Loss Of Disc Height Research Articles

Inflammaging in the intervertebral disc

Degeneration of the intervertebral disc – triggered by ageing, mechanical stress, traumatic injury, infection, inflammation and other factors – has a significant role in the development of low back pain. Back pain not only has a high prevalence, but also a major socio-economic impact. With the ageing population, its occurrence and costs are expected to grow even more in the future. Disc degeneration is characterized by matrix breakdown, loss in proteoglycans and thus water content, disc height loss and an increase in inflammatory molecules. The accumulation of cytokines, such as interleukin (IL)-1β, IL-8 or tumor necrosis factor (TNF)-α, together with age-related immune deficiency, leads to the so-called inflammaging – low-grade, chronic inflammation with a crucial role in pain development. Despite the relevance of these molecular processes, current therapies target symptoms, but not underlying causes. This review describes the biological and biomechanical changes that occur in a degenerated disc, discuss...

Preflight, In-Flight, and Postflight Imaging of the Cervical and Lumbar Spine in Astronauts

Back pain is a common complaint during spaceflight that is commonly attributed to intervertebral disc swelling in microgravity. Ultrasound (US) represents the only imaging modality on the International Space Station (ISS) to assess its etiology. The present study investigated: 1) The agreement and correlation of spinal US assessments as compared to results of pre- and postflight MRI studies; and 2) the trend in intervertebral disc characteristics over the course of spaceflight to ISS. Seven ISS astronauts underwent pre- and postflight US examinations that included anterior disc height and anterior intervertebral angles with comparison to pre- and postflight MRI results. In-flight US images were analyzed for changes in disc height and angle. Statistical analysis included repeated measures ANOVA with Bonferroni post hoc analysis, Bland-Altman plots, and Pearson correlation. Bland-Altman plots revealed significant disagreement between disc heights and angles for MRI and US measurements while significant Pearson correlations were found in MRI and US measurements for lumbar disc height (r2 = 0.83) and angle (r2 = 0.89), but not for cervical disc height (r2 = 0.26) or angle (r2 = 0.02). Changes in anterior intervertebral disc angle-initially increases followed by decreases-were observed in the lumbar and cervical spine over the course of the long-duration mission. The cervical spine demonstrated a loss of total disc height during in-flight assessments (∼0.5 cm). Significant disagreement but significant correlation was noted between US and MRI measurements of disc height and angle. Consistency in imaging modality is important for trending measurements and more research related to US technique is required.Harrison MF, Garcia KM, Sargsyan AE, Ebert D, Riascos-Castaneda RF, Dulchavsky SA. Preflight, in-flight, and postflight imaging of the cervical and lumbar spine in astronauts. Aerosp Med Hum Perform. 2018; 89(1):32-40.

Normal aging of the lumbar spine in women.

Lumbar lordosis is required for bipedalism. To investigate age-related changes in lumbar lordosis and to clarify the relationships between lumbar lordosis and vertebral wedging and disc degeneration. A total of 300 women were included in this retrospective study, 50 in each of six age groups (20-, 30-, 40-, 50-, 60- and 70-year-olds). Patients with vertebral collapse, instable fracture or disc sequestration were excluded. In each patient, lumbar lordosis angle, posterior vertebral wedging, L5-S1 intervertebral disc angle, L5/L1 vertebral height ratio and L5-S1 intervertebral disc/L1-L2 intervertebral disc height ratio were examined. Significance level was set at p< 0.05 and two-sided tests were used. Significant differences were found in lumbar lordosis according to age group (p< 0.001). Lumbar lordosis correlated most strongly with L4 posterior vertebral wedging, L5 posterior vertebral wedging and L5-S1 intervertebral disc angle, in that order (r= 0.50, r= 0.40, r= 0.32, respectively; p< 0.001). In this cohort, strong spinal structure was maintained during physiological aging from 20 to 40 years of age; lumbar lordosis increased by 50 years of age. Increased lordosis correlated with increased posterior vertebral wedging and loss of posterior disc height.

