Results of applying ADCON-L gel after lumbar discectomy: the German ADCON-L study

Chinese Neurosurgical Randomized Controlled Trials: Dynamics in Trial Implementation and Completion

BACKGROUND AND OBJECTIVES

The focus on evidence-based neurosurgery has led to a considerable amount of neurosurgical evidence based on randomized controlled trials (RCTs) being published. Nevertheless, there has been no systematic appraisal of China's contribution to RCTs. Information about the changes in characteristics of Chinese neurosurgical RCTs before and during the COVID-19 pandemic is limited. This study aims to perform a detailed examination and comprehensive analysis of the characteristics of Chinese neurosurgical RCTs and to examine the differences before and during the COVID-19 pandemic.

METHODS

We conducted a comprehensive database search including PubMed, Web of Science, Embase, and Cochrane Library up to March 2023, with a criterion of inclusion based on an impact factor above 0. We subsequently examined the design and quality parameters of the included RCTs and assessed the differences before and during the COVID-19 pandemic (based on follow-up ending before or after January 2020). Moreover, we investigated potential factors that may affect the quality and developmental trends of neurosurgical RCTs in China.

RESULTS

The main focus of the 91 neurosurgical RCTs was vascular disease (47.3%) and trauma (18.7%). Over half of the trials used Consolidated Standards of Reporting Trial diagrams (69.2%), and the majority compared nonsurgical treatments (63.7%). Larger trials tended to have better quality scores, but those with significant efficacy were less likely to have power calculations. Over time, there was an increase in the use of Consolidated Standards of Reporting Trial diagrams and well-specified outcomes. The COVID-19 pandemic may have hindered the completion of neurosurgical RCTs in China, but it has had little impact on the design and quality so far.

CONCLUSION

Chinese neurosurgeons have made significant progress in advancing neurosurgical RCTs despite challenges. However, shortcomings in sample size and power calculation need attention. Improving the rigor, rationality, and completeness of neurosurgical RCT design is crucial.

Spinal epidural fibrosis following hemostatic agent employment

OBJECTIVE

Failed Back Surgery Syndrome (FBSS) refers to a subset of patients who have new or persistent pain after spinal surgery for back or leg pain. Epidural fibrosis (EF) is a common cause of FBSS. Many agents aiming to prevent EF have been tested. However, hemostatic agents are readily available at hospitals, easy to reach and frequently used. For these reasons, oxidized regenerated cellulose, polysaccharide hemostat, hemostatic thrombin-gelatin matrix and chitosan linear polymer were evaluated for their effects on epidural fibrosis on rats after laminectomy.

METHODS

40 Sprague-Dawley rats were randomly divided into 5 equal groups including the control group where only the laminectomy was performed. The other 4 groups received hemostatic agents after laminectomy. The rats were euthanized 45 days later and were assessed by a blinded observer to grade the fibrosis level.

RESULTS

The study revealed that oxidized regenerated cellulose, polysaccharide hemostat and hemostatic thrombin-gelatin matrix lowered the epidural fibrosis grade which was statistically significant (p < 0.001). Although chitosan linear polymer created fibrosis similar to the control group it was not proven to be statistically significant (p = 0.8999). However, when compared with other hemostatic agents it resulted in a higher fibrosis grade (p < 0.001).

CONCLUSION

The results obtained from this experimental study revealed that Pahacel, Sealfoam and Surgiflo, were effective in reducing epidural fibrosis after laminectomy in rats.

Effects of adhesion barrier gel on functional outcomes of patients with lumbar disc herniation surgery; A systematic review and meta-analysis of clinical trials

