (ADD) and to analyse the major risk factors after instrumented lumbar fusion. Materials and methods Retrospective consecutive study of 230 patients, with lumbar degenerative disease, who underwent lumbar or lumbosacral instrumented spine fusion between 1990 and 2000. We used radiographic criteria (X-RAY and MRI) in order to determine ADD, and we analysed the following risk factors: age, gender, number of levels fused, adjacent disc status before surgery, segmental lordosis and lumbosacral lordosis, and finally, the facet joint angle of adjacent disc. Results ADD was found in 41 (17.82%) patients, the mean follow-up period was 8.5 years. The average age was 59 years with female predominance. L5-S1 fusion showed a significant (P < .05) lower risk for developing degenerative changes at the adjacent segments than any other fusions. The cranial level of the fused segment was mainly affected in 36 (87.8%) patients and 19 (46%) patients required surgery. The average interval from surgery to the development of ADD was 6.1 years. Conclusions There is a risk of 17.82% (41 patients) of being affected by radiographic ADD in an average of 6 years after the first surgery, with a risk of 6.26% (19 patients) of having surgery. The gender, number of levels fused and fusion to the sacrum were the main risk factors.

Unilateral Spondylolysis and the Presence of Facet Joint Tropism

Retrospective review of the CT scans performed in a group of patients examined for a possible spondylolysis. To investigate whether there is an association between unilateral spondylolysis and facet joint tropism. Spondylolysis is a fatigue fracture of the pars interarticularis of great importance in sports injury. The demonstration of a unilateral spondylolysis is important because there is a potential for full healing if the athletic activity is modified, whereas bilateral spondylolysis frequently leads to established nonunion. Coronally orientated facet joints are known to predispose to spondylolysis by increasing the point loading of the pars interarticularis. The importance of this finding has not been investigated in unilateral spondylolysis. A review of patients with low back pain and a possible diagnosis of spondylolysis who were investigated with multislice CT was performed. The coronal orientation of the facet joints at L4/5 and L5/S1 was measured and comparison was done between those with and without a spondylolysis. The coronal angle of 140 facet joints in 35 patients was recorded. Of 35 patients, 23 had a spondylolysis which was unilateral in 12 patients. The facet joint angle was significantly more coronally orientated in the presence of a spondylolysis when compared with an intact pars (means, 53° and 43°, respectively; P < 0.01). In the presence of a unilateral spondylolysis, the facet joint was significantly more coronally orientated on the side of the spondylolysis (means, 52° and 45°, respectively; P < 0.01). CONCLUSION.: This study is the first investigation of facet joint anatomy in unilateral spondylolysis. Asymmetric facet joints do increase the force through one side of the spine, with a unilateral spondylolysis occurring on the side of the more coronally orientated facet joint.

Morphologic Evaluation of Cervical and Lumbar Facet Joints: Intra‐Articular Facet Block Considerations

Needle orientations for lumbar and cervical facet injection were measured in cadavers and compared with facet angles measured on magnetic resonance images (MRIs). To establish facet orientation relative to clinical procedures of a facet joint block in the cervical and lumbar spine. Needle orientation angles were measured from 20 unembalmed human cadaveric specimens (13 cervical and 7 lumbar). Spinal needles were inserted into the midpoints of the facet joint spaces from C3 to C7 and L1 to L5. Needle trajectories were measured with an optical tracking system. For comparison, facet angles from 100 clinical MRIs of lumbar spines were also measured. Facet orientations on MRIs were measured at their intersection with the transverse plane, and angles were quantified using image analysis software. Typical angles for insertion of the needle into the cervical facets were oriented closer to the coronal plane, whereas insertion angles for lumbar needles were oriented closer to the sagittal plane. Relative to the sagittal plane, the mean cervical angle was 72 degrees and the mean lumbar angle was 33 degrees. The insertion points of the cervical facets were a mean of 29 mm from the midsagittal plane compared with a mean of 22 mm for the lumbar facets. MRI-based facet joint angles correlated poorly with actual injection angles, which were overestimated 5 to 23 degrees, depending on the lumbar level. Knowledge of the quantitative anatomy of the facets may help improve clinical diagnosis and treatment. These data also may aid in constructing more realistic computer simulations.

