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

No evidence of association between either Modic change or disc degeneration and five circulating inflammatory proteins

Introduction

Intervertebral disc degeneration and Modic change are the main spinal structural changes associated with chronic low back pain (LBP). Both conditions are thought to manifest local inflammation and if inflammatory proteins translocate to the blood circulation could be detected systemically. The work here assesses whether the presence of disc degeneration is associated with detectable blood level changes of five inflammatory markers and whether chronic LBP is associated with these changes.

Materials and Methods

Two hundred and forty TwinsUK cohort participants with both MRI disc degeneration grade and Modic change extent, and IL-6, IL-8, IL-8 TNF, and CX3CL1 protein blood concentration measurements were included in this work. Linear mixed effects models were used to test the association of blood cytokine concentration with disc degeneration score and Modic change volumetric score. Association of chronic LBP status from questionnaires with disc degeneration, Modic change, and cytokine blood concentration was also tested.

Results

No statistically significant association between disc degeneration or Modic change with cytokine blood concentration was found. Instead, regression analysis pointed strong association between cytokine blood concentration with body mass index for IL-6 and with age for IL-6 and TNF. Mild association was found between IL-8 blood concentration and body mass index. Additionally, LBP status was associated with Modic change volumetric score but not associated with any cytokine concentration.

Conclusions

We found no evidence that Modic change and disc degeneration are able to produce changes in tested blood cytokine concentration. However, age and body mass index have strong influence on cytokine concentration and both are associated with the conditions studied which may confound associations found in the literature. It is then unlikely that cytokines produced in the disc or vertebral bone marrow induce chronic LBP.

Postoperative Time Course of Avulsion-Type Herniation Focused on the Development of New Modic Changes and Their Effect on Short-Term Residual Low Back Pain

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the characteristics of newly developing Modic changes following discectomy and their impact on residual low back pain (LBP) in the early postoperative stage of lumbar disc herniation.

METHODS

We included 96 patients who underwent microscopic discectomy. Through MRI, we assessed new developments of Modic changes and the progression of disc degeneration at the surgical level. The presence of cartilaginous endplates was evaluated using resected specimens, and the main outcome was assessed using the visual analog scale (VAS). Further, the prevalence and time course of Modic changes, and their effects on clinical outcomes in the early postoperative period were examined.

RESULTS

A new development of Modic changes was detected in 28% of cartilaginous herniations at 6 months. Modic changes were observed more frequently in patients with cartilaginous herniation than in those without cartilaginous herniation postoperatively (P < .001). The VAS scores for LBP up to 6 months were greater in patients with Modic changes (P < .001) than those without; however, no significant differences were identified in the presence or absence of Modic changes over the year follow-up. The development of Modic changes was closely associated with residual LBP at 6 months (β:0.511, P < .001).

CONCLUSIONS

Modic changes develop predominantly in patients with avulsion-type herniation than in those with annular rupture at an earlier phase after discectomy. Furthermore, disc herniation with cartilaginous endplates may be associated with a slower decrease in LBP for up to 6 months, supporting the notion that newly developing endplate changes may cause residual LBP.

Evaluation of the efficacy, in terms of pain and disability, of a functional restoration programme in patients with chronic low back pain according to the presence of Modic 1 discopathy

OBJECTIVES

Modic type 1 disc disease (MD1) appears to be related to severe Chronic Low Back Pain (CLBP). Functional Restoration Programmes (FRP) recommended in CLBP may not be suitable for patients with MD1. The main objective was to evaluate the effectiveness of a FRP, on the perceived incapacity and the pain intensity, in patients with non-specific CLBP according to the presence of MD1.

METHODS

We performed a single-centre retrospective cohort study in which 271 patients were included. After one month in the FRP, this programme was considered "successful" if the pain visual analog scale had decreased by at least 20/100 millimetres and if the score of the French version of the Roland-Morris disability questionnaire had decreased by at least 4/24 points.

RESULTS

The 271 patients had an average age of 43.2 (8.0) years and 58.3% were women. Out of our entire population, 128 (47.2%) patients were considered successful, and 51 (18.8%) patients had MD1. In patients without MD1, there was 49.1% success while this rate was 39.2% in those with MD1, but this difference was not statistically significant.

CONCLUSIONS

We found no significant difference in the combination of pain and perceived disability after one month of a FRP in patients with CLBP without MD1 compared to those with CLBP with MD1. It therefore seems legitimate to offer FRP-type rehabilitation in patients with non-specific CLBP with MD1.

The effects of lumbar fusion and non-fusion surgery on the development of Modic changes

Background

The aim of this study was to investigate the influence of lumbar fusion and non-fusion surgery on the postoperative development of Modic changes (MCs).

Methods

A total of 270 patients who underwent lumbar fusion, microsequestrectomy, microdiscectomy, and microdecompression, and who were examined by pre- and postoperative magnetic resonance imaging during the period of January 2012 to December 2018, were included in this retrospective study. The incidence of new postoperative MCs and the change of volume of preexisting MCs after surgery were investigated.

Results

The total incidence of new MCs following lumbar surgical procedures was 36.3%. Lumbar fusion showed a tendency towards a lower postoperative incidence of new MCs than the other three lumbar surgical procedures. The first postoperative year seems to be the most active phase for the development of new MCs. The postoperative volumes of MCs in patients who underwent lumbar non-fusion procedures were significantly greater than those before surgery (P < 0.01). However, no significant difference was detected between pre- and postoperative volumes of MCs in patients with lumbar fusion (P > 0.05).

Conclusion

Lumbar surgical procedures contribute to the development of new MCs, particularly non-fusion surgeries. However, further studies are needed to confirm the clinical relevance of these findings.

