Role of peridural fibrosis in the failed back: a review

Polymeric Dural Biomaterials in Spinal Surgery: A Review

Laminectomy is a commonly performed surgical procedure by orthopedic and neurosurgeons, aimed at alleviating nerve compression and reducing pain. However, in some cases, excessive proliferation of fibrous scar tissue in the epidural space post-surgery can lead to persistent and intractable lower back pain, a condition known as Failed Back Surgery Syndrome (FBSS). The persistent fibrous tissue causes both physical and emotional distress for patients and also makes follow-up surgeries more challenging due to reduced visibility and greater technical difficulty. It has been established that the application of biomaterials to prevent epidural fibrosis post-lumbar surgery is more beneficial than revision surgeries to relieve dural fibrosis. Hydrogel-based biomaterials, with their excellent biocompatibility, degradability, and injectability and tunable mechanical properties, have been increasingly introduced by clinicians and researchers. This paper, building on the foundation of epidural fibrosis, primarily discusses the strategies for the preparation of natural and polymeric biomaterials to prevent epidural fibrosis, their physicochemical properties, and their ability to mitigate the excessive proliferation of fibroblasts. It also emphasizes the challenges that need to be addressed to translate laboratory research into clinical practice and the latest advancements in this field.

Is Tranexamic Acid an Effective Prevention in the Formation of Epidural Fibrosis? Histological Evaluation in the Rats

OBJECTIVE

The present study aimed to determine the topical and systemic efficacy of tranexamic acid (TXA) on epidural fibrosis in a rat laminectomy model.

METHODS

Thirty-two 12-month-old adult Sprague-Dawley rats were used in this study. Each rat underwent bilateral laminectomy at the L1 and L2 vertebral levels. Rats were divided into four groups : in group I (control group, n=8), a laminectomy was performed and saline solution was applied into the surgical space. In group II (topical group, n=8), laminectomy was performed and 30 mg/ kg TXA was applied to the surgical site before skin closure. In group III (systemic group, n=8), 30 mg/kg TXA was administered intravenously via the tail vein in the same session as the surgical procedure. In group IV (topical and systemic group, n=8), TXA was administered 30 mg/kg both topical and intravenous. The rats were sacrificed at 4 weeks postoperatively. Masson's trichrome and hematoxylin and eosin were used to assess acute inflammatory cells, chronic inflammatory cells, vascular proliferation, and epidural fibrosis.

RESULTS

Epidural fibrosis, acute inflammation, chronic inflammation, and sum histologic score value were significantly lower in the systemic TXA group, systemic and topical TXA groups than in the control group (p<0.05). In addion, the sum histologic score was significantly lower in the topical TXA group than in the control group (p<0.05).

CONCLUSION

In this study, epidural fibrosis formation was prevented more by systemic application, but the topical application was found to be effective when compared to the control group. As a result, we recommend the systemic and topical use of TXA to prevent epidural fibrosis during spinal surgery.

Continuous release of mefloquine featured in electrospun fiber membranes alleviates epidural fibrosis and aids in sensory neurological function after lumbar laminectomy

Recurrent low back pain after spinal surgeries, such as lumbar laminectomy, is a major complication of excessive epidural fibrosis. Although multiple preclinical and clinical methods have been aimed at ameliorating epidural fibrosis, their safety and efficacy remain largely unclear. Single implanted electrospun fibrous membranes provide physical barriers that can decrease tissue fibrosis after surgery; however, they also trigger local inflammation due to the implantation of a foreign body, thus subsequently attenuating their anti-fibrosis properties. Here, we designed a strategy that permits easy incorporation of mefloquine into polylactic acid membranes, and stable long-term mefloquine release, to potentially improve anti-fibrosis effects and relieve or prevent low back pain. The electrospun fibrous membranes grafted with mefloquine showed a well-controlled early temporary peak release, and secondary drug release occurred smoothly over several weeks. Histopathological and histomorphometric results indicated that the drug-loaded membranes had excellent anti-fibrosis effects after laminectomy in rats. Inflammation and neovascularization at the surgical site indicated that the mefloquine-grafted electrospun fibrous membranes provided sustained anti-inflammatory outcomes while effectively alleviating associated neuropathic pain hypersensitivity. In summary, our study indicated that polylactic acid-mefloquine grafted electrospun fibrous membranes may be a potential local agent to mitigate epidural fibrosis and support sensory neurological function after laminectomy, thereby potentially improving patients' postoperative outcomes.

Neuromodulation in the treatment of postoperative epidural fibrosis: comparison of the extent of epidural fibrosis and the effect of stimulation

The goal was to prove that when a cohort of patients is chosen precisely, dorsal column stimulation provides significant improvement to quality of life. We studied a cohort of 50 patients with the history of failed back surgery syndrome coupled with epidural fibrosis (EF). A percutaneous implantation technique was used in each of the 50 patients. The study group was composed of 20 women and 28 men aged 26-67 years (mean age 49). A prospective observational questionnaire-based study was used. According to the methods, Ross's classification was adjusted to four degrees of scar size for our study objective. Despite this adjustment, it was not possible to statistically evaluate our research, due to very similar results in Groups I, III and IV. Patients without epidural fibrosis were assigned to Group 0, and patients with EF of different ranges were assigned to Group 1. The mean change in visual analogue scale DeltaVAS after our division into Group 0 was 4.82; for Group 1 it was 6.13. Evaluation of EF and DeltaVAS correlation by paired t-test shows a statistically higher effect of spinal cord stimulation (SCS) in the epidural fibrosis group, compared to group 0 without postoperative epidural fibrosis (p=0.008). The extent of epidural fibrosis is an important factor for Failed back surgery syndrome (FBSS). FBSS is the basis for the existence of neuropathic pain after lumbar spinal surgery. There is clear evidence of a correlation between patients with epidural scar formation on MR scan and the effect of dorsal column stimulation.

Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain

Objective

To determine whether changes in the transiting nerve rootlet or its surroundings, as seen on MRI performed after lumbar hemilaminectomy, are associated with persistent postoperative pain (PPP), commonly known as the failed back surgery syndrome.

Materials and Methods

Seventy-three patients (mean age, 61 years; 43 males and 30 females) who underwent single-level partial hemilaminectomy of the lumbar spine without postoperative complications or other level spinal abnormalities between January 2010 and December 2018 were enrolled. Two musculoskeletal radiologists evaluated transiting nerve rootlet abnormalities (thickening, signal alteration, distinction, and displacement), epidural fibrosis, and intrathecal arachnoiditis on MRI obtained one year after the operations. A spine surgeon blinded to the radiologic findings evaluated each patient for PPP. Univariable and multivariable analyses were used to evaluate the association between the MRI findings and PPP.