Analysis of the Relationship Between Facet Joint Angle Orientation and Lumbar Spine Canal Diameter With Respect to the Kinematics of the Lumbar Spinal Unit

Retrospective cross-sectional study. This study aimed to elucidate the relationship among facet orientation, kinematics of a spinal unit, and change in lumbar spine canal diameter by using kinetic magnetic resonance imaging. Some studies have suggested an association between increased sagittally oriented facet angles and degenerative lumbar spondylolisthesis. However, no study has specifically addressed the association of facet orientation with the kinematics of a spinal unit and change in canal diameter. Kinetic magnetic resonance imagings were performed with patients in flexion, neutral, and extension positions. Study subjects were classified into 6 groups-AA, BB, CC, AB (BA), BC (CB), and AC (CA)-on the basis of bilateral facet angles (A, narrow; B, normal; and C, wide) and disc and facet joint degeneration. A magnetic resonance imaging analyzer was used for anatomic measurements and for calculating changes in canal diameters and disc bulging as well as the lumbar spine kinematics. Osseous canal diameters were significantly smaller in the group AA than in the group BB, whereas they were significantly larger in the group CC than in the group BB. Canal diameter at the disc level was significantly smaller in the group AA than in the group BB in all 3 positions, whereas it was significantly larger in the group CC than in the group BB. Translational motion was significantly more in the group AA than in the group BB, whereas it was significantly lesser in the group CC than in the group BB. We demonstrated the relationship among facet orientation, osseous canal diameter, kinematics of a spinal unit, and change in lumbar spine canal diameter. Patients with sagittally oriented facets had narrow osseous canals with mobility, whereas those with coronally oriented facets had stable and wider osseous canals. This finding is helpful in understanding the mechanism underlying lumbar spinal canal stenosis and degenerative spondylolisthesis.

LUMBAR FACET JOINT ANGLE AND ITS IMPORTANCE ON JOINT VIOLATION IN LUMBAR MICRODISCECTOMY

We investigated facet joint angle at the level of the nucleus pulposus in herniated disks and documented the importance of this angle in preserving articulation and surgical view in patients undergoing lumbar microdiscectomy. In this prospective study using pre- and postoperative magnetic resonance imaging scans, two blinded radiologists measured and inspected the facet joint angles in 168 patients. Patients were treated with single-level, unilateral, lumbar microdiscectomy. Postoperatively, patients were divided into two groups according to whether or not any portion of the facet joint had been violated during surgery. Using the magnetic resonance imaging scans, the angles of the facet joints were measured and then correlated with whether or not the facet joint was preserved. The follow-up period for this study was 6 months. Postoperative radicular and back pain during the follow-up period and the need for opioids in the early postsurgery period (48 h) were higher in the nonpreserved group, but these differences were not statistically significant (P > 0.05). If the facet joint angle at the disc was lower than 35 degrees in the horizontal plane, articulation cannot be preserved. However, if this angle is greater than 35 degrees, articulation may be preserved and the surgical view is satisfactory for lumbar microdiscectomy. The angle of the lumbar facet joint is important to protect articulation during lumbar microdiscectomy, and violating the facet joint may affect early postoperative pain. A facet angle of less than 35 degrees does not allow for a safe surgical corridor in which to use instruments, nor does it provide a satisfactory view for the surgeon.