Schmorl's nodes could be associated with intervertebral disc degeneration at upper lumbar levels and end-plate disease at lower lumbar level in patients with low back pain

Schmorl's nodes (SNs) have increasingly been recognized on vertebral end-plates using advanced imaging techniques. Even though vertebral end-plates are the closest structures to discs, their pathologies are underestimated in the etiology of low back pain (LBP). We aimed to detect the prevalence of SNs and other end-plate defects in subjects with/without LBP and to understand whether SNs were associated with LBP and spinal degeneration. Subjects were evaluated in terms of end-plate defects, intervertebral disc degeneration (IVDD), and vertebral end-plate changes (Modic changes) at all lumbar levels on lumbar spine magnetic resonance imagings (MRI). Control subjects were compared to patients with LBP. Higher Pfirrmann scores (OR: 2.696) and higher SN scores (OR: 8.076) were significantly associated with Modic changes at L4-L5 disc level. Patients with higher SN scores at L1-L2 or L2-L3 levels had approximately 7-fold increased risk of severe IVDD at the corresponding levels. The most significant factor associated with presence of SNs was body weight of the patients (OR: 1.417). The most significant factor associated with intensity of LBP was severe IVDD at L5-S1 level (OR: 3.670). Having higher total SN score had an OR of 1.230 (95% CI: 1.003-1.509; p = 0.047) for predicting LBP. Schmorl's nodes were seen in 33.1% of patients and 11.5% of asymptomatic subjects. Body weight was the most significant factor associated with SNs. The most significant factor associated with LBP was severe IVDD at L5-S1 level.

Novel use of robotics and navigation for anterior lumbar total disc replacement surgery

The ability to navigate the anterior lumbar disc space may improve clinical outcomes and implant longevity. However, no robotic navigation systems are presently authorized by the U.S. Food and Drug Administration to assist with anterior retroperitoneal lumbar interbody surgery. Furthermore, no studies to date have investigated such an application of this technology. This study examines the application of robotic navigation to anterior lumbar total disc replacement surgery to improve retroperitoneal exposure and orientation of the anterior lumbar spine, enhance coronal plane centralization of the implant, optimize surgical trajectory, and mitigate radiologic exposure. Postoperative outcomes of a small cohort of patients undergoing anterior lumbar total disc replacement surgery using robotic navigation were analyzed. The results of the study revealed that a modified use of the aforementioned robot-assisted surgical technology enhances coronal plane centralization and trajectory, all while mitigating radiologic exposure, resulting in more accurate placement of the implant within the intervertebral space at each level.

Posterior Dynamic Stabilization with Limited Rediscectomy for Recurrent Lumbar Disc Herniation

Objective

Recurrent lumbar disc herniation (RLDH) is the most common cause of sciatica after primary discectomy. The purpose of this study was to evaluate the efficacy of transpedicular dynamic stabilization (TDS) combined with limited rediscectomy in the treatment of single-level RLDH.

Methods

We retrospectively evaluated a consecutive series of 24 middle-aged patients who underwent TDS (Dynesys system) combined with limited rediscectomy (i.e., removing only extruded or loose disc fragments) for single-level Carragee type II and type IV RLDH between April 2012 and September 2017. Clinical results were evaluated with visual analog scale (VAS) for leg and low back pain, Oswestry Disability Index (ODI) scores, and complications. Imaging data include lumbar segment motion and intervertebral height.

Results

The mean follow-up period was 38 months. The VAS and ODI scores were significantly improved at the last follow-up. The average range of motion (ROM) at the stabilized segment was 6.4° before surgery and 4.2° at the last follow-up, with a 78.6% mean preservation (P < 0.05). Intervertebral height at the stabilized segment decreased slightly after surgery (P < 0.05). However, there was no further decline at the last follow-up. There were no cases of reherniation, screw loosening, or segmental instability.

Conclusions

TDS combined with limited rediscectomy resulted in an effective procedure in middle-aged patients with Carragee type II and type IV RLDH. It was able to stabilize the operated segment with partial motion preservation. Moreover, it could maintain disc height and decrease the risk of recurrence in patients with a large posterior annular defect.

The effectiveness of chemonucleolysis with condoliase for treatment of painful lumbar disc herniation

BACKGROUND

Chemonucleolysis with condoliase, which degrades chondroitin sulfate, could be a new, minimally invasive therapeutic option for patients with lumbar disc herniation (LDH). The purpose of this study was to analyze prognostic factors for clinical outcomes in LDH patients subjected to chemonucleolysis with condoliase.

METHODS

Inclusion criteria for this procedure were 1) 18-70 years of age; 2) unilateral leg pain and positive straight leg raise (SLR) (<70°) or femoral nerve stretching test; 3) subligamentous extrusion verified on magnetic resonance imaging; 4) neurological symptoms consistent with a compressed nerve root on magnetic resonance imaging (MRI) images; and 5) minimum six months of follow-up. In total, 82 patients (55 men, 27 women; mean age, 47.2 ± 15.5 years; mean follow-up, 9.1 ± 3.0 months) who underwent chemonucleolysis with condoliase for painful LDH were included. An improvement of 50% or more in the Visual analogue scale (VAS) of leg pain was classified as effective.

RESULTS

Seventy patients (85.4%) were classified into the effective (E) group and 12 patients (14.6%) into the less-effective (L) group. Surgical treatment was required in four patients. No severe adverse complications were reported; 41.3% of the patients developed disc degeneration of Pfirrmann grade 1 or more at the injected disc level. Univariate analysis revealed that young age (p = 0.036), without history of epidural or nerve root block (p = 0.024), and injection into the central portion of the intervertebral disc (p = 0.014) were significantly associated with clinical effectiveness. A logistic regression analysis revealed that injection into the central portion of the intervertebral disc (p = 0.049; odds ratio, 4.913; 95% confidence interval, 1.006-26.204) was significantly associated with clinical effectiveness.

CONCLUSIONS

Chemonucleolysis with condoliase is a safe and effective treatment for painful LDH; 85.4% of the patients showed improvement after the treatment without severe adverse events. To obtain the best outcome, condoliase should be injected into the center of the intervertebral disc.

Incidence and clinical impact of vertebral endplate changes after limited lumbar microdiscectomy and implantation of a bone-anchored annular closure device

BACKGROUND

An annular closure device (ACD) could potentially prevent recurrent herniation by blocking larger annular defects after limited microdiscectomy (LMD). The purpose of this study was to analyze the incidence of endplate changes (EPC) and outcome after LMD with additional implantation of an ACD to prevent reherniation.