Results

The presence of transiting nerve rootlet thickening, signal alteration, and ill-distinction was significantly different between the patients with PPP and those without, for both readers (p ≤ 0.020). Conversely, the presence of transiting nerve rootlet displacement, epidural fibrosis, and intrathecal arachnoiditis was not significantly different between the two groups (p ≥ 0.128). Among the above radiologic findings, transiting nerve rootlet thickening and signal alteration were the most significant findings in the multivariable analyses (p ≤ 0.009).

Conclusion

On MRI, PPP was associated with transiting nerve rootlet abnormalities, including thickening, signal alterations, and ill-distinction, but was not associated with epidural fibrosis or intrathecal arachnoiditis. The most relevant findings were the nerve rootlet thickening and signal alteration.

Successful transforaminal epidural blood patch in a patient with multilevel spinal fusion

Introduction

Epidural blood patch (EBP) is a vital tool in treating postdural puncture headache (PDPH). Traditional interlaminar epidural needle insertion into the epidural space, however, may be challenging due to anatomical variations. As an alternative method, we successfully performed an EBP via transforaminal approach.

Case report

A mid-50-year-old male patient with multilevel spinal fusion developed PDPH after a failed spinal cord stimulator electrode placement. A transforaminal EBP was carried out by injecting a total of 8 mL of autologous blood into the neuroforamen at the L1–L2 level bilaterally. Our patient’s positional headache resolved immediately after the procedure.

Discussion

To our knowledge, this is the first case reported of a transforaminal EBP in a patient with diffuse epidural adhesive fibrosis secondary to multilevel laminectomies and spinal fusion. This case report highlights potential risks and benefits of this novel technique and also discusses its therapeutic mechanism of action. We believe that a transforaminal EBP should be considered in patients who are poor candidates for the traditional interlaminar EBP.

Transforaminal Epidural Balloon Adhesiolysis via a Contralateral Interlaminar Retrograde Foraminal Approach: A Retrospective Analysis and Technical Considerations

Several treatment modalities have been proposed for foraminal stenosis, but the treatment options remain unsatisfactory. Previous studies have shown that transforaminal balloon adhesiolysis may be effective in patients with refractory lumbar foraminal stenosis. However, in patients with a high iliac crest, balloon catheter insertion may be difficult via a conventional transforaminal approach (particularly targeting the L5–S1 foramen). It has been reported that an epidural catheter can be placed easily by a contralateral interlaminar retrograde foraminal approach. Therefore, we applied this approach to L5–S1 transforaminal balloon adhesiolysis in patients with a high iliac crest. We retrospectively analyzed data from 22 patients who underwent combined epidural adhesiolysis and balloon decompression (balloon adhesiolysis) using the novel foraminal balloon catheter via a contralateral interlaminar retrograde foraminal approach. The pain intensity significantly decreased over the three-month period after balloon adhesiolysis (p < 0.001). There were no complications associated with the balloon procedure. The present study suggests that balloon adhesiolysis for L5-S1 foramen via a contralateral interlaminar retrograde foraminal approach may be an effective alternative for patients with a high iliac crest and refractory lumbar radicular pain due to lumbar foraminal stenosis. In addition, detailed procedural aspects are described here.

Using cross-linked hyaluronic acid gel to prevent postoperative lumbar epidural space adhesion: in vitro and in vivo studies

PURPOSE

Hyaluronic acid prevents tissue adhesion after different surgeries. Physical barriers and inflammatory regulation have been suggested to be involved in the mechanism of these clinical effects. However, the molecular mechanism by which hyaluronic acid prevents epidural adhesion has not yet been reported.

METHODS

In the current in vivo studies, we investigated cross-linked hyaluronic acid gel in the regulation of scar gene expression, the accumulation of fibroblasts in scar tissue, and the prevention of epidural adhesion. The effect of cross-linked hyaluronic acid gel on the secretion of inflammatory factors was observed in vitro. In addition, to ensure the accuracy and reliability of the in vivo gene expression results, we used a cell model to detect the target genes in vitro.

RESULTS

The expression levels of TGFβ1 and COL1A1 mRNA were decreased in the cross-linked hyaluronic acid gel-treated group, and the protein expression of levels TGFβ1 and COL1A1 were also reduced, as detected by Western blotting in vitro and in vivo (P < 0.05). Histomorphometry results demonstrated that the number of fibroblasts in the experimental group was significantly lower than that in the control group 2 weeks postoperatively. Micro-CT scans showed that the cross-linked hyaluronic acid gel could reduce adhesion in the epidural space after laminectomy. Additionally, the cross-linked hyaluronic acid gel could inhibit IL-6 secretion.

CONCLUSIONS

These results indicate that cross-linked hyaluronic acid gel can prevent epidural adhesion by inhibiting inflammatory factors, such as IL-6, and downregulating TGFβ1 and COL1A1 mRNA expression. These slides can be retrieved under Electronic Supplementary Material.

Effectiveness of continuous hypertonic saline infusion with an automated infusion pump for decompressive neuroplasty: a randomized clinical trial

Background

Hypertonic saline (HS) injections for decompressive neuroplasty (DN) can cause pain. We assessed whether a continuous infusion of HS through an infusion pump would reduce injection-related pain compared with repeated bolus administrations.

Methods

Fifty patients scheduled for DN were randomized to either the bolus injection or the continuous infusion group. After appropriately placing the epidural catheter, 4 mL of 5% NaCl was injected as four boluses of 1 mL each at 15-minute intervals or infused over 1 hour using an infusion pump. The severity of pain induced by HS injection, as measured by the 11-point numerical rating scale (NRS), was the primary outcome. The severity of low back or lower extremity pain, as measured by the 11-point NRS and Oswestry Disability Index (ODI), 3 months following the procedure, was the secondary outcome.

Results

Data from 21 patients in the bolus group and 23 in the continuous infusion group were analyzed. No statistically significant difference in injection-related pain was identified between the two groups during the initial HS administration (P = 0.846). However, there was a statistically significant reduction in injection-related pain in the continuous infusion group compared to the bolus injection group from the second assessment onwards (P = 0.001, < 0.001, and < 0.001, respectively). No significant between-group differences in the NRS and ODI scores 3 months post-procedure were noted (P = 0.614 and 0.949, respectively).

Conclusions

Our study suggests that administering HS through a continuous infusion is a useful modality for reducing HS injection-related pain during DN.

Persistent radiculopathy after surgical treatment for lumbar disc herniation: causes and treatment options

PURPOSE

Lumbar disc surgery is a common procedure in the USA. It is frequently performed with good or excellent results in most patients. This article reviews common causes of persistent radiculopathy after surgical intervention.

METHODS

We performed an extensive review of the literature as well as applying our own experience.

RESULTS

Common causes of persistent leg pain following operative intervention include re-herniation, epidural fibrosis, biochemical/physiologic changes in the nerve root, and psychosocial issues.