333 Intervertebral Disc Repair Following Microdiscectomy Mediated by Pentosan Polysulfate Primed Mesenchymal Progenitor Cells in an Ovine Model

Abstract INTRODUCTION Lumbar microdiscectomy treats neural compression but fails to halt disc degeneration. Consequently, 10 20% of patients develop debilitating back pain and approximately 15% undergo further surgical intervention. In-vitro pre-incubation of mesenchymal precursor cells (MPCs) with pentosan polysulfate (PPS), enhances viability and chondrogenic differentiation, but inhibits osteogenesis. This study investigated the potential of PPS primed mesenchymal precursor cells (pMPCs) in a gelatin scaffold to facilitate disc repair in an ovine model. METHODS Eighteen adult ewes underwent pre-operative 3T MRI followed by lumbar microdiscectomy at two levels. Sheep were randomized into three groups. The injured control (IC) group received no further treatment; the MPC group were implanted with non-primed MPC + scaffold; the pMPC group received the pMPC + scaffold. Necropsies were performed at six months. Analysis consisted of 3T and 9.4T MRI, gross morphological, histological and biochemical analysis for proteoglycans, collagen and DNA content. RESULTS &gt;MPC and pMPC discs demonstrated significantly reduced disc height loss (P &lt; 0.05) and reduced Pfirrmann grades (P &lt; 0.001) relative to IC discs. pMPC disc segments were significantly less degenerate than IC discs on gross morphology. Proteoglycan content of pMPC discs was significantly greater than IC discs and not significantly different to controls for the injured annulus fibrosus (AF) region and nucleus pulposus (NP) region contralateral to the injury. DNA content for pMPC discs was significantly less than IC discs for the NP &amp; AF injury and adjacent regions. Histological analysis demonstrated increased organization and decreased degeneration in pMPC discs while MPC discs displayed increased vascular infiltration. CONCLUSION pMPCs post microdiscectomy reduced disc degeneration, improved disc height and matrix organization, NP proteoglycan content and histological degeneration relative to microdiscectomy alone. This suggests a potential therapeutic application of pMPCs in promoting disc repair and reducing the incidence of low back pain and further surgery following microdiscectomy.

A study of the damage behaviour of porcine intervertebral discs in a bioreactor environment

The intervertebral discs are cartilaginous, articulating structures that lie between vertebral bodies, allowing flexibility, transmission, modification, and also distribution of the forces to the spinal column. Disc degeneration is characterised by progressive loss of disc height and exaggerated radial bulging. Therefore, the spine becomes shorter, stiffer, and less mobile. In the last several decades, there is a strong need for a tissue engineering strategy that alleviates pain and restores spine function by directly addressing the underlying biological causes of disc degeneration. Numerous studies that are currently showing potential have been conducted on developing regenerative and reparative strategies for treating this condition. In this study, to numerically describe the anisotropic mechanical damage behaviour of discs, the pseudo-elastic damage model was applied. To experimentally picture the biomechanical response of discs and to study the damage mechanisms as well as the spinal disc herniation, a special bioreactor was evolved. The specimens were obtained from pigs aged six months. A total of eight functional spine units were taken from porcine lumbar spines (L1-L2). Firstly, the experiments were performed by using long-term cyclic uniaxial compression tests. Secondly, the mean value of experimental results with consideration of the different shapes and sizes of the samples was calculated. Afterwards, the experimental results were compared with outcomes of numerical simulations.