METHODS

This analysis includes data from a) RCT study-arm of patients undergoing LMD with ACD implantation and b) additional patients undergoing ACD implantation at our institution. Clinical findings (VAS, ODI), radiological outcome (reherniation, implant integrity, volume of EPC) and risk factors for EPC were assessed.

RESULTS

Seventy-two patients (37 men, 47 ± 11.63yo) underwent LMD and ACD implantation between 2013-2016. A total of 71 (99%) patients presented with some degree of EPC during the follow-up period (14.67 ± 4.77 months). In the multivariate regression analysis, localization of the anchor was the only significant predictor of EPC (p = 0.038). The largest EPC measured 4.2 cm3. Reherniation was documented in 17 (24%) patients (symptomatic: n = 10; asymptomatic: n = 7). Six (8.3%) patients with symptomatic reherniation underwent rediscectomy. Implant failure was documented in 19 (26.4%) patients including anchor head breakage (n = 1, 1.3%), dislocation of the whole device (n = 5, 6.9%), and mesh dislocation into the spinal canal (n = 13, 18%). Mesh subsidence within the EPC was documented in 15 (20.8%) patients. Seven (9.7%) patients underwent explantation of the entire, or parts of the device.

CONCLUSION

Clinical improvement after LMD and ACD implantation was proven in our study. High incidence and volume of EPC did not correlate with clinical outcome. The ACD might prevent disc reherniation despite implant failure rates. Mechanical friction of the polymer mesh with the endplate is most likely the cause of EPC after ACD.

Clinical Implications of Vertebral Endplate Disruptions After Lumbar Discectomy: 3-Year Results from a Randomized Trial of a Bone-Anchored Annular Closure Device

Objective

Vertebral endplate disruptions (VEPD) are common findings on imaging after lumbar surgery. The objective of this study was to explore the clinical implications of VEPD development following lumbar discectomy with or without implant with a bone-anchored annular closure device (ACD).

Methods

This was a multicenter randomized controlled trial of patients with large postsurgical annular defects after limited lumbar discectomy who were randomized to additionally receive an ACD or no additional treatment. VEPD were identified on computed tomography and confirmed by an imaging core laboratory. Clinical outcomes included recurrent herniation, reoperation, Oswestry Disability Index, leg pain, and back pain. Patient follow-up in this study was 3 years.

Results

In the ACD group (n=272), the risk of reoperation was lower in patients with vs without VEPD (8% vs 24%, p<0.01), but no other clinical outcomes differed when stratified by VEPD prevalence or size. In the Control group (n=278), the risk of symptomatic reherniation was higher in patients with VEPD (41% vs 23%, p<0.01) and patients with the largest VEPD had the highest reoperation rates. Patient-reported outcomes were not associated with VEPD prevalence or size in the Control group.

Conclusion

VEPD had no significant influence on patient-reported outcomes at 3 years after lumbar discectomy. VEPD increased the risk of recurrence in patients treated with lumbar discectomy only, but had no negative influence in patients treated with the ACD.

Predictors of Treatment Success Following Limited Discectomy With Annular Closure for Lumbar Disc Herniation

Background

Previous studies have demonstrated bone-anchored annular closure to significantly reduce reherniation and reoperation rates after lumbar discectomy in patients with large annular defects. It is important to identify the prognostic factors that may be associated with successful treatment. This study aimed to identify predictors of treatment success in patients with lumbar disc herniation treated with limited microdiscectomy supplemented by a bone-anchored annular closure device (ACD).

Methods

This study was a retrospective analysis of 133 consecutive patients with lumbar disc herniation treated with the ACD. Treatment success was defined as ≥24% improvement in visual analog scale (VAS) for back pain, ≥39% improvement in VAS leg pain, and ≥33% in the Oswestry Disability Index (ODI), with the raw ODI score ≤48. Success was calculated at 3, 6, and 12 months after surgery. Potentially predictive outcomes included patient characteristics, operative data, and imaging outcomes, such as disc, facet, and end plate morphology. Logistic regression was used to determine the significant predictive factors for treatment success.

Results

After 3, 6, and 12 months, 97 of 131 (74%), 104 of 129 (81%), and 112 of 126 (89%) patients, respectively, achieved the success criteria. At 3 months follow-up, a higher proportion of younger (17-40 years) versus older (41-65 years) patients met the success criteria (P = .025). On the basis of logistic regression, the following factors were significantly associated with treatment success at 1 or more of the follow-up time points: sex (male), lower body mass index, higher baseline pain and ODI scores, lower grade preoperative disc degeneration, and the absence of a postoperative complication. The rates of index-level recurrent herniation and reoperation were 1.5% and 3.0%, respectively.

Conclusions

This real-world evidence supports a promising benefit-risk profile for augmenting limited microdiscectomy with a bone-anchored ACD and provides some insights into the patient populations that may have a greater chance of realizing significant improvements in pain and function.

Level of Evidence

2 (Cohort study).

Association between MRI findings and clinical outcomes in a period of 5 years after lumbar spine microdiscectomy

BACKGROUND

To evaluate the associations between magnetic resonance imaging (MRI) findings and pain, disability and quality of life before surgery and up to 5 years after lumbar microdiscectomy.

MATERIALS AND METHODS

Sixty-one patients who underwent one-level lumbar microdiscectomy by the same surgeon participated in this analytic, observational, prospective study. Lumbar spine MRI was performed preoperatively and 5 years postoperatively. Pain, disability and quality of life were measured with VAS, ODI, Roland Morris and SF-36 pre- and up to 5 years postoperatively. Subsequently associations between radiological findings and clinical outcomes were recorded.

RESULTS

Before surgery patients with disc extrusion or sequestration, with increased thecal sac compression (d > 2/3), with Modic changes (MC) 2 and 3 on the operated level and Pfirrmann grades IV and V on the operated and both adjacent discs presented the worst preoperative clinical outcomes. MC preoperatively were not related with postoperative results, in contrast with the type of disc herniation and thecal sac compression. Preoperative Pfirrmann grade IV and V on the operated and both adjacent discs and postoperative MC 2 and 3 on the operated level were related to poor clinical outcomes 36-60 months post-discectomy.

