Loss Of Disc Height Research Articles

ISSLS Prize Winner: Vertebral Endplate (Modic) Change is an Independent Risk Factor for Episodes of Severe and Disabling Low Back Pain.

Longitudinal cohort study of twins representative of the general population. To assess the relationship between Modic change (MC) and severe, disabling low back pain (LBP), features of intervertebral disc degeneration (DD) and incident MC during 10-year follow-up. MC describes vertebral endplate and bone marrow lesions visible on magnetic resonance imaging (MRI). MC has been associated with DD. It remains unclear whether MC causes LBP independently or through association with DD. Moreover, association of MC with severe, disabling LBP is uncertain. Volunteers were recruited from the TwinsUK register to MRI and interview between 1996 and 2000 with a subset attending for follow-up a decade later. MC, DD (evaluated by loss of disc height and signal intensity, presence of disc bulge and anterior osteophytes) and Schmorl's nodes (SN) were determined on T2-weighted lumbar MR scans. Complete data were available for 823 subjects at baseline and 429 at follow-up. Mean age at baseline was 54.0 years (range 32-70) with 96% females. The prevalence of MC was 32.2% at baseline and 48.7% at follow-up. Subjects with MC were older (P < 0.001) and more overweight (BMI: P = 0.026, weight: P < 0.001). At both baseline and follow-up, more subjects reporting severe LBP demonstrated MC (subjects with MC vs. without MC: 35.0% vs. 16.4% respectively, P < 0.001 at baseline; and 35.1% vs. 20.0% respectively, P < 0.001 at follow-up). In multivariable analyses, MC remained significantly associated with episodes of severe, disabling LBP (OR 1.58; 95% CI 1.04-2.41) after adjustment for age, BMI, DD, and SN at baseline. Loss of disc height and disc signal intensity were independently associated with prevalent MC at baseline, and disc height and disc bulge with incident MC during follow-up. MC is an independent risk factor for episodes of severe and disabling LBP in middle-aged women. These observations support further work aimed at identifying the precise histology underlying MC. 2.

Poroelastic behaviour of the degenerating human intervertebral disc: a ten-day study in a loaded disc culture system.

The intervertebral disc (IVD) allows flexibility to the vertebral column, and transfers the predominant axial loads during daily activities. Its axial biomechanical behaviour is poroelastic, due to the water-binding and releasing capacity of the nucleus pulposus. Degeneration of the intervertebral disc presumably affects both the instantaneous elastic response to the load on the IVD and the subsequent interstitial flow of fluid. This study aims to quantify the poroelastic behaviour of the IVD and its change with degeneration, as defined by the magnetic resonance imaging-based Pfirrmann Score (PS). For a period of ten days, 36 human lumbar IVDs were loaded with a simulated physiological axial loading regime, while deformation was monitored. The IVDs responded to the loads with instantaneous elastic and slow poroelastic axial deformation. Several mechanical parameters changed throughout the first five days of the experiment, until the IVDs settled into a dynamic equilibrium. In this equilibrium, degeneration was significantly related to a decrease in disc height loss during the daytime high load phase (ρ=-0.49), and to a decrease in the rate of this deformation during the final half hour of each day (ρ=-0.53). These properties were related to the nucleus glycosaminoglycan/hydroxyproline (GAG/HYP) ratio, rather than GAG content alone, indicating that remodelling of the extracellular matrix reduces poroelastic properties of the IVD. This implies that the degenerated discs have a reduced capacity to bind water and/or a reduced resistance against fluid flow. The resulting loss in hydrostatic pressure may further change cell behaviour in the nucleus pulposus.

Defining the inherent stability of degenerative spondylolisthesis: a systematic review.