Functional compressive mechanics and tissue biocompatibility of an injectable SF/PU hydrogel for nucleus pulposus replacement

In spinal degenerative disease, an injectable liquid hydrogel can fill in defect entirely, lessen the danger of implant relocation and following loss of disc height, minimizing the operative trauma. Here, we propose an injectable in-situ chemically cross-linked hydrogel by a two-component reaction of liquid silk fibroin with liquid polyurethane at physiological temperature conditions. Confined compression tests and fatigue tests were reported to assess physical properties of the hydrogel. Impact of different diameter on the biomechanical behaviours was tested to evaluate the clinical potentiality of the hydrogel for replacing nucleus pulposus. Degradation behaviours in different solutions and animal experiments were also investigated to examine the tissue biocompatibility of the hydrogel. The hydrogel modulus was affected by the hydrogel geometrical (diameter) parameters. SF/PU composite hydrogel can survive a million cycles, unconstrained fatigue resistance. More importantly, in vivo biocompatibility using New Zealand white rabbits, showed good biocompatibility over a three-month period in culture. Particularly, they showed the significant clinical merit of providing stronger axial compressive stiffness on confined compression test. Based on the outcomes of the present research, the SF/PU composite hydrogel may provide significant advantages for use in future clinical application in replacing nucleus pulposus field.

Elimination of Subsidence with 26-mm-Wide Cages in Extreme Lateral InterbodyFusion.

Extreme lateral interbody fusion (ELIF) has gained popularity as a minimally invasive technique for indirect decompression. However, graft subsidence potentially threatens long-term success of ELIF. This study evaluated whether 26-mm-wide cages can eliminate subsidence and subsequent loss of decompression in ELIF. Patients undergoing ELIF surgery using a 26-mm-wide cage were analyzed retrospectively. Patient demographics and perioperative data for radiographic and clinical outcomes were recorded. Radiographic parameters included regional sagittal lumbar lordosis and foraminal and disc height. Clinical parameters were evaluated using the Oswestry Disability Index and visual analog scale. Subsidence of 26-mm-wide cages was compared with previous outcomes of patients undergoing ELIF using 18-mm-wide and 22-mm-wide cages. There were 21 patients and 28 spinal segments analyzed. Radiographic outcome measures such as disc and foraminal height revealed significant improvement at follow-up compared with before surgery (P=0.001). Postoperative to last follow-up cage subsidence translated into 0.34 mm ± 0.26 and-0.55 mm ± 0.64 in disc and foraminal height loss, respectively. Patients with 26-mm-wide cages experienced less subsidence by means of disc (26 mm vs. 18 mm and 22 mm, P ≤ 0.05) and foraminal height (26 mm vs. 18 mm, P= 0.005; 26 mm vs. 22mm, P= 0.208) loss compared with patients receiving 18-mm-wide and 22-mm-wide cages. The 26-mm-wide cages almost eliminated cage subsidence in ELIF. Compared with 18-mm-wide and 22-mm-wide cages, 26-mm-wide cages significantly reduced cage subsidence in ELIF at midterm follow-up. A 26-mm-wide cage should be used in ELIF to achieve sustained indirect decompression.

Are axial intervertebral disc biomechanics determined by osmosis?

The intervertebral disc faces high compressive forces during daily activities. Axial compression induces creeping fluid loss and reduction in disc height. With degeneration, disc fluids and height are progressively lost, altering biomechanics. It is assumed that this reduction of fluids is caused by a decline of osmolality within the disc due to proteoglycan depletion. Here we investigate the isolated effect of a reduction in osmosis on the biomechanical properties of the intervertebral disc. Continuous diurnal loading was applied to healthy caprine intervertebral discs in a loaded disc culture system for a total of 6days. We increased testing bath osmolality with two doses of polyethylene-glycol (PEG), thereby reducing the osmotic gradient between the disc and the surrounding fluid. This way we could study the isolated effect of reduced osmosis on axial creep, without damaging the disc. We evaluated: daily creep and recovery, recovery time-constants and compressive stiffness. Additionally, we investigated water content. There was a strong dose-dependent effect of PEG concentration on water content and axial creep behaviour: disc height, amplitude and rate of creep and recovery were all significantly reduced. Axial compressive stiffness of the disc was not affected. Reduction of water content and amplitude of creep and recovery showed similarity to degenerative disc biomechanics. However, the time-constants increased, indicating that the hydraulic permeability was reduced, in contrast to what happens with degeneration. This suggests that besides the osmotic gradient, the permeability of the tissues determines healthy intervertebral disc biomechanics.