CONCLUSIONS

Extrusion or sequestration of the operated disc, increased compression of thecal sac, MC 2 and 3 on the operated level and Pfirrmann grades IV and V on the operated and adjacent discs were associated with the worst clinical outcomes. Nerve root impingement, facet joint arthritis, perineural fibrosis and disc granulation tissue had no effect on clinical scores.

Postoperative MRI findings 5 years after lumbar microdiscectomy

BACKGROUND

Lumbar microdiscectomy is a common procedure with satisfactory results; however, postoperative events like progressive adjacent level degeneration and perineural fibrosis can contribute to long-term pain. The purpose of the study was to evaluate MRI changes 5 years after lumbar microdiscectomy and assess their association with clinical parameters.

MATERIALS AND METHODS

A prospective study enrolling 61 patients who underwent microdiscectomy. Changes between preoperative and postoperative MRI findings were recorded, and these findings were tested for associations with demographic, clinical and perioperative parameters. The measured imaging parameters were degeneration of the operated and adjacent discs and endplates, morphology of the disc herniation, facet joints arthritis and the presence of postoperative perineural fibrosis.

RESULTS

Statistically significant differences were found between preoperative and postoperative morphology of the operated disc, facet joints arthritis and degeneration of the operated and caudal adjacent disc. There were no differences between preoperative and postoperative disc degeneration of the superior adjacent disc and in degeneration of the operated and adjacent endplates. Postoperatively perineural fibrosis was common; however, thecal sac compression and nerve root impingement were reduced. Age at the time of surgery was the only parameter associated with postoperative changes.

CONCLUSION

Five years after microdiscectomy, several postoperative MRI changes including operated disc's morphology, facet joints arthritis and degeneration of the operated and caudal adjacent disc were shown. Taking into consideration that participants were on average middle-aged, these changes could be attributed not only to the impact of the surgery but also to the natural history of lumbar spine degeneration.

Morphology and Clinical Relevance of Vertebral Endplate Changes Following Limited Lumbar Discectomy With or Without Bone-anchored Annular Closure

STUDY DESIGN

Post hoc analysis of a randomized controlled trial.

OBJECTIVE

To characterize the morphology and clinical relevance of vertebral endplate changes (VEPC) following limited lumbar discectomy with or without implantation of a bone-anchored annular closure device (ACD).

SUMMARY OF BACKGROUND DATA

Implantation of an ACD following limited lumbar discectomy has shown promise in reducing the risk of recurrent herniation in patients with large annular defects. However, the interaction between the ACD and the lumbar endplate over time is not well understood.

METHODS

Patients undergoing limited lumbar discectomy with large postsurgical annular defects were randomized intraoperatively to receive additional ACD implantation or limited lumbar discectomy only (Controls). VEPC morphology, area, and volume were assessed with low-dose computed tomography preoperatively and at 1 and 2 years follow-up.

RESULTS

Of 554 randomized patients, the as-treated population consisted of 550 patients (267 ACD, 283 Controls). VEPC were preoperatively identified in 18% of patients in the ACD group and in 15% of Controls. At 2 years, VEPC frequency increased to 85% with ACD and 33% in Controls. Device- or procedure-related serious adverse event (8% vs. 17%, P = 0.001) and secondary surgical intervention (5% vs. 13%, P < 0.001) favored the ACD group over Controls. In the ACD group, clinical outcomes were comparable in patients with and without VEPC at 2 years follow-up. In the Control group, patients with VEPC at 2 years had higher risk of symptomatic reherniation versus patients without VEPC (35% vs. 19%, P < 0.01) CONCLUSION.: In patients with large annular defects following limited lumbar discectomy, additional implantation with a bone-anchored ACD reduces risk of postoperative complications despite a greater frequency of VEPC. VEPC were associated with higher risk of symptomatic reherniation in patients treated with limited lumbar discectomy, but not in those who received additional ACD implantation.

LEVEL OF EVIDENCE

2.

Recurrent lumbar disc herniation recurrence after percutaneous endoscopic lumbar discectomy: A case report

RATIONALE

Lumbar disc herniation (LDH) is a degenerative disease and affects human health. Although percutaneous endoscopic lumbar discectomy (PELD) can redeem the living quality of patient with LDH rapidly, it appears weak to limit the recurrence rate of LDH.

PATIENT CONCERNS

A 52-year-old male suffered lower back pain and lower limb paralysis for 20 years. However, conservative treatment could not relieve above-mentioned symptoms after doing heavy labor.

DIAGNOSES

Computed tomography (CT) revealed a disc fragment had migrated to the inferior edge of the L5 pedicle. Magnetic resonance imaging (MRI) demonstrated a type 2 Modic change (MC) at L5 and spinal canal stenosis at L4-L5. Based on these findings, the patient was diagnosed with L4-L5 disc herniation and secondary lumbar stenosis.

INTERVENTIONS

The patient underwent surgery twice for PELD at L4-L5 in 1 month. Symptoms were not improved effectively until the conventional posterior discectomy with fusion was performed.

OUTCOMES

No signs of recurrence have been detected in 6 months of follow-up, except for mild lower back pain meeting the temperature change.

LESSONS

Rapid decompression and instant therapeutic effect do not mean extending the indications of PELD. It is unreasonable to revise the recurrent LDH or treat the primary LDH with PELD under inadequate preoperative assessment.

Lumbar Vertebral Endplate Defects on Magnetic Resonance Images: Classification, Distribution Patterns, and Associations with Modic Changes and Disc Degeneration

STUDY DESIGN

A cross-sectional magnetic resonance (MR) imaging study.

OBJECTIVE

To classify and characterize endplate defects using routine lumbar MR images and to determine associations of endplate defects with Modic changes (MCs) and disc degeneration.

SUMMARY OF BACKGROUND DATA

Previously, a cadaveric study revealed that endplate lesions were common and associated with back pain history. New in vivo approaches appropriate for clinical studies are needed to further this potentially important line of research on the clinical significance of endplate lesions, including their relation with MCs, disc degeneration, and back pain.