OBJECT A range of surgical options exists for the treatment of degenerative lumbar spondylolisthesis (DLS). The chosen technique inherently depends on the stability of the DLS. Despite a substantial body of literature dedicated to the outcome analysis of numerous DLS procedures, no consensus has been reached on defining or classifying the disorder with respect to stability or the role that instability should play in a treatment algorithm. The purpose of this study was to define grades of stability and to develop a guide for deciding on the optimal approach in surgically managing patients with DLS. METHODS The authors conducted a qualitative systematic review of clinical or biomechanical analyses evaluating the stability of and surgical outcomes for DLS for the period from 1990 to 2013. Research focused on nondegenerative forms of spondylolisthesis or spinal stenosis without associated DLS was excluded. The primary extracted results were clinical and radiographic parameters indicative of DLS instability. RESULTS The following preoperative parameters are predictors of stability in DLS: restabilization signs (disc height loss, osteophyte formation, vertebral endplate sclerosis, and ligament ossification), no disc angle change or less than 3 mm of translation on dynamic radiographs, and the absence of low-back pain. The validity and magnitude of each parameter's contribution can only be determined through appropriately powered prospective evaluation in the future. Identifying these parameters has allowed for the creation of a preliminary DLS instability classification (DSIC) scheme based on the preoperative assessment of DLS stability. CONCLUSIONS Spinal stability is an important factor to consider in the evaluation and treatment of patients with DLS. Qualitative assessment of the best available evidence revealed clinical and radiographic parameters for the creation of the DSIC, a decision aid to help surgeons develop a method of preoperative evaluation to better stratify DLS treatment options.

The high-throughput phenotyping of the viscoelastic behavior of whole mouse intervertebral discs using a novel method of dynamic mechanical testing

Intervertebral disc (IVD) degeneration is highly correlated with lower back pain, and thus understanding the mechanisms of IVD degeneration is critical for the treatment of this disease. Utilizing mouse models to probe the mechanisms of degeneration is especially attractive due to the ease of manipulating mouse models and the availability of transgenics. Yet characterizing the mechanical behavior of mice IVDs remain challenging due to their minute size (approximately 540μm in height and 1080μm2 in cross sectional area). We have thus developed a simple method to dynamically characterize the mechanical properties of intact mouse IVDs. The IVDs were dissected with the endplates intact, and dynamically compressed in the axial direction at 1% and 5% peak strains at 1Hz. Utilizing this novel approach, we examined the effects of in vitro ribosylation and trypsin digestion for 24 or 72h on the viscoelastic behavior of the whole murine IVD. Trypsin treatment resulted in a decrease of proteoglycans and loss of disc height, while ribosylation had no effect on structure or proteoglycan composition. The 72h ribosylation group exhibited a stiffening of the disc, and both treatments significantly reduced viscous behavior of the IVDs, with the effects being more pronounced at 5% strain. Here we demonstrate a novel high-throughput method to mechanically characterize murine IVDs and detect strain-dependent differences in the elastic and the viscous behavior of the treated IVDs due to ribose and trypsin treatments.

Two Years Experiences with a New Titanium-Coated Radiolucent TLIF Carbon-PEEK Cage

Introduction PLIF and TLIF are standard treatment methods for many degenerative spinal diseases that result in spinal stenosis or segmental instability. The cage-bone surface has a role in facilitating osteointegration. A significant quality and quantity increase of bone on growth was achieved with the titanium (Ti) coating by vacuum plasma spraying (VPS). This study aimed to evaluate the short-term radiological and clinical results of the carbon fiber-reinforced PEEK (carbon/PEEK) interbody fusion cage, coated with VPS-Ti. Patients and Methods A total of 42 Patients (47 levels), mean age 59.6, receiving cage treatment were scanned retrospectively. Pre-, postoperative, and final follow-up graphs, and clinical information were obtained. Primary diagnoses were degenerative spinal diseases. Pedicle screws were used in all cases. TLIF and PLIF technique was applied in 28 and 72% of patients. Around 51% were L4–5, 23% L5–S1, 17% L3–4, and 9% L2–3. Local graft was used in 39 patients, DBM in 2 patients, and BCT in 1 patient. The following were measured/evaluated: (1) Segmental lumbar lordosis; (2) Radiological fusion according to the IBF grading system of Bridwell; (3) Early degeneration in neighboring disks; (4) Foraminal and segmental height and loss of disc height using the Mochida index; (5) Pedicle screws' loosening. Results A mean change of 1.38 degrees was observed in the angle of neighboring segment lordosis, and an increase of 0.59 degrees was obtained in the global lumbar lordosis. Grade 1 fusion (according to the four-point Bridwell classification) was achieved in 94% of all patients 18 months after the operation (6% grade 2, 0% grades 3 and 4). Two (4.3%) patients underwent operation due to neighboring segment degeneration during the follow-up period. Progression of degeneration in the neighboring segment discs increased by 10.95% between preoperative and final follow-up graphs. In two patients, a pedicle screw loosening angle of 2 degrees and/or above was observed, no reintervention was needed. In the final follow-up at 24 months, the segmental height and foraminal height Mochida index were 5.8 and 3.82, as compared with the early postoperative graph. Around 87% of the patients had good or perfect results. Discussion Solid fusion was achieved in all but one patient after 2 years, the complication rate was low. Limitations of the study include its predominantly radiological structure, the lack of control group, and the relatively short follow-up of 2 years that may explain the relatively low number of patients who underwent a secondary operation due to neighboring segment degeneration. PEEK and carbon/PEEK increases the formation of surrounding fibrous tissue because of the hydrophobic surface structure. Therefore, carbon/PEEK was coated with VPS Ti, facilitating osteointegration while remaining its radiolucent properties. The first VPS Ti-coated cage proved to be clinically successful and is commonly accepted as a suitable geometrical shape. These findings must be supported with long-term results.

