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

Ex-vivo biomechanical evaluation of the application of a novel annulus closure device to closure of annulus fibrosus

Objective

To investigate the technical feasibility of applying a simple suture guide device to close the annulus fibrosus (AF) of the intervertebral discs (IVD).

Methods

30 sheep functional discal units (FDUs) were obtained and subjected to mock discectomy. Mock sutures were performed using 3-0 non-absorbable sutures under a novel AF suture device following a suture procedure. The FDUs were compressed under axial loading at 1.8 mm/min and evaluated for Failure load (N).

Results

The failure loads of the hand stitching group (Group H) and suture device stitching group (Group S) were significantly higher than those of the control group (Group C) (p = 0.033; p < 0.001).

Conclusion

This study provides reasonable reasons to believe that the simple suture guide device described here is technically feasible for AF defect closure. It thus constitutes an encouraging proof of concept for the proposed device; however, it does not constitute a complete demonstration of the device's feasibility in the clinical setting considering that the annulus closure operation is performed ex vivo on functional spinal units, as opposed to within an environment that mimics the clinical setting. To this end, confirmatory experiments will be conducted such as more multiaxial or dynamic mechanical testing, and notably performing the surgery on sheep models instead of on ex vivo functional spinal units.

Cellular behavior and extracellular matrix turnover in bovine annulus fibrosus cells under hydrostatic pressure and deviatoric strain

Intervertebral disc herniation is a common spinal disorder that is often treated with discectomy when conservative measures fail. To devise therapeutic strategies for tears in the annulus fibrosus (AF), the regenerative capability of AF cells under spinal loading needs to be addressed. We hypothesized that the compressive loading associated with deformation in AF cells reduces synthetic and degradative activities in extracellular matrix and cell proliferation. We evaluated expression of key matrix molecules and cell proliferation by RT-PCR and immunohistochemistry by inner and outer bovine AF cells incubated under hydrostatic pressure (HP), arc-bending strain (Strain), and combined HP and Strain (HP/Strain) mimicking spinal loading. Inner AF cells showed significantly increased levels of aggrecan core protein, chondroitin sulfate N-acetylgalactosaminyltransferase-1, and tissue inhibitor of metalloproteinases-2 by 6 days under HP (p < 0.05), with a tendency toward increased matrix metalloproteinase-13. Outer AF cells demonstrated a significant decline in collagen type-2 under Strain and HP/Strain (p < 0.05) and a tendency toward suppression of collagen type-1 and elastin expression compared to HP and unloaded control. On the other hand, proliferating cell nucleus antigen increased significantly under Strain and HP/Strain in inner AF and declined under unloaded and HP in outer AF (p < 0.05). Immunohistology findings supported reductions in gene expressions of matrix molecules. Thus, changes in HP/Strain in AF appear to diminish synthetic and degradative activities while increasing cell proliferation. To promote regeneration, continuous overloading should be avoided, as it converts the synthetic activity to a state in which tissue repair is limited.

Annulus Fibrosus Repair for Lumbar Disc Herniation: A Meta-Analysis of Clinical Outcomes From Controlled Studies

STUDY DESIGN

Meta-analysis.

OBJECTIVES

This study aimed to summarize the clinical efficacy and safety of the various annular defect repair methods that have emerged in recent years.

METHODS

A meta-analysis of randomized and non-randomized controlled trials was conducted. Articles from PubMed, Embase, and the Cochrane Library (CENTRAL) on Lumbar disc herniation treatment with annular repair published from inception to April 2, 2022 were included. We summarized the clinical efficacy and safety of annular repair techniques based on a random-effects model meta-analysis.

RESULTS

7 randomized controlled studies and 8 observational studies with a total of 2161 participants met the inclusion criteria. The pooled data analysis showed that adding the annular repair technique reduced postoperative recurrence rate, reoperation rate, and loss of intervertebral height compared with lumbar discectomy alone. Subgroup analysis based on different annular repair techniques showed that the Barricaid Annular Closure Device (ACD) was effective in preventing re-protrusion and reducing reoperation rates, while there was no significant difference between the other subgroups. The annulus fibrosus suture (AFS) did not improve the postoperative Oswestry Disability Index (ODI). No statistically significant difference was observed in the incidence of adverse events between the annular repair and control groups.

CONCLUSIONS

Lumbar discectomy combined with ACD can effectively reduce postoperative recurrence and reoperation rates in patients with LDH. AFS alone was less effective in reducing recurrence and reoperation rates and did not improve postoperative pain and function.

Morphological changes after open lumbar microdiscectomy at 2-year follow-up

BACKGROUND

It is known that a possible decrease in disc height (DH) and foraminal size after open lumbar microdiscectomy (OLM) may cause pain in the long term. However, there is still insufficient information about the short- or long-term pathoanatomical and morphological effects of microdiscectomy. For example, the exact temporal course of the change in DH is not well known.

OBJECTIVE

The purpose of this study was to examine morphological changes in DH and foramen dimensions after OLM.

METHODS

In patients who underwent OLM for single-level lumbar disc herniation, MRI scans were obtained before surgery, and at an average of two years after surgery. In addition to DH measurements, foraminal area (FA), foraminal height (FH), superior foraminal width (SFW), and inferior foraminal width (IFW), were measured bilaterally.

RESULTS

A postoperative increase in DH was observed at all vertebral levels, with an average of 5.5%. The mean right FHs were 15.3 mm and 15.7 mm before and after surgery, respectively (p= 0.062), while the left FHs were 14.8 mm and 15.8 mm before and after surgery (p= 0.271). The mean right SFW was 5.4 mm before surgery and 5.7 mm after surgery, while the mean right IFW ranged from 3.6 mm to 3.9 mm. The mean left SFW was 4.8 mm before surgery and 5.2 mm after surgery, while the mean left IFW ranged from 3.5 mm to 3.9 mm. Before surgery, the FAs were, on average, 77.1 mm2 and 75.6 mm2 on the right and left sides, respectively. At the 2-year follow-up, the mean FAs were 84.0 mm2 and 80.2 mm2 on the right and left sides, respectively.

CONCLUSIONS

Contrary to prevalent belief, in patients who underwent single-level unilateral OLM, we observed that there may be an increase rather than a decrease in DH or foramen size at the 2-year follow-up. Our findings need to be confirmed by studies with larger sample sizes and longer follow-ups.

Design principles in mechanically adaptable biomaterials for repairing annulus fibrosus rupture: A review

Annulus fibrosus (AF) plays a crucial role in the biomechanical loading of intervertebral disc (IVD). AF is difficult to self-heal when the annulus tears develop, because AF has a unique intricate structure and biologic milieu in vivo. Tissue engineering is promising for repairing AF rupture, but construction of suitable mechanical matching devices or scaffolds is still a grand challenge. To deeply know the varied forces involved in the movement of the native annulus is highly beneficial for designing biomimetic scaffolds to recreate the AF function. In this review, we overview six freedom degrees of forces and adhesion strength on AF tissue. Then, we summarize the mechanical modalities to simulate related forces on AF and to assess the characteristics of biomaterials. We finally outline some current advanced techniques to develop mechanically adaptable biomaterials for AF rupture repair.

Combining adhesive and nonadhesive injectable hydrogels for intervertebral disc repair in an ovine discectomy model

Background

Intervertebral disc (IVD) disorders (e.g., herniation) directly contribute to back pain, which is a leading cause of global disability. Next-generation treatments for IVD herniation need advanced preclinical testing to evaluate their ability to repair large defects, prevent reherniation, and limit progressive degeneration. This study tested whether experimental, injectable, and nonbioactive biomaterials could slow IVD degeneration in an ovine discectomy model.

Methods

Ten skeletally mature sheep (4-5.5 years) experienced partial discectomy injury with cruciate-style annulus fibrosus (AF) defects and 0.1 g nucleus pulposus (NP) removal in the L1-L2, L2-L3, and L3-L4 lumbar IVDs. L4-L5 IVDs were Intact controls. IVD injury levels received: (1) no treatment (Injury), (2) poly (ethylene glycol) diacrylate (PEGDA), (3) genipin-crosslinked fibrin (FibGen), (4) carboxymethylcellulose-methylcellulose (C-MC), or (5) C-MC and FibGen (FibGen + C-MC). Animals healed for 12 weeks, then IVDs were assessed using computed tomography (CT), magnetic resonance (MR) imaging, and histopathology.

Results

All repaired IVDs retained ~90% of their preoperative disc height and showed minor degenerative changes by Pfirrmann grading. All repairs had similar disc height loss and Pfirrmann grade as Injury IVDs. Adhesive AF sealants (i.e., PEGDA and FibGen) did not herniate, although repair caused local endplate (EP) changes and inflammation. NP repair biomaterials (i.e., C-MC) and combination repair (i.e., FibGen + C-MC) exhibited lower levels of degeneration, less EP damage, and less severe inflammation; however, C-MC showed signs of herniation via biomaterial expulsion.

Conclusions

All repair IVDs were noninferior to Injury IVDs by IVD height loss and Pfirrmann grade. C-MC and FibGen + C-MC IVDs had the best outcomes, and may be appropriate for enhancement with bioactive factors (e.g., cells, growth factors, and miRNAs). Such bioactive factors appear to be necessary to prevent injury-induced IVD degeneration. Application of AF sealants alone (i.e., PEGDA and FibGen) resulted in EP damage and inflammation, particularly for PEGDA IVDs, suggesting further material refinements are needed.