METHODS

Using a MRI archive, 1564 endplates of 133 subjects (59 men and 74 women, mean age 58.9 ± 11.9 years) with the presence of MCs were retrospectively collected from April of 2014 to June of 2015. On the basis of morphological characteristics, a protocol was proposed to identify three distinct types of endplate defects, including focal, corner, and erosive defects. The location, size, and distribution patterns of various endplate lesions were characterized. MCs and disc degeneration were measured to examine their associations with endplate defects.

RESULTS

Endplate defects were observed in 27.8% of endplates studied. Greater age was associated with the presence of endplate defects. Focal defects were the most common (13.5%), followed by erosive defects (11.1%) and corner defects (3.2%). Defect types also differed in size and distribution patterns. Endplate defects and MCs had similar distribution patterns in the lumbar spine. The presence of endplate defects were associated with the presence of MCs (odds ratio = 4.29, P < 0.001), and associated with less disc signal intensity and disc height, and greater disc bulging (P < 0.05).

CONCLUSION

The three endplate defects identified on routine MR images appear to represent different pathologies and may play a key role in the pathogenesis of MCs. This classification system may facilitate clinical studies on endplate defects.

LEVEL OF EVIDENCE

4.

Quantification of Propionic Acid in the Bovine Spinal Disk After Infection of the Tissue With Propionibacteria acnes Bacteria

STUDY DESIGN

Research.

OBJECTIVE

The goal of this study was to investigate whether Propionibacteria acnes infection of the intervertebral disc can be detected noninvasively by nuclear magnetic resonance (NMR) spectroscopy.

SUMMARY OF BACKGROUND DATA

Microbiological studies of surgical samples suggest that a significant subpopulation of back pain patients may have occult disc infection with P. acnes bacteria. This hypothesis is further supported by a double-blind clinical trial showing that back pain patients with Modic type 1 changes may respond to antibiotic treatment. Because significant side effects are associated with antibiotic treatment, there is a need for a noninvasive method to detect whether specific discs in back pain patients are infected with P acnes bacteria.

METHODS

P. acnes bacteria were obtained from human patients. NMR detection of a propionic acid (PA) in the bacteria extracts was conducted on 500 MHz high-resolution spectrometer, whereas in vivo NMR spectroscopy of an isolated bovine disk tissue infected with P. acnes was conducted on 7 T magnetic resonance imaging scanner.

RESULTS

NMR spectra of P. acnes metabolites revealed a distinct NMR signal with identical chemical shits (1.05 and 2.18 ppm) as PA (a primary P. acne metabolite). The 1.05 ppm signal does not overlap with other bacteria metabolites, and its intensity increases linearly with P. acnes concentration. Bovine disks injected with P. acnes bacteria revealed a very distinct NMR signal at 1.05 ppm, which linearly increased with P. acnes concentration.

CONCLUSION

The 1.05 ppm NMR signal from PA can be used as a marker of P. acnes infection of discs. This signal does not overlap with other disc metabolites and linearly depends on P. acnes concentration. Consequently, NMR spectroscopy may provide a noninvasive method to detect disc infection in the clinical setting.

LEVEL OF EVIDENCE

N/A.

Cartilage Endplate Thickness Variation Measured by Ultrashort Echo-Time MRI Is Associated With Adjacent Disc Degeneration

STUDY DESIGN

A magnetic resonance imaging study of human cadaver spines.

OBJECTIVE

To investigate associations between cartilage endplate (CEP) thickness and disc degeneration.

SUMMARY OF BACKGROUND DATA

Damage to the CEP is associated with spinal injury and back pain. However, CEP morphology and its association with disc degeneration have not been well characterized.

METHODS

Ten lumbar motion segments with varying degrees of disc degeneration were harvested from six cadaveric spines and scanned with magnetic resonance imaging in the sagittal plane using a T2-weighted two-dimensional (2D) sequence, a three-dimensional (3D) ultrashort echo-time (UTE) imaging sequence, and a 3D T1ρ mapping sequence. CEP thicknesses were calculated from 3D UTE image data using a custom, automated algorithm, and these values were validated against histology measurements. Pfirrmann grades and T1ρ values in the disc were assessed and correlated with CEP thickness.

RESULTS

The mean CEP thickness calculated from UTE images was 0.74 ± 0.04 mm. Statistical comparisons between histology and UTE-derived measurements of CEP thickness showed significant agreement, with the mean difference not significantly different from zero (P = 0.32). Within-disc variation of T1ρ (standard deviation) was significantly lower for Pfirrmann grade 4 than Pfirrmann grade 3 (P < 0.05). Within-disc variation of T1ρ and adjacent CEP thickness heterogeneity (coefficient of variation) had a significant negative correlation (r = -0.65, P = 0.04). The standard deviation of T1ρand the mean CEP thickness showed a moderate positive correlation (r = 0.40, P = 0.26).

CONCLUSION

This study demonstrates that quantitative measurements of CEP thickness measured from UTE magnetic resonance imaging are associated with disc degeneration. Our results suggest that variability in CEP thickness and T1ρ, rather than their mean values, may serve as valuable diagnostic markers for disc degeneration.

LEVEL OF EVIDENCE

N/A.

Inflammatory response of disc cells against Propionibacterium acnes depends on the presence of lumbar Modic changes

PURPOSE

Intervertebral disc with Propionibacterium acnes (P. acnes) is suggested to be an etiology of Modic type I changes in the adjacent bone marrow. However it is unknown if disc cells can respond to P. acnes and if bone marrow cells respond to bacterial and disc metabolites draining from infected discs.

METHODS

Human disc cells (n = 10) were co-cultured with 10- and 100-fold excess of P. acnes over disc cells for 3 h and 24 h. Lipopolysaccharide was used as positive control. Expression of IL1, IL6, IL8, and CCL2 by disc cells was quantified by quantitative PCR. Lipase activity was measured in culture supernatants (n = 6). Human vertebral bone marrow mononuclear cells (BMNCs) (n = 2) were cultured in conditioned media from disc cell/P. acnes co-cultures and expression of IL1, IL6, IL8, and CCL2 was measured after 24 h.

RESULTS

All disc cells responded to lipopolysaccharide but only 6/10 responded to P. acnes with increased cytokine expression. Cytokine increase was time- but not P. acnes concentration-dependent. Disc cell responsiveness was associated with the presence of lumbar Modic changes in the donor. Lipase activity was increased independent of disc cell responsiveness. BMNCs responded with inflammatory activity only when cultured in supernatants from responsive disc cell lines.