Extreme Lateral Interbody Fusion for Unilateral Symptomatic Vertical Foraminal Stenosis

Introduction Spinal deformity of the adult lumbar spine may occur de novo because of the degenerative disease or following decompressive surgery. Asymmetric loss of disc height may lead to unilateral vertical foraminal stenosis and radiculopathy. Aims/Objectives: This study aimed to investigate whether restoration of foraminal height at the symptomatic level using single-level extreme lateral interbody fusion (ELIF) may alleviate unilateral radicular pain. Methods In a retrospective cohort study, patients with single-level unilateral vertical foraminal stenosis (foraminal height &lt; 15 mm) and corresponding unilateral radicular pain who underwent ELIF were included. Demographic and perioperative data were collected. Functional data (Visual Analogue Scale [VAS] for buttock, leg and back, as well as Oswestry Disability Index [ODI]) and radiographic measurements (bilateral foraminal height, disc height, segmental coronal Cobb angle, and regional lumbar lordosis) were collected preoperatively, postoperatively, and at the last follow-up. Results A total of 23 patients with a mean age of 66 years were included. The foraminal height of stenotic side was significantly increased by ELIF from the preoperative value of 11.0 to 18.1 mm postoperatively ( p &lt; 0.001). The increase was durable at last follow-up of 11 ± 3.7 (SE) months (17.1 mm; p &lt; 0.001). Preoperative VAS buttock and leg on the stenotic side, VAS back, and the ODI (7.3, 7.2, 6.5 and 48.0, respectively) were significantly improved postoperatively (1.5, 2.3, 3.3 and 25.4, respectively) and at the last follow-up (to 0.7, 1.1, 3.3 and 23.0). The postoperative FH on the stenotic side showed correlation with the VAS buttock and VAS leg on the stenotic side. In addition, at the last follow-up, FH on the stenotic side showed correlation with VAS leg on the stenotic side. Conclusion Single-level ELIF is an effective procedure for treatment of symptomatic unilateral vertical foraminal stenosis.

Biomechanical analysis between PEEK and titanium screw-rods spinal construct subjected to fatigue loading.

An in vitro fatigue loading test with porcine specimens. To comparatively analyze the in vitro biomechanical performance of Polyetheretherketone (PEEK) and Titanium rods construct subjected to a battery of fatigue loading testing. PEEK rods construct has been proposed to allow better load sharing among spinal components than the more traditional Titanium rods constructs. However, such proposal has largely derived from single-load in vitro testing and the biomechanical differences when subjected to fatigue loading remain unknown. Twenty-four fresh 4-level motion segment were harvested from porcine. Specimens were randomly assigned into 3 groups: (1) intact, (2) destabilized group with Titanium alloy rods, and (3) destabilized group with PEEK rods. All specimens were subjected to a fatigue loading procedure with the disk height and intradiscal pressure (IDP) of the instrumented and adjacent levels were recorded and used for analysis. The stress levels on the rods and bone stress near the screw-bone interface were also collected to investigate the likely failure rates of the 2 constructs. Titanium rods construct demonstrated a minimum amount of loss of disk height and IDP at the instrumented level; however, a significant loss of the disk height and IDP at adjacent levels compared with the intact spine were identified. In contrast, the disk height and IDP of the PEEK rods were found to be comparable with those of the intact spine for all levels. The PEEK rods group also showed significantly less bone stress near the screw-bone interface compared with the Titanium rods group. The current study has demonstrated the differences in biomechanical characteristics of PEEK and Titanium rods construct when subjected to fatigue loading. More specifically, the result is indicative of the potential benefits of the PEEK rods construct in reducing the risks of adjacent segment disease and implant failure rates.