Interventional Therapy and Surgical Management of Lumbar Disc Herniation in Spine Surgery: A Narrative Review

Significant advancements in lumbar disc herniation (LDH) management have been made in interventional pain therapy, operative therapy, peri-operative management, and cost analysis of various procedures. The present review aims to provide a concise narrative of all these topics, current trends, and possible future directions in the management of LDH. Interventional pain management using intradiscal injections often serves as a minimally invasive non-surgical approach. Surgical modalities vary, including traditional open laminectomy, microdiscectomy, endoscopic discectomy, tubular discectomy, percutaneous laser disc decompression, and transforaminal foraminotomy. Prevention of infections during surgery is paramount and is often done via a single-dose preoperative antibiotic prophylaxis. Recurrence of LDH post-surgery is commonly observed and thus mitigative strategies for prevention have been proposed including the use of annular closure devices. Finally, all treatments are well-associated with clear as well as hidden costs to the health system and society as described by billing codes and loss of patients' quality-adjusted life-years. Our summary of recent literature regarding LDH may allow physicians to employ up-to-date evidence-based practice in clinical settings and can help drive future advancements in LDH management. Future longitudinal and comprehensive studies elucidating how each type of treatments fare against different types of herniations are warranted.

Tension-activated nanofiber patches delivering an anti-inflammatory drug improve repair in a goat intervertebral disc herniation model

Conventional microdiscectomy treatment for intervertebral disc herniation alleviates pain but does not repair the annulus fibrosus, resulting in a high incidence of recurrent herniation and persistent dysfunction. The lack of repair and the acute inflammation that arise after injury can further compromise the disc and result in disc-wide degeneration in the long term. To address this clinical need, we developed tension-activated repair patches (TARPs) for annulus fibrosus repair and local delivery of the anti-inflammatory factor anakinra (a recombinant interleukin-1 receptor antagonist). TARPs transmit physiologic strain to mechanically activated microcapsules embedded within the patch, which release encapsulated bioactive molecules in direct response to spinal loading. Mechanically activated microcapsules carrying anakinra were loaded into TARPs, and the effects of TARP-mediated annular repair and anakinra delivery were evaluated in a goat model of annular injury in the cervical spine. TARPs integrated with native tissue and provided structural reinforcement at the injury site that prevented aberrant disc-wide remodeling resulting from detensioning of the annular fibrosus. The delivery of anakinra by TARP implantation increased matrix deposition and retention at the injury site and improved maintenance of disc extracellular matrix. Anakinra delivery additionally attenuated the inflammatory response associated with TARP implantation, decreasing osteolysis in adjacent vertebrae and preserving disc cellularity and matrix organization throughout the annulus fibrosus. These results demonstrate the therapeutic potential of TARPs for the treatment of intervertebral disc herniation.

Emerging tissue engineering strategies for annulus fibrosus therapy

Low back pain is a major public health concern experienced by 80% of the world's population during their lifetime, which is closely associated with intervertebral disc (IVD) herniation. IVD herniation manifests as the nucleus pulposus (NP) protruding beyond the boundaries of the intervertebral disc due to disruption of the annulus fibrosus (AF). With a deepening understanding of the importance of the AF structure in the pathogenesis of intervertebral disc degeneration, numerous advanced therapeutic strategies for AF based on tissue engineering, cellular regeneration, and gene therapy have emerged. However, there is still no consensus concerning the optimal approach for AF regeneration. In this review, we summarized strategies in the field of AF repair and highlighted ideal cell types and pro-differentiation targeting approaches for AF repair, and discussed the prospects and difficulties of implant systems combining cells and biomaterials to guide future research directions. STATEMENT OF SIGNIFICANCE: Low back pain is a major public health concern experienced by 80% of the world's population during their lifetime, which is closely associated with intervertebral disc (IVD) herniation. However, there is still no consensus concerning the optimal approach for annulus fibrosus (AF) regeneration. In this review, we summarized strategies in the field of AF repair and highlighted ideal cell types and pro-differentiation targeting approaches for AF repair, and discussed the prospects and difficulties of implant systems combining cells and biomaterials to guide future research directions.

Tissue-mimetic hybrid bioadhesives for intervertebral disc repair

Intervertebral disc (IVD) degeneration and herniation often necessitate surgical interventions including a discectomy with or without a nucleotomy, which results in a loss of the normal nucleus pulposus (NP) and a defect in the annulus fibrosus (AF). Due to the limited regenerative capacity of the IVD tissue, the annular tear may remain a persistent defect and result in recurrent herniation post-surgery. Bioadhesives are promising alternatives but show limited adhesion performance, low regenerative capacity, and inability to prevent re-herniation. Here, we report hybrid bioadhesives that combine an injectable glue and a tough sealant to simultaneously repair and regenerate IVD post-nucleotomy. The glue fills the NP cavity while the sealant seals the AF defect. Strong adhesion occurs with the IVD tissues and survives extreme disc loading. Furthermore, the glue can match native NP mechanically, and support the viability and matrix deposition of encapsulated cells, serving as a suitable cell delivery vehicle to promote NP regeneration. Besides, biomechanical tests with bovine IVD motion segments demonstrate the capacity of the hybrid bioadhesives to restore the biomechanics of bovine discs under cyclic loading and to prevent permanent herniation under extreme loading. This work highlights the synergy of bioadhesive and tissue-engineering approaches. Future works are expected to further improve the tissue specificity of bioadhesives and prove their efficacy for tissue repair and regeneration.

A retrospective study of the mid-term efficacy of full-endoscopic annulus fibrosus suture following lumbar discectomy

AIMS

Full-endoscopic discectomy is associated with a high risk of disc reherniation due to the poor mechanical strength of the annulus fibrosus after scar healing. It is technically difficult to place a full-endoscopic annulus fibrosus suture. We designed an annulus fibrosus suture device that can be used to suture annulus defects under microendoscopy. The present study investigated the safety and feasibility of this technology.

PATIENTS AND METHODS

We retrospectively analyzed the outcomes of patients who underwent surgical treatment for lumbar disc herniation (LDH) from January 2018 to October 2020. We compared 40 patients with LDH treated with full-endoscopic annulus fibrosus suture following lumbar discectomy (LD + AFS group) with 42 patients treated with lumbar discectomy alone (LD group) regarding demographic data, symptoms, and recurrence and reoperation rates. Lumbar MRI and CT were performed 3 and 12 months. A 10-point visual analog scale (VAS) and the Oswestry Disability Index (ODI) was used to evaluate pain and the lumbar spine function.

RESULTS

The cohort comprised 82 patients, including 40 patients in the LD + AFS group and 42 in the LD group. All operations were successfully completed without serious complications. Reherniation occurred in no patients in the LD + AFS group and three patients in the LD group. The VAS scores for lumbar and leg pain and ODI score were significantly improved postoperatively (p < 0.05).

CONCLUSION

Compared with conventional lumbar discectomy, full-endoscopic annulus fibrosus suture following full-endoscopic lumbar discectomy is a safe and effective minimally invasive technique that reduces the LDH recurrence rate.

[Early effectiveness of unilateral biportal endoscopic discectomy combined with annulus fibrosus suture in the treatment of lumbar disc herniation]

OBJECTIVE

To analyze the early effectiveness of unilateral biportal endoscopic discectomy (UBED) combined with annulus fibrosus suture in the treatment of lumbar disc herniation (LDH).

METHODS

The clinical data of 19 patients with LDH treated with UBED and annulus fibrosus suture between October 2020 and October 2021 were retrospectively analyzed. There were 12 males and 7 females with an average age of 39.1 years (range, 26-59 years). The operative segment was L _{4, 5} in 13 cases, and L ₅, S ₁ in 6 cases. The mean disease duration was 6.7 months (range, 3-15 months). Preoperative neurological examination showed that muscle strength, sensation, and tendon reflex weakened or disappeared in varying degrees. Single annulus fibrosus suture (14 cases) or anchor assisted annulus fibrosus suture (5 cases) was selected according to the location of annulus fibrosus tears. Visual analogue scale (VAS) score was used to assess the low back and leg pain before operation and at 3 days, 3 months, and 6 months after operation. Oswestry disability index (ODI) was used to evaluate the function recovery of lumbar spine before operation and at 3 days, 3 months, and 6 months after operation. At 3 days and 3 months after operation, MRI was used to examine the removal of nucleus pulposus and decompression of nerve root. MacNab criteria was used to evaluate the effectiveness at 6 months after operation and the recovery of nerve root function was recorded.

RESULTS

All operations were successfully completed with a mean operation time of 52.7 minutes (range, 40-75 minutes). There was no complication such as nerve injury, spinal cord hypertension syndrome, or dural sac tear during operation, and no complication such as infection, aggravation of nerve damage, or cerebrospinal fluid leakage after operation. All the patients were followed up 6-10 months (mean, 8.2 months). Postoperative MRI showed that the herniated disc was completely removed and nerve roots were fully decompressed. During the follow-up, there was no recurrence of disc herniation. The VAS scores of low back pain and leg pain and ODI at each time point after operation significantly improved when compared with those before operation, and those at 6 months after operation further improved than those at 3 days and 3 months after operation, all showing significant differences ( P<0.05). At 6 months after operation, MacNab standard was used to evaluate the effectiveness, and the results were excellent in 14 cases, good in 4 cases, and fair in 1 case, with an excellent and good rate of 94.7%. Neurological examination showed that the sensation and muscle strength of the affected nerve root innervated area recovered significantly when compared with those before operation ( P<0.05); the recovery of tendon reflex was not obvious, showing no significant difference when compared with that before operation ( P>0.05).