Review and retrospective analysis of degenerative lumbosacral stenosis in 156 dogs treated by dorsal laminectomy

The medical records of 156 dogs with degenerative lumbosacral stenosis (DLS) that underwent decompressive surgery were reviewed for signalment, history, clinical signs, imaging and surgical findings. The German Shepherd Dog (GSD) was most commonly affected (40/156, 25.6%). Pelvic limb lameness, caudal lumbar pain and pain evoked by lumbosacral pressure were the most frequent clinical findings. Radiography showed lumbosacral step formation in 78.8% (93/118) of the dogs which was associated with elongation of the sacral lamina in 18.6% (22/118). Compression of the cauda equina was diagnosed by imaging (epidurography, CT, or MRI) in 94.2% (147/156) of the dogs. Loss of the bright nucleus pulposus signal of the L7-S1 disc was found on T2-weighted MR images in 73.5% (25/34) of the dogs. The facet joint angle at L7-S1 was significantly smaller, and the tropism greater in GSD than in the other dog breeds. The smaller facet joint angle and higher incidence of tropism seen in the GSD may predispose this breed to DLS. Epidurography, CT, and MRI allow adequate visualization of cauda equina compression. During surgery, disc protrusion was found in 70.5% (110/156) of the dogs. Overall improvement after surgery was recorded in the medical records in 79.0% (83/105) of the dogs. Of the 38 owners that responded to questionnaires up to five years after surgery, 29 (76%) perceived an improvement.

Contribution of sagittal orientation of facet joints and disc degeneration to degenerative spondylolisthesis in lumbar spine: A finite element research

目的 探讨小关节矢状化与椎间盘退变间的关系及其对退变性腰椎滑移的作用和意义.方法 采用一种新型CAD方法精确构建65°小关节角、45°小关节角、25°小关节角与正常椎间盘、轻度退变椎间盘、重度退变椎间盘相组配的9种腰椎L4-L5活动节段有限元模型.生理压缩载荷下,分别对9种有限元模型的生物力学参数进行测试.结果 与小关节角45°和25°有限元模型相比,小关节角65°有限元模型的矢状方向椎体前移位增加,关节突、峡部等效应力和关节突水平方向接触力明显增加;小关节角65°有限元模型的终板膨出减小,纤维环基质应力增加.与正常有限元模型相比,椎间盘轻度退变有限元模型刚度下降,小关节突及峡部应力轻度增加.9种有限元模型中,轻度退变椎间盘结合小关节角65°有限元模型的抗前剪力能力最差.结论 小关节角矢状化既是退变性腰椎滑移的原发诱因,又是局部应力变化导致关节突再塑形的继发病理改变,矢状型小关节腰椎活动节段矢状方向内在不稳定性受椎间盘退变程度的影响,椎间盘退变对小关节角矢状化无明显促进作用。

Alteration of Facet Joint Orientation and Asymmetry With Time in Lumbar Disc Herniation

In the previous studies, the facet tropism and its relation to the development of lumbar disc herniation (LDH) were investigated. However, these studies have shown inconsistent conclusions. The aim of this study was to investigate the alteration of facet joint angle and (a)symmetry in LDH. Fifty-four patients with LDH were included. In the first and second computed tomography images, all facet angles were measured from the similar axial slice by the same observer who was blinded with regard to the date of computed tomography scan. Total reproducibility of the variability was found to be ±1.85 degrees. Thirty-one patients had a change in the orientation of at least 1 facet joint. The mean rate of the change in the facet orientation varied from 2.69 to 3.63 degree/y. The most common observed change in the orientation was sagittalization. Females, taller patients, cases with median herniation, and patients with longer course of LDH had a higher risk of this change (P=0.011). The facet asymmetry was found to develop in 7 patients and to recover in 7 patients (P=0.002). The facet orientation could change and the facet asymmetry could develop or recover in the same patient with time in LDH. These results could explain contradictory results in the literature.