Extreme lateral interbody fusion for unilateral symptomatic vertical foraminal stenosis.

Asymmetric loss of disc height in adult deformity patients may lead to unilateral vertical foraminal stenosis and radiculopathy. The current study aimed to investigate whether restoration of foraminal height on the symptomatic side using extreme lateral interbody fusion (XLIF) would alleviate unilateral radiculopathy. In a retrospective study, patients with single-level unilateral vertical foraminal stenosis and corresponding radicular pain undergoing XLIF were included. Functional data (visual analog scale (VAS) for buttock, leg and back, as well as Oswestry Disability Index (ODI)) and radiographic measurements (bilateral foraminal height, disc height, segmental coronal Cobb angle and regional lumbar lordosis) were collected preoperatively, postoperatively and at the last follow-up. Twenty-three patients were included, among whom 61 % had degenerative scoliosis. History of previous surgery at the level of index was present in 43 % of patients. Additional instrumentation was performed in 91 %. The foraminal height on the stenotic side was significantly increased postoperatively (p < 0.001), and remained significantly increased at the last follow-up of 11 ± 3.7 months (p < 0.001). Additionally, VAS buttock and leg on the stenotic side, VAS back and ODI were significantly improved postoperatively and at the last follow-up (p ≤ 0.001 for all parameters). The foraminal height on the stenotic side showed correlation with the VAS leg on the stenotic side, both postoperatively and the last follow-up (r = -0.590; p = 0.013, and r = -0.537; p = 0.022, respectively). Single-level XLIF is an effective procedure for treatment of symptomatic unilateral foraminal stenosis leading to radiculopathy. In deformity patients with radicular pain caused by nerve compression at a single level, when not associated with other symptoms attributable to general scoliosis, treatment with single-level XLIF can result in short- and mid-term satisfactory outcome.

The correlation between patient selection and heterotopic ossification after cervical artificial disc replacement

Objective To analysis the correlation between patient selection and heterotopic ossification (HO) after cervical artificial disc replacement. Methods Data of 48 patients with cervical spondylosis (34 cervical spondylotic myelopathy and 14 nerve-root type) who had undergone Bryan cervicadisc replacement from December 2003 to December 2008 were reviewed retrospectively, and all the patients had been followed up for more than 5 years. There were 21 males and 27 females with an average age of 42 years old (range, 20-53 years). There were 38 single level replacement (C3-4 3 cases, C4-5 5 cases, C5-6 28 cases, C6-7 2 cases), 9 double level replacement (C4-5, C5-6 4 cases; C5-6, C6-7 5 cases) and 1 three level replacement (C3-4, C4-5, C5-6) as a total of 59 surgical segments. The occurrence of HO was defined by McAfee classification on cervical lateral X-ray. Four factors were used in patient selection including gender, range of motion (ROM) of the target level, alignment of the functional spine unit (FSU) of the index level, and the disc height ratio between surgical level and the adjacent levels. The correlation between these four factors and HO was evaluated by logistic regression. The receiver operating characteristic (ROC) curve and area under the ROC curve were used to evaluate the significant result of logistic regression and the optimal diagnostic value. Results 48 patients were all followed up for an average period of 70.3 months (range, 60-120 months). The occurrence rate in this study was 33.9% (20/59 segments). Only one factor, the disc height ratio of the target level and its adjacent levels, presented statistical correlation with HO. ROC analysis showed that the area under the ROC curve of disc height ratio was 0.813 and the optimal diagnostic threshold was 0.9. Conclusion The disc height ratio of the target level and adjacent levels was the only patient selective factor correlated with the occurrence of HO. For those with disc height loss exceeding 10% comparing to adjacent levels, it is not indicated for cervical artificial disc replacement with Bryan prosthesis. Key words: Cervical vertebrae; Total disc replacement; Ossification, heterotopic

Effect of anular closure on disk height maintenance and reoperated recurrent herniation following lumbar diskectomy: two-year data.