Failed Back Surgery Syndrome (FBSS) is persistent pain and disability following lumbar laminectomy which is associated with decreased quality of life and disability and has been reported in up to 40% of the patients undergoing lumbar laminectomy. Several approaches have been introduced to reduce the rate of the FBSS. Among these, applying anti-adhesive barrier gels have been studied with interest with controversial results. The aim of the current study was to determine the effects of anti-adhesive barrier gels on functional outcome and recurrence of patients undergoing lumbar disc surgery. We searched databases including EMBASE, PUBMED, Web of Science, Scopus, Cochrane Library, and scholar databases until November 2019. To assess the heterogeneity across included studies was used Cochran's Q and I-square (I²) statistics. Standardized mean difference (SMD) and 95% CI between were used to estimate pooled effect sizes. Out of 4507, 10 clinical trials found to be appropriate for current meta-analysis. The pooled results of included clinical trials indicated that adhesion barrier gel significantly decreased leg pain (LP) (SMD = −0.31; 95% CI, −0.60, −0.03; P = 0.032; I²: 59.2%) among patients with lumbar disc herniation surgery. Back pain (BP) (SMD = −0.03; 95% CI, −0.23, 0.16; P = 0.734; I²: 40.2%), and Oswestry disability index (ODI) (SMD = −0.11; 95% CI, −0.27, 0.05; P = 0.178; I²: 0.0%), were not significantly affected following adhesion barrier gel application. Application of adhesion barrier gel in single level lumbar disc surgery is associated with deceased leg pain. However, its application does not affect the low back pain, disability and gate. Further, larger randomized clinical trials are required.

Celecoxib-Loaded Electrospun Fibrous Antiadhesion Membranes Reduce COX-2/PGE2 Induced Inflammation and Epidural Fibrosis in a Rat Failed Back Surgery Syndrome Model

To date, failed back surgery syndrome (FBSS) remains a therapy-refractory clinical condition after spinal surgery. The antiadhesion membrane is applied to prevent FBSS by isolating fibrosis; however, the inflammation stimulated by the foreign body and surgical trauma needs to be further resolved simultaneously. Therefore, we developed new electrospun polycaprolactone (PCL) fibrous membranes loaded with celecoxib (CEL) to prevent fibrosis and inflammation associated with FBSS. The CEL-loaded PCL fibers were randomly distributed, and the drug was released over two weeks. Fluorescence micrographs revealed that the fibroblasts proliferated less on the PCL-CEL fibrous membranes than in the PCL group and the blank control. In the rat laminectomy model after 4 weeks, magnetic resonance imaging of epidural fibrosis was least in the PCL-CEL group. Expression of COX-2 and PGE2 was lower in the PCL-CEL group. It concluded that the CEL-loaded PCL membrane could reduce fibrosis and inflammation in a rat model of FBSS via COX-2/PGE2 signaling pathways.

Analysis of pain markers and epidural fibrosis caused by repeated spinal surgery in Sprague-Dawley rats

Background

Epidural fibrosis is one of the aetiologies of pain following a spinal revision surgery. It is reported that the specific members of the mitogen – activated protein kinases (MAPK) family might mediate neuropathic pain. However, roles of epidural fibrosis caused by repeated spinal surgeries and pain-related proteins in causing the post spinal surgery syndrome remain unknown. Using a rat spinal surgery epidural fibrosis and adhesion model, in this study, we evaluated and investigated the relationship between pain markers and epidural fibrosis.

Methods

Sprague–Dawley rats that underwent the spinal surgery were divided into three groups: group A (single laminectomy), group B (two repeated surgeries) and group C (three repeated surgeries). Dural thickness was measured in each experimental group, and immunohistochemical analysis and western blotting of mitogen-activated protein kinases were performed (ERK, p38 and JNK) using the spine cord.

Results

Dural thickness was 6.363 ± 1.911 μm in group A, 13.238 ± 2.123 μm in group B and 19.4 ± 2.115 μm in group C, respectively. In the western blotting, phosphorylated ERK expression gradually increased with the number of repeated surgeries, and expression in groups B (1.77-fold) and C (2.42-fold) increased as compared to expression in group A. Phosphorylated p38 showed an increasing trend with the number of repeated surgeries, and groups B (1.17-fold) and C (1.33-fold) expression increased compared with group A. However, phosphorylated JNK expression did not gradually increase with the number of repeated surgeries, and groups B (1.62-fold) and C (1.43-fold) expression increased compared with group A. Excluding phosphorylated JNK, immunohistochemical analysis revealed that phosphorylated ERK and p38 expression gradually increased with the number of repeated surgeries in the spine dorsal horn, as evidenced by western blotting.