CONCLUSION

Disc cell responsiveness to P. acnes associates with the presence of lumbar Modic changes. Furthermore, bone marrow cells had an inflammatory response to the cocktail of disc cytokines and P. acnes metabolites. These data indicate that low virulent P. acnes infection of the disc is a potential exacerbating factor to Modic changes.

Modic type 1 change is an autoimmune response that requires a proinflammatory milieu provided by the 'Modic disc'

BACKGROUND CONTEXT

Modic changes (MCs) are magnetic resonance imaging (MRI) evidence of inflammatory and fibrotic vertebral bone marrow lesions that associate with adjacent disc degeneration and end plate damage. Although MC etiology is uncertain, historical data suggest a linkage to an autoimmune response of bone marrow triggered by the nucleus pulposus (NP).

PURPOSE

The aim of this study was to test whether bone marrow has an autoimmune response to NP cells that is amplified by an inflammatory milieu and ultimately leads to MC development in vivo. We hypothesized that an inflammatory co-stimulus is required for bone marrow/NP crosstalk to stimulate MC.

STUDY DESIGN

This is an in-vitro cell co-culture study plus in-vivo experiments in rat caudal vertebrae.

METHODS

In in-vitro study, bone marrow mononuclear cells (BMNCs) and NP cells (NPCs) from rats were co-cultured with and without interleukin (IL)-1α stimulation. Cell viability (n=3) of BMNCs and NPCs and gene expression (n=7) were analyzed. In in-vivo study, proinflammatory lipopolysaccharide (LPS) and control disc nucleus surrogates (NP micromass pellets) were generated in vitro from rat NPCs and implanted into rat tail vertebrae, and the response was compared with sham surgery (n=12 each). Tissue changes were investigated with T1w and T2w MRI (7T), histology, and immunohistochemistry (tumor necrosis factor, CD3) 1 (n=6) and 2 weeks (n=6) after implantation.

RESULTS

BMNC/NPC co-culture significantly increased lymphocyte viability (42%-69%, p<.05) and reduced NPC viability (96%-88%, p<.001), indicating immunogenicity of NPC. However, IL-1α was required to cause significant transcriptional upregulation of IL-1, IL-6, IL-10, and tropomyosin receptor kinase A. Therefore, an inflammatory activation is required to amplify the immune response. Immunogenicity of the NP was corroborated in vivo by CD3 cell accumulation around LPS and control disc surrogates at Day 7. However, only the LPS disc surrogate group demonstrated infiltration of CD3 cells at Day 14. Furthermore, end plate defects (p<.05, LPS: n=4/6, Ctrl: n=0/6, sham: n=0/6) and MC1-like MRI changes (T2w hyperintensity, p<.05) were only seen with LPS disc surrogates.

CONCLUSIONS

NPCs are immunogenic but cannot trigger MC without an additional proinflammatory stimulus. Our data suggest that MC requires end plate defects that allow marrow/NPC co-mingling plus an adjacent inflammatory "MC disc" that can amplify the immune response.

Endplate changes after lumbar discectomy with and without implantation of an annular closure device

BACKGROUND

The implantation of a bone-anchored annular closure device (ACD) might be associated with the developed new endplate changes (EPC) after surgery.

METHODS

A post hoc analysis has been done in patients from a prospective randomized multicenter study. All patients underwent limited lumbar discectomy with intraoperative randomization into the groups limited lumbar discectomy alone or additional ACD implantation. Low-dose lumbar computed tomography (CT) and clinical investigations were performed preoperatively and 12 months after the operation.

RESULTS

A total of 554 patients were randomized. After exclusion of dropouts, the per-protocol population included 493 patients (251 in the control group and 242 in the ACD group); the follow-up rate was ≥ 90%. The number of patients showing EPC at baseline was similar in both groups. The number of patients showing EPC and the total EPC lesion area significantly increased in both groups over time, but significantly increased more in the EPC group for the superior and inferior endplate (all P < 0.0001). There was no association of pre-existing number and size of EPC with sex, age, or smoking habits. Correlation of clinical variables showed no relation with number, size, and increase of EPC area after surgery.

CONCLUSIONS

Patients with primary lumbar disc herniation show EPC in the corresponding segments. There is a significant increase of lesion number and size within 12 months after discectomy. This increase is significantly more pronounced in the ACD group. Presence and growth of EPC is not correlated with low-back pain or ODI.

Performance of an Annular Closure Device in a 'Real-World', Heterogeneous, At-Risk, Lumbar Discectomy Population

Study design/setting

Retrospective analysis of single-center registry outcomes data.

Objective

Assess the utility of an annular closure device (ACD) as an adjunct to limited discectomy for lumbar disc herniation (LDH).

Background

Recurrent lumbar disc herniation (rLDH) following limited discectomy persists at clinically significant rates, especially in large annular defect (at least 6 mm width) patients. While the etiology of reherniation is often multifactorial, inadequate annular occlusion remains one of the foremost considerations. Accordingly, annular closure has emerged as a promising technique and is the focus of this analysis.

Methods

This was a retrospective analysis of 171 patients who underwent limited lumbar discectomy with an ACD for LDH. Standardized patient assessment was performed preoperatively, three months postoperatively, and 12 months postoperatively, in addition to self-presented visits. No minimum last follow-up was required for inclusion. Oswestry Disability Index (ODI) and Visual Analog Scale (VAS Leg/Back) pain scores were collected at all visits. Plain radiographs were obtained at all visits, with magnetic resonance imaging (MRI) scans performed annually and/or when patients presented as symptomatic. ACD-related complications due to partial or complete mesh detachment from the titanium anchor were reported. All secondary surgical interventions were also reported. The Wilcoxon Rank-sum test was used to compare outcomes and events between sub-groups (p < 0.05).