To assess the potential benefits of disk reherniation reduction and disk height maintenance in limited diskectomy combined with the implantation of the anular closure device. Postoperative disk height loss is apparent in most patients undergoing lumbar diskectomy for herniated nucleus pulposus. Less favorable patient outcomes are associated with significant loss in disk height that can occur after aggressive disk tissue removal. More conservative disk removals, however, are often burdened by the increased risk of recurrent disk herniation. Two prospective single-arm studies on patients treated with limited diskectomy and an anular closure device were conducted. Outcome measures included disk height maintenance relative to preoperative values, Oswestry Disability Index, back pain, leg pain, and complications such as reherniations. Patients were evaluated preoperatively and postoperatively at 6 weeks and at 3-, 6-, 12-, and 24-month time points. A total of 75 patients were included in this cohort consisting of 40 men and 35 women with an average age of 40 years. Disk height maintenance within the group overall was 90% at 24 months. Overall, 97% of the treated disks demonstrated disk height maintenance of at least 75% of preoperative levels at 12 months and 92% at 24 months. Disk height maintenance was correlated with less nucleus removal. Patient disability, back pain, and leg pain were significantly improved from preoperative levels at 6 weeks and maintained over the course of study. There was a single symptomatic reherniation requiring surgical intervention within this series. Limited lumbar diskectomy combined with the use of an anular closure device provided very low rates of disk reherniation and exhibited excellent disk height maintenance and sustained disability, leg pain, and back pain improvement within a 24-month postoperative study period. As with prior diskectomy studies, disk height maintenance was correlated with lower nucleus removal, although recurrence was less than in prior reports of limited diskectomy. Anular closure may allow for achievement of both objectives.

Time-dependent response of intact intervertebral disc – In Vitro and In-Silico study on the effect of loading mode and rate

Article history: Received March 6, 2014 Accepted 28 November 2014 Available online 28 November 2014 The investigation of dynamic response of intervertebral disc is beneficial for the development of new synthetic and engineered tissues for treating diseased or injured disc. There are limited experimental studies on comparing the effect of loading mode and rate on global response of intervertebral disc. In this study, in-vitro experiments were performed using a total of 24 porcine motion segments. The harvested specimens were assigned to prolong and 2 different cyclic loadings. Both disc deformations and water contents were measured to investigate how the mode and rate of loading affect the response of intervertebral disc. In parallel, a backward FE poroelastic model combined with in-vitro experiments were used to find the material properties of intervertebral discs. The experimental result showed that the final disc height loss under creep loading was significantly greater than cyclic groups. Increasing the frequency of cyclic loading decreased the disc height loss. The water content decreased significantly in cyclic loading from those in prolong loading. The backward FE models showed that, the elastic modulus of anulus fibrosus and nucleus pulposus were 2.43 (±0.48) MPa and 1.46 (±0.29) MPa, respectively. The hydraulic permeability was 2.08 (±0.42) ×10-16m4/Ns, and the Poisson’s ratio was 0.21 (±0.03). In conclusion, this study investigated how the loading mode and rate affect porcine intervertebral disc deformation. It is found that dynamic stiffness is greater at higher frequencies which resulted from interactions between the solid phase and fluid flow within the disc. © 2015 Growing Science Ltd. All rights reserved.

Endplate changes following discectomy: natural history and associations between imaging and clinical data.

Some patients will experience post-operative back pain following lumbar discectomy, and the potential sources for that pain are poorly understood. One potential source is the vertebral endplates. The goal of this study was to document the changes that occur in lumbar endplates following discectomies, and to assess associations between endplate changes and clinical outcomes. Changes in lumbar endplates and discs were assessed from X-rays, CT and MRI exams by comparing preoperative imaging with imaging obtained at yearly intervals up to 5 years. 260 endplates in 137 patients with single-level herniation and discectomy were analyzed. The geometry of osseous defects in the endplates was measured from the CT exams, and marrow and disc changes adjacent to endplates were assessed from the MRI exams. Clinical outcome assessments were collected at each time point. Descriptive statistics were used to describe endplate defect sizes, and logistic regression and analysis of variance were used to identify potential associations between endplate and vertebral body changes and clinical outcomes. Approximately 14 % of the endplates had osseous defects prior to surgery. After surgery, 24 % of inferior and 43 % of superior endplates had defects. Change occurred within the first year and remained relatively constant over the next few years. Disc signal intensity worsened and disc height decreased following surgery. New Modic changes were also observed. None of these changes were associated with having achieved a clinically significant improvement in outcome scores. The follow-up rates were low at the later time points and significant associations cannot be ruled out. This study documents lesion characteristics in detail and supports that osseous defects in the endplates at the level of a lumbar discectomy may be a relatively common finding following surgery, along with disc height loss, loss of disc signal intensity, and Modic changes. The clinical significance of these imaging findings could not be conclusively determined in this study.