CONCLUSION

UBED combined with annulus fibrosus suture is a safe and effective technique for LDH and early effectiveness is satisfactory.

Is annular repair technique useful for reducing reherniation and reoperation after limited discectomy?

The annular defect because of the primary lumbar disc herniation (LDH) or surgical procedure is considered a primary reason for recurrent herniation and eventually reoperation. Efforts to close the defect with annular repair devices have been attempted several times, but the results were controversial. The present aims to detect whether the annular repair techniques were useful for reducing the re-herniation and re- operation rate. The Pubmed, Cochrane library, and Embase databases were searched to retrieve relevant studies published before January 1, 2021. Continuous variables were compared by calculating the standard difference of the means (SDM), whereas categorical dichotomous variables were assessed using relative risks (RRs). A random-effects model was used if the heterogeneity statistic was significant; otherwise, a fixed-effects model was used. A total of 10 researches were suitable for the meta-analysis, including four different repair techniques and 1907 participates. Compared with the control group, there was no statistical difference with the ODI, VAS-leg, and VAS-back scales for patients treated with the annular repair. However, using an annular repair device was associated with a significant reduction in the re- herniation (p=0.004) and re-operation (0.004) rates. There was no difference between the groups with perioperative complications. However, much more device-related long-term complications happened in the annual repair group (p=0.031) though it still decreased the overall re-operation rate significantly (p=0.006).Our results demonstrated that using an annular repair device was safe and beneficial for reducing re-herniation and re-operation rates.

Correlation between Pain Scores and Disc Height Changes after Discectomy in Patients with Lumbar Disc Herniation: A Systematic Review and Meta-Analysis

Background

Surgery can reduce and improve lumbar disc herniation, but some patients still have pain after surgery, and the relationship between lumbar disc height and pain after surgery is still unclear.

Objective

The main objective is to investigate the relationship between lumbar disc height and postoperative pain.

Methods

We searched Pubmed, Web of Science, the Cochrane library, and Embase online for cohort studies or RCT studies on discectomy and assessed the quality of the included articles using the Newcastle-Ottawa Scale (NOS scale), with disc height (DH) and postoperative back pain as the main clinical outcome indicators, and the correlation coefficient between DH and back pain as the statistic to assess the pooled effect size.

Results

10 kinds of literature were included in this study for quantitative analysis. A total of 589 patients participated in the study. The follow-up time was between 1 and 2.3 years. Meta-analysis showed that after surgery, the relief of back pain was statistically significant (MD = −2.57, 95% CI (−3.10,−2.04), Z = −9.570, P < 0.0001), the reduction of disc height was statistically significant (MD = −0.82, 95% CI (−1.11, −0.52), Z = −5.477, P < 0.0001), the combined value of correlation coefficient Fisher's Z value was 0.33, 95% CI (0.25,0.42), with statistical significance (P < 0.00001), suggesting that the degree of back pain after surgery showed a moderate positive correlation with disc height in the short term. Discussion. After discectomy, the degree of pain is relieved, the disc height is reduced, and low back pain in the short term and disc height showed a moderate positive correlation, but the long-term correlation remains to be studied in depth.

Genipin-crosslinked fibrin seeded with oxidized alginate microbeads as a novel composite biomaterial strategy for intervertebral disc cell therapy

Discectomy procedures alleviate disability caused by intervertebral disc (IVD) herniation, but do not repair herniation-induced annulus fibrosus (AF) defects. Cell therapy shows promise for IVD repair, yet cell delivery biomaterials capable of sealing AF defects and restoring biomechanical function have poor biological performance. To balance the biomechanical and biological demands of IVD cell delivery biomaterials, we engineered an injectable composite biomaterial using cell-laden, degradable oxidized alginate (OxAlg) microbeads (MBs) to deliver AF cells within high-modulus genipin-crosslinked fibrin (FibGen) hydrogels (FibGen + MB composites). Conceptually, the high-modulus FibGen would immediately stabilize injured IVDs, while OxAlg MBs would protect and release cells required for long-term healing. We first showed that AF cells microencapsulated in OxAlg MBs maintained high viability and, upon release, displayed phenotypic AF cell morphology and gene expression. Next, we created cell-laden FibGen + MB composites and demonstrated that OxAlg MBs functionalized with RGD peptides (MB-RGD) minimized AF cell apoptosis and retained phenotypic gene expression. Further, we showed that cell-laden FibGen + MB composites are biomechanically stable and promote extracellular matrix (ECM) synthesis in long-term in vitro culture. Lastly, we evaluated cell-laden FibGen + MB-RGD composites in a long-term bovine caudal IVD organ culture bioreactor and found that composites had low herniation risk, provided superior biomechanical and biological repair to discectomy controls, and retained anabolic cells within the IVD injury space. This novel injectable composite hydrogel strategy shows promise as an IVD cell delivery sealant with potentially broad applications for its capacity to balance biomechanical and biological performance.

Construction of tissue-engineered nucleus pulposus by stimulation with periodic mechanical stress and BMP-2

Intervertebral disc (IVD) degeneration, which is common among elderly individuals, mainly manifests as low back pain and is caused by structural deterioration of the nucleus pulposus (NP) due to physiological mechanical stress. NP mesenchymal stem cells (NPMSCs) around the IVD endplate have multidirectional differentiation potential and can be used for tissue repair. To define favorable conditions for NPMSC proliferation and differentiation into chondroid cells for NP repair, the present study simulated periodic mechanical stress (PMS) of the NP under physiological conditions using MSC chondrogenic differentiation medium and recombinant human BMP-2 (rhBMP-2). rhBMP-2 effectively promoted NPMSC proliferation and differentiation. To clarify the mechanism of action of rhBMP-2, integrin alpha 1 (ITG A1) and BMP-2 were inhibited. PMS regulated the BMP-2/Smad1/RUNX2 pathway through ITG A1 and promoted NPMSC proliferation and differentiation. During tissue-engineered NP construction, PMS can effectively reduce osteogenic differentiation and promote extracellular matrix protein synthesis to enhance structural NP recovery.

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Extraction of NPMSCs from degenerated nucleus pulposus

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NPMSCs cultured in vitro by simulating physiological mechanical stress

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ITG A1 to promote proliferation and differentiation of NPMSCs through BMP-2/Smad1/RUNX2

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Injectable tissue-engineered nucleus pulposus

Lumbar discectomy with annulus fibrosus closure: a retrospective series of 53 consecutive patients

INTRODUCTION

Lumbar disc herniation is most common degenerative alteration of the spine. Whenever surgical therapy proves to be necessary, recurrent disc herniation is most frequent concern. Here, primary aim was to determine the percentage of patients eligible for insertion of an annular closure device (ACD). Secondary aim to evaluate 12-month incidence of recurrent disc herniation at the operated level. Our hypothesis was that ACD might help in preventing recurrent disc herniation.

METHODS

Patients in a single XXX neurosurgical center underwent limited discectomy alone (n=41, group 1) versus limited discectomy plus ACD (n=12, group 2). Mean postoperative follow-up period was 12 months.

RESULTS

Twelve out of 53 patients (22.6 %) were eligible for ACD implantation. Patients of group 2 were significantly taller (mean 176 cm, p= 0.007) as compared with group 1 (mean 170). The only statistically significant difference of intraoperative parameters between group 1 and 2 was amount of nucleus materiel removed (p= 0.01), being greater in group 2 (mean 0.9) as compared with group 1 (mean 0.3). In group 1 six patients (6/41, 14.6%) presented with symptomatic reherniation at same level of surgery, while in group 2 only one patient experienced recurrence (1/12, 8.3%). No adverse events were reported.

DISCUSSION

In the current study one out of five patients with lumbar disc herniation was considered suitable for ACD placement. In vast majority of these patients reherniation was precluded on the short-term basis. Patients with ACD were taller and had intraoperatively a higher volume of the nucleus pulposus materiel removed.

Fundamentals of Intervertebral Disc Degeneration

Lumbar disc degeneration is one of the leading causes of chronic low back pain. The degenerative cascade is often initiated by an imbalance between catabolic and anabolic processes in the intervertebral discs. As a consequence of extracellular matrix degradation, neoinnervation and neovascularization take place. Ultimately, this degenerative process results in disc bulging and loss of nucleus pulposus and water content and subsequent loss of disc height. Most patients respond to conservative management and surgical interventions well initially, yet a significant number of patients continue to suffer from chronic low back pain. Because of the high prevalence of long-term discogenic pain, regenerative biological therapies, including gene therapies, growth factors, cellular-based injections, and tissue-engineered constructs, have attracted significant attention in light of their potential to directly address the degenerative process. Understanding the pathophysiology of degenerative disc disease is important in both refining existing technologies and developing innovative techniques to reverse the degenerative processes in the discs. In this review, we aimed to cover the underlying pathophysiology of degenerative disc disease as well as its associated risk factors and give a comprehensive summary about the developmental, structural, radiological, and biomechanical properties of human intervertebral discs.