A videofluoroscopy-based tracking algorithm for quantifying the time course of human intervertebral displacements

The motions of individual intervertebral joints can affect spine motion, injury risk, deterioration, pain, treatment strategies, and clinical outcomes. Since standard kinematic methods do not provide precise time-course details about individual vertebrae and intervertebral motions, information that could be useful for scientific advancement and clinical assessment, we developed an iterative template matching algorithm to obtain this data from videofluoroscopy images. To assess the bias of our approach, vertebrae in an intact porcine spine were tracked and compared to the motions of high-contrast markers. To estimate precision under clinical conditions, motions of three human cervical spines were tracked independently ten times and vertebral and intervertebral motions associated with individual trials were compared to corresponding averages. Both tests produced errors in intervertebral angular and shear displacements no greater than 0.4° and 0.055 mm, respectively. When applied to two patient cases, aberrant intervertebral motions in the cervical spine were typically found to correlate with patient-specific anatomical features such as disc height loss and osteophytes. The case studies suggest that intervertebral kinematic time-course data could have value in clinical assessments, lead to broader understanding of how specific anatomical features influence joint motions, and in due course inform clinical treatments.

Micro-CT evaluation of asymmetrical ovine intervertebral disc height loss from surgical approach.

The primary goal of this study is to clearly define and evaluate new intervertebral disc height parameters in analysing the morphological pathology of disc degeneration for application in damage model and regeneration therapy development, as well as applying traditional variables to 3-D characterization methods. A posterolateral surgical approach was used to induce disc degeneration in an ovine model. At 12-months post-operation, sheep vertebral segments were removed and characterized using micro-CT to evaluate disc height parameters in regard to injury localization. Statistically significant differences between the disc height loss of the left and right side of the disc, consistent with the lateral surgical approach used were seen using the modified average disc height method by Dabbs et al. However, convexity index and the newly proposed Cross Tilt Index did not conclusively demonstrate a difference. Two-dimensional morphological evaluations can be applied in 3-D to provide a more complete picture of disc height loss for injury models. New 3-D parameters that are tailored to the type of surgical approach used should be investigated, with the 9-point system described herein providing a useful basis for derived values. Additionally, the surgical approach chosen when artificially injuring the disc can result in asymmetrical degeneration, as indicated by uneven disc height loss.

Outcomes of autograft alone versus PEEK+ autograft interbody fusion in the treatment of adult lumbar isthmic spondylolisthesis

ObjectivesBone resulting from a complete resection of the posterior arch can be cut into an autograft bone that contains the facet joint structure and morselised bone for interbody fusion. However, whether a strut autograft that contains this trimmed facet joint can produce the same clinical and radiographic outcomes as a cage for interbody fusion remains unclear. The aim of this study was to compare the outcomes of a local facet joint autograft alone to those of polyetheretherketone (PEEK)+autograft for posterior lumbar interbody fusion (PLIF) in the treatment of adult isthmic spondylolisthesis. Patients and methodsA retrospective analysis was performed on 84 patients with single lumbar isthmic spondylolisthesis who were treated with a local facet joint autograft alone (group A; n=44) or PEEK+autograft (group B; n=40) in PLIF with a minimum follow-up period of 24 months. Pain and disability were assessed using the visual analogue scale, Oswestry disability index and Kirkaldy-Willis criteria. In the radiological evaluation, disc height, slippage reduction, and fusion status were examined. Postoperative complications were also monitored. ResultsAt the last follow-up examination, 84.1% (37/44) of the patients in group A and 82.5% (33/40) of the patients in group B had a good outcome, and there were no significant differences between the two groups. Boh Methods led to significant improvements in disc height, and while PEEK+autograft produced a smaller loss in disc height, the difference was insignificant. The improvements in slippage and the fusion and complication rates between the two groups were similar. ConclusionThere were no significant differences in the clinical outcomes or radiographic improvements of both fusion methods in the treatment of adult isthmic spondylolisthesis. An autograft excised from a complete posterior arch containing a facet joint for interbody fusion is effective and affordable for treating isthmic spondylolisthesis.