Spondylolisthesis of the thoracic spine

The thoracic spine is stabilized in the anteroposterior direction by the rib cage and the facet joints. Spondylolisthesis of the thoracic spine is less common than that of the lumbar spine. The authors describe a rare case of thoracic spondylolisthesis in which the patient suffered back pain and myelopathy. The patient was a 44-year-old woman. Plain radiography revealed Grade I T11-12 spondylolisthesis. The pedicle-facet joint angle at T-11 was 118 degrees, greater than that of T-10 or T-12. Postmyelography computerized tomography scanning revealed posterior compression of the dural sac as well as enlargement of and degenerative changes in the facet joint at T-11. Magnetic resonance imaging showed anterior and posterior compression of the spinal cord at the level of the spondylolisthesis. To achieve posterior T10-12 decompression, the surgeons performed a laminectomy and posterolateral fusion in which a pedicle screw fixation system was placed. The patient's back pain disappeared immediately after the operation. The authors conclude that the enlargement of the pedicle-facet joint angle and the degenerative changes of the facet joint caused the thoracolumbar spondylolisthesis.

Effects of anatomic conformation on three-dimensional motion of the caudal lumbar and lumbosacral portions of the vertebral column of dogs

To determine the association between the 3-dimensional (3-D) motion pattern of the caudal lumbar and lumbosacral portions of the canine vertebral column and the morphology of vertebrae, facet joints, and intervertebral disks. Vertebral columns of 9 German Shepherd Dogs and 16 dogs of other breeds with similar body weights and body conditions. Different morphometric parameters of the vertebral column were assessed by computed tomography (CT) and magnetic resonance imaging. Anatomic conformation and the 3-D motion pattern were compared, and correlation coefficients were calculated. Total range of motion for flexion and extension was mainly associated with the facet joint angle, the facet joint angle difference between levels of the vertebral column in the transverse plane on CT images, disk height, and lever arm length. Motion is a complex process that is influenced by the entire 3-D conformation of the lumbar portion of the vertebral column. In vivo dynamic measurements of the 3-D motion pattern of the lumbar and lumbosacral portions of the vertebral column will be necessary to further assess biomechanics that could lead to disk degeneration in dogs.

Facet Angles in Lumbar Disc Herniation: Their Relation to Anthropometric Features

Cross-sectional study. To investigate the alteration of facet joint angle and its relation to anthropometric features in lumbar disc herniation. In the previous studies, the facet tropism and its relation to the level, type, side, and development of lumbar disc herniation were reported. This study was the first to correlate anthropometric feature, facet angle, and asymmetry in patients with lumbar disc herniation. METHODS.: Sixty-one patients with lumbar disc herniation were included in this study. The body height, vertex-to-spina iliaca posterior superior distance, spina iliaca posterior superior-to-floor distance, and net weight were measured and body mass index calculated. The facet angles were measured for each facet joint using computed tomography. The intraobserver error was found to be +/- 1.66 degrees. We defined facet tropism as the bilateral angle difference greater than 2 intraobserver errors. The asymmetry rate was a ratio of degree of angles of the more coronally oriented facet joint to the more sagittally oriented facet joint at the same intervertebral level. The facet asymmetry was observed at the herniation level in 70.5% of the patients. There was a correlation between the degree of the more sagittally oriented facet joint angle and facet asymmetry rate at the herniation level (R = -0.684, P = 0.0001 for L4-L5 lumbar disc herniation; R = -0.509, P = 0.008 for L5-S1 lumbar disc herniation). The body height correlated with the degree of the more sagittally oriented facet joint angle, the degree of more coronally oriented facet joint angle, and asymmetry rate, respectively (R = -0.571, P = 0.0001; R = -0.474, P = 0.002; R = 0.314, P = 0.045, respectively). There was no correlation between the degree of these angles and the vertex-to-spina iliaca posterior superior distance. The spina iliaca posterior superior-to-floor distance was correlated with the degree of the more sagittally oriented facet joint angle (R = -0.457, P = 0.0001) and more coronally oriented facet joint angle (R = -0.435, P = 0.004) but not with the asymmetry rate. The degree of facet angles was not correlated with body weight and body mass index. This study revealed that patients with lumbar disc herniation had the asymmetry and sagittalization of facet joints, and these alterations were more evident in the taller patients.