Putting the Pieces in Place: Mobilizing Cellular Players to Improve Annulus Fibrosus Repair

The intervertebral disc (IVD) is an integral load-bearing tissue that derives its function from its composite structure and extracellular matrix composition. IVD herniations involve the failure of the annulus fibrosus (AF) and the extrusion of the nucleus pulposus beyond the disc boundary. Disc herniations can impinge the neural elements and cause debilitating pain and loss of function, posing a significant burden on individual patients and society as a whole. Patients with persistent symptoms may require surgery; however, surgical intervention fails to repair the ruptured AF and is associated with the risk for reherniation and further disc degeneration. Given the limitations of AF endogenous repair, many attempts have been made toward the development of effective repair approaches that reestablish IVD function. These methods, however, fail to recapitulate the composition and organization of the native AF, ultimately resulting in inferior tissue mechanics and function over time and high rates of reherniation. Harnessing the cellular function of cells (endogenous or exogenous) at the repair site through the provision of cell-instructive cues could enhance AF tissue regeneration and, ultimately, improve healing outcomes. In this study, we review the diverse approaches that have been developed for AF repair and emphasize the potential for mobilizing the appropriate cellular players at the site of injury to improve AF healing. Impact statement Conventional treatments for intervertebral disc herniation fail to repair the annulus fibrosus (AF), increasing the risk for recurrent herniation. The lack of repair devices in the market has spurred the development of regenerative approaches, yet most of these rely on a scarce endogenous cell population to repair large injuries, resulting in inadequate regeneration. This review identifies current and developing strategies for AF repair and highlights the potential for harnessing cellular function to improve AF regeneration. Ideal cell sources, differentiation strategies, and delivery methods are discussed to guide the design of repair systems that leverage specialized cells to achieve superior outcomes.

Selective Retention of Bone Marrow Stromal Cells with Gelatin Sponge for Repair of Intervertebral Disc Defects after Microendoscopic Discectomy: A Prospective Controlled Study and 2-Year Follow-Up

Objective

Discectomy remains the classic procedure for treating lumbar intervertebral disc (IVD) herniation, but the occurrence of defects after discectomy is thought to be an important cause generating recurrent and accelerated IVD degeneration. Previous studies attempted suture of the annulus fissure, but the validity of this technique on restraining the degenerative process is controversial. On the other hand, cell therapies have been shown in multiple clinical and basic studies. Our purpose was to investigate the effectiveness of selective retention of autologous Bone Marrow Stromal Cells (BMSCs) with gelatin sponge in combination with annulus fibrosus suture (AFS) for the repair of IVD defects following mobile microendoscopic discectomy (MMED).

Methods

This prospective, two-armed, and controlled clinical study was conducted from December 2016 to December 2018. Written informed consent was obtained from each patient. Forty-five patients with typical symptoms, positive signs of radiculopathy, and obvious lumbar disc herniation observed by MRI were enrolled. Patients were divided into 3 groups with different treating methods: MMED (n = 15), MMED+AFS (n = 15), and MMED+AFS+BMSCs (n = 15). A postoperative 2-year follow-up was performed to evaluate the patient-reported outcomes of VAS, ODI, and SF-36. The improvement rate of VAS and ODI was calculated as [(latest‐preoperative)/preoperative] to evaluate the therapeutic effect of the three groups. Assessment parameters included Pfirrmann grade, intervertebral disc height (IDH), and disc protrusion size (DPS), as measured by MRI to evaluate the morphological changes.

Results

All patients enrolled had a postoperative follow-up at 3, 6, 12, and 24 months. VAS and ODI scores were significantly improved compared to the preoperative status in all three groups with a mean DPS reduction rate over 50%. At the final follow-up, the improvement rate of the VAS score in the MMED+AFS+BMSCs group was significantly higher than the MMED+AFS and MMED groups (80.1% ± 7.6% vs. 71.3% ± 7.0% vs. 70.1% ± 7.8%), while ODI improvement showed a significant change (65.6% ± 8.8% vs. 59.9% ± 5.5% vs. 57.8% ± 8.1%). All participants showed significant improvement in SF-36 PCS and MCS; the differences between each group were not significant. The mean IDH loss rate of the MMED+AFS+BMSCs group was also significantly lower than other groups (−17.2% ± 1.3% vs. −27.6% ± 0.7% vs. −29.3% ± 2.2%). The Pfirrmann grade was aggravated in the MMED and MMED+AFS groups while maintained at the preoperative grade in the MMED+AFS+BMSCs group. No adverse events of cell transplantation or recurrence were found in all patients during the postoperative follow-up period.

Conclusions

It is feasible and effective to repair lumbar IVD defects using SCR-enriched BMSCs with gelatin sponges, which warrants further study and development as a cell-based therapy for IVD repair.

Combined nucleus pulposus augmentation and annulus fibrosus repair prevents acute intervertebral disc degeneration after discectomy

Tissue-engineered approaches for the treatment of early-stage intervertebral disc degeneration have shown promise in preclinical studies. However, none of these therapies has been approved for clinical use, in part because each therapy targets only one aspect of the intervertebral disc's composite structure. At present, there is no reliable method to prevent intervertebral disc degeneration after herniation and subsequent discectomy. Here, we demonstrate the prevention of degeneration and maintenance of mechanical function in the ovine lumbar spine after discectomy by combining strategies for nucleus pulposus augmentation using hyaluronic acid injection and repair of the annulus fibrosus using a photocrosslinked collagen patch. This combined approach healed annulus fibrosus defects, restored nucleus pulposus hydration, and maintained native torsional and compressive stiffness up to 6 weeks after injury. These data demonstrate the necessity of a combined strategy for arresting intervertebral disc degeneration and support further translation of combinatorial interventions to treat herniations in the human spine.

The association between pain scores and disc height change following discectomy surgery in lumbar disc herniation patients: a systematic review and meta-analysis

PURPOSE

To evaluate the impact of discectomy on disc height (DH) in lumbar disc herniation (LDH) patients following discectomy surgery and address the association of DH change with pain score change.

METHODS

We searched three online databases for randomized controlled trials (RCTs) and observational studies. In LDH patients, eligible for discectomy surgery, the changes in pre- and post-operative back and/or leg pain score and DH and/or disc height index (DHI) were considered as primary outcomes. Standardize mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The GRADE approach was used to summarize the strength of evidence.

RESULTS

Two RCTs and sixteen observational studies were included in the analysis of 893 LDH patients undergoing discectomy surgery. The mean overall follow-up was 211 weeks. There was a statistically significant reduction in DH (14.4% reduction: SMD =  -0.74 (95% CI =  -0.86 to -0.61)) and DHI (11.5% reduction: SMD =  -0.81 (95% CI =  -0.97 to -0.65)) following discectomy surgery. There was a significant relationship between the reduction in DH and decrease in back pain score (r = 0.68, (95% CI = 0.07-1.30), p = 0.034) after discectomy surgery. No significant relationship between DHI change and decrease in clinical pain scores (back and leg pain) could be established.

CONCLUSION

Discectomy surgery produces significant and quantifiable reductions in DH and DHI. Additionally, the reduction in DH is responsible for the decrease in back pain scores post discectomy, but further studies will improve understanding and aid preoperative counselling.

A challenging playing field: Identifying the endogenous impediments to annulus fibrosus repair

Intervertebral disc (IVD) herniations, caused by annulus fibrosus (AF) tears that enable disc tissue extrusion beyond the disc space, are very prevalent, especially among adults in the third to fifth decade of life. Symptomatic herniations, in which the extruded tissue compresses surrounding nerves, are characterized by back pain, numbness, and tingling and can cause extreme physical disability. Patients whose symptoms persist after nonoperative intervention may undergo surgical removal of the herniated tissue via microdiscectomy surgery. The AF, however, which has a poor endogenous healing ability, is left unrepaired increasing the risk for re-herniation and pre-disposing the IVD to degenerative disc disease. The lack of understanding of the mechanisms involved in native AF repair limits the design of repair systems that overcome the impediments to successful AF restoration. Moreover, the complexity of the AF structure and the challenging anatomy of the repair environment represents a significant challenge for the design of new repair devices. While progress has been made towards the development of an effective AF repair technique, these methods have yet to demonstrate long-term repair and recovery of IVD biomechanics. In this review, the limitations of endogenous AF healing are discussed and key cellular events and factors involved are highlighted to identify potential therapeutic targets that can be integrated into AF repair methods. Clinical repair strategies and their limitations are described to further guide the design of repair approaches that effectively restore native tissue structure and function.

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.

Annular closure device breakage due to recurrent lumbar disc herniation: a case report

Detailed surgical management, magnetic resonance imaging (MRI), and computer tomography (CT) images of a broken annular closure device (ACD) have not been reported yet. In this case, a 28-year-old male presented with a new onset of radiculopathy three years after lumbar discectomy and placement of an ACD. The CT-myelography and MRI revealed a recurrent disc herniation (RDH) and dislocation of a broken ACD. ACD removal was performed and confirmed breakage due to RDH with scarring around the RDH and displaced ACD. Implant-associated complications and management should be reported in detail in order to enhance knowledge on device-related complications.

