Peridural Adhesion Research Articles

Prevention of peridural adhesions in spinal surgery: Assessing safety and efficacy of Chitogel with Deferiprone in a sheep model

IntroductionSpinal laminectomy is a common procedure performed to relieve neural compression in patients suffering from myelopathy or radiculopathy. However, up to 40% of patients suffer from persistent post-operative pain and disability, a condition known as Failed Back Surgery Syndrome (FBSS). Excessive scarring in the surgical bed is implicated as a cause. Hydrogels have been proposed to prevent adhesion formation post-laminectomy; however, their efficacy has not been proven. This study uses Chitogel complexed with the iron chelator Deferiprone (Def) to prevent adhesion formation in a sheep laminectomy model. Material & methodsFifteen Adult Merino sheep (Ovis Aries, 1–5 yrs old) underwent laminectomy at lumbar levels 1–5 and had hydrated aluminum silicate (kaolin) applied to promote adhesion formation. Subjects were randomised to receive at each laminectomy level no-treatment control, Chitogel, Chitogel with Def at 20 mM or 40 mM or Carboxy-methyl-cellulose and Polyethylene oxide (CMC/PEO) gel. The animals were recovered for 3 months post-surgery, followed by assessment with Magnetic Resonance Imaging (MRI) and histopathology of the spinal tissues for evaluating the presence and extent of adhesions. ResultsMRI and Histology assessment indicated that Kaolin induced severe inflammation with adhesion formation. Chitogel with and without 20 mM Def decreased inflammation (p < 0.01) and trended to reduce adhesions (p < 0.1). Chitogel with Def 40 mM was not significantly dis-similar to CMC/PEO and did not reduce inflammation or adhesions compared to no-treatment control. ConclusionChitogel in combination with Def 20 mM is safe and effective in decreasing the inflammatory process and may possibly reduce post-operative adhesions following laminectomy.

Chitosan Dextran gel as an anti adhesion agent in a postlaminectomy spinal sheep model

Introduction: Post-operative peridural adhesions increase morbidity after neurosurgical procedures. Aim of this study is to assess safety and efficacy of Chitosan-Dextran (CD) gel as an anti–adhesion agent in a spinal laminectomy sheep model. Methods: Eighteen sheep were used in this study with 6 animals in each treatment arm (namely, CD gel, Gelfoam paste and normal saline control). Posterior lumbar laminectomy was performed in all animals and the dura was exposed intact. Test agents were applied over the exposed dura and the wound was closed in layers. Sheep were euthanized at the end of three months. MRI spine was performed after euthanasia to assess epidural fibrosis. Adhesion in the spinal specimen was assessed by Peel test and histopathology was used to assess safety of the agents. Results: Average scores for the Peel test for CD gel, Gelfoam and normal saline control groups were 1.16 (95% CI, 0.5–1.7), 1.5 (95% CI, 0.6–2.3) and 3 (95% CI, 2.1–3.8) respectively. There was significant reduction in adhesions between treatment and normal saline treated groups (p=0.0292), with no difference between Gelfoam and CD gel groups (p=0.56). Average scores on MRI for CD gel, Gelfoam and normal saline groups were 1.4 (95% CI, 0.9–1.8), 1.5 (95% CI, 1.2–1.8) and 1.6 (95% CI, 1.3–1.8) respectively, with no significant difference in fibrosis amongst (p=0.2992). Histopathology did not show any adverse effects. Conclusion: CD gel is an effective agent to reduce epidural adhesions with a good safety profile in neural tissue.