Conclusions

Repeated spinal surgeries may increase dural thickness and expression of phosphorylated ERK and p38 in the spinal dorsal horn, and it suggests that the neuropathic pain is likely induced by epidural fibrosis and that the pain increases with the number of repeated surgeries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03920-z.

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.

A novel bacterial cellulose membrane immobilized with human umbilical cord mesenchymal stem cells-derived exosome prevents epidural fibrosis

Introduction

Failed back surgery syndrome is a situation where there is failure after lumbar surgery aimed at correcting lumbar disease that is characterized by continuous back and/or leg pain. Epidural fibrosis and adhesions are among the major causes of failed back surgery syndrome. In recent years, several biomaterials have been applied as barriers or deterrents to prevent the compression of neural structures by postsurgical fibrosis.

Methods

In this study, a new bacterial cellulose (BC) anti-adhesion membrane, composed of exosomes from human umbilical cord mesenchymal stem cells, was developed. Its structure and morphology, water content, thickness, and mechanical properties of elasticity were analyzed and characterized. The degradation of the BC+exosomes (BC+Exos) membrane in vitro was evaluated, and its in vitro cytotoxicity and in vivo biocompatibility were tested. The prevention effect of BC+Exos membrane on epidural fibrosis post-laminectomy in a rabbit model was investigated.

Results

The BC+Exos membrane showed a three-dimensional network structure constituted of high-purity cellulose and moderate mechanical properties. No degeneration was observed. The BC+Exos membrane showed no cytotoxicity and displayed biocompatibility in vivo. The BC+Exos film was able to inhibit epidural fibrosis and peridural adhesions.

Conclusion

Based on the current findings, the BC+Exos membrane is a promising material to prevent postoperative epidural fibrosis and adhesion.

Is the use of hemostatic matrix (Floseal) and alkylene oxide copolymer (Ostene) safe in spinal laminectomies? Peridural fibrosis assessment

Objective

Failed Back Syndrome (FBS) is unacceptable relief of pain or recurrence of symptoms in patients after spinal surgery, such as laminectomy. One possible cause of FBS is peridural fibrosis (PF). PF is the overproduction of scar tissue adjacent to the dura mater. Bleeding can cause PF after laminectomy. Ostene is an alkylene oxide copolymer material used to stop bleeding from bony surfaces. Floseal is a gelatin thrombin matrix sealant used to assist fibrin formation and to promote coagulation.

Methods

Total of 32 female Sprague–Dawley rats were evenly allotted to 4 experimental groups: laminectomy only, laminectomy + Ostene (Baxter International, Inc., Deerfield, IL, USA), laminectomy + Floseal (Baxter International, Inc., Deerfield, IL, USA), and laminectomy + Adcon-L (aap Implantate AG, Berlin, Germany). After performing total laminectomy, agents were placed over dura mater. Spinal column of test subjects was harvested 6 weeks after laminectomy. Histopathological examination of samples was based on Masson's trichrome and hematoxylin and eosin staining. PF observed in the groups was graded using system previously described by He et al. Statistically significant p value was defined as p < 0.005.

Results

Present study revealed that Adcon-L, Ostene, and Floseal groups had reduced PF compared with laminectomy only group (p = 0.001). Comparison of Ostene and Floseal groups with Adcon-L group yielded no significant difference.

Conclusion

Reoperation as result of FBS has greater risk and often has poor outcome; surgeons must take precautions to avoid FBS, such as careful selection of appropriate patient and operation technique. Ostene and Floseal may be applied and left in the operation field safely during laminectomy to reduce occurrence of PF after procedure.

An Experimental Study of Histopathologic Effects of Hemostatic Agents Used in Spinal Surgery

OBJECTIVE

To evaluate and compare the histopathologic effects of various hemostatic agents used in spinal surgery on an experimental laminectomy model in rats.

