Instability Of Lumbar Spine Research Articles

Curative effect of short segment of unilateral laminectomy decompression of intervertebral bone graft fusion with pedicle screw fixation in treatment of lumbar spine instability

Objective To investigate the curative effect of short segment of unilateral laminectomy decompression of intervertebral bone graft fusion with pedicle screw fixation in treatment of lumbar spine instability. Methods 100 cases with lumbar instability were randomly divided into the study group and control group with 50 cases in each group,the study group was treated with short segment of unilateral laminectomy decompression of intervertebral bone graft fusion with pedicle screw fixation for treatment, while the control group was treated with conventional methods of treatment. The intraoperative, postoperative situation and clinical efficacy of the two groups were observed and compared. Results The operation time, intraoperative bleeding, drainage, hospital stay and cost of hospitalization of the study group were(121.31±13.73)min, (151.24±24.65)mL, (35.34±6.79)mL,(12.03±3.22)d and(22 012.23±3 018.67)yuan respectively, which were significantly lower than those of the control group[(161.32±11.60)min,(201.32±25.46)mL,(102.35±11.87)mL,(19.42±4.31)d and(26 278.65±3 216.53)yuan](t=9.829,10.829,7.984,10.983,9.593,all P<0.05). The excellent and good rate of the study group was 92%, which was significantly higher than 70%of the control group(χ2=13.927,all P<0.05). Conclusion Short segment of unilateral laminectomy decompression of intervertebral bone graft fusion has a high curative effect in the treatment of lumbar instability, with short operation time and hospitalization time, less blood loss and postoperative drainage volume, low medical cost, which is a good operation scheme. Key words: Spinal diseases; Laminectomy; Spinal fusion; Internal fixators

Lumbar subcutaneous edema and degenerative spinal disease in patients with low back pain: a retrospective MRI study.

This study was designed to determine the association between LSE, spondylolisthesis, facet arthropathy, lumbar canal stenosis, BMI, radiculopathy and bone marrow edema at conventional lumbar spine MR imaging. This is a retrospective radiological study; 441 consecutive patients with low back pain (224 men and 217 women; mean age 57.3 years; mean BMI 26) underwent conventional lumbar MRI using a 1.5-T magnet (Avanto, Siemens). Lumbar MR images were reviewed by consensus for the presence of LSE, spondylolisthesis, facet arthropathy, lumbar canal stenosis, radiculopathy and bone marrow edema. Descriptive statistics and association studies were conducted using STATA software 11.0. Association studies have been performed using linear univariate regression analysis and multivariate regression analysis, considering LSE as response variable. The overall prevalence of LSE was 40%; spondylolisthesis (p = 0.01), facet arthropathy (p < 0.001), BMI (p = 0.008) and lumbar canal stenosis (p < 0.001) were included in the multivariate regression model, whereas bone marrow edema, radiculopathy and age were not. LSE is highly associated with spondylolisthesis, facet arthropathy and BMI, suggesting underestimation of its clinical impact as an integral component in chronic lumbar back pain. Longitudinal simultaneous X-ray/MRI studies should be conducted to test the relationship of LSE with lumbar spinal instability and low back pain.

요추부 불안정성을 가진 요통환자의 복부 드로우-인 기법과 복부 확장 기법을 이용한 체간안정화운동의 효과 비교

This study aimed to investigate the effect of the abdominal drawing-in maneuver (ADIM) and abdominal expansion maneuver (AEM) on trunk stabilization, as well as trunk muscle activities and differences in quadruple visual analogue scale, Korean Oswestry Disability Index, and Fear Avoidance Beliefs Questionnaire scores, in patients with chronic low back pain and lumbar spine instability. To increase intra-abdominal pressure during the trunk stabilization exercise, the technique of pushing the abdomen out using diaphragmatic abdominal breathing suggested by Pavel Koral was used, which we termed the AEM. Fifty patients who tested positive on more than three of the five lumbar spine instability tests were separated from 138 patients with chronic low back pain of these patients, 16 were placed in the control group (trunk stabilization exercise), 17 were placed in the ADIM group (trunk stabilization exercise with ADIM), and 17 were placed in the AEM group (trunk stabilization exercise with AEM). Each group participated in the study for 30 minutes three times weekly for 4 weeks. Surface electromyography was used to measure the trunk muscle activities during the kneeling forward and supine bridging positions, and one-way repeated analysis of variance was used to determine the statistical significance of the trunk muscle activities in the rectus abdominis, internal oblique (IO), erector spinae, and multifidus (MF) muscles. The ADIM and AEM groups showed relatively larger improvements in psychosocial and functional disability level than control group. There were significant changes among the three groups, those from the measured values of the AEM group was significantly higher than the other two groups in changes in IO and MF trunk muscle activities (p