Magnetic resonance imaging of disc space infection revisited: temporal changes

Background Magnetic resonance imaging (MRI) has advantages in showing pathologic changes of disc space infection, which is important in clinical treatment. The purpose of this study was to describe the MRI findings of disc space infections in relation to chronicity. Methods MRI of 60 patients from January 1, 2002 to April 30, 2012 in Ottawa Hospital were retrospectively evaluated by two radiologists blindly. All patients had histological confirmation, with 55 having microbiological confirmation as well. These patients were divided into acute (n=18), subacute (n=21) and chronic (n=21) based on histological findings. The following potential signs of MRI finding were assessed: marrow edema, endplate erosions, disk fluid and height change, paraspinal mass, epidural collection, facet fluid and enhancement in the marrow, disc, paraspinal mass, and epidural involvement. Statistical analysis consisted of t- or F-tests and chi-square test. Results In the 60 patients, 83 infected discs (single disc in 45 patients, 2-4 discs in 15 patients) were found, including 22 discs in the acute group, 30 discs in the subacute group, and 31 discs in the chronic group. There was a significant difference in the extent of marrow edema between the acute, subacute and chronic groups (P &lt;0.05), with a gradually increasing extent from acute to chronic. The extent of endplate erosions increased with chronicity, but was not statistically significant. There were significant differences in the disc fluid, epidural collection, and disc enhancement among the acute, subacute and chronic groups, as well as the facet fluid between acute and chronic groups (P &lt;0.05). There were no significant differences in the present probability of disc height loss, paraspinal mass, and marrow enhancement among the three groups (P &gt;0.05). Conclusions From acute to chronic infections, the extent of marrow edema and endplate erosions appeared to gradually increase. Epidural collections and facet fluid are most frequently found in the acute group, while disc fluid and disc enhancement are more common in the chronic patients.

Mimickers of Cervical Radiculopathy.

Degenerative changes of the cervical spine are the primary cause of nerve root compression leading to symptomatic radiculopathy. Genetic and age-related changes, including loss of intervertebral disc height, as well as facet and uncovertebral joint hypertrophy, produce narrowing of the neural foramen. A herniated nucleus pulposus may cause acute foraminal stenosis. Symptomatic nerve root compression may ensue, leading to pain radiating from the neck into the shoulder, arm, forearm, and/or hand, with or without accompanying numbness and paresthesias. Several musculoskeletal and nonmusculoskeletal entities have a presentation similar to that of cervical radiculopathy and can be easily overlooked if the diagnosis of radiculopathy is assumed (Table I). Therefore, the clinician should be familiar with the classic signs and symptoms of cervical radiculopathy as well as a spectrum of differential diagnoses that may mimic it. View this table: TABLE I Mimickers of Cervical Radiculopathy by Nerve Root Patients with cervical radiculopathy may report antecedent trauma, but the typical onset is more insidious. Acute, severe pain in a dermatomal distribution typically results from cervical disc herniation, whereas subacute, chronic, or intermittent radicular pain tends to be secondary to a chronically herniated disc or degenerative foraminal stenosis. Henderson et al.1, in a report on >700 patients who had been diagnosed with cervical radiculopathy, noted upper extremity pain in 99.4% of the patients, sensory changes to pinprick in 85.2%, neck pain in 79.7%, diminished reflexes in 71.2%, and diminished strength in 68%. Nearly 54% of the patients experienced pain or paresthesias in a dermatomal pattern, …

A novel classification system of lumbar disc degeneration

The Pfirrmann and modified Pfirrmann grading systems are currently used to classify lumbar disc degeneration. These systems, however, do not incorporate variables that have been associated with lumbar disc degeneration, including Modic changes, a high intensity zone, and a significant reduction in disc height. A system that incorporates these variables that is easy to apply may be useful for research and clinical purposes. A grading system was developed that incorporates disc structure and brightness, presence or absence of Modic changes, presence or absence of a high intensity zone, and reduction in disc height (disc height less than 5mm). MRI of 300 lumbar discs in 60 patients were analyzed twice by two neurosurgeons. Intra and inter-observer reliabilities were assessed by calculating Cohen’s κ values. There were 156 grade zero (“normal”), 50 grade one, 57 grade two, 26 grade three, 10 grade four, and one grade five (“worst”) discs. Inter-observer reliability was substantial (κ=0.66 to 0.77) for disc brightness/structure, Modic changes, and disc height. Inter-observer reliability was moderate (κ=0.41) for high intensity zone. Intra-observer reliability was moderate to excellent (κ=0.53 to 0.94) in all categories. Agreement on the total grade between reviewers occurred 71% of the time and a difference of one grade occurred in an additional 25% of cases. Lumbar disc degeneration can be graded reliably by this novel system. The advantage of this system is that it incorporates disc brightness/structure, Modic changes, high intensity zone, and a rigid definition of loss of disc height. This system might be useful in research studies evaluating disc degeneration. Further studies are required to demonstrate possible clinical utility in predicting outcomes after spinal treatments such as fusion.