METHODS

There were 110 rats randomly allocated into 11 groups, including sham, control, AnkaferdBlood Stopper (herbal hemostatic), SeraSeal (agar and bovine factor proteins), FLOSEAL (gelatin granules and thrombin), SURGIFLO (gelatin paste), HELITENE (absorbable collagen), Beriplast (fibrin sealant containing fibrinogen, factor XIII, and thrombin), TISSEEL (fibrin sealant), BLOODCARE (hemostatic powder), and SURGICEL (oxidized cellulose polymer) groups. Hemostatic agents were applied on the epidural region after laminectomy was performed until the identification of dura mater and nerve root. After a follow-up period of 12 weeks, rats were sacrificed, and histologic sections were performed proximal and distal to laminectomy zone. Groups were histopathologically compared in terms of chronic inflammation, fibrosis, and vascularization.

RESULTS

There was no difference between groups in terms of acute inflammation (P = 0.159). Chronic inflammation was more remarkable in the herbal hemostatic group (P = 0.036), and there was severe fibrosis in absorbable collagen hemostatic, fibrin sealant, and powder hemostatic agent groups (P < 0.001). Vascularity was more obvious in herbal hemostatic; fibrin sealant; absorbable collagen; fibrin sealant containing fibrinogen, factor XIII, and thrombin; hemostatic powder; and oxidized cellulose polymer groups (P < 0.001).

CONCLUSIONS

Hemostatic agents can cause notable histopathologic alterations, including inflammation, fibrosis, and vascularity. In this context, flowable hemostats such as gelatin granules and thrombin or gelatin paste seem to provide more promising results in spinal surgery.

Role of lumbar interspinous distraction on the neural elements

The interspinous distraction devices are used to treat variable pathologies ranging from facet syndrome, diskogenic low back pain, degenerative spinal stenosis, diskopathy, spondylolisthesis, and instability. The insertion of a posterior element with an interspinous device (ISD) is commonly judged responsive to a relative kyphosis of a lumbar segment with a moderate but persistent increase of the spinal canal and of the foraminal width and area, and without influence on low-grade spondylolisthesis. The consequence is the need of shared specific biomechanical concepts to give for each degenerative problem the right indication through a critical analysis of all available experimental and clinical biomechanical data. We reviewed systematically the available clinical and experimental data about kyphosis, enlargement of the spinal canal, distraction of the interspinous distance, increase of the neural foramina, ligamentous structures, load of the posterior annulus, intradiskal pressure, strength of the spinous processes, degeneration of the adjacent segment, complications, and cost-effectiveness of the ISD. The existing literature does not provide actual scientific evidence over the superiority of the ISD strategy, but most of the experimental and clinical data show a challenging potential. These considerations are applicable with different types of ISD with only few differences between the different categories. Despite--or because of--the low invasiveness of the surgical implantation of the ISD, this technique promises to play a major role in the future degenerative lumbar microsurgery. The main indications for ISD remain lumbar spinal stenoses and painful facet arthroses. A clear documented contraindication is the presence of an anterolisthesis. Nevertheless, the existing literature does not provide evidence of superiority of outcome and cost-effectiveness of the ISD strategy over laminectomy or other surgical procedures. At this time, the devices should be used in clinical randomized independent trials in order to obtain more information concerning the most advantageous optimal indication or, in selected cases, to treat tailored indications.

Delayed Detected Unexpected Complication of ADCON-L® Gel in Lumbar Surgery

The ADCON-L gel® (Gliatech, Cleveland, OH, USA), a carbohydrate polymer gel, has been shown in a controlled clinical study to inhibit postsurgical adhesions and improve a patient's clinical outcome. Immediate complication of this gel has been reported in the recent literature including back pain, radiculitis and durotomy. However, delayed detection of disturbance of muscle healing and attachment in late postoperative state has been rarely reported. This report documents an unexpected delayed detected complication of the anti-adhesion barrier gel, which was used after lumbar discectomy one year ago, with review of literature.