Amyloid deposits derived from transthyretin in the ligamentum flavum as related to lumbar spinal canal stenosis

Amyloidosis is a protein conformational disorder with the distinctive feature of extracellular accumulation of amyloid fibrils that come from different proteins. In the ligamentum flavum of the lumbar spine, amyloid deposits were frequently found in elderly patients with lumbar spinal canal stenosis and were at least partially formed by wild-type transthyretin. However, how amyloid deposits in the ligamentum flavum affect lumbar spinal canal stenosis has remained unclear. In this study, we analyzed clinical, pathologic, and radiologic findings of patients with lumbar spinal canal stenosis who had amyloid deposits in the ligamentum flavum. We studied 95 ligamentum flavum specimens obtained from 56 patients with lumbar spinal canal stenosis and 21 ligamentum flavum specimens obtained from 19 patients with lumbar disk herniation. We evaluated histopathologic findings and clinicoradiologic manifestations, such as thickness of the ligamentum flavum and lumbar spinal segmental instability. We found that all 95 ligamentum flavum specimens resected from patients with lumbar spinal canal stenosis had amyloid deposits, which we classified into two types, transthyretin-positive and transthyretin-negative, and that transthyretin amyloid formation in the ligamentum flavum of patients with lumbar spinal canal stenosis was an age-associated phenomenon. The amount of amyloid in the ligamentum flavum was related to clinical manifestations of lumbar spinal canal stenosis, such as thickness of the ligamentum flavum and lumbar spinal segmental instability, in the patients with lumbar spinal canal stenosis with transthyretin-positive amyloid deposits. To our knowledge, this report is the first to show clinicopathologic correlations in transthyretin amyloid deposits of the ligamentum flavum. In conclusion, transthyretin amyloid deposits in the ligamentum flavum may be related to the pathogenesis of lumbar spinal canal stenosis in elderly patients.

Lumbar Spinal Instability: An Updated Rewiew

Supine Magnetic Resonance Imaging (MRI) is routinely used in the assessment of low- back pain and radiculopathy. However, imaging findings often correlate poorly with clinical findings. This is partly related to the positional dependence of spinal stenosis, which reflects dynamic changes in soft-tissue structures. Upright MRI in the flexed, extended, rotated, standing, and bending positions allows patients to reproduce the positions that bring about their symptoms. Assessment of the degree of spinal stability in the degenerate and postoperative lumbar spine is also possible and it offers many diagnostic opportunities. The aim of this rewiew is to present the findings concerning the spine instability using conventional and upright MRI.

Development of a novel radiographic measure of lumbar instability and validation using the facet fluid sign.

Lumbar spinal instability is frequently referenced in clinical practice and the scientific literature despite the lack of a standard definition or validated radiographic test. The Quantitative Stability Index (QSI) is being developed as a novel objective test for sagittal plane lumbar instability. The QSI is calculated using lumbar flexion-extension radiographs. The goal of the current study was to use the facet fluid sign on MRI as the "gold standard" and determine if the QSI is significantly different in the presence of the fluid sign. Sixty-two paired preoperative MRI and flexion-extension exams were obtained from a large FDA IDE study. The MRI exams were assessed for the presence of a facet fluid sign, and the QSI was calculated from sagittal plane intervertebral rotation and translation measurements. The QSI is based on the translation per degree of rotation (TPDR) and is calculated as a Z-score. A QSI > 2 indicates that the TPDR is > 2 std dev above the mean for an asymptomatic and radiographically normal population. The reproducibility of the QSI was also tested. The mean difference between trained observers in the measured QSI was between -0.28 and 0.36. The average QSI was significantly (P = 0.047, one-way analysis of variance) higher at levels with a definite fluid sign (2.3±3.2 versus 0.60±2.4). Although imperfect, the facet fluid sign observed may be the best currently available test for lumbar spine instability. Using the facet fluid sign as the "gold standard" the current study documents that the QSI can be expected to be significantly higher in the presence of the facet fluid sign. This supports that QSI might be used to test for sagittal plane lumbar instability. A validated, objective and practical test for spinal instability would facilitate research to understand the importance of instability in diagnosis and treatment of low-back related disorders.