CONCLUSIONS

Patients with persistent leg pain after surgical treatment of lumbar disc herniation can pose a challenging clinical problem. Summary of these topics and available treatment options are reviewed.

Effects of silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model

The authors investigated the effects of a silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model. They found that it significantly reduced postlaminectomy dural adhesion formation and inflammation. Dural adhesion formation, thought to be an inevitable consequence of laminectomy, is one of the most common complications following spinal surgery, and the authors' results indicate that the silk solution might be a potential novel therapeutic agent for dural adhesion formation.

Outcomes of Revision Surgery Following Instrumented Posterolateral Fusion in Degenerative Lumbar Spinal Stenosis: A Comparative Analysis between Pseudarthrosis and Adjacent Segment Disease

Study Design

Retrospective study.

Purpose

We examined the clinical and radiological outcomes of patients who received revision surgery for pseudarthrosis or adjacent segment disease (ASD) following decompression and instrumented posterolateral fusion (PLF).

Overview of Literature

At present, information regarding the outcomes of revision surgery for complications such as pseudarthrosis and ASD following instrumented PLF is limited.

Methods

This study examined 60 patients who received PLF for degenerative lumbar spinal stenosis and subsequently developed pseudarthrosis or ASD leading to revision surgery. Subjects were divided into a group of 21 patients who received revision surgery for pseudarthrosis (Group P) and a group of 39 patients who received revision surgery for ASD (Group A). Clinical outcomes were evaluated using the visual analogue scales for back pain (VAS-BP) and leg pain (VAS-LP), the Korean Oswestry disability index (K-ODI), and each patient's subjective satisfaction. Radiological outcomes were evaluated from the extent of bone union, and complications in the two groups were compared.

Results

VAS-LP at final follow-up was not statistically different between the two groups (p =0.353), although VAS-BP and K-ODI at final follow-up were significantly worse in Group P than in Group A (all p <0.05), and only 52% of the patients in Group P felt that their overall well-being had improved following revision surgery. Fusion rates after the first revision surgery were 71% (15/21) in Group P and 95% (37/39) in Group A (p =0.018). The rate of reoperation was significantly higher in Group P (29%) than in Group A (5%) (p =0.021) due to complications.

Conclusions

Clinical and radiological outcomes were worse in patients who had received revision surgery for pseudarthrosis than in those who had revision surgery for ASD. Elderly patients should be carefully advised of the risks and benefits before planning revision surgery for pseudarthrosis.

A novel experimental rat model of peripheral nerve scarring that reliably mimics post-surgical complications and recurring adhesions

Inflammation, fibrosis and perineural adhesions with the surrounding tissue are common pathological processes following nerve injury and surgical interventions on peripheral nerves in human patients. These features can reoccur following external neurolysis, currently the most common surgical treatment for peripheral nerve scarring, thus leading to renewed nerve function impairment and chronic pain. To enable a successful evaluation of new therapeutic approaches, it is crucial to use a reproducible animal model that mimics the main clinical symptoms occurring in human patients. However, a clinically relevant model combining both histological and functional alterations has not been published to date. We therefore developed a reliable rat model that exhibits the essential pathological processes of peripheral nerve scarring. In our study, we present a novel method for the induction of nerve scarring by applying glutaraldehyde-containing glue that is known to cause nerve injury in humans. After a 3-week contact period with the sciatic nerve in female Sprague Dawley rats, we could demonstrate severe intra- and perineural scarring that resulted in grade 3 adhesions and major impairments in the electrophysiological peak amplitude compared with sham control (P=0.0478). Immunohistochemical analysis of the nerve structure revealed vigorous nerve inflammation and recruitment of T cells and macrophages. Also, distinct nerve degeneration was determined by immunostaining. These pathological alterations were further reflected in significant functional deficiencies, as determined by the analysis of relevant gait parameters as well as the quantification of the sciatic functional index starting at week 1 post-operation (P<0.01). Moreover, with this model we could, for the first time, demonstrate not only the primary formation, but also the recurrence, of severe adhesions 1 week after glue removal, imitating a major clinical challenge. As a comparison, we tested a published model for generating perineural fibrotic adhesions, which did not result in significant pathological changes. Taken together, we established an easily reproducible and reliable rat model for peripheral nerve scarring that allows for the effective testing of new therapeutic strategies.

Efficacy of Poly(D,L-Lactic Acid-co-Glycolic acid)-Poly(Ethylene Glycol)-Poly(D,L-Lactic Acid-co-Glycolic Acid) Thermogel As a Barrier to Prevent Spinal Epidural Fibrosis in a Postlaminectomy Rat Model

STUDY DESIGN

Experimental animal study.

OBJECTIVE

The authors conducted a study to determine the efficacy and safety of the poly(D,L-lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) thermogel to prevent peridural fibrosis in an adult rat laminectomy model.

SUMMARY OF BACKGROUND DATA

Peridural fibrosis often occurs after spinal laminectomy. It might cause persistent back and/or leg pain postoperatively and make a reoperation more difficult and dangerous. Various materials have been used to prevent epidural fibrosis, but only limited success has been achieved.

MATERIALS AND METHODS

The PLGA-PEG-PLGA thermogel was synthesized by us. Total L3 laminectomies were performed on 24 rats. The PLGA-PEG-PLGA thermogel or chitosan (CHS) gel (a positive control group) was applied to the operative sites in a blinded manner. In the control group, the L3 laminectomy was performed and the defect was irrigated with the NS solution 3 times. All the rats were killed 4 weeks after the surgery.

RESULTS

The cytotoxicity of this thermogel was evaluated in vitro and the result demonstrated that no evidence of cytotoxicity was observed. The extent of epidural fibrosis, the area of epidural fibrosis, and the density of the fibroblasts and blood vessel were evaluated histologically. There were statistical differences among the PLGA-PEG-PLGA thermogel or CHS gel group compared with the control group. Although there was no difference between the PLGA-PEG-PLGA thermogel and CHS gel, the efficiency of the PLGA-PEG-PLGA thermogel was shown to be slightly improved compared with the CHS gel.

CONCLUSIONS

The biocompatibility of the PLGA-PEG-PLGA thermogel was proven well. The application of this thermogel effectively reduced epidural scarring and prevented the subsequent adhesion to the dura mater. No side effects were noted in the rats.

Postoperative computed tomography and low-field magnetic resonance imaging findings in dogs with degenerative lumbosacral stenosis treated by dorsal laminectomy

OBJECTIVES

To describe postoperative computed tomography (CT) and magnetic resonance imaging (MRI) findings in dogs with degenerative lumbosacral stenosis (DLSS) treated by dorsal laminectomy and partial discectomy.

METHODS

Prospective clinical case study of dogs diagnosed with and treated for DLSS. Surgical and clinical findings were described. Computed tomography and low field MRI findings pre- and postoperatively were described and graded. Clinical, CT and MRI examinations were performed four to 18 months after surgery.