Peridural scar and its relation to clinical outcome: a randomised study on surgically treated lumbar disc herniation patients

A prospective randomised 2-year follow-up study on patients undergoing lumbar disc herniation surgery. The objective was to investigate the relationship between peridural scarring and clinical outcome, the scar development 6 and 24 months postoperatively by using MRI, and if ADCON-L (a bioresorbable carbohydrate polymer gel) has an effect on scar size and/or improve patients' outcome after lumbar disc herniation surgery. The association between peridural scarring and recurrent pain after lumbar disc herniation surgery is debated. Numerous materials have been used in attempts to prevent or reduce postoperative peridural scarring; however, there are conflicting data regarding the clinical effects. The study included 119 patients whose mean age was 39 years (18-66); 51 (47%) were women. Sixty patients (56%) were perioperatively randomised to receive ADCON-L, and 48 (44%) served as controls. All patients underwent MRI at 6 and 24 months postoperatively, and an independent radiologist graded the size, location and development of the scar, by using a previously described scoring system. Pre- and 2-year postoperatively patients graded their leg pain on a visual analogue scale (VAS). At the 2-year follow-up patients rated their satisfaction with treatment (subjective outcome) and were evaluated by an independent neurologist (objective outcome), using MacNab score. There was no relationship between size or localisation of the scar and any of the clinical outcomes (VAS, subjective and objective outcome). The scar size decreased between 6 and 24 months in 49%, was unchanged in 42% and increased in 9% of the patients. Patients treated with ADCON-L did not demonstrate any adverse effects, nor did they demonstrate less scarring or better clinical outcome than control patients. No significant association between the presence of extensive peridural scar or localisation of scar formation and clinical outcome could be detected in the present study. Further, no positive or negative effects of ADCON-L used in disc herniation surgery could be seen.

Surgical interventions for lumbar disc prolapse

BACKGROUND

Disc prolapse accounts for five percent of low-back disorders but is one of the most common reasons for surgery.

OBJECTIVES

The objective of this review was to assess the effects of surgical interventions for the treatment of lumbar disc prolapse.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Spine and abstracts of the main spine society meetings within the last five years. We also checked the reference lists of each retrieved articles and corresponded with experts. All data found up to 1 January 2007 are included.

SELECTION CRITERIA

Randomized trials (RCT) and quasi-randomized trials (QRCT) of the surgical management of lumbar disc prolapse.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial quality and extracted data from published papers. Additional information was sought from the authors if necessary.

MAIN RESULTS

Forty RCTs and two QRCTs were identified, including 17 new trials since the first edition of this review in 1999. Many of the early trials were of some form of chemonucleolysis, whereas the majority of the later studies either compared different techniques of discectomy or the use of some form of membrane to reduce epidural scarring. Despite the critical importance of knowing whether surgery is beneficial for disc prolapse, only four trials have directly compared discectomy with conservative management and these give suggestive rather than conclusive results. However, other trials show that discectomy produces better clinical outcomes than chemonucleolysis and that in turn is better than placebo. Microdiscectomy gives broadly comparable results to standard discectomy. Recent trials of an inter-position gel covering the dura (five trials) and of fat (four trials) show that they can reduce scar formation, though there is limited evidence about the effect on clinical outcomes. There is insufficient evidence on other percutaneous discectomy techniques to draw firm conclusions. Three small RCTs of laser discectomy do not provide conclusive evidence on its efficacy, There are no published RCTs of coblation therapy or trans-foraminal endoscopic discectomy.

AUTHORS' CONCLUSIONS

Surgical discectomy for carefully selected patients with sciatica due to lumbar disc prolapse provides faster relief from the acute attack than conservative management, although any positive or negative effects on the lifetime natural history of the underlying disc disease are still unclear. Microdiscectomy gives broadly comparable results to open discectomy. The evidence on other minimally invasive techniques remains unclear (with the exception of chemonucleolysis using chymopapain, which is no longer widely available).

The influence of vertebral instability on peridural circulation and concomitant peridural fibrosis formation