Optimization of segmental lumbar spine instability treatment using minimally invasive spinal fusion technique

Open transforaminal lumbar interbody fusion (TLIF) using transpedicular rods and interbody cage, which is used to treat segmental instability, is associated with a significant paravertebral muscle and ligament injury. A new rigid fusion method was introduced to improve the outcome of patients' treatment. To conduct a comparative analysis of the effectiveness of minimally invasive fusion technique and TLIF to improve the treatment results in patients with symptomatic lumbar spine degeneration concomitant with moderate segmental instability of the lumbar spine. The study involved 90 patients, which were divided into 2 groups. Transforaminal interbody fusion with Pezo-T PEEK cage was performed after spinal canal reconstruction in both groups. In the first group (n=45), interbody fusion was augmented by 4-point transpedicular rod fixation (Konmet, Russia); in the second group (n=45), by Coflex-F rigid interspinous spacer. Patients were followed up and the results were assessed within 24 months after surgery. The intergroup comparison of pain level using the visual analogue scale, the need for analgesics, and quality of life according to Oswestry Disability Index score during the early postoperative period demonstrated significantly better outcomes in the second group of patients due to lesser operative trauma of the paravertebral soft tissue. Interbody fusion was observed within 20-36 months in 95% of group I patients and 94% of group II patients (p>0.05). Postoperative complications were observed in 17.8% of patients in group I and in 2.2% of cases in group II (p<0.001). Stabilization by rigid interspinous spacer and transforaminal interbody cage provides better clinical outcomes and fewer postoperative complications as compared to the conventional TLIF technique with similar X-ray rate of bone block formation in patients with moderate segmental instability of the lumbar spine, thus optimizing the treatment of such patients.

Comparison of three-dimensional transient motion characteristics under physiological load between isthmic and degenerative lumbar spondylolisthesis

Objective To observe and compare in vivo segmental lumbar motion between symptomatic L4 isthmic spondy- lolisthesis （IS） patients and L4 degenerative spondylolisthesis （DS） patients during functional weight-bearing activities. Methods Fifteen symptomatic L4 IS patients and fifteen symptomatic L4 DS patients were recruited. Fifteen asymptomatic volunteers were en- rolled as the control group. The L4.5 vertebral segment motion of each subject was reconstructed using three-dimensional computed tomography and a solid modeling software. In vivo, lumbar vertebral motion during functional postures （flexion-extension, left-right twisting and left-right bending） was observed using a dual fluoroscopic imaging technique. The spinal function unit was divided into anterior and posterior segments by the isthmic cleft. Local coordinate systems were established at the vertebral body, to obtain the 6 degree-of-freedom （DOF） intervertebral range of motion （ROM） at L4.5 and the ROM between the anterior and the posterior segments of L4 IS. Results The motion of IS at L4.5 was found to be increased. The migrations along both sagittal and vertical axis were significantly larger than control group （P 〈 0.05）. During left-right twisting, the migration along sagittal axis was significantly larger than control group （P 〈 0.05）; the rotation along vertical axis was significantly larger than DS and control group （P 〈 0.05）. During left-right bending, the migration along frontal axis was significantly larger than DS and control group （P 〈 0.05）. The inter- vertebral ROM at L4.5 showed no significant difference between DS and control group. The migration between anterior and posteri- or segments of IS L4 was larger in standing than supine （P 〈 0.05）. The relative migration along sagittal axis between anterior and posterior segments of IS L4 was significantly larger in flexion than standing （P 〈 0.05）. Conclusion A spondylolytic defect does lead to detectable instability or hypermobility in the lumbar spine compared with degenerative spondylolisthesis and normal group. From supine to standing posture, migration at isthmic cleft along sagittal and coronal axis are identified in IS spondylolithesis. Key words: Lumbar vertebrae; Spondylolysis; Biomechanics; Fluoroscopy

A conceptual model of compensation/decompensation in lumbar segmental instability