Intervertebral disc height loss demonstrates the threshold of major pathological changes during degeneration.

Quantitative MRI techniques were utilized to study intervertebral disc degeneration. Main focus was to develop a novel approach to quantify disc height loss associated with disc degeneration. Currently there is no universally accepted metric of degeneration based on measurement of disc height. Such quantitative imaging methods would complement qualitative visual assessment methods currently used and offer a valuable diagnostic tool. 51 adult participants took part in this MRI study. T2 weighted images were used to obtain disc height index (DHI) and also a semi-quantitative metric based on relative voxel intensities. For DHI, each disc was given a score based on standard deviations from the mean DHI of healthy discs. Diffusion Weighted MRI was used to assess morphological changes in the nucleus pulposus. Conventional Pfirrmann classification was used as the gold standard to assess these quantitative approaches. At deviations of up to 1.5σ below normative disc height, levels of apparent diffusion coefficient (ADC) and normalized T2 intensity were maintained. Once disc compression reached 1.5σ, there was a massive drop in ADC and normalized T2 intensity. Pfirrmann degeneration scores also increased after the 1.5σ mark. This study provides new, unbiased quantitative imaging tools to assess disc degeneration. We observed that these quantitative MRI measures indicate a threshold beyond which major pathological changes take place concurrently. Combined information from DHI, ADC and T2 images construct a set of novel biomarkers that could be used to identify degenerating discs that are approaching the threshold and possibly intervene before major pathologic changes occur.

Single space transforaminal lumbar interbody fusion in spondylolisthesis: initial experience of 30 cases.

Spondylolisthesis in adults is characterized by the loss of disc height across the affected segment with sagital translation. The goal of stabilizing the spine is accomplished by fusion. Transforaminal approach for lumbar interbody fusion is a very good approach and reduces the complications associated with traditional posterior approach. It has been reported to be safe and effective in the treatment of spondylolisthesis. It has done to assess the functional outcome of Transforaminal Lumbar Interbody Fusion (TLIF) in spondylolisthesis. This prospective interventional study was performed from July 2008 to June 2011 included 30 patients (male 07, female 23), within a age range of 30-59 years. Nineteen cases were lytic, 08 cases were degenerative, 02 were post-traumatic and 01 dysplastic variety of spondylolisthesis. Follow up ranged from 12 to 24 months and outcome assessed by VAS and ODI regarding pain and disability. Achievement of fusion and complications were documented accordingly. Statistical analysis was done by unpaired t-test and chi-squared test in appropriate instances. We included twenty One (70.00%) patient had Grade-II Spondylolisthesis and L4 over L5 had been the commonest level (53.33%) involved. Pain and disability improved significantly and 22 (73.33%) patients returned to their previous level of activity. One (03.33%) patient developed superficial wound infection and 01 (03.33%) had persistent low back pain. All patients had neurological improvement. We concluded that Transforaminal Lumbar Interbody Fusion is an effective alternative surgical procedure for the treatment of spondylolisthesis. Overall outcome is satisfactory in 93.33% cases.

Physiological loading can restore the proteoglycan content in a model of early IVD degeneration.