An animal model of vertebral instability was used to analyze the effect of chronic lumbar instability on the peridural vasculature and fibrosis formation. Fifty mature male domestic rabbits were divided into five equal groups. The vertebral instability was performed by excision of supra and interspinous ligaments between L2-L3 and L3-L4, excision of transverse and spinous processes and making bilateral laminectomies and facetectomies in groups I, II, III and IV. In group V only para vertebral muscle dissection was performed without vertebral instability. The simulation of the long term effects of overuse model on unstable spines (chronic instability) were performed with the use of Electrical Neuromuscular Stimulator to simulate cyclic flexion-extension movement in groups I, II. The rabbits in group I and III were sacrified for the histological evaluation at postoperative fifth day. The rabbits in groups I II, IV and V were sacrified at postoperative 21st day. There was no peridural venous endothelial injury or stasis but there was an increased amount of polymorph nuclear leukocytes in both group I (unstable-overuse) and group III (unstable-no overuse) after sacrification at postoperative fifth day. Peridural fibrosis and also vascular changes with different grades were seen in group II, VI and V after sacrification at postoperative 21st day. The grade of the venous changes and the mean amount of peridural scar formation were prominently higher in group II (unstable-overuse) than in group IV (unstable-no overuse) and V (control group). There was no difference between group IV and V for peridural scar formation and vascular changes. In conclusion, the instability of the lumbar spine with overuse could be a cause of peridural venous circulatory impairment, resulting in fibrosis formation.

Ergebnisse der alleinigen Sequestrektomie bei lumbaler Bandscheibenoperation

BACKGROUND

While performing microsurgical disc excision, usually the sequestrated disc fragments as well as loosened or degenerated parts of the nucleus pulposus are removed. It is controversial whether this strategy is always necessary. The aim of this study was to examine this question based on clinical results.

MATERIAL AND METHODS

Prospectively all relevant data from 149 consecutive patients after sequestrectomy were collected including the clinical course of the patients with a mean follow-up of 2.3 years. A detailed analysis of the actual pain status, the functional capacity and possible additional spinal operations was performed.

RESULTS

During early follow-up, there was one superficial wound infection, which was treated conservatively. The success rate, as measured by patient self-assessment, was 62% for excellent and good and 25% for fair results; 13% of the patients treated declared a poor result having no benefits from surgery. The average FFbH score during follow-up was 74% (100% means no functional restriction). Radicular pain and low back pain had the same intensity on the average, in contrast to some other investigations, where low back pain was lower than radicular pain [14]. Of the 149 patients, 4 underwent a second spine surgery at the same level, 2 of which were recurrent disc herniations (=1.3%).

CONCLUSION

Simple fragment excision revealed similar results compared to standard microdiscectomy. There was an especially low number of recurrences in contrast to former reports [16]. This was probably caused by the conscientious selection of patients for sequestrectomy according to well-defined criteria. Whether simple sequestrectomy can effectively treat an additional low back pain component must be clarified by further prospective studies.

Inhibition of spinal fusion by use of a tissue ingrowth inhibitor

"Spinal instrumentation without fusion" techniques, which do not interfere with spinal growth, have been used extensively in the treatment of progressive spinal scoliosis in very young children. Due to subperiosteal exposure, the process of spinal instrumentation may induce spontaneous bony fusion. Instrumentation and surgical techniques have been modified in order to prevent spontaneous posterior fusion from occurring in children. An absorbable ADCON-L gel has been shown to inhibit scar and epidural adhesions following spinal surgeries. However, little is known about its influence on spinal fusion. In the present study, a single-level intertransverse arthrodesis at L4-5 on both sides was performed on each of nine pigs. Each side was randomly designed to receive autogenous bone graft with or without ADCON-L gel. The animals were followed for 10 weeks postoperatively. A fusion rate of 78% (7/9) was obtained in the autograft treatment by plain X-ray and CT evaluation, while the autograft/ADCON-L treatment yielded a 0% (0/9) fusion rate ( p = 0.001). Histomorphometric evaluation revealed that the addition of ADCON-L gel to bone graft decreased bone and bone marrow formation and significantly increased fibrous tissue formation. No statistical difference between the two treatments was found in cartilage, bone surface density, osteoid surfaces or osteoclast-covered surfaces in any zone. We conclude that ADCON-L gel mixed into autogenous bone graft can delay or decrease bone formation at spinal arthrodesis sites, thus influencing the extent of spinal fusion. This accords with our hypothesis that the use of ADCON-L gel can prevent not only the occurrence of spontaneous fusion in very young scoliosis patients after instrumentation without fusion, but also re-ossification of a decompressed spinal canal.