Lumbar spinal instability (LSI) is a common spinal disorder and can be associated with substantial disability. The concept of defining clinically relevant classifications of disease or ‘target condition’ is used in diagnostic research. Applying this concept to LSI we hypothesize that a set of clinical and radiological criteria can be developed to identify patients with this target condition who are at high risk of ‘irreversible’ decompensated LSI for whom surgery becomes the treatment of choice. In LSI, structural deterioration of the lumbar disc initiates a degenerative cascade of segmental instability. Over time, radiographic signs become visible: traction spurs, facet joint degeneration, misalignment, stenosis, olisthesis and de novo scoliosis. Ligaments, joint capsules, local and distant musculature are the functional elements of the lumbar motion segment. Influenced by non-functional factors, these functional elements allow a compensation of degeneration of the motion segment. Compensation may happen on each step of the degenerative cascade but cannot reverse it. However, compensation of LSI may lead to an alleviation or resolution of clinical symptoms. In return, the target condition of decompensation of LSI may cause the new occurrence of symptoms and pain. Functional compensation and decompensation are subject to numerous factors that can change which makes estimation of an individual’s long-term prognosis difficult. Compensation and decompensation may influence radiographic signs of degeneration, e.g. the degree of misalignment and segmental angulation caused by LSI is influenced by the tonus of the local musculature. This conceptual model of compensation/decompensation may help solve the debate on functional and psychosocial factors that influence low back pain and to establish a new definition of non-specific low back pain. Individual differences of identical structural disorders could be explained by compensated or decompensated LSI leading to changes in clinical symptoms and pain. Future spine surgery will have to carefully define and measure functional aspects of LSI, e.g. to identify a point of no return where multidisciplinary interventions do not allow a re-compensation and surgery becomes the treatment of choice.

FRI0108 Correlation between Cervical and Lumbar Spinal Instability in Patients with Rheumatoid Arthritis

BackgroundFew studies have compared rheumatoid arthritis (RA)-related disorders of the cervical and lumbar spine.ObjectivesThe objectives of this study were to examine the correlation between cervical and lumbar spinal instability in...

Minimally invasive versus open posterior lumbar interbody fusion: a systematic review.

Although conventional open posterior lumbar interbody fusion (open PLIF) is efficacious in management of lumbar spinal instability, concerns exist regarding lengthy hospital stays, blood loss, and postoperative complications. Minimally invasive posterior lumbar interbody fusion (MIS PLIF) may be able to address these concerns, but the research on this topic has not been systematically reviewed. We performed a systematic review to determine whether MIS PLIF or open PLIF results in (1) better perioperative parameters, including blood loss, operative times, and length of hospital stay; (2) improved patient-reported outcome scores; and (3) improved disc distraction and (4) frequency of reoperation and complications when compared with open PLIF procedures. A literature search of the MEDLINE database identified seven studies that met our inclusion criteria. A total of seven articles were included; quality was assessed using the Methodological Index for Non-Randomised Studies (MINORS) scale. Descriptive statistics were used to describe the included articles. In most studies, MIS PLIF was associated with decreased blood loss and shorter hospital stay but longer operative times. MIS PLIF resulted in better patient-related outcomes when compared with open PLIF in two studies in the short term, but most of the studies in this review found no short-term differences, and there was no difference at long-term followup in any studies. There was no significant difference in disc distraction. Both techniques appeared to have similar complication rates and reoperation rates. Based on the available evidence, which we restricted to prospective and retrospective studies with control groups, but did not include any well-designed randomized trials, MIS PLIF might lead to better perioperative parameters, but there was little evidence for improved patient-reported outcomes in the MIS groups. Randomized controlled trials are needed to compare these two surgical techniques.

Dynamic Stabilization for Degenerative Spondylolisthesis and Lumbar Spinal Instability

Lumbar interbody fusion is a widely accepted surgical procedure for patients with lumbar degenerative spondylolisthesis and lumbar spinal instability in the active age group. However, in elderly patients, it is often questionable whether it is truly necessary to construct rigid fixation for a short period of time. In recent years, we have been occasionally performing posterior dynamic stabilization in elderly patients with such lumbar disorders. Posterior dynamic stabilization was performed in 12 patients (6 women, 70.9 ± 5.6 years old at the time of operation) with lumbar degenerative spondylolisthesis in whom % slip was less than 20% or instability associated with lumbar disc herniation between March 2011 and March 2013. Movement occurs through the connector linked to the pedicle screw. In practice, 9 pairs of D connector system where the rod moves in the perpendicular direction alone and 8 pairs of Dynamic connector system where the connector linked to the pedicle screw rotates in the sagittal direction were installed. The observation period was 77–479 days, and the mean recovery rate of lumbar Japanese Orthopedic Association (JOA) score was 65.6 ± 20.8%. There was progression of slippage due to slight loosening in a case with lumbar degenerative spondylolisthesis, but this did not lead to exacerbation of the symptoms. Although follow-up was short, there were no symptomatic adjacent vertebral and disc disorders during this period. Posterior dynamic stabilization may diminish the development of adjacent vertebral or disc disorders due to lumbar interbody fusion, especially in elderly patients, and it may be a useful procedure that facilitates decompression and ensures a certain degree of spinal stabilization.