RESULTS

Eleven of 13 dogs were clinically improved and two dogs had unchanged clinical status postoperatively despite imaging signs of neural compression. Vacuum phenomenon, spondylosis, sclerosis of the seventh lumbar (L7) and first sacral (S1) vertebrae endplates and lumbosacral intervertebral joint osteoarthritis became more frequent in postoperative CT images. Postoperative MRI showed mild disc extrusions in five cases, and in all cases contrast enhancing non-discal tissue was present. All cases showed contrast enhancement of the L7 spinal nerves both pre- and postoperatively and seven had contrast enhancement of the lumbosacral intervertebral joints and paraspinal tissue postoperatively. Articular process fractures or fissures were noted in four dogs.

CLINICAL SIGNIFICANCE

The study indicates that imaging signs of neural compression are common after DLSS surgery, even in dogs that have clinical improvement. Contrast enhancement of spinal nerves and soft tissues around the region of disc herniation is common both pre- and postoperatively and thus are unreliable criteria for identifying complications of the DLSS surgery.

[DIPROSPAN, LONGIDAZA AND THEIR COMBINED ACTION AGAINST FIBROSIS CAUSED BY MECHANICAL INJURY OF THE INTERVERTEBRAL DISCS IN RATS]

The formation of connective tissue changes in the spinal canal of rats, caused by the method of intervertebral disc ruptures, in association with a mixture of epidural injection of longidaza and diprospan has been researched. Simultaneous injection of hialuronidase and betamethasone in composition of diprospan and longidaza, revealed a high synergistic effect and anti-fibrotic activity. Combined antifibrosis action of these two drugs is stronger than the sum of the actions of the two drugs in their separate use. Reducion of the maximum thickness of the fibrous layer was 49%, compared with the reference value and reduction of the total area of the fibrous formation was 46%. In our opinion, due to anti-inflammatory effects and the ability to reduce epidural scar adhesion, this complex is promising for its therapeutic use in treatment of spinal epidural fibrosis.

Mitomycin C induces apoptosis in human epidural scar fibroblasts after surgical decompression for spinal cord injury

Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C (1, 5, 10, 20, 40 μg/mL) for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 (Z-IETD-FMK and Z-LEHD-FMK, respectively) did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein (CHOP) and caspase-4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.

Effects of cepae extract, allantoin, and heparin mixture on developing andalready formed epidural fibrosis in a rat laminectomy model

BACKGROUND/AIM

The study was designed to investigate whether local administration of a mixture composed of cepae extract, allantoin, and heparin (CAH) decreased already formed epidural fibrosis (EF) at the laminectomy site.

MATERIALS AND METHODS

Twenty-four adult male Sprague Dawley rats were equally divided into four groups. Laminectomy was performed at the L5 level in all rats. The group 2 and group 4 rats were treated with local drug administration. While the group 1 and 2 rats were sacrificed after 6 weeks, the remaining rats were reoperated and CAH mixture was applied in group 4. The vertebral columns of all rats were removed en bloc. Fibroblast numbers, EF, and arachnoidal involvement (AI) were evaluated.

RESULTS

The results of the treatment groups were separately compared with the control groups. The numbers of fibroblasts in the treatment groups were significantly lower than those in the control groups (P < 0.001). The grade of EF in group 2 was significantly less than that in group 1 (P < 0.05). There was no statistically significant difference regarding EF and AI grade between group 3 and group 4, and local application of the drug on EF and AI yielded better results than in the control groups.

CONCLUSION

The mixture composed of CAH might be a successful candidate for preventing EF in clinical practice.

An injectable extracellular matrix for the reconstruction of epidural fat and the prevention of epidural fibrosis

Extensive epidural fibrosis is a common complication following spinal surgery and can cause pain and limited mobility. In the present study, a novel biomimetic approach was developed to prevent postsurgical adhesion of the dura. We aimed to reconstruct epidural fat, which prevents scar-tissue adhesion, through the development of an injectable decellularized adipose matrix (DAM)-containing hyaluronic acid (HA) hydrogel loaded with adipose stromal cells (ASCs). Injectable DAM was prepared from porcine adipose tissue by four freeze-thaw cycles with subsequent pepsin digestion. Residual analyses confirmed the efficacy of detergent-free decellularization, while most sulfated glycosaminoglycans and collagen were preserved. The Transwell migration assay demonstrated the anti-infiltrative property of the DAM-containing HA hydrogel. After 14 d of 3D culture, the DAM-containing HA hydrogel showed inductive potential in the adipogenic differentiation of ASCs. For an in vivo study, the ASC-loaded DAM-containing HA hydrogel (DAM/ASC-incorporated HA hydrogel) was injected into adult laminectomized male rats, and the results were assessed by microscopic histological examination. The in vivo data indicated that HA hydrogel, DAM, and ASCs were all required for the ability of the engineered fat tissue to block the invasion of the fibrous tissue. Our results suggested that this injectable DAM/ASC-incorporated HA hydrogel has potential applications in minimally invasive surgery for soft-tissue reconstruction and epidural fibrosis prevention.

Efficacy of Percutaneous Adhesiolysis in the Treatment of Lumbar Post Surgery Syndrome

Context

Lumbar post-surgery syndrome is common and often results in chronic, persistent pain and disability, which can lead to multiple interventions. After failure of conservative treatment, either surgical treatment or a nonsurgical modality of treatment such as epidural injections, percutaneous adhesiolysis is often contemplated in managing lumbar post surgery syndrome. Recent guidelines and systematic reviews have reached different conclusions about the level of evidence for the efficacy of epidural injections and percutaneous adhesiolysis in managing lumbar post surgery syndrome. The objective of this systematic review was to determine the efficacy of all 3 percutaneous adhesiolysis anatomical approaches (caudal, interlaminar, and transforaminal) in treating lumbar post-surgery syndrome.

Evidence Acquisition

Data Sources: A literature search was performed from 1966 through October 2014 utilizing multiple databases. Study Selection: A systematic review of randomized trials published from 1966 through October 2014 of all types of epidural injections and percutaneous adhesiolysis in managing lumbar post-surgery syndrome was performed including methodological quality assessment utilizing Cochrane review criteria, Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment (IPM–QRB), and grading of evidence using 5 levels of evidence ranging from Level I to Level V. Data Extraction: The search strategy emphasized post-surgery syndrome and related pathologies treated with percutaneous adhesiolysis procedures.

Results

The search criteria yielded 16 manuscripts on percutaneous adhesiolysis assessing post-surgery syndrome. Of these, only 4 randomized trials met inclusion criteria for methodological quality assessment, 3 of them were of high quality; and the fourth manuscript was of low quality. Based on these 3 randomized controlled trials, 2 of them with one-day procedure and one with a 3-day procedure, the level of evidence for the efficacy of percutaneous adhesiolysis is Level II based on best evidence synthesis.