Results

Mean last follow-up for all patients was 15 months. Large annular defects were present in 154 patients (90%). Symptomatic reherniations were observed in six patients (3.5%; five were present in the large annular defect subpopulation). All patients demonstrated clinically meaningful improvement in clinical outcome scores at both follow-up intervals. ACD mesh detachment was observed in 15 patients (8.8%; two underwent a subsequent surgical intervention). No symptomatic reherniations were observed in secondary herniation patients compared to six (4.1%) in the primary herniation group (p = 0.60).

Conclusions

Annular closure with the ACD results in clinically meaningful improvements in both primary and secondary LDH patients, with decreased rates of reherniation in high-risk patients compared to previous discectomy reports.

MRI findings in lumbar spine following O2-O3 chemiodiscolysis: A long-term follow-up

Intradiscal O2-O3 injections are conventionally used as a minimally invasive treatment for lumbar disc herniation in patients not responding to conservative treatments. The aim of the present study is to report data of long-term imaging follow-up (3 years) of patients treated with intradiscal O2-O3 lumbar chemiodiscolysis. We evaluated the changes of disc volume and the modifications in disc appearance (in terms of disc degeneration) and endplate changes (according to Modic), comparing the results with a control group of patients. Our results showed a stable reduction of the disc herniation volume in patients treated compared with the control group, while we did not find statistically significant differences in terms of disc degeneration and endplate changes (Modic). We concluded that the O2-O3 discolysis, despite leading to a significant shrinkage of the disc herniation, does not involve - in the long term - biomechanical changes of the spine in terms of acceleration of the disc degeneration process in comparison with the natural course.

Endoscope-Assisted Abscess Drainage Secondary to Endoscope-Assisted Transforaminal Lumbar Interbody Fusion: 1-Year Follow-Up

INTRODUCTION

Endoscopic discectomy and fusions have been gaining popularity in the recent past and are noted to be safe for their application in elderly population. The procedure involves ultra-small incision for discectomy followed by placement of percutaneous screws in awake patients. Treatment of advanced spinal pathology with endoscope-assisted techniques is challenging. Although not common with the endoscopic approach, postoperative infection can be problematic, as there are no established guidelines on its management.

METHODS

A 76-year-old female patient underwent lumbar 4-5 endoscopic-assisted transforaminal lumbar interbody fusion for severe degenerative changes leading to back and radicular leg pain. She did well postoperatively and was discharged home the following day. She presented to the outside hospital with new onset of severe back pain, sepsis, and positive methicillin-susceptible Staphylococcus aureus with blood culture and demonstrated no improvement while on antibiotics.

RESULTS

Initial magnetic resonance imaging revealed postoperative changes only. With positive blood culture and localized pain, she was then offered to undergo a percutaneous drainage of the abscess. Under local anesthesia and intravenous sedation, a small pocket of collection was found along the endoscopic trajectory from previous surgery. After evacuation of the collection, the interbody device was irrigated with vancomycin through endoscope. Postoperatively, immediate symptomatic improvement was noted in back pain. She was discharged home on oxacillin and continues to do well at 12 months' follow-up with excellent fusion.

CONCLUSIONS

The present case illustrates the successful treatment of a surgical-site infection after endoscope-assisted transforaminal lumbar interbody fusion via a repeat percutaneous endoscopic approach.

Minimum Clinically Important Difference: Current Trends in the Spine Literature

STUDY DESIGN

Review of the 2011 to 2015 minimum clinically important difference (MCID)-related publications in Spine, Spine Journal, Journal of Neurosurgery-Spine, and European Spine Journal.

OBJECTIVE

To summarize the various determinations of MCID and to analyze its usage in the spine literature of the past 5 years in order to develop a basic reference to help practitioners interpret or utilize MCID.

SUMMARY OF BACKGROUND DATA

MCID represents the smallest change in a domain of interest that is considered beneficial to a patient or clinician. The many sources of variation in calculated MCID values and inconsistency in its utilization have resulted in confusion in the interpretation and use of MCID.

METHODS

All articles from 2011 to 2015 were reviewed. Only clinical science articles utilizing patient reported outcome scores (PROs) were included in the analysis. A keyword search was then performed to identify articles that used MCID. MCID utilization in the selected papers was characterized and recorded.

RESULTS

MCID was referenced in 264/1591 (16.6%) clinical science articles that utilized PROs: 22/264 (8.3%) independently calculated MCID values and 156/264 (59.1%) used previously published MCID values as a gauge of their own results. Despite similar calculation methods, there was a two- or three-fold range in the recommended MCID values for the same instrument. Half the studies recommended MCID values within the measurement error. Most studies (97.2%) using MCID to evaluate their own results relied on generic MCID. The few studies using specific MCID (MCID calculated for narrowly defined indications or treatments) did not consistently match the characteristics of their sample to the specificity of the MCID. About 48% of the studies compared group averages instead of individual scores to the MCID threshold.

CONCLUSION

Despite a clear interest in MCID as a measure of patient improvement, its current developments and uses have been inconsistent.

LEVEL OF EVIDENCE

N/A.

Defects of the vertebral end plate: implications for disc degeneration depend on size

BACKGROUND CONTEXT

Bony vertebral end plates must be porous to allow metabolite transport into the disc, and yet strong to resist high intradiscal pressure (IDP). End plate defects may therefore have nutritional and mechanical consequences for the disc, depending on their size and type. We hypothesize that broad, diffuse defects are more closely associated with disc decompression and degeneration than are focal Schmorl's node-type defects.

PURPOSE

This study aimed to determine how the size and type of end plate defects are related to decompression and degeneration in the adjacent intervertebral disc.

STUDY DESIGN

Mechanical, histologic, and micro-computed tomographic investigations were carried out in cadaver spines.

METHODS

The study involved 40 motion segments (T8-T9 to L4-L5) dissected from 23 cadavers aged 48-98 years. Intradiscal stresses were measured, under 1 kN compression, by pulling a pressure transducer along the disc's midsagittal diameter. The resulting "stress profiles" revealed nucleus pressure (IDP) and maximum stresses in the anterior and posterior annulus. Micro-computed tomography was then used to examine all 40 discs, with 5 mm of adjacent bone on either side, so that end plate defects could be characterized at a resolution of 35 µm. Cross-sectional area (in the transverse plane), volume, location, and morphologic type were determined for all bony defects in the 80 end plates. Finally, discs from each motion segment (with hyaline cartilage and bone attached) were sectioned (undecalcified) at 7 µm for histology to allow degeneration to be assessed.