Systematic review of countermeasures to minimise physiological changes and risk of injury to the lumbopelvic area following long-term microgravity

BackgroundNo studies have been published on an astronaut population to assess the effectiveness of countermeasures for limiting physiological changes in the lumbopelvic region caused by microgravity exposure during spaceflight. However, several studies in this area have been done using spaceflight simulation via bed-rest. The purpose of this systematic review was to evaluate the effectiveness of countermeasures designed to limit physiological changes to the lumbopelvic region caused by spaceflight simulation by means of bed-rest. MethodsElectronic databases were searched from the start of their records to November 2014. Studies were assessed with PEDro, Cochrane Risk of Bias and a bed-rest study quality tool. Magnitude based inferences were used to assess countermeasure effectiveness. ResultsSeven studies were included. There was a lack of consistency across studies in reporting of outcome measures. Some countermeasures were found to be successful in preventing some lumbopelvic musculoskeletal changes, but not others. For example, resistive vibration exercise prevented muscle changes, but showed the potential to worsen loss of lumbar lordosis and intervertebral disc height. ConclusionFuture studies investigating countermeasures should report consistent outcomes, and also use an actual microgravity environment. Additional research with patient reported quality of life and functional outcome measures is advocated.

Effect of a titanium cage as a stand-alone device on biomechanical stability in the lumbosacral spine of canine cadavers

Degenerative lumbosacral stenosis is a common disease in dogs characterised by intervertebral disc herniation, loss of disc height and stenosis. Decompressive dorsal laminectomy and partial discectomy can cause spinal instability and worsen foraminal stenosis. Pedicle screw and rod fixation (PSRF) with an intervertebral body cage allows for distraction and restoration of disc height and restores foraminal apertures. The aim of this study was to evaluate the ex vivo biomechanical properties of a titanium intervertebral cage alone and in combination with PSRF in the lumbosacral spine of dogs. The range of motion, neutral zone, neutral zone stiffness and elastic zone stiffness of the lumbosacral joint (L7-S1) of nine canine cadavers were determined in flexion/extension, lateral bending and axial rotation for four conditions: (1) native (unmodified) spine; (2) dorsal laminectomy and discectomy; (3) stand-alone cage; and (4) cage in combination with PSRF. The intervertebral disc height decreased after dorsal laminectomy, but increased after insertion of the cage. Insertion of the stand-alone cage decreased the range of motion and neutral zone compared to the laminectomy-discectomy and increased neutral zone stiffness in all directions. The range of motion further decreased after PSRF. From a biomechanical point of view, the use of a stand-alone intervertebral cage is a potential alternative to dorsal fixation of the lumbosacral junction, since it increases spinal stability and restores disc height.

Effect of an Annular Closure Device (Barricaid) on Same-Level Recurrent Disk Herniation and Disk Height Loss After Primary Lumbar Discectomy: Two-year Results of a Multicenter Prospective Cohort Study.