Conclusions

Based on this systematic review, percutaneous adhesiolysis is effective in managing patients with lumbar post-surgery syndrome after the failure of conservative management including fluoroscopically directed epidural injections.

Ibuprofen-conjugated hyaluronate/polygalacturonic acid hydrogel for the prevention of epidural fibrosis

The formation of fibrous tissue is part of the natural healing response following a laminectomy. Severe scar tissue adhesion, known as epidural fibrosis, is a common cause of failed back surgery syndrome. In this study, by combining the advantages of drug treatment with a physical barrier, an ibuprofen-conjugated crosslinkable polygalacturonic acid and hyaluronic acid hydrogel was developed for epidural fibrosis prevention. Conjugation was confirmed and measured by 1D 1H NMR spectroscopy. In vitro analysis showed that the ibuprofen-conjugated polygalacturonic acid–hyaluronic acid hydrogel showed low cytotoxicity. In addition, the conjugated ibuprofen decreased prostaglandin E2 production of the lipopolysaccharide-induced RAW264.7 cells. Histological data in in vivo studies indicated that the scar tissue adhesion of laminectomized male adult rats was reduced by the application of our ibuprofen-conjugated polygalacturonic acid-hyaluronic acid hydrogel. Its use also reduced the population of giant cells and collagen deposition of scar tissue without inducing extensive cell recruitment. The results of this study therefore suggest that the local delivery of ibuprofen via a polygalacturonic acid-hyaluronic acid-based hydrogel reduces the possibility of epidural fibrosis.

Effects of hemostatic polysaccharide agent on epidural fibrosis formation after lumbar laminectomy in rats

BACKGROUND CONTEXT

Epidural fibrosis is a common adverse outcome of spinal surgery that can compress the dural sac and nerve root. Local hemostatic agents have many indications in numerous types of spinal surgery. As these agents may behave as foreign bodies, inducing inflammation and delaying regeneration, they could enhance the risk of epidural fibrosis.

PURPOSE

We evaluated the effects of hemostatic polysaccharide on epidural fibrosis development in laminectomized rats.

STUDY DESIGN

This is a randomized controlled trial.

OUTCOME MEASURES

One month after surgery, tissues were histopathologically examined. Spinal tissue surrounding the laminectomy site was cut with a microtome and stained with hematoxylin and eosin and Masson trichrome. Slides were evaluated by a pathologist in a blinded fashion. The extent of epidural fibrosis, fibroblast cell density, cartilage, and bone regeneration was evaluated.

METHODS

Rats were randomly assigned to receive sham surgery, laminectomy, or laminectomy with hemostatic polysaccharide (seven rats per group). Sham surgery that consisted of a skin incision was performed without laminectomy. Laminectomy was performed at the L1 and L2 vertebrae. In the experimental group, the polysaccharide hemostatic material, HaemoCer was placed in the laminectomy area.

RESULTS

The proportion of rats with epidural fibrosis in laminectomized mice (both with and without hemostatic material) was higher than in sham-operated rats (p<.01). There was no difference in fibrosis between the two groups of laminectomized rats (p>.05).

CONCLUSIONS

Our study indicates that hemostatic polysaccharide does not enhance epidural fibrosis following laminectomy in rodents, suggesting that absorbable polysaccharides may be appropriate for use in hemostasis during spinal surgery.

The effects of ankaferd blood stopper and microporous polysaccharide hemospheres on epidural fibrosis in rat laminectomy model

PURPOSE

To investigate whether topically administered hemostatic agents ankaferd blood stopper and microporous polysaccharide hemospheres can decrease epidural fibrosis after laminectomy in rats.

METHODS

Eighteen adult male Sprague-Dawley rats were equally and randomly divided into three groups. In the treatment groups, ankaferd blood stopper and microporous polysaccharide hemospheres topically administrated upon duramater surface after laminectomy. Fibroblast count, epidural fibrosis and arachnoidal involvement were evaluated and graded histopathologically.

RESULTS

Our data revealed that the count of fibroblasts, the grading of epidural fibrosis and arachnoideal involvement in the rats treated with microporous polysaccharide hemospheres were significantly less than the control group. Although the arachnoideal involvement in ankaferd blood stopper group were significantly less than the control group, there were no statistical differences when comparing the grading of epidural fibrosis and the fibroblasts count between the treatment groups and the control group.

CONCLUSION

The ankaferd blood stopper and microporous polysaccharide hemospheres reduced epidural fibrosis and arachnoideal involvement after laminectomy in rats.

Tumor necrosis factor-α blockade in recurrent and disabling chronic sciatica associated with post-operative peridural lumbar fibrosis: results of a double-blind, placebo randomized controlled study

INTRODUCTION

The aim of this study was to assess the efficacy and safety of tumor necrosis factor (TNF)-α inhibition with infliximab (IFX) in treating recurrent and disabling chronic sciatica pain associated with post-operative peridural lumbar fibrosis.

METHOD

A double-blind, placebo-controlled study randomized 35 patients presenting with sciatica pain associated with post-operative peridural lumbar fibrosis to two groups: IFX (n = 18), a single intravenous injection of 3 mg/kg IFX; and placebo (n = 17), a single saline serum injection. The primary outcome was a 50 % reduction in sciatica pain on a visual analog scale (VAS) at day 10. Secondary outcomes were radicular and lumbar VAS pain at day 0 and radicular and lumbar VAS pain, Québec disability score, drug-sparing effect and tolerance at days 10, 30, 90, and 180.

RESULTS

At day 10, the placebo and IFX groups did not differ in the primary outcome (50 % reduction in sciatica pain observed in three (17.6 %) versus five (27.8 %) patients; p = 0.69). The number of patients reaching the patient acceptable symptom state for radicular pain was significantly higher in the placebo than IFX group after injection (12 (70.6 %) versus five (27.8 %) patients; p = 0.01). The two groups were comparable for all other secondary outcomes.

CONCLUSION

Treatment with a single 3 mg/kg IFX injection for post-operative peridural lumbar fibrosis-associated sciatica pain does not significantly reduce radicular symptoms at day 10 after injection.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00385086 ; registered 4 October 2006 (last updated 15 October 2015).

Interventional therapies for chronic low back pain

OBJECTIVE

Low back pain (LBP) is a highly prevalent condition and one of the leading causes of lost productivity and health-care costs. The objective of this review is to discuss the role of interventional pain procedures and evidence of their effectiveness in treatment of chronic LBP.

METHODS

This is a narrative review examining published studies on interventional procedures for LBP. The rationales, indications, technique, evidence, and complications for the interventional procedures are discussed.