RESULTS

Substantial defects were identified in 24 of 40 specimens (35 of 80 end plates). Of these, 83% was centrally located, and 17% was laterally located. Defects occurred more frequently in male than female specimens (p=.043), and were more common in thoracic than lumbar end plates (p=.002), although lumbar defects were greater in volume (p=.05). Defect area and volume increased with decreasing IDP, with decreasing peak stress in the annulus, and with increasing tissue degeneration. Stepwise multiple regression showed that average defect area depended most strongly on IDP, whereas maximum defect area and volume depended most strongly on peak stress in the anterior annulus. Multiple end plate defects were associated with lower values of IDP and higher degeneration scores when compared with erosions and Schmorl's nodes.

CONCLUSIONS

Disc degeneration has a stronger association with large or multiple end plate defects than with small or single defects (of any type). Large end plate defects probably allow greater volume changes within the disc, leading to greater nucleus decompression.

ISSLS PRIZE IN BASIC SCIENCE 2017: Intervertebral disc/bone marrow cross-talk with Modic changes

STUDY DESIGN

Cross-sectional cohort analysis of patients with Modic Changes (MC).

OBJECTIVE

Our goal was to characterize the molecular and cellular features of MC bone marrow and adjacent discs. We hypothesized that MC associate with biologic cross-talk between discs and bone marrow, the presence of which may have both diagnostic and therapeutic implications.

BACKGROUND DATA

MC are vertebral bone marrow lesions that can be a diagnostic indicator for discogenic low back pain. Yet, the pathobiology of MC is largely unknown.

METHODS

Patients with Modic type 1 or 2 changes (MC1, MC2) undergoing at least 2-level lumbar interbody fusion with one surgical level having MC and one without MC (control level). Two discs (MC, control) and two bone marrow aspirates (MC, control) were collected per patient. Marrow cellularity was analyzed using flow cytometry. Myelopoietic differentiation potential of bone marrow cells was quantified to gauge marrow function, as was the relative gene expression profiles of the marrow and disc cells. Disc/bone marrow cross-talk was assessed by comparing MC disc/bone marrow features relative to unaffected levels.

RESULTS

Thirteen MC1 and eleven MC2 patients were included. We observed pro-osteoclastic changes in MC2 discs, an inflammatory dysmyelopoiesis with fibrogenic changes in MC1 and MC2 marrow, and up-regulation of neurotrophic receptors in MC1 and MC2 bone marrow and discs.

CONCLUSION

Our data reveal a fibrogenic and pro-inflammatory cross-talk between MC bone marrow and adjacent discs. This provides insight into the pain generator at MC levels and informs novel therapeutic targets for treatment of MC-associated LBP.

Pathobiology of Modic changes

PURPOSE

Low back pain (LBP) is the most disabling condition worldwide. Although LBP relates to different spinal pathologies, vertebral bone marrow lesions visualized as Modic changes on MRI have a high specificity for discogenic LBP. This review summarizes the pathobiology of Modic changes and suggests a disease model.

METHODS

Non-systematic literature review.

RESULTS

Chemical and mechanical stimulation of nociceptors adjacent to damaged endplates are likely a source of pain. Modic changes are adjacent to a degenerated intervertebral disc and have three generally interconvertible types suggesting that the different Modic change types represent different stages of the same pathological process, which is characterized by inflammation, high bone turnover, and fibrosis. A disease model is suggested where disc/endplate damage and the persistence of an inflammatory stimulus (i.e., occult discitis or autoimmune response against disc material) create predisposing conditions. The risk to develop Modic changes likely depends on the inflammatory potential of the disc and the capacity of the bone marrow to respond to it. Bone marrow lesions in osteoarthritic knee joints share many characteristics with Modic changes adjacent to degenerated discs and suggest that damage-associated molecular patterns and marrow fat metabolism are important pathogenetic factors. There is no consensus on the ideal therapy. Non-surgical treatment approaches including intradiscal steroid injections, anti-TNF-α antibody, antibiotics, and bisphosphonates have some demonstrated efficacy in mostly non-replicated clinical studies in reducing Modic changes in the short term, but with unknown long-term benefits. New diagnostic tools and animal models are required to improve painful Modic change identification and classification, and to clarify the pathogenesis.

CONCLUSION

Modic changes are likely to be more than just a coincidental imaging finding in LBP patients and rather represent an underlying pathology that should be a target for therapy.

Propionibacterium acnes infected intervertebral discs cause vertebral bone marrow lesions consistent with Modic changes

Modic type I change (MC1) are vertebral bone marrow lesions adjacent to degenerated discs that are specific for discogenic low back pain. The etiopathogenesis is unknown, but occult discitis, in particular with Propionibacteria acnes (P. acnes), has been suggested as a possible etiology. If true, antibiotic therapy should be considered for patients with MC1. However, this hypothesis is controversial. While some studies report up to 40% infection rate in herniated discs, others fail to detect infected discs and attribute reports of positive cultures to contamination during sampling procedure. Irrespective of the clinical controversy, whether it is biologically plausible for P. acnes to cause MC1 has never been investigated. Therefore, the objective of this study was to test if P. acnes can proliferate within discs and cause reactive changes in the adjacent bone marrow. P. acnes was aseptically isolated from a symptomatic human L4/5 disc with MC1 and injected into rat tail discs. We demonstrate proliferation of P. acnes and up-regulation of IL-1 and IL-6 within three days of inoculation. At day-7, disc degeneration was apparent along with fibrotic endplate erosion. TNF-α immunoreactivity was enhanced within the effected endplates along with cellular infiltrates. The bone marrow appeared normal. At day-14, endplates and trabecular bone close to the disc were almost completely resorbed and fibrotic tissue extended into the bone marrow. T-cells and TNF-α immunoreactivity were identified at the disc/marrow junction. On MRI, bone marrow showed MC1-like changes. In conclusion, P. acnes proliferate within the disc, induce degeneration, and cause MC1-like changes in the adjacent bone marrow. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1447-1455, 2016.