A prospective cohort study. To evaluate whether an annular closure device could be implanted safely to reduce same-level recurrent disk herniation, or attenuate disk height loss and improve the outcome after lumbar discectomy. Same-level recurrent disk herniation, disk height loss, and progressive degeneration are common complications and sequelae after lumbar discectomy. Techniques to reduce these consequences may improve outcomes. Forty-six consecutive patients undergoing lumbar discectomy for single-level herniated disk at 2 institutions were followed prospectively with clinical and radiographic evaluations at 6 weeks and 3, 6, 12, and 24 months (control cohort). A second consecutive cohort of 30 patients undergoing 31 lumbar discectomies with implantation of an annular closure device was followed similarly. Incidence of recurrent disk herniation, disk height loss, the leg and back pain visual analog scale (VAS), and the Oswestry Disability Index were assessed at each follow-up. Cohorts were well matched at baseline. By 2 years of follow-up, symptomatic recurrent same-level disk herniation occurred in 3 (6.5%) patients in the control cohort versus 0 (0%) patients in the annular repair cohort (P=0.27). A trend of greater preservation of disk height was observed in the annular repair versus the control cohort 3 months (7.9 vs. 7.27 mm, P=0.08), 6 months (7.81 vs. 7.18 mm, P=0.09), and 12 months (7.63 vs. 6.9 mm, P=0.06) postoperatively. The annular closure cohort reported less leg pain (VAS-LP: 5 vs. 16, P<0.01), back pain (VAS-BP: 13 vs. 22, P<0.05), and disability (Oswestry Disability Index: 16 vs. 22, P<0.05) 1 year postoperatively. Implantation of a novel annular repair device was associated with greater maintenance of disk height and improved 1-year leg pain, back pain, and low-back disability. Recurrent disk herniation did not occur in any patient after annular repair. Closure of annular defect after lumbar discectomy may help preserve the physiological disk function and prevent long-term disk height loss and associated back and leg pain.

Creation of an injectable in situ gelling native extracellular matrix for nucleus pulposus tissue engineering

Background ContextDisc degeneration is the leading cause of low back pain and is often characterized by a loss of disc height, resulting from cleavage of chondroitin sulfate proteoglycans (CSPGs) present in the nucleus pulposus. Intact CSPGs are critical to water retention and maintenance of the nucleus osmotic pressure. Decellularization of healthy nucleus pulposus tissue has the potential to serve as an ideal matrix for tissue engineering of the disc because of the presence of native disc proteins and CSPGs. Injectable in situ gelling matrices are the most viable therapeutic option to prevent damage to the anulus fibrosus and future disc degeneration. PurposeThe purpose of this research was to create a gentle decellularization method for use on healthy nucleus pulposus tissue explants and to develop an injectable formulation of this matrix to enable therapeutic use without substantial tissue disruption. Study DesignPorcine nuclei pulposi were isolated, decellularized, and solubilized. Samples were assessed to determine the degree of cell removal, matrix maintenance, gelation ability, cytotoxic residuals, and native cell viability. MethodsNuclei pulposi were decellularized using serial detergent, buffer, and enzyme treatments. Decellularized nuclei pulposi were solubilized, neutralized, and buffered. The efficacy of decellularization was assessed by quantifying DNA removal and matrix preservation. An elution study was performed to confirm removal of cytotoxic residuals. Gelation kinetics and injectability were quantified. Long-term in vitro experiments were performed with nucleus pulposus cells to ensure cell viability and native matrix production within the injectable decellularized nucleus pulposus matrices. ResultsThis work resulted in the creation of a robust acellular matrix (>96% DNA removal) with highly preserved sulfated glycosaminoglycans (>47%), and collagen content and microstructure similar to native nucleus pulposus, indicating preservation of disc components. Furthermore, it was possible to create an injectable formulation that gelled in situ within 45 minutes and formed fibrillar collagen with similar diameters to native nucleus pulposus. The processing did not result in any remaining cytotoxic residuals. Solubilized decellularized nucleus pulposus samples seeded with nucleus pulposus cells maintained robust viability (>89%) up to 21 days of culture in vitro, with morphology similar to native nucleus pulposus cells, and exhibited significantly enhanced sulfated glycosaminoglycans production over 21 days. ConclusionsA gentle decellularization of porcine nucleus pulposus followed by solubilization enabled the creation of an injectable tissue-specific matrix that is well tolerated in vitro by nucleus pulposus cells. These matrices have the potential to be used as a minimally invasive nucleus pulposus therapeutic to restore disc height.

Radiographic Changes in the Cervical Spine Following Anterior Arthrodesis: A Long-Term Analysis of 166 Patients.