Effects of Rapamycin on Reduction of Peridural Fibrosis: An Experimental Study

BackgroundPeridural fibrosis (PF) is a normal complication after lumbar surgery. It is a challenge for both surgeons and patients. Rapamycin (RPM), a novel antibiotic with anti-proliferative and immunosuppressive properties, has been shown to be effective in preventing uncontrolled scar proliferation diseases. The object of the present research was to investigate the effects of RPM on inhibiting PF in vitro and in vivo.Material/MethodsIn vitro, the fibroblasts collected and isolated from the rat tail skin were cultured with/without RPM and cell counting was performed. In vivo, the double-blinded study was conducted in 60 healthy Wistar rats divided randomly into 3 groups: 1) RPM treatment group; 2) Vehicle treatment group; 3) Control group. Rats underwent a L1-L2 level laminectomy with a satisfactory anesthetization. Four weeks post-operatively, the Rydell score, histological analysis, hydroxyproline content, vimentin expressional level, and inflammatory cytokines expressional levels were assessed.ResultsIn vitro, RPM showed ability to prevent fibroblast proliferation. In vivo, the laminectomy was well tolerated by all rats, which were killed 4 weeks post-operatively. The Rydell score, histological evaluation, hydroxyproline content, vimentin expression level, and inflammatory activity showed the positive effect of RPM in preventing peridural adhesion, inhibiting fibrotic formation and collagen synthesis, and down-regulating inflammation.ConclusionsIn the present primary study, RPM showed good efficacy in preventing the proliferation of fibroblasts. RPM can prevent rat peridural adhesion through inhibiting collagen synthesis, fibroblasts proliferation, and inflammatory activity.

Antiadhesive effect of bioresorbable polylactide film in abraded middle ear mucosa

Background and objectivePolylactide film (PLF) is used to prevent postoperative peridural adhesion in spinal surgery. Up until now, the antiadhesive effect of bioresorbable PLF in ear middle surgery has not been reported. The purpose of this study is to evaluate the antiadhesive effect of PLF in guinea pigs serving as a model for middle ear mucosal trauma. Materials and methodsThe animals were divided into two groups: the PLF group and the silastic sheeting group. There were seven guinea pigs (fourteen ears) in both groups. Under aseptic conditions, the middle ear mucosa was abraded using a pick inserted transbullaly. A PLF or silicone sheet was then placed into the guinea pigs’ middle ear cavities. The auditory brainstem responses (ABRs) were assessed preoperatively and at three weeks postoperatively while the animals were under general anesthesia. A histopathological study was performed 3 weeks after the operation. ResultsThe difference between the ABR results before the operation and three weeks postoperatively were not statistically significant. The adhesion formation did not appeared in either group. Prominent fibrous capsule formation and inflammation were observed in the silastic sheeting group, but not in the PLF group. Mild fibrous thickening of regenerated mucosa was observed in the PLF group. ConclusionFrom our results, bioresorbable PLF is nonototoxic and biocompatible with the guinea pig's middle ear cavity by short-term evaluation. Further long-term evaluation study is necessary before clinical application.

The prevention effect of poly (L-glutamic acid)/chitosan on spinal epidural fibrosis and peridural adhesion in the post-laminectomy rabbit model.

Spinal epidural fibrosis and adhesion are implicated as one of the key factors of failed back surgery syndrome, which may cause dura mater compression or peridural tethering, resulting in persistent backache and leg pain. Various materials or drugs have been used to inhibit formation of epidural fibrosis and reduce the compressive effect on neural structures. Nevertheless, the effects are not satisfied. In this study, we investigated the prevention effect of poly (L-glutamic acid)/chitosan (PLGA/CS) barrier on epidural fibrosis developing post-laminectomy in a rabbit model. Sixteen rabbits were divided randomly into two equal groups: group A (experimental group, n = 8) and group B (non-treatment group, n = 8). In both groups, total L5-6 laminectomy was performed; further both ligamentum flavum and epidural fat were removed gently. In experimental group, the laminectomy sites were treated with PLGA/CS barriers, while no additional treatment was received in non-treatment group. At 1, 12 and 24 weeks post-surgery, the animals were subjected to magnetic resonance imaging (MRI) evaluation. Following last MRI examination, all rabbits were sacrificed and their spinal columns were totally removed for further macroscopic and histological evaluation. MRI showed that rabbits treated with PLGA/CS barrier at 12 and 24 weeks post-surgery had less epidural fibrosis or scar tissue, peridural adhesion, foreign body reaction and low pressure of spinal cord in comparison with the non-treatment group. In consistence with the radiographic results, macroscopic analysis and histological examination showed that the amount of scar tissue and the extent