Mitomycin C in preventing spinal epidural fibrosis in a laminectomy model in rats

Object. Extensive epidural fibrosis after lumbar surgery may be the underlying cause in most cases of failed—back surgery syndrome. Various materials have been used to prevent epidural fibrosis, but only moderate success has been shown.

Mitomycin C, an alkylosing antibiotic substance isolated from Streptomyces caespitosus, potentially supresses fibroblast proliferation after surgery. In this study, the authors investigated the effect of mitomycin C by local application on spinal epidural fibrosis in a rat laminectomy model.

Methods. Five Wistar rats underwent laminectomy at cervical, thoracic, and lumbar levels. Based on data obtained from ophthalmological studies, mitomycin C was applied to the laminectomy sites in various concentrations (0.01, 0.05, and 0.1 mg/ml). One laminectomy site in each rat was left untreated and thus served as a control. Evoked potentials were measured pre- and postoperatively, and all rats underwent clinical evaluation. Mobility status and evidence of neurological deficit were recorded. Twelve weeks later, the rats were killed, and the spinal column, including surrounding muscle tissue, was removed en bloc, decalcified, and fixed in formaldehyde. Epidural fibrosis was evaluated histologically.

In all mitomycin C—treated laminectomy sites, epidural scarring was significantly reduced compared with control sites. Remarkably, dural adhesions were absent in laminectomy defects treated with mitomycin C concentrations of 0.05 and 0.1 mg/ml. Moderate to marked epidural fibrosis with adhesion to the dura mater was noted at sites receiving 0.01 mg/ml of mitomycin C. All control sites showed dense epidural fibrosis with marked dura adherence.

Conclusions. In this experimental model, mitomycin C applied locally at a concentration of 0.1 mg/ml effectively reduced epidural fibrosis, completely avoided dural adherence, and induced no side effects.

The effect of epidural free fat graft on the outcome of lumbar disc surgery

Numerous materials have been used to prevent epidural scar tissue after lumbar disc surgery. Free fat grafts are common both experimentally and clinically, but there is some doubt about their protection against fibrosis, and some complications have been reported. In this prospective study, the usefulness of free fat grafts during lumbar disc surgery was evaluated. Ninety-nine patients who had undergone operation due to lumbar disc herniation were divided in two groups: those with implantation of free fat grafts (group A) and those without (group B). Outcome was evaluated at a mean of 2.6 years postoperatively according to the following criteria: visual analog scale for back and leg pain, Hannover Questionnaire on activities of daily living, reflex findings, sensory and motor deficits, consumption of analgesics, walking distance, straight leg raising test, and clinical examination. The outcome variables showed no significant differences between the two groups ( P>0.05). This study suggests that the use of free fat grafts during lumbar disc surgery was clinically ineffective.

Use of polylactide resorbable film as an adhesion barrier

OBJECT

The present investigation evaluates two thicknesses of a resorbable polylactic acid (PLA) barrier film as an adhesion barrier to posterior spinal scar formation.

METHODS

A readily contourable, thin film was placed directly over the dura. The thick film was placed above the lamina defect to act as a physical barrier inhibiting the prolapse of soft tissue into the epidural space. Through a combination of gross dissection with and without scar scores, quantitative analysis of collagen adjacent to the scar site, and histological evaluation, the resorbable adhesion barrier membranes were found to be effective treatment for reduction of posterior adhesions.

CONCLUSIONS

The gross dissection demonstrated that both thicknesses of resorbable PLA barrier films created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the tissue adherent to the dura.

Use of polylactide resorbable film as an adhesion barrier

The present investigation evaluates two thicknesses of a resorbable polylactide barrier film as an adhesion barrier to posterior spine scar formation. A readily contourable, thin film was placed directly over the dura. The thick film was placed above the lamina defect to act as a physical barrier inhibiting the prolapse of soft tissue into the epidural space. Through a combination of gross dissection with and without scar scores, quantitative analysis of collagen adjacent to the scar site, and histologic evaluation, the resorbable adhesion barrier membranes were found to be effective treatment for reduction of posterior adhesions. The gross dissection demonstrated that both thicknesses of resorbable polymer barrier films created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the tissue adhered to the dura.