Adjacent segment degeneration frequently develops following anterior cervical discectomy and fusion. The objectives of the present study were to characterize the long-term evolution of degenerative radiographic changes at segments adjacent to anterior cervical fusion and to identify factors associated with the development of these changes, including the preoperative condition of the cervical spine and parameters related to arthrodeses. One hundred and sixty-six patients who underwent anterior cervical discectomy and fusion for symptomatic cervical spondylosis or disc herniation were followed radiographically for a mean time of 12.7 years (range, 5 to 30 years). Radiographic changes representing degeneration at adjacent levels, including disc height loss, osteophyte formation, end-plate sclerosis, and facet arthrosis, along with changes in sagittal alignment of the fusion segment and cervical spine, were recorded preoperatively and at the time of the latest follow-up. Regression models were used to identify the parameters that affect these degenerative changes. More than 90% of patients had worsened anterior and posterior osteophytes at segments immediately adjacent to the fusion. Degenerative changes were significantly affected by the proximity of the level to the fusion and were inversely affected by the preoperative degenerative changes present at the segment (p < 0.0001). The time elapsed since the surgical procedure was a significant predictor of degenerative changes (p < 0.0001). However, the patient age, the number of levels fused, and the sagittal alignment of the fusion segment had no influence on the degenerative changes at adjacent segments. Multiple factors likely contribute to adjacent segment degeneration following cervical arthrodesis. Although mechanical parameters associated with arthrodesis, such as length and alignment of the fusion, did not appear to play a role, the preoperative degenerative condition of the spine and inclusion of C5-C6 in the arthrodesis influenced the incidence of adjacent segment degeneration. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The relationship between Modic changes and intervertebral disc degeneration

BackgroundRecent reported results have added to the weight of evidence supporting association between disc degeneration and Modic changes. Endplate or Modic changes are also associated with increased body mass index. The most recent study from Teichtahl et al. titled ‘Modic changes in the lumbar spine and their association with body composition, fat distribution and intervertebral disc height – a 3.0 T-MRI study’ showed associations of Modic changes with quantitatively measured reduced disc height and fat mass index. However, there were some facts, which we would like to address in this Correspondence to their article.DiscussionThe different components of intervertebral disc degeneration such as loss of disc height and disc signal intensity have already been shown associated with endplate changes – but not disc height if it is assessed using newer more precise methods of quantitation of disc height. A possible protective effect of different adiposity distribution in the body to Modic change development would be of interest if observed in a longitudinal study in the future.SummaryModic changes have been associated with different components of intervertebral disc degeneration such as loss of disc height and disc signal intensity previously. The influence of body fat distribution on endplate changes would be interesting to study longitudinally.

A Novel, Minimally-Invasive Approach to Repair Degenerative Disk Disease in an Ovine Model Using Injectable Polymethyl-Methacrylate and Bovine Collagen (PMMA/BC).

Background :The natural, inflammatory repair processes of an injured intervertebral degenerative disc can propagate further injury and destruction. While there are many different treatment modalities of the pain related to degenerative disc disease, none are actually reparative in nature. Treatment strategies to repair a degenerative disc without inducing a destructive inflammatory milieu have been elusive. Purpose:The purpose of this experiment is to discover the feasibility of reconstructing an injured intervertebral disc using an injected, inert polymer as the foundation for endogenous collagen growth.Study Design:In this ovine model of six subjects in total, we introduce a modality where a large inert polymer, polymethyl methacrylate (PMMA), in conjunction bovine collagen (BC) is injected into the intervertebral disc. Following six months of observation, histologic specimens were evaluated macroscopically and microscopically for evidence of a benefit of the injectable PMMA/BC.Methods:We obtained six merino sheep for this study. Concentric injuries were made to four of their lumbar intervertebral discs. Two of those levels were treated with a percutaneous injection of 0.3 cc of PMMA/BC. The remaining lumbar levels were left untreated and were our controls. After six months, all subjects were sacrificed. Their four levels were extracted and were examined macroscopically and microscopically.Results:All subjects tolerated the lumbar injury and percutaneous injection of PMMA/BC well. After the six month interval, all subjects have demonstrated an intact architecture of their lumbar disc height at the macroscopic and microscopic level. Microscopically, there was no evidence of external migration of the PMMA/BC microspheres, nor was there any evidence of an inflammatory response by its presence. Notably, the PMMA/BC microspheres were well-incorporated into the concentric disc tears and had undergone endogenous collagen formation in its environment. Treatment levels were revealing for maintenance of disc height without evidence of an ongoing degeneration. The controlled levels were revealing for continued disc degeneration with loss of disc height and evolving injury at the level of the concentric tear.Conclusions:This ovine model demonstrates a novel and promising technique for prevention and arrest of lumbar intervertebral disc degeneration.