A hallmark of early IVD degeneration is a decrease in proteoglycan content. Progression will eventually lead to matrix degradation, a decrease in weight bearing capacity and loss of disc height. In the final stages of IVD degradation, fissures appear in the annular ring allowing extrusion of the NP. It is crucial to understand the interplay between mechanobiology, disc composition and metabolism to be able to provide exercise recommendations to patients with early signs of disc degeneration. This study evaluates the effect of physiological loading compared to no loading on matrix homeostasis in bovine discs with induced degeneration. Bovine discs with trypsin-induced degeneration were cultured for 14 days in a bioreactor under dynamic loading with maintained metabolic activity. Chondroadherin abundance and structure was used to confirm that a functional matrix was preserved in the chosen loading environment. No change was observed in chondroadherin integrity and a non-significant increase in abundance was detected in trypsin-treated loaded discs compared to unloaded discs. The proteoglycan concentration in loaded trypsin-treated discs was significantly higher than in unloaded disc and the newly synthesised proteoglycans were of the same size range as those found in control samples. The proteoglycan showed an even distribution throughout the NP region, similar to that of control discs. Significantly more newly synthesised type II collagen was detected in trypsin-treated loaded discs compared to unloaded discs, demonstrating that physiological load not only stimulates aggrecan production, but also that of type II collagen. Taken together, this study shows that dynamic physiological load has the ability to repair the extracellular matrix depletion typical of early disc degeneration.

Developing a Mechanical and Chemical Model of Degeneration in Young Bovine Lumbar Intervertebral Disks and Reversing Loss in Mechanical Function

A mechanical and chemical model of intervertebral disk (IVD) degeneration was developed by examining the enzymatic degradation of the nucleus pulposus (NP), and a gelatin-based restoration study was performed. It was hypothesized that forced enzymatic degradation of the NP will mimic natural degeneration through the loss of disk height and that an injection of a gelatin solution will restore mechanical function. Collagen and proteoglycans are essential for normal NP function. Their chemical destruction, combined with light mechanical loading, will mimic degeneration. Previous studies have determined that collagenase and matrix metalloproteinase-3 are directly implicated in IVD degradation; therefore, these enzymes were used in this model. On the basis of preliminary testing, 0.5% collagenase, 1% collagenase, and 0.0025% metalloproteinase-3 in phosphate-buffered saline (PBS) were injected directly into the NP of various motion segments from a young bovine lumbar spine and subjected to light cyclic loading. To restore disk height and mechanical function, 20% gelatin in PBS at 70°C was injected into a degraded disk and subjected to the same loading conditions after an allotted hardening time. Mechanical testing showed statistically significant changes in disk height between control segments, 1% collagenase, and 0.5% collagenase. 0.5% collagenase had the most accurate appearance and loading pattern of degeneration upon disk transection postloading. A trend in restoration of disk function, given by the lessened loss of disk height upon loading, was observed with injection of gelatin after degradation with 0.5% collagenase. This study demonstrated the potential to create a degenerative model using enzymatic degradation of the NP and the possibility to restore function with an injectable therapy. Although gelatin is not a clinically viable option, it provides preliminary data for other injectable IVD therapies.

Stand-alone anterior lumbar interbody fusion for degenerative disc disease of the lumbar spine: results with a 2-year follow-up.

Retrospective chart review. To report outcomes of a consecutive series of patients diagnosed with degenerative disc disease (DDD) between L4 and S1, treated with stand-alone anterior lumbar interbody fusion (ALIF, either 1 or 2 levels) and use of recombinant human bone morphogenetic protein 2 for bony fusion with instrumented fixation. Degeneration of the lumbar spine is described as lumbar spondylosis, or DDD. To treat DDD, surgical interventions include: ALIF, circumferential fusion (360° fusion), posterior spinal fusion, and total disc replacement. Currently, there has been paucity in the literature on the evaluation of ALIFs. Researchers reviewed a consecutive series of patients with DDD who had undergone a 1-level or 2-level ALIF between 2005 and 2010, with the use of recombinant human bone morphogenetic protein 2. Patients' clinical and functional outcomes were documented. Radiographs were analyzed for disc height, mean optical density, and integrated optical density. Operative time, length of hospital stay, and estimated blood loss were also reported. Patients' 2-year Oswestry Disability Index and visual analogue scale presurgery scores significantly improved (P ≤ 0.0001). Patients' 2-year postoperative disc height was significantly greater than the preoperative disc height at the fused level (P ≤ 0.0001); there was no significant difference at the level adjacent to fusion. Majority of patients (107 of 115, 93.0%) satisfied fusion criteria based on mean optical density. Intraoperative time, estimated blood loss, and hospital stay was significantly fewer with 1-level and 2-level ALIFs than 360° fusions and total disc replacement. Stand-alone ALIF used to treat DDD can produce comparative clinical and functional outcomes. ALIFs showed significant decreases in blood loss, operative time, and hospital stay. Furthermore, at 2 years' time, mean optical density suggests high rate of bony fusion, and no significant loss of disc height was noted at the adjacent level. 4.