The Functional Role of Interface Tissue Engineering in Annulus Fibrosus Repair: Bridging Mechanisms of Hydrogel Integration with Regenerative Outcomes

Hydrogels are extraordinarily versatile by design and can enhance repair in diseased and injured musculoskeletal tissues. Biological fixation of these constructs is a significant determinant factor that is critical to the clinical success and functionality of regenerative technologies for musculoskeletal repair. In the context of an intervertebral disc (IVD) herniation, nucleus pulposus tissue protrudes through the ruptured annulus fibrosus (AF), consequentially impinging on spinal nerve roots and causing debilitating pain. Discectomy is the surgical standard of care to treat symptomatic herniation; however these procedures do not repair AF defects, and these lesions are a significant risk factor for recurrent herniation. Advances in tissue engineering utilize adhesive hydrogels as AF sealants; however these repair strategies have yet to progress beyond preclinical animal models because these biomaterials are often plagued by poor integration with AF tissue and lead to large variability in repair outcomes. These critical barriers to translation motivate this article to review the material composition of hydrogels that have been evaluated in situ for AF repair, proposed mechanisms of how these biomaterials interface with AF tissue, and their functional outcomes after treatment in order to inform the development of new hydrogels for AF repair. In this systematic review, we identify 18 hydrogel formulations evaluated for AF repair, all of which demonstrate large heterogeneity in their interfacing mechanisms and reported outcome measures to assess the effectiveness of repair. Hydrogels that covalently bond to AF tissue were found to be the most successful in improving IVD biomechanical properties from the injured state, but none were able to restore properties to the intact state suggesting that new repair strategies with innovative surface chemistries are an important future direction. We additionally review biomechanical evaluation methods and recommend standardization in the field of AF tissue engineering to establish mechanical benchmarks for translation and ensure clinical feasibility.

Balancing biological and biomechanical performance in intervertebral disc repair: a systematic review of injectable cell delivery biomaterials

Discogenic back pain is a common condition without approved intervertebral disc (IVD) repair therapies. Cell delivery using injectable biomaterial carriers offers promise to restore disc height and biomechanical function, while providing a functional niche for delivered cells to repair degenerated tissues. This systematic review advances the injectable IVD cell delivery biomaterials field by characterising its current state and identifying themes of promising strategies. Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) guidelines were used to screen the literature and 183 manuscripts met the inclusion criteria. Cellular and biomaterial inputs, and biological and biomechanical outcomes were extracted from each study. Most identified studies targeted nucleus pulposus (NP) repair. No consensus exists on cell type or biomaterial carrier, yet most common strategies used mesenchymal stem cell (MSC) delivery with interpenetrating network/co-polymeric (IPN/CoP) biomaterials composed of natural biomaterials. All studies reported biological outcomes with about half the studies reporting biomechanical outcomes. Since the IVD is a load-bearing tissue, studies reporting compressive and shear moduli were analysed and two major themes were found. First, a competitive balance, or 'seesaw' effect, between biomechanical and biological performance was observed. Formulations with higher moduli had inferior cellular performance, and vice versa. Second, several low-modulus biomaterials had favourable biological performance and matured throughout culture duration with enhanced extracellular matrix synthesis and biomechanical moduli. Findings identify an opportunity to develop next-generation biomaterials that provide high initial biomechanical competence to stabilise and repair damaged IVDs with a capacity to promote cell function for long-term healing.

MRI predictors of revision surgery after primary lumbar discectomy

The prognostic significance of preoperative MRI findings in patients undergoing discectomy is incompletely understood. Identifying the radiological predictors of revision surgery on pre-operative MRI can guide management decisions and potentially prevent multiple surgeries. We included 181 patients who underwent primary lumbar discectomy between 2010 and 2014. All patients were contacted via a short telephone interview to determine if they had revision surgery within 5 years of their index surgery. Preoperative MRI of the lumbosacral spine was evaluated for various radiological factors including type of disc herniation, anatomical location of herniation, direction of herniation, degree of disc degeneration, end plate changes and presence of listhesis. Other potential confounders including age, gender, smoking status and index level of surgery were also recorded. Multivariate model of all radiological predictors and confounders were developed and a step-wise approach was used to remove insignificant variables in order to develop final significant multivariate model. P value of <0.05 was considered statistically significant. Patients with retrolisthesis were found to be 2.7 times more likely than the patients without listhesis to require revision surgery (p = 0.019). Patients with foraminal disc herniation were 3.45 times more likely than the patients with paramedian disc herniation to require revision surgery (p = 0.026). Other MRI predictors failed to achieve statistical significance. Based on the data presented patients with retrolisthesis and/or foraminal disc herniation should be counselled on the relatively higher risk of revision surgery when proceeding with discectomy, or alternative options should be considered.

Advanced Strategies for the Regeneration of Lumbar Disc Annulus Fibrosus

Damage to the annulus fibrosus (AF), the outer region of the intervertebral disc (IVD), results in an undesirable condition that may accelerate IVD degeneration causing low back pain. Despite intense research interest, attempts to regenerate the IVD have failed so far and no effective strategy has translated into a successful clinical outcome. Of particular significance, the failure of strategies to repair the AF has been a major drawback in the regeneration of IVD and nucleus replacement. It is unlikely to secure regenerative mediators (cells, genes, and biomolecules) and artificial nucleus materials after injection with an unsealed AF, as IVD is exposed to significant load and large deformation during daily activities. The AF defects strongly change the mechanical properties of the IVD and activate catabolic routes that are responsible for accelerating IVD degeneration. Therefore, there is a strong need to develop effective therapeutic strategies to prevent or reconstruct AF damage to support operational IVD regenerative strategies and nucleus replacement. By the way of this review, repair and regenerative strategies for AF reconstruction, their current status, challenges ahead, and future outlooks were discussed.

Crosslinker concentration controls TGFβ-3 release and annulus fibrosus cell apoptosis in genipin-crosslinked fibrin hydrogels

Back pain is a leading cause of global disability associated with intervertebral disc (IVD) pathologies. Discectomy alleviates disabling pain caused by IVD herniation without repairing annulus fibrosus (AF) defects, which can cause accelerated degeneration and recurrent pain. Biological therapies show promise for IVD repair but developing high-modulus biomaterials capable of providing biomechanical stabilisation and delivering biologics remains an unmet challenge. The present study identified critical factors and developed an optimal formulation to enhance the delivery of AF cells and transforming growth beta-3 (TGFβ-3) in genipin-crosslinked fibrin (FibGen) hydrogels. Part 1 showed that AF cells encapsulated in TGFβ-3-supplemented high-modulus FibGen synthesised little extracellular matrix (ECM) but could release TGFβ-3 at physiologically relevant levels. Part 2 showed that AF cells underwent apoptosis when encapsulated in FibGen, even after reducing fibrin concentration from 70 to 5 mg/mL. Mechanistic experiments, modifying genipin concentration and integrin binding site presence demonstrated that genipin crosslinking caused AF cell apoptosis by inhibiting cell-biomaterial binding. Adding integrin binding sites with fibronectin partially rescued apoptosis, indicating genipin also caused acute cytotoxicity. Part 3 showed that FibGen formulations with 1 mg/mL genipin had enhanced ECM synthesis when supplemented with fibronectin and TGFβ-3. In conclusion, FibGen could be used for delivering biologically active compounds and AF cells, provided that formulations supplied additional sites for cell-biomaterial binding and genipin concentrations were low. Results also highlighted a need for developing strategies that protect cells against acute crosslinker cytotoxicity to overcome challenges of engineering high-modulus cell carriers for musculoskeletal tissues that experience high mechanical demands.

Nucleus replacement could get a new chance with annulus closure

Purpose

Disc herniations are usually treated by decompression of the spinal nerves via a partial nucleotomy. As a consequence of reduced disc height (DH), reduced intradiscal pressure (IDP) and increased range of motion (ROM), accelerated degeneration may occur. Nucleus replacement implants are intended to restore those values, but are associated with the risk of extrusion.

Methods

In six fresh frozen lumbar spinal segments (L2-3/L3-4/L4-5/L5-S1, age median 64.5 years (57–72), Pfirrmann grade 2–3), a prolapse was provoked through a box defect (6 × 10 mm) in the annulus. The herniated nucleus material was removed and replaced by a novel collagen-based nucleus implant. An annulus closure device sealed the defect. ROM, neutral zone (NZ) and IDP were measured in the (1) intact and (2) defect state, (3) postoperatively and (4) after cyclic loading (n = 100,000 cycles) applying pure moments (± 7.5 Nm) in flexion–extension, lateral bending and axial rotation. Additionally, the change in DH was determined. Extrusion of implants or nucleus material was evaluated macroscopically.

Results

In all specimens, a prolapse could be provoked which decreased DH. Subsequent nucleotomy changed ROM/NZ and IDP considerably. Initial values could be restored by the implantation. Macroscopically, none of the implants nor nucleus material did migrate after cyclic loading.

Conclusions

In this study, a prolapse followed by a nucleotomy resulted in a biomechanical destabilisation. Implantation of the nucleus replacement combined with an annulus closure restored the intact condition without showing signs of extrusion nor migration after cyclic loading. Hence, nucleus replacements could have a new chance in combination with annulus closure devices.