Factors affecting reduction in low-grade lumbosacral spondylolisthesis

Lumbosacral spondylolisthesis (LSS) is a common disorder that often requires a stabilization and fusion procedure. The aim of this study was to determine the early neuroimaging-detected results of instrumentation-assisted (in situ) fusion with no attempt at surgical reduction of the deformity in patients with low-grade LSS. The neuroimaging results were evaluated to determine the extent of reduction and its correlation with different parameters. Thirty patients with low-grade LSS underwent short-segment transpedicular screw fixation; surgical reduction was not attempted. All patients underwent plain anteroposterior and lateral lumbar radiography, flexion-extension lateral lumbar radiography, and computerized tomography and magnetic resonance imaging of the lumbar spine before and after surgery. Postoperative measurements were determined on the late (9 to 12-month) postoperative radiographs. The findings were recorded and grouped. Correlation analysis was performed among the radiological findings, body mass index, age, and sex. Paired-sample t-tests were performed for each paired group to determine statistically significant differences. There was no significant difference in extent of deformity reduction in patients with different lordotic angles, sagittal-plane rotation angles, and intervertebral disc heights. The extent of reduction was statistically significant at the L4-5 level (p < 0.05), in patients younger than 50 years of age (p < 0.05), and in those in whom the facet joint angle was increased (p < 0.05). The authors found that in cases of low-grade LSS, short-segment posterior stabilization (in situ fusion and fixation) does not require surgical reduction and in fact is associated with a measurable reduction when used as the sole treatment.

Facet joint geometry and intervertebral disk degeneration in the L5-S1 region of the vertebral column in German Shepherd Dogs

To evaluate the possible association between facet joint geometry and intervertebral disk degeneration in German Shepherd Dogs. 25 German Shepherd Dogs and 11 control dogs of similar body weight and condition. Facet joint angles in the caudal portion of the lumbar region of the vertebral column (L5-S1) were measured by use of computed tomography, and the intervertebral discs were evaluated microscopically. The relationship between facet joint geometry and disk degeneration was evaluated by use of statistical methods. German Shepherd Dogs had significantly more facet joint tropism than control dogs, but an association with disk degeneration was not found. However, German Shepherd Dogs had a different facet joint conformation, with more sagittally oriented facet joints at L5-L6 and L6-L7 and a larger angle difference between the lumbar and lumbosacral facet joints, compared with control dogs. A large difference between facet joint angles at L6-L7 and L7-S1 in German Shepherd Dogs may be associated with the frequent occurrence of lumbosacral disk degeneration in this breed.

Influence of Facet Joint Angles and Asymmetric Disk Collapse on Degenerative Olisthesis of the Cervical Spine

This study examined the facet angles of the joint facets of the intervertebral joints, the anterior and posterior heights of the intervertebral disks, and cervical lordosis as possible parameters of olisthesis. Lateral radiographs of the cervical spine in 123 patients were examined, and parameters were correlated to anterolisthesis and retrolisthesis in each segment. Results indicate anterolisthesis is caused by a decrease of the facet angles of the caudal joint facets. This process is favored by loss of anterior height of the intervertebral disks and a flattened position of the cervical spine. Loss of posterior height of the intervertebral disks promotes retrolisthesis.

Degenerative spondylolisthesis. Developmental or acquired?

Degenerative spondylolisthesis is four times more common in women than in men. Although this gender difference has long been recognised there has been no explanation for it. We have examined the radiographs and CT scans of 118 patients over the age of 55 years and of a control group under the age of 46 years. Our findings confirmed the presence of more sagittally-orientated facet joints in patients with degenerative spondylolisthesis but did not show that the gender difference can be explained by the morphology of the facet joint. Furthermore, we conclude that the increased angle of the facet joint is the result of arthritic remodelling and not the primary cause of degenerative spondylolisthesis. It is more likely to be due to loss of soft-tissue resilience with subsequent failure of the facet joints which are acting as the last restraints to subluxation.