RESULTS

Interventional pain procedures are used extensively in diagnosis and treatment of chronic pain. LBP is multifactorial, and while significant progress has been made in understanding its pathophysiology, this has not resulted in a proportional improvement of functional outcomes. For certain procedures, such as spinal cord stimulation, medical branch blocks and radiofrequency ablations, and epidural steroid injections for radiculopathy, safety, efficacy, and cost-effectiveness in treating LBP have been well studied. For others, such as interventions for discogenic pain, treatment successes have been modest at best.

CONCLUSIONS

Implementation of interventional pain procedures in the treatment framework of LBP has resulted in improvement of pain intensity in at least the short and medium terms, but equivocal results have been observed in functional improvement.

Efficacy and Safety of Sodium Hyaluronate with 1,4-Butanediol Diglycidyl Ether Compared to Sodium Carboxymethylcellulose in Preventing Adhesion Formation after Lumbar Discectomy

OBJECTIVE

Epidural injection of hyaluronic acid may prevent adhesion formation after spine surgery, but the compounds used to stabilize hyaluronidase could interfere with its anti-adhesion effects. The present study was conducted as a clinical trial to evaluate the efficacy and safety of an experimental medical gel in preventing adhesion formation.

METHODS

This study was designed as a multicenter, randomized, double-blind, and comparative controlled clinical trial with an observation period of 6 weeks. Subjects were randomly assigned into two groups: group A with sodium hyaluronate + 1,4-butanediol diglycidyl ether (BDDE) and group B with sodium hyaluronate + sodium carboxymethylcellulose (CMC). Visual analogue scale (VAS) of back and leg pain and the Oswestry disability index (ODI) and scar score ratings were assessed after surgery.

RESULTS

Mean scar grade was 2.37±1.13 in group A and 2.75±0.97 in group B, a statistically significant difference (p=0.012). VAS of back and leg pain and ODI scores decreased significantly from baseline to 3 and 6 weeks postoperatively in both groups (p<0.001). However, VAS and ODI scores were not statistically different between groups A and B at baseline or at 3 and 6 weeks after operation (p>0.3). The number of adverse reactions related to the anti-adhesion gels was not statistically different (p=0.569), but subsequent analysis of nervous adverse reactions showed group B was superior with a statistically difference (p=0.027).

CONCLUSION

Sodium hyaluronate with BDDE demonstrated similar anti-adhesion properties to sodium hyaluronate with CMC. But, care should be used to nervous adverse reactions by using sodium hyaluronate with BDDE.

In situ forming hydrogel composed of hyaluronate and polygalacturonic acid for prevention of peridural fibrosis

Hyaluronic acid-based hydrogels can reduce postoperative adhesion. However, the long-term application of hyaluronic acid is limited by tissue mediated enzymatic degradation. To overcome this limitation, we developed a polygalacturonic acid and hyaluronate composite hydrogel by Schiff's base crosslinking reaction. The polygalacturonic acid and hyaluronate composite hydrogels had short gelation time (less than 15 s) and degraded by less than 50 % in the presence of hyaluronidase for 7 days. Cell adhesion and migration assays showed polygalacturonic acid and hyaluronate composite hydrogels prevented fibroblasts from adhesion and infiltration into the hydrogels. Compared to hyaluronate hydrogels and commercial Medishield™ gels, polygalacturonic acid and hyaluronate composite hydrogel was not totally degraded in vivo after 4 weeks. In the rat laminectomy model, polygalacturonic acid and hyaluronate composite hydrogel also had better adhesion grade and smaller mean area of fibrous tissue formation over the saline control and hyaluronate hydrogel groups. Polygalacturonic acid and hyaluronate composite hydrogel is a system that can be easy to use due to its in situ cross-linkable property and potentially promising for adhesion prevention in spine surgeries.

Utilization of spinal cord stimulation in patients with failed back surgery syndrome

STUDY DESIGN

Retrospective analysis of a population-based insurance claims data set.

OBJECTIVE

To evaluate the use of spinal cord stimulation (SCS) and lumbar reoperation for the treatment of failed back surgery syndrome (FBSS), and examine their associated complications and health care costs.

SUMMARY OF BACKGROUND DATA

FBSS is a major source of chronic neuropathic pain and affects up to 40% of patients who undergo lumbosacral spine surgery for back pain. Thus far, few economic analyses have been performed comparing the various treatments for FBSS, with these studies involving small sample sizes. In addition, the nationwide practices in the use of SCS for FBSS are unknown.

METHODS

The MarketScan data set was used to analyze patients with FBSS who underwent SCS or spinal reoperation between 2000 and 2009. Propensity score methods were used to match patients who underwent SCS with those who underwent lumbar reoperation to examine health care resource utilization. Postoperative complications were analyzed with multivariate logistic regression. Health care use was analyzed using negative binomial and general linear models.

RESULTS

The study cohort included 16,455 patients with FBSS, with 395 undergoing SCS implantation (2.4%). Complication rates at 90 days were significantly lower for SCS than spinal reoperation (P < 0.0001). Also in the matched cohort, hospital stay (P < 0.0001) and associated charges (P = 0.016) were lower for patients with SCS. However outpatient, emergency room, and medication charges were similar between the 2 groups. Overall cost totaling $82,586 at 2 years was slightly higher in the lumbar reoperation group than in the SCS group with total cost of $80,669 (P = 0.88).

CONCLUSION

Although previous studies have demonstrated superior efficacy for the treatment of FBSS, SCS remains underused. Despite no significant decreases in overall health care cost with SCS implantation, because it is associated with decreased complications and improved outcomes, this technology warrants closer consideration for the management of chronic pain in patients with FBSS.

Reduction of epidural fibrosis and dural adhesions after lamina reconstruction by absorbable cement: an experimental study

BACKGROUND CONTEXT

Post-laminectomy epidural fibrosis complicates revision spine surgery and is implicated in cases of "failed back syndrome." Several materials have been used to minimize epidural fibrosis with varying results.

PURPOSE

The aim of this study was to examine the impact of reconstruction of laminectomy site with a type of absorbable cement (Jectos) to reduce epidural fibrosis.

STUDY DESIGN

This investigation is an experimental controlled study, which is designed to evaluate the preventive effects of laminectomy site reconstruction in rat laminectomy model.

METHODS

Twenty wistar rats were included in this study and divided randomly to two equal groups, namely, subject and control. In both groups, laminectomy was performed in L2 and L4 levels. Control group received no additional treatment. In the subject group, L4 levels were reconstructed by Jectos and L2 levels were non-reconstructed as internal controls. Six months after surgery the rats were sacrificed and the dural adhesion and epidural fibrosis were evaluated macroscopically and microscopically. The study was financially supported by Brain and Spinal Cord Injuries Repair Center. None of the authors have any conflict of interest.

RESULTS

Non-reconstructed levels in both groups showed dense epidural fibrosis with marked dural adherence. L4 reconstructed levels in subject group showed reduced epidural fibrosis macroscopically (p=.024) and microscopically (p=.041). No foreign body reaction or ossification occurred at reconstructed sites.