Expert review with meta-analysis of randomized and nonrandomized controlled studies of Barricaid annular closure in patients at high risk for lumbar disc reherniation

Introduction: Patients with lumbar disc herniation and associated sciatica are often referred for lumbar discectomy. The surgical defect in the annulus fibrosus is typically left unrepaired after lumbar discectomy. Patients with large postsurgical annular defects (≥6 mm width) have a higher risk of symptom recurrence and reoperation compared to those with small defects. In these high-risk patients, a treatment gap exists due to the lack of effective treatments for durable annulus fibrosus repair.Areas covered: This article highlights the therapeutic need and summarizes the clinical results of a bone-anchored annular closure device (Barricaid) that was designed to fill the treatment gap in patients with large postsurgical annular defects. Clinical results were summarized by means of a systematic review with meta-analysis of two randomized and two nonrandomized controlled studies.Expert opinion: Professional societal recommendations and clinical study results support the adoption of bone-anchored annular closure for use in properly selected patients undergoing lumbar discectomy who are at high-risk for reherniation due to a large postsurgical defect in the annulus fibrosus. The risks of symptomatic reherniation and reoperation are approximately 50% lower in patients treated with lumbar discectomy and the Barricaid device compared to lumbar discectomy only, representing a clinically effective treatment strategy.

Degeneration of Lumbar Intervertebral Discs: Characterization of Anulus Fibrosus Tissue and Cells of Different Degeneration Grades

Intervertebral disc (IVD) herniation and degeneration is a major source of back pain. In order to regenerate a herniated and degenerated disc, closure of the anulus fibrosus (AF) is of crucial importance. For molecular characterization of AF, genome-wide Affymetrix HG-U133plus2.0 microarrays of native AF and cultured cells were investigated. To evaluate if cells derived from degenerated AF are able to initiate gene expression of a regenerative pattern of extracellular matrix (ECM) molecules, cultivated cells were stimulated with bone morphogenetic protein 2 (BMP2), transforming growth factor β1 (TGFβ1) or tumor necrosis factor-α (TNFα) for 24 h. Comparative microarray analysis of native AF tissues showed 788 genes with a significantly different gene expression with 213 genes more highly expressed in mild and 575 genes in severe degenerated AF tissue. Mild degenerated native AF tissues showed a higher gene expression of common cartilage ECM genes, whereas severe degenerated AF tissues expressed genes known from degenerative processes, including matrix metalloproteinases (MMP) and bone associated genes. During monolayer cultivation, only 164 differentially expressed genes were found. The cells dedifferentiated and altered their gene expression profile. RTD-PCR analyses of BMP2- and TGFβ1-stimulated cells from mild and severe degenerated AF tissue after 24 h showed an increased expression of cartilage associated genes. TNFα stimulation increased MMP1, 3, and 13 expression. Cells derived from mild and severe degenerated tissues could be stimulated to a comparable extent. These results give hope that regeneration of mildly but also strongly degenerated disc tissue is possible.

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).

Needle-Guided Suture Technique for Lumbar Annular Fiber Closure in Microendoscopic Discectomy: A Technical Note and Case Series

BACKGROUND Annular fiber closure techniques have been proven effective in reducing short-term recurrence after discectomy. However, annular fiber closure devices are expensive and still fail at a low rate. We present a novel suture method, needle-guided annular closure suture (NGACS) that does not require a special device and can be performed for annular fiber closure following microendoscopic discectomy. MATERIAL AND METHODS Twenty-five patients who underwent treatment with NGACS were reviewed by analysis of the medical records. The clinical outcomes were assessed and compared preoperatively and immediately, 1, 6, and 12 months postoperatively. The parameters included the Visual Analog Scale (VAS)-back and VAS-leg scores and the Oswestry Disability Index (ODI). Midsagittal T2WI images were obtained to evaluate lumbar disc degeneration using the Pfirrmann grade. Additional adverse events were also recorded and tracked. RESULTS The VAS-back and VAS-leg scores and the ODI were significantly different at each follow-up time point (P<0.001), and improvements in pain and disability were maintained well during the follow-up period. Lumbar disc reherniation or other serious adverse events were not observed in this series. There was no significant difference between the initial and final Pfirrmann grades (Z=-1.414, P=0.157). The preoperative average disc height was 9.94±1.97 mm, and the disc height at 12 months after surgery was 9.14±1.88 mm. The average decrease in disc height was 8.11±3.36%. CONCLUSIONS This study demonstrates the feasibility and superior clinical outcomes of the NGACS technique. This method can be a good substitution when annular fiber closure devices are not available. Moreover, this technique can be easily popularized due to its low cost and few restrictions.

Dynamic Bioreactor Culture for Infiltration of Bone Mesenchymal Stem Cells within Electrospun Nanofibrous Scaffolds for Annulus Fibrosus Repair

Objective

To compare the ability of three culture strategies of static culture, intermittent centrifugal culture and dynamic bioreactor culture in promoting the infiltration of bone marrow mesenchymal stem cells (BMSCs) throughout electrospun nanoporous aligned nanoyarn scaffold (AYS).

Methods

AYS was constructed by the method of conjugated electrospinning, using the blended solution of poly (L‐lactide‐co‐caprolactone) (P (LLA‐CL)) and gelatin. Then the bone marrow mesenchymal stem cells (BMSCs) were transplanted on the scaffolds. Culture the scaffold‐cells using three methods of static culture, intermittent centrifugal culture and dynamic bioreactor culture. After 7 and 14 days in culture, the infiltration depth of the cells were observed and measured by hematoxylin and eosin (HE) or 4′, 6‐diamidino‐2‐phenylindole (DAPI) staining.

Result

In the current study, on the 7th day, the BMSCs in the scaffolds of static culture group, intermittent centrifugal culture group, and dynamic bioreactor culture group infiltrated to an average depth of 11.88 ± 1.82 μm, 21.17 ± 13.17 μm, and 26.27 ± 7.42 μm, respectively. There were differences between the bioreactor culture group with the static culture group and the intermittent centrifugal culture group. On the time point of 14 days, the depth of infiltration of BMSCs in dynamic bioreactor culture was the most (115.13 ± 25.44 μm, P < 0.05), and the infiltration of the cells in the intermittent centrifugal culture group was 42.53 ± 13.07 μm, deeper than that of the static culture group (24.53 ± 6.06, P < 0.05).

Conclusion

Dynamic bioreactor culture may be a preferred method for tissue engineering approaches involving scaffolds with a low porosity, such as those needed for repair of the annulus fibrosus (AF).

Novel Intervertebral Technologies

Surgical procedures, such as spinal fusion and disk replacement, are commonly used for treatment following failure of conservative treatment in degenerative spine disease. However, there is growing consensus that currently available surgical technologies may have long-term inefficacy for successful management. Intervertebral disk degeneration is the most common manifestation of degenerative spine disease, hence, replacement/repair of this tissue is an important component of surgical treatment. Restoration of spinal alignment and preservation of natural kinematics is also essential to a good outcome. This article reviews novel intervertebral implant technologies that have the potential to significantly impact elective spine surgery for degenerative spine disease.

Efficacy of a Novel Annular Closure Device after Lumbar Discectomy in Korean Patients : A 24-Month Follow-Up of a Randomized Controlled Trial

Objective

Lumbar discectomy is an effective treatment for lumbar disc herniation (LDH); however, up to 2–18% of patients with LDH have experienced recurrent disc herniation. The purpose of this study was to evaluate the efficacy of a novel annular closure device (ACD) for preventing LDH recurrence and re-operation compared with that of conventional lumbar discectomy (CLD).

Methods

In this prospective randomized controlled trial, we compared CLD with discectomy utilizing the Barricaid® (Intrinsic Therapeutics, Inc., Woburn, MA, USA) ACD. Primary radiologic outcomes included disc height, percentage of preoperative disc height maintained, and re-herniation rates. Additional clinical outcomes included visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI) scores, and 12-item short-form health survey (SF-12) quality of life scores. Outcomes were measured at preoperation and at 1 week, 1, 3, 6, 12, and 24 months postoperation.

Results

Sixty patients (30 CLD, 30 ACD) were enrolled in this study. At 24-month follow-up, the disc height in the ACD group was significantly greater than that in the CLD group (11.4±1.5 vs. 10.2±1.2 mm, p=0.006). Re-herniation occurred in one patient in the ACD group versus six patients in the CLD group (χ²=4.04, p=0.044). Back and leg VAS scores, ODI scores, and SF-12 scores improved significantly in both groups compared with preoperative scores in the first 7 days following surgery and remained at significantly improved levels at a 24-month follow-up. However, no statistical difference was found between the two groups.

Conclusion

Lumbar discectomy with the Barricaid® (Intrinsic Therapeutics, Inc.) ACD is more effective at maintaining disc height and preventing re-herniation compared with conventional discectomy. Our results suggest that adoption of ACD in lumbar discectomy can help improve the treatment outcome.