What is the Role of InterspinousFusion Devices (IFD) in the Lumbar Spine Instability?

What is the Role of InterspinousFusion Devices (IFD) in the Lumbar Spine Instability? Approximately 99% of people have experienced an episode of disabling low back pain or “back pain” at least once in a lifetime. About 14% of new outpatient visits are related to episodes of low back pain or sciatica and, of these, at least 4% undergo surgery. For this reasons the question is spontaneous: Why is back pain a phenomenon of such great deal? The explanation lies in the quality of life of every individual: normal daily activities (work, sports, habits, posture, etc.) that lead to an acceleration of the physiological age-related changes of the spine.

Double insurance transfacetal screws for lumbar spinal stabilization.

Aim:The authors report experience with 14 cases where two screws or “double insurance” screws were used for transfacetal fixation of each joint for stabilization of the lumbar spinal segment. The anatomical subtleties of the technique of insertion of screws are elaborated.Materials and Methods:During the period March 2011 to June 2014, 14 patients having lumbar spinal segmental instability related to lumbar canal stenosis were treated by insertion of two screws into each articular assembly by transfacetal technique. After a wide surgical exposure, the articular cartilage was denuded and bone chips were impacted into the joint cavity. For screw insertion in an appropriate angulation, the spinous process was sectioned at its base. The screws (2.8 mm in diameter and 18 mm in length) were inserted into the substance of the medial or inferior articular facet of the rostral vertebra via the lateral limit of the lamina approximately 6–8 mm away from the edge of the articular cavity. The screws were inserted 3 mm below the superior edge and 5 mm above the inferior edge of the medial (inferior) facets and directed laterally and traversed through the articular cavity into the lateral (superior) articular facet of the caudal vertebra toward and into the region of junction of base of transverse process and of the pedicle. During the period of follow-up all treated spinal levels showed firm bone fusion. There was no complication related to insertion of the screws. There was no incidence of screw misplacement, displacementor implant rejection.Conclusions:Screw insertion into the firm and largely cortical bones of facets of lumbar spine can provide robust fixation and firm stabilization of the spinal segment. The large size of the facets provides an opportunity to insert two screws at each spinal segment. The firm and cortical bone material and absence on any neural or vascular structure in the course of the screw traverse provides strength and safety to the process.

Short-term clinical outcomes and safety evaluation of extreme lateral interbody fusion for the treatment of lumbar degenerative diseases

Objective To investigate the short-term clinical effect and safety of extreme lateral interbody fusion (XLIF) for the treatment of lumbar degenerative diseases.Methods Sixteen patients (6 males and 10 females) with an average age of 62 (36 to 82) years were included,consisting of lumbar spinal instability in 9 cases and lumbar spinal stenosis in 7 cases.All patients had undergone XLIF procedure with posterior percutaneous pedicle screw fixation from September 2009 to January 2013.The fusion level was one in 11 cases,two in 4 cases,and three in 1 case.The visual analogue scale (VAS),Oswestry disability index (ODI) and Macnab criteria were used to assess the clinical effect postoperatively while X-ray and CT were used to evaluate the fusion.The operation time,blood loss and postoperative complications were also analyzed.Results Mean operation time and blood loss for discectomy and interbody placement was 75 min and 83 ml per level.We found transient thigh numbness and weakness of hip flexor in 2 cases,which resumed automatically within 2 weeks.All patients were followed up for an average of 15 (6 to 48) months.The VAS score was 4.6 and 3.1 lower in back pain and leg pain while ODI score was 50％ lower in six months postoperatively.According to the Macnab criteria,the excellent and good rate was 87.5％.There were 4 complete fusion cases and 11 partial fusion cases in 6 months.7 cases out of 8 achieved complete fusion while 1 case achieved partial fusion after 12 months.The fusion rate was 87.5％.Conclusion XLIF can provide a satisfactory short-term outcome for the treatment of lumbar degenerative diseases. Key words: Spinal fusion; Lumbar vertebrae; Intervertebral disc degeneration

Comparison of Spinous Process-Splitting Laminectomy versus Conventional Laminectomy for Lumbar Spinal Stenosis.