CONCLUSIONS

In the present study, lamina reconstruction with absorbable cement was a safe method that significantly reduced post-laminectomy epidural fibrosis and dural adhesions in rat laminectomy model.

Alpha-lipoic acid reduces peridural fibrosis after laminectomy of lumbar vertebrae in rabbits

BACKGROUND

Peridural fibrosis is an inevitable healing process causing failed back surgery syndrome after lumbar spinal operations. In this study, alpha-lipoic acid (ALA), reported to reduce fibrosis in liver, oral mucosa, and peritoneum, investigated as a potential candidate for prevention of peridural fibrosis.

METHOD

Twelve adult New Zealand white male rabbits were divided into control (n = 5) and ALA groups (n = 7). Laminectomy of lumbar spine was performed and ALA was applied on the exposed dura mater topically in ALA group.

RESULTS

According to histological peridural grading, the ALA group (median grade 1) showed significantly less peridural fibrosis than the control group (median grade 3, p = 0.005).

CONCLUSIONS

ALA is a promising substance in the prevention of peridural fibrosis, especially in early preoperative and postoperative period.

The effectiveness of poloxamer 407-based new anti-adhesive material in a laminectomy model in rats

PURPOSE

In the laminectomy model in rats, to verify anti-adhesive effectiveness of the new material, a mixture composed of poloxamer 407, calcium chloride, and xanthorrhizol, we compared it with that of commercially used solution form anti-adhesive agent GUARDIX-SL, Biorane.

MATERIALS AND METHODS

A total of 108 Sprague-Dawley rats (SD rats) were divided equally into three groups: negative control group (NCG), positive control group (PCG), and experimental group (EG). After exposing the dura on L4 level, we closed the wound shortly after hemostasis, after administering the anti-adhesive agent. To evaluate effectiveness, 18 SD rats from each group were killed after 1 week of rearing. Nine were examined by grading of gross adhesion and the other nine, by grading of histological adhesion. The degree of adhesion in the remainder of 18 SD rats in each group was examined with the same method after four weeks of rearing.

RESULTS

Comparing the degree of adhesion after growth for 1 week, the gross and histological adhesion of the EG was lower than that of the NCG. There was no statistical significance in the gross score (P = 0.63), but there was statistical significance in the histological score (P = 0.04). The EG showed similar or improved degrees of adhesion in comparison with the PCG. In comparison after growth for 4 weeks, although gross adhesion of the EG was not significantly lower than the NCG, histological adhesion was remarkably low in the EG (P = 0.01). The EG showed similar or improved degrees of gross and histological adhesion in comparison to that of the PCG. (P = 0.20, 0.07).

CONCLUSION

The new anti-adhesive material showed similar or improved effectiveness with the existing agents for commercial use. This result suggests that the new anti-adhesive material will be a successful candidate as a future product for clinical use.

The effect of hyaluronate-carboxymethyl cellulose on bone graft substitute healing in a rat spinal fusion model

OBJECTIVE

The aim of this study was to evaluate the impact of sodium hyaluronate-sodium carboxymethyl cellulose (HA-CMC), an anti-adhesive material for spinal surgery, on bone fusion by applying it to rat spinal models after lumbar posterolateral fusion.

METHODS

Lumbar posterolateral fusion was performed at L4-5 using bone graft substitutes in 30 rats. HA-CMC was injected in 15 rats at a dose of 0.2 cc (HA-CMC group) and a saline solution of 0.2 cc in the other 15 rats (control group). Simple radiographs were taken until postoperative 9 weeks with an interval of one week. At postoperative 4 and 9 weeks, three dimensional computed tomography (3D CT) scanning was performed to observe the process of bone fusion. At 9 weeks, bone fusion was confirmed by gross examination and manual palpation.

RESULTS

There were no statistically significant differences in bone fusion between the two groups. 3D CT scanning did not reveal significant differences between the groups. The gross examination and manual palpation after autopsy performed at 9 weeks confirmed bone union in 93.3% of both groups.

CONCLUSION

The anti-adhesive material used for spinal surgery did not have adverse effects on spinal fusion in rats.

Effect of amniotic membrane to reduce postlaminectomy epidural adhesion on a rat model

OBJECTIVE

Epidural fibrosis and adhesion are the main reasons for post-laminectomy sustained pain and functional disability. In this study, the authors investigate the effect of irradiated freeze-dried human amniotic membrane on reducing epidural adhesion after laminectomy on a rat model.

METHODS

A total of 20 rats were divided into two groups. The group A did not receive human amniotic membrane implantation after laminectomy and group B underwent human amniotic membrane implantation after laminectomy. Gross and microscopic findings were evaluated and compared at postoperative 1, 3 and 8 weeks.

RESULTS

The amount of scar tissue and tenacity were reduced grossly in group of rats with human amniotic membrane implantation (group B). On a microscopic evaluation, there were less inflammatory cell infiltration and fibroblast proliferation in group B.

CONCLUSION

This experimental study shows that implantation of irradiated freeze-dried human amniotic membrane reduce epidural fibrosis and adhesion after spinal laminectomy in a rat model.

AxiaLIF system: minimally invasive device for presacral lumbar interbody spinal fusion

Lumbar fusion is commonly performed to alleviate chronic low back and leg pain secondary to disc degeneration, spondylolisthesis with or without concomitant lumbar spinal stenosis, or chronic lumbar instability. However, the risk of iatrogenic injury during traditional anterior, posterior, and transforaminal open fusion surgery is significant. The axial lumbar interbody fusion (AxiaLIF) system is a minimally invasive fusion device that accesses the lumbar (L4–S1) intervertebral disc spaces via a reproducible presacral approach that avoids critical neurovascular and musculoligamentous structures. Since the AxiaLIF system received marketing clearance from the US Food and Drug Administration in 2004, clinical studies of this device have reported high fusion rates without implant subsidence, significant improvements in pain and function, and low complication rates. This paper describes the design and approach of this lumbar fusion system, details the indications for use, and summarizes the clinical experience with the AxiaLIF system to date.