The Disability Cascade: A Preventable Consequence of the Loss of Disc Height following Lumbar Microdiscectomy

Lumbar discectomy is a mainstay surgical treatment for herniation of the lumbar discs and is effective at treating radicular symptomology. Despite the overall success of the procedure; the potential for reherniation and reoperation is significant. To avoid this potential recurrence, surgeons often perform discectomy more aggressively, removing a larger volume of nuclear material in the hopes of minimizing the likelihood of reherniation. This approach, while beneficial in minimizing the chance of reherniation, is associated with a volumetric reduction of the nucleus within the disc space, making the disc more prone to collapse and thus inducing a significant post-operative loss of disc height. While potentially minor in isolation, the loss of disc height, in fact, impacts several aspects of overall patient well-being. We hypothesize that the loss of disc height following discectomy causes an increase in pain and subsequent disability, the combination of which ultimately impacts socioeconomic factors affecting both the patient and the healthcare system as a whole. In this report, we outline the evidence in support of this disability cascade and provide recommendations on methods for limiting its impact. Given the current focus on cost-effectiveness in healthcare decision-making, methods for limiting this potentially damaging sequence of events must be investigated.

Postoperative direct health care costs of lumbar discectomy are reduced with the use of a novel annular closure device in high-risk patients

BACKGROUND CONTEXT

Lumbar discectomy is largely successful surgical procedure; however, reherniation rates in patients with large annular defects are as high as 27%. The expense associated with a revision surgery places significant burden on the healthcare system.

PURPOSE

To compare the direct health care costs through 5 years follow-up of conventional discectomy (Control) with those of discectomy supplemented by an adjunctive annular closure device (ACD) in high-risk patients with large annular defects.

STUDY DESIGN

This was a cost-effectiveness study.

METHODS

All-cause index level reoperations were reviewed from a multicenter, randomized controlled superiority trial that allocated 554 high-risk discectomy patients with large annular defects to either control or ACD. Medicare and private insurer (Humana) direct costs were derived from a commercially available payer database to estimate costs in the US healthcare system, including those associated with facility, surgeon, imaging, follow-up visits, physical therapy, and injections. A 50:50 split between Medicare and commercial insurers was assumed for the base case analysis. The analysis was also performed on a 80:20 commercial:Medicare payer basis. For the base case scenario, a 2-year time horizon and outpatient cost setting was established for the index procedure. Repeat discectomy was assumed to be performed on a 60:40 outpatient-to-inpatient basis. Complications requiring surgery, revisions, and/or fusion were assumed to be managed in the inpatient setting. Total costs of reoperation and per-patient costs of reoperation were compared between groups for both forms of insurers. One author received consulting fees of <$50,000 for the completion of this study, and the other eight authors did not have any financial associations with the current work. Funding for this study was provided by Intrinsic Therapeutics, but all analyses, interpretation, and writing were performed independently by the authors.

RESULTS

At two years follow-up, use of the ACD reduced the rate of symptomatic reherniations in a large defect population to 13% compared with 25% in the control group (p<.001). This reduction in symptomatic reherniations in the ACD group translated to a savings of $2,802 per patient in direct health care costs compared with Control at 2 years and $5,315 per patient by 5 years based on 50% private and 50% public (Medicare) payer split. Under the scenario of 80:20 private:public insurance reimbursement, the estimated direct cost savings were $3,215 and $6,099 per patient at 2- and 5-years postoperatively, respectively, with the use of the ACD.

CONCLUSIONS

Symptomatic reherniation and reoperation rates were nearly double among control patients compared with ACD-treated patients, which translated to markedly greater per-patient healthcare costs in the control group, where the ACD was not used.

Three-year results from a randomized trial of lumbar discectomy with annulus fibrosus occlusion in patients at high risk for reherniation

BACKGROUND

A larger defect in the annulus fibrosus following lumbar discectomy is a well-known risk factor for reherniation. Procedures intended to prevent reherniation by sealing or occluding the annular defect warrant study in high-risk patients. This study sought to determine 3-year results of lumbar discectomy with a bone-anchored annular closure device (ACD) or lumbar discectomy only (controls) in patients at high risk for reherniation.

METHODS

This multicenter randomized trial enrolled patients with sciatica due to lumbar intervertebral disc herniation who failed conservative treatment. Patients with large annular defects after lumbar limited microdiscectomy were intraoperatively randomly assigned to receive ACD or control. Clinical and imaging follow-up was performed at routine intervals over 3 years. Main outcomes included rate of reherniations, reoperations, and endplate changes; leg and back pain scores on a visual analogue scale; Oswestry Disability Index (ODI); Physical Component Summary (PCS) and Mental Component Summary (MCS) scores from the SF-36; and adverse events adjudicated by a data safety monitoring board.

RESULTS

Among 554 randomized patients, the modified intent-to-treat population consisted of 272 patients in which ACD implantation was attempted and 278 receiving control; device implantation was not attempted in 4 patients assigned to ACD. Outcomes at 3 years favored ACD for symptomatic reherniation (14.8% vs. 29.5%; P < 0.001), reoperation (11.0% vs. 19.3%; P = 0.007), leg pain (21 vs. 30; P < 0.01), back pain (23 vs. 30; P = 0.01), ODI (18 vs. 23; P = 0.02), PCS (47 vs. 44; P < 0.01), and MCS (52 vs. 49; P < 0.01). The frequency of all-cause serious adverse events was comparable between groups (42.3% vs. 44.5%; P = 0.61).

CONCLUSIONS

The addition of a bone-anchored ACD in patients with large annular defects following lumbar discectomy reduces the risk of reherniation and reoperation, and has a similar safety profile over 3-year follow-up compared with lumbar limited discectomy only.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01283438.

Surgical Experience and Complications in 50 Patients Treated with an Anular Closure Device Following Lumbar Discectomy

OBJECTIVE

To examine the results of an anular closure device for prevention of lumbar disc reherniation in daily routine practice.

METHODS

Fifty patients with large anular defects were treated with limited discectomy and a bone-anchored anular closure device. The device physically occludes the defect in the anulus fibrosus and is intended for prevention of lumbar disc reherniation. Pain scores on a visual analogue scale, back function on the Oswestry Disability Index, and neurological status were noted. Symptomatic reherniation and reoperation rates were assessed at each follow-up. Surgical findings and complications, device-related and/or procedure-related, were recorded. Follow-up was 6, 12, 26, and 52 weeks.

RESULTS

Mean anular defect height/width was 4.6 mm/10.1 mm. The overall symptomatic reherniation and reoperation rate was 2%. During the 1-year follow-up period, mean back pain decreased from 43 to 8 (P < 0.001), leg pain decreased from 71 to 4 (P < 0.001), and the Oswestry Disability Index decreased from 46 to 5 (P < 0.001). Among 15 patients with preoperative neurological deficits, improvements in neurological function were noted in 14 (93%). There were no serious device-related complications.

CONCLUSIONS

The presented study shows promising early results in using the anular closure device. The procedure is safe with significantly fewer reherniations than for patients with large anular defects without anular closure. Further studies with longer follow-up periods are warranted to prove these findings for long-term outcomes.

Injectable cellulose-based hydrogels as nucleus pulposus replacements: Assessment of in vitro structural stability, ex vivo herniation risk, and in vivo biocompatibility

Current treatments for intervertebral disc degeneration and herniation are palliative only and cannot restore disc structure and function. Nucleus pulposus (NP) replacements are a promising strategy for restoring disc biomechanics and height loss. Cellulose-based hydrogel systems offer potential for NP replacement since they are stable, non-toxic, may be tuned to match NP material properties, and are conducive to cell or drug delivery. A crosslinked, carboxymethylcellulose-methylcellulose dual-polymer hydrogel was recently formulated as an injectable NP replacement that gelled in situ and restored disc height and compressive biomechanical properties. The objective of this study was to investigate the translational potential of this hydrogel system by examining the long-term structural stability in vitro, the herniation risk and fatigue bending endurance in a bovine motion segment model, and the in vivo biocompatibility in a rat subcutaneous pouch model. Results showed that the hydrogels maintained their structural integrity over a 12-week period. AF injury significantly increased herniation risk and reduced fatigue bending endurance in bovine motion segments. Samples repaired with cellulosic hydrogels demonstrated restored height and exhibited herniation risk and fatigue endurance comparable to samples that underwent the current standard treatment of nucleotomy. Lastly, injected hydrogels elicited a minimal foreign body response as determined by analysis of fibrous capsule development and macrophage presence over 12 weeks. Overall, this injectable cellulosic hydrogel system is a promising candidate as an NP substitute. Further assessment and optimization of this cellulosic hydrogel system in an in vivo intradiscal injury model may lead to an improved clinical solution for disc degeneration and herniation.

In vitro and in vivo evaluation of an electrospun-aligned microfibrous implant for Annulus fibrosus repair

Annulus fibrosus (AF) impairment is associated with reherniation, discogenic pain, and disc degeneration after surgical partial discectomy. Due to a limited intrinsic healing capacity, defects in the AF persist over time and it is hence necessary to adopt an appropriate strategy to close and repair the damaged AF. In this study, a cell-free biodegradable scaffold made of polycaprolactone (PCL), electrospun, aligned microfibers exhibited high levels of cell colonization, alignment, and AF-like extracellular matrix deposition when evaluated in an explant culture model. The biomimetic multilayer fibrous scaffold was then assessed in an ovine model of AF impairment. After 4 weeks, no dislocation of the implants was detected, and only one sample out of six showed a partial delamination. Histological and immunohistochemical analyses revealed integration of the implant with the surrounding tissue as well as homogeneously aligned collagen fiber organization within each lamella compared to the disorganized and scarcer fibrous tissue in a randomly organized control fibrous scaffold. In conclusion, this biomimetic electrospun implant exhibited promising properties in terms of AF defect closure, with AF-like neotissue formation that fully integrated with the surrounding ovine tissue.