A multicenter, prospective, randomized study protocol to demonstrate the superiority of a bone-anchored prosthesis for anular closure used in conjunction with limited discectomy to limited discectomy alone for primary lumbar disc herniation

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Same-level reherniation and progressive degeneration with disc height loss are main causes of poor outcome after discectomy and may necessitate reoperation. A novel prosthesis for anular closure was developed to address these causes.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; The design of a multicenter, prospective, randomized, post-market superiority trial comparing limited lumbar discectomy augmented with this device (intervention group) with limited lumbar discectomy alone (control group) is presented.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Patients with single-level (L1-S1) posterior or posterolateral disc herniation and radiologic confirmation of neural compression for whom at least six weeks of conservative treatment has failed are eligible. Patients must have posterior disc height ≥5 mm at index level and baseline Oswestry and VAS leg pain scores of ≥40/100. Intraoperatively, subjects meeting anular defect size criteria post-discectomy (4-6 mm tall and 6-10 mm wide) will be randomized to study groups in a 1:1 ratio using centralized, web-based software. A Bayesian statistical approach will be used to enroll 400 to 800 subjects who will be followed for at least 24 months. Two co-primary endpoints will be assessed at 24 months: 1) a composite of leg pain, clinical function, disc height maintenance, and absence of reherniation, reoperation, and device failure; and 2) absence of reherniation based upon independent radiologic analysis. &lt;/p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; This type of analysis is becoming increasingly important as governments and health insurers continue to be pressured to spend limited healthcare funding wisely.

Investigation of Sacral Needle Depth in Minimally Invasive Sacrocolpopexy

The aims of the study were to optimize surgical safety and to minimize vertebral disc puncture during sacral needle placement at the time of minimally invasive sacrocolpopexy. Cadaveric studies report that the anterior longitudinal ligament (ALL), which covers the vertebral disc and vertebrae, has a reported thickness of only 1.4 to 2.3 mm at L5-S1. Intervertebral disc puncture can accelerate disc degeneration, disc herniation, and loss of disc height, a risk that may be avoidable. After institutional review board approval, research consent was obtained from women undergoing primary laparoscopic sacrocolpopexy. Intraoperatively, sacral sutures were placed in the ALL with a 1.5 cm diameter CV-2 needle using Gore-Tex suture. Depth measurements were collected using a laparoscopic ultrasound transducer positioned on the sacral promontory (SP) between the 2 ends of the needle visible through the ALL. Two still-frame US images of the single needle were taken using the BK Medical software. Needle depth was calculated by measuring the distance from the top of the ALL to the needle. Two satisfactory intraoperative images were obtained for all 9 participants. The mean needle depth at the SP was 3.96 mm. The interpatient needle depth varied from 2.07 to 9.04 mm. In most participants (78%), the sacral needle depth exceeded 2.3 mm, suggesting that there may be risk to sacral suture placement without depth guidance at the promontory. During minimally invasive sacrocolpopexy, the depth of the ALL and the placement of the needle at the SP may result in inadvertent disc penetration. Surgeons should be conscious of the minimal depth of the ALL and consider placing the suture below the promontory to avoid the disc.