Study on the optimal concentration of topical mitomycin-C in preventing postlaminectomy epidural adhesion

There is increasing evidence that topical application of mitomycin-C can be beneficial in reducing epidural scar adhesion. However, the ideal concentration of mitomycin-C is unknown. The purpose of this study was to verify its efficacy for preventing epidural adhesion and the immediate electrophysiological responses caused by it in a laminectomy model. Seventy rats underwent laminectomy at L-1 and L-2. Cotton pads soaked with saline and various concentrations of mitomycin-C (0.1 mg/ml, 0.3 mg/ml, 0.5 mg/ml and 0.7 mg/ml) were applied to the exposed dura for 5 min. Spine somatosensory evoked potentials (SSEP) were monitored in preoperative and the immediate electrophysiological responses of mitomycin-C used. Four weeks postlaminectomy the rats were killed. The area of epidural scar tissue and degree of epidural adhesion were determined by 7.0 T Micro MR imaging. Macroscopic evaluations were performed according to the Rydell standard. The results showed that severe epidural adhesion was formed in the saline group and no dural adherence or incomplete adhesions were found in the mitomycin-C group. The Rydell classification and the degree of epidural adhesion and the area of the scar in 0.5 mg/ml group and 0.7 mg/ml mitomycin-C group revealed a significant decrease compared with the control group and 0.1 mg/ml group and 0.3 mg/ml mitomycin-C group. The spine sensory evoked potentials did not alter obviously in both preoperative and the immediate electrophysiological responses of mitomycin-C used. In conclusion, locally applied mitomycin-C in a concentration of 0.5 mg/ml and 0.7 mg/ml mitomycin-C may be the optimal concentration in preventing postlaminectomy epidural adhesion.

Mitomycin C-polyethylene glycol controlled-release film inhibits collagen secretion and induces apoptosis of fibroblasts in the early wound of a postlaminectomy rat model

BACKGROUND CONTEXT

Recovery from spine surgery is usually accompanied with the development of epidural scar adhesions from the abnormal proliferation of fibroblast and extracellular matrix-related metabolism. Polyethylene glycol (PEG) could alleviate the postsurgical adhesion formation with still leaving a gap between the sheet and the dura. However, PEG film could not function as a three-dimensional barrier to prevent adhesion completely. Mitomycin C (MMC) could also reduce the scar formation after surgery, but cytotoxicity and the administrative pathway prevent its application.

PURPOSE

Our purpose was to design and attest the role of new delivery system MMC-PEG controlled-release film in preventing the epidural scar adhesions after laminectomy in the rat model.

STUDY DESIGN/SETTING

A total laminectomy of L1 in the rat model was used to assess epidural fibrosis between and around the spinal nerves using a histochemistry assessment along with flow cytometry analysis.

PATIENT SAMPLE

The sample comprises 64 adult male Sprague-Dawley rats.

OUTCOME MEASURES

The outcome measures are macroscopic evaluation, histological analysis, and flow cytometry analysis.

METHODS

Lumbar laminectomies at L1 and L2 with a L1-L2 disc injury were performed on 64 adult male Sprague-Dawley rats. The rats were then randomized into four groups. In Group I, 25 mg PEG film was applied on the dura mater in the laminectomy area before the layers were sutured. In Group II, a cotton pad soaked with 0.05% MMC solution was kept on the laminectomy area for 5 minutes. In Group III, 25 mg PEG film containing 0.01% MMC was implanted on the laminectomy area. In Group IV, the laminectomy area was flushed with saline before wound closure. The rats were sacrificed 4 weeks after the operation. Macroscopic evaluation and histological analysis of epidural scar adhesion with the hematoxylin and eosin stain and Masson stain were used followed by the quantification of hydroxyproline (Hyp) and flow cytometry analysis of the apoptosis of fibroblasts in the scar tissues.

RESULTS

The recovery of all rats was uneventful after the operations. In the laminectomy sites of rats treated with MMC or MMC-PEG, the dura mater was clean without any evident adhesion or membrane. Collagen tissue hyperplasia significantly decreased in the MMC- or MMC-PEG-treated models. Accordingly, Hyp concentration was significantly reduced in these two groups compared with saline-control group. In addition, the apoptosis of fibroblasts, however, was significantly elevated in the MMC or MMC-PEG group compared with the saline-control group.

CONCLUSIONS

These results demonstrate that the treatment of postlaminectomy wounds with MMC-PEG film reduces the severity of adhesion by decreasing the concentration of Hyp and increasing the apoptosis of fibroblasts.

Use of pimecrolimus to prevent epidural fibrosis in a postlaminectomy rat model

OBJECT

Epidural fibrosis is the scar tissue formed over the dura mater after a laminectomy. Extensive epidural fibrosis may be an important underlying cause of failed back syndrome. Pimecrolimus, an ascomycin derivative, is one of the new classes of immunomodulating macrolactams and was specifically developed for the treatment of inflammatory diseases. This study examined the preventive effects of the local application of pimecrolimus in minimizing spinal epidural fibrosis in a rat laminectomy model.

METHODS

Thirty Wistar rats were divided into 3 equal groups: control, mitomycin C (MMC), and pimecrolimus groups. Each rat underwent a laminectomy at the L-3 lumbar level. In the experimental groups, a cotton pad soaked with MMC (0.5 mg/ml) or 5 mg pimecrolimus was placed on the exposed dura mater. No treatment was performed in the control group rats. Thirty days after surgery, the rats were killed and the dura mater thickness, epidural fibrosis, and arachnoidal involvement were quantified.

RESULTS

The mean dura thickness was measured at 9.28 +/- 3.39 microm in the MMC group and at 8.69 +/- 2.32 microm in the pimecrolimus group, compared with 14.70 +/- 4.14 microm in the control group. In addition, the epidural fibrosis and arachnoidal involvement were reduced significantly in the treatment groups compared with the control group.

CONCLUSIONS

In this animal model, it was shown that locally applied pimecrolimus effectively reduces epidural fibrosis and dural adherence in rats that underwent lumbar laminectomy. Mitomycin C was equally effective as pimecrolimus in reducing epidural fibrosis and dural adherence in this study.

Implantation of amniotic membrane to reduce postlaminectomy epidural adhesions

Postlaminectomy epidural adhesion is implicated as a main cause of "failed back surgery syndrome" and associated with increased risk of complications during revision surgery. Various materials acting as mechanical barriers to reduce fibroblasts infiltration into epidural space have met with limited success. In present research, amniotic membrane (AM) was studied to investigate its effects on reducing epidural scar adhesion after laminectomy in a canine model. Laminectomy sites were created at L-1, L-3, L-5, and L-7 levels in 24 adult mongrel dogs. Freeze dried AM (FAM), cross-linked AM (CAM), and autologous free fat (AFF) were implanted, respectively, at a randomly assigned site in each dog with the remaining untreated site serving as internal control. The animals were sacrificed at 1, 6, and 12 weeks postoperatively. Then, gross pathologic observation including scar amount and adhesion tenacity, qualitative histology evaluation, and quantitative histology analysis were compared. Gross observation demonstrated that scar amount and adhesion tenacity of CAM group were significantly lower in comparison with those of FAM and non-treatment groups. A white, slightly vascularized CAM layer covered the dura mater without tenacious scar adhesion. The histology analysis also indicated reduced fibroblasts infiltration and consequent epidural fibrosis, which were similar to the results of AFF group. In conclusion, the CAM is effective in reducing epidural fibrosis and scar adhesion after laminectomy in canine model. It is a promising biomaterial for future clinical applications.