Discogenic Back Pain: Literature Review of Definition, Diagnosis, and Treatment

Discogenic back pain is multifactorial; hence, physicians often struggle to identify the underlying source of the pain. As a result, discogenic back pain is often hard to treat—even more so when clinical treatment strategies are of questionable efficacy. Based on a broad literature review, our aim was to define discogenic back pain into a series of more specific and interacting pathologies, and to highlight the need to develop novel approaches and treatment strategies for this challenging and unmet clinical need. Discogenic pain involves degenerative changes of the intervertebral disc, including structural defects that result in biomechanical instability and inflammation. These degenerative changes in intervertebral discs closely intersect with the peripheral and central nervous systems to cause nerve sensitization and ingrowth; eventually central sensitization results in a chronic pain condition. Existing imaging modalities are nonspecific to pain symptoms, whereas discography methods that are more specific have known comorbidities based on intervertebral disc puncture and injection. As a result, alternative noninvasive and specific diagnostic methods are needed to better diagnose and identify specific conditions and sources of pain that can be more directly treated. Currently, there are many treatments/interventions for discogenic back pain. Nevertheless, many surgical approaches for discogenic pain have limited efficacy, thus accentuating the need for the development of novel treatments. Regenerative therapies, such as biologics, cell‐based therapy, intervertebral disc repair, and gene‐based therapy, offer the most promise and have many advantages over current therapies. © 2019 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research

Reduction of direct costs in high-risk lumbar discectomy patients during the 90-day post-operative period through annular closure

Purpose

Despite being an extremely successful procedure, recurrent disc herniation is one of the most common post-discectomy complications in the lumbar spine and contributes significant health care and socioeconomic costs. Patients with large annular defects are at a high risk for reherniation, but an annular closure device (ACD) has been designed to reduce reherniation risk in this population and may, in turn, help control direct health care costs after discectomy.

Patients and methods

This analysis examined the 90-day post-discectomy cost estimates among ACD-treated (n=272) and control (discectomy alone; n=278) patients in a randomized controlled trial (RCT). Direct medical costs were estimated based on 2017 Humana and Medicare claims. Index discectomies were assumed to occur in an outpatient (OP) setting, whereas repeat discectomies were assumed to be 60% in OP and 40% in inpatient (IP). A sensitivity analysis was performed on this assumption. The device cost was not included in the analysis in order to focus on costs in the 90-day post-operative period.

Results

Within 90 days of follow-up, post-operative complications occurred in 3.3% of the ACD patients and 8.6% of the control patients (P=0.01). The average 90-day cost to treat an ACD patient was $10,257 compared to $11,299 per control patient for a 80:20 distribution of Commercial:Medicare coverage ($1,042 difference). This difference varied from $687 with 100% Medicare to $1,132 with 100% Commercial coverage. Varying the IP vs OP distribution resulted in a cost difference range of $968 to $1,156 with the ACD.

Conclusion

Augmenting discectomy with an ACD in high-risk patients with a large annular defect reduced reherniation and reoperation rates, which translated to a reduction of direct health care costs between $687 and $1,156 per patient during the 90-day post-operative period. Large annular defect patients are an easily identifiable high-risk population. Operative strategies that reduce complication risks in these patients, such as the ACD, could be advantageous from both patient care and economic perspectives.

Comparison of treatments for lumbar disc herniation: Systematic review with network meta-analysis

STUDY DESIGN

Systematic review with network meta-analysis.

OBJECTIVE

To compare patient outcomes of lumbar discectomy with bone-anchored annular closure (LD + AC), lumbar discectomy (LD), and continuing conservative care (CC) for treatment of lumbar disc herniation refractory to initial conservative management.

SUMMARY OF BACKGROUND DATA

Several treatment options are available to patients with refractory symptoms of lumbar disc herniation, but their comparative efficacy is unclear.

METHODS

A systematic review was performed to compare efficacy of LD + AC, LD, and CC for treatment of lumbar disc herniation. Outcomes included leg pain, back pain, disability (each reported on a 0-100 scale), reherniation, and reoperation. Data were analyzed using random effects network meta-analysis.

RESULTS

This review included 14 comparative studies (8 randomized) involving 3947 patients-11 studies of LD versus CC (3232 patients), 3 studies of LD + AC versus LD (715 patients), and no studies of LD + AC versus CC. LD was more effective than CC in reducing leg pain (mean difference [MD] -10, P < .001) and back pain (MD -7, P < .001). LD + AC was more effective than LD in reducing risk of reherniation (odds ratio 0.38, P < .001) and reoperation (odds ratio 0.33, P < .001). There was indirect evidence that LD + AC was more effective than CC in reducing leg pain (MD -25, P = .003), back pain (MD -20, P = .02), and disability (MD -13, P = .02) although the treatment effect was smaller in randomized trials.

CONCLUSIONS

Results of a network meta-analysis show LD is more effective than CC in alleviating symptoms of lumbar disc herniation refractory to initial conservative management. Further, LD + AC lowers risk of reherniation and reoperation versus LD and may improve patient symptoms more than CC.

Annular closure device for disc herniation: meta-analysis of clinical outcome and complications

Background

Lumbar intervertebral disc herniation is a common cause of lower back and leg pain, with surgical intervention (e.g. discectomy to remove the herniated disc) recommended after an appropriate period of conservative management, however the existing or increased breach of the annulus fibrosus persists with the potential of reherniation. Several prosthesis and techniques to reduce re-herniation have been proposed including implantation of an annular closure device (ACD) – Barricaid™ and an annular tissue repair system (AR) – Anulex-Xclose™. The aim of this meta-analysis is to assist surgeons determine a potential approach to reduce incidences of recurrent lumbar disc herniation and assess the current devices regarding their outcomes and complications.

Methods

Four electronic full-text databases were systematically searched through September 2017. Data including outcomes of annular closure device/annular repair were extracted. All results were pooled utilising meta-analysis with weighted mean difference and odds ratio as summary statistics.

Results

Four studies met inclusion criteria. Three studies reported the use of Barricaid (ACD) while one study reported the use of Anulex (AR). A total of 24 symptomatic reherniation were reported among 811 discectomies with ACD/AR as compared to 51 out of 645 in the control group (OR: 0.34; 95% CI: 0.20,0.56; I² = 0%; P < 0.0001). Durotomies were lower among the ACD/AR patients with only 3 reported cases compared to 7 in the control group (OR: 0.54; 95% CI: 0.13, 2.23; I² = 11%; P = 0.39). Similar outcomes for post-operative Oswestry Disability Index and visual analogue scale were obtained when both groups were compared.

Conclusion

Early results showed the use of Barricaid and Anulex devices are beneficial for short term outcomes demonstrating reduction in symptomatic disc reherniation with low post-operative complication rates. Long-term studies are required to further investigate the efficacy of such devices.

Critical aspects and challenges for intervertebral disc repair and regeneration-Harnessing advances in tissue engineering

Low back pain represents the highest burden of musculoskeletal diseases worldwide and intervertebral disc degeneration is frequently associated with this painful condition. Even though it remains challenging to clearly recognize generators of discogenic pain, tissue regeneration has been accepted as an effective treatment option with significant potential. Tissue engineering and regenerative medicine offer a plethora of exploratory pathways for functional repair or prevention of tissue breakdown. However, the intervertebral disc has extraordinary biological and mechanical demands that must be met to assure sustained success. This concise perspective review highlights the role of the disc microenvironment, mechanical and clinical design considerations, function vs mimicry in biomaterial‐based and cell engineering strategies, and potential constraints for clinical translation of regenerative therapies for the intervertebral disc.

Chemokine CCL25 Induces Migration and Extracellular Matrix Production of Anulus Fibrosus-Derived Cells

Intervertebral disc degeneration is a major source of back pain. For intervertebral disc regeneration after herniation a fast closure of anulus fibrosus (AF) defects is crucial. Here, the use of the C-C motif chemokine ligand 25 (CCL)25 in comparison to differentiation factors such as transforming growth factor (TGF)β3, bone morphogenetic protein (BMP)2, BMP7, BMP12, and BMP14 (all in concentrations of 10, 50 and 100 ng/mL) was tested in an in vitro micro mass pellet model with isolated and cultivated human AF-cells (n = 3) to induce and enhance AF-matrix formation. The pellets were differentiated (serum-free) with supplementation of the factors. After 28 days all used factors induced proteoglycan production (safranin O staining) and collagen type I production (immunohistochemical staining) in at least one of the tested concentrations. Histomorphometric scoring revealed that TGFβ3 delivered the strongest induction of proteoglycan production in all three concentrations. Furthermore, it was the only factor able to facilitate collagen type II production, even higher than in native tissue samples. CCL25 was also able to induce proteoglycan and collagen type I production comparable to several BMPs. CCL25 could additionally induce migration of AF-cells in a chemotaxis assay and therefore possibly aid in regeneration processes after disc herniation by recruiting AF-cells.