Study DesignSeventy-five patients who had been treated for lumbar spinal stenosis (LSS) were reviewed retrospectively.PurposeInvasion into the paravertebral muscle can cause major problems after laminectomy for LSS. To address these problems, we performed spinous process-splitting laminectomy. We present a comparative study of decompression of LSS using 2 approaches.Overview of LiteratureThere are no other study has investigated the lumbar spinal instability after spinous process-splitting laminectomy.MethodsThis study included 75 patients who underwent laminectomy for the treatment of LSS and who were observed through follow-ups for more than 2 years. Fifty-five patients underwent spinous process-splitting laminectomy (splitting group) and 20 patients underwent conventional laminectomy (conventional group). We evaluated the clinical and radiographic results of each surgical procedure.ResultsJapanese Orthopaedic Association score improved significantly in both groups two years postoperatively. The following values were all significantly lower, as shown with p-values, in the splitting group compared to the conventional group: average operating time (p=0.002), postoperative C-reactive protein level (p=0.006), the mean postoperative number of days until returning to normal body temperature (p=0.047), and the mean change in angulation 2 years postoperatively (p=0.007). The adjacent segment degeneration occurred in 6 patients (10.9%) in the splitting group and 11 patients (55.0%) in the conventional group.ConclusionsIn this study, the spinous process-splitting laminectomy was shown to be less invasive and more stable for patients with LSS, compared to the conventional laminectomy.

CT-Guided Transfacet Pedicle Screw Fixation in Facet Joint Syndrome: A Novel Approach.

Axial microinstability secondary to disc degeneration and consequent chronic facet joint syndrome (CFJS) is a well-known pathological entity, usually responsible for low back pain (LBP). Although posterior lumbar fixation (PIF) has been widely used for lumbar spine instability and LBP, complications related to wrong screw introduction, perineural scars and extensive muscle dissection leading to muscle dysfunction have been described. Radiofrequency ablation (RFA) of facet joints zygapophyseal nerves conventionally used for pain treatment fails in approximately 21% of patients. We investigated a "covert-surgery" minimal invasive technique to treat local spinal instability and LBP, using a novel fully CT-guided approach in patients with axial instability complicated by CFJS resistant to radioablation, by introducing direct fully or partially threaded transfacet screws (transfacet fixation - TFF), to acquire solid arthrodesis, reducing instability and LBP. The CT-guided procedure was well tolerated by all patients in simple analogue sedation, and mean operative time was approximately 45 minutes. All eight patients treated underwent clinical and CT study follow-up at two months, revealing LBP disappearance in six patients, and a significant reduction of lumbar pain in two. In conclusion, CT-guided TFF is a fast and safe technique when facet posterior fixation is needed.

Lumbar artery pseudoaneurysm as a late complication of osteomyelitis with vertebral body destruction

We report the case of a 79-year-old patient whose acute back pain revealed a 9-cm nonruptured lumbar artery pseudoaneurysm occurring 5 years after a vertebral body osteomyelitis that induced a significant vertebral destruction. She underwent an urgent percutaneous selective arterial embolization. Lumbar artery false aneurysm should, thus, be suspected as a possible etiology of any new painful symptoms in patients suffering from a chronic vertebral destructive disease.

Trunk muscle activation patterns in subjects with low back pain

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Pelvic Incidence and Lumbar Spine Instability Correlations in Patients with Chronic Low Back Pain

Many factors such as lumbar instability and spinopelvic alignment are associated with low back pain. Our purpose was to analyze the pelvic incidence - one of spinopelvic alignment parameters- and spine instability correlations in patients with chronic low back pain. Fifty-two patients suffering from chronic low back pain entered this case control study. Lateral spine radiography was taken from patients. pelvic incidence and L3, L4 and L5's vertebral body width were measured for all patients, and lumbar instability was evaluated in 3 different levels: L5-S1, L4-L5 and L3-L4. Thirty-two patients having lumbar instability formed group A and 20 patients without lumbar spine instability allocated to group B. Average age, mean weight, height, body mass index and mean vertebral width of both groups did not differ meaningfully. Pelvic incidence's mean amounts set to 53.9 in group B and 57.7 in group A without any significant difference; but pelvic incidence was significantly lower in patients with lumbar instability of L5-S1 origin (P=0.01). Overall, pelvic incidence did not differ between two groups. However, separate evaluation of each level revealed lumbar instability of L5-S1 segment to be associated with lower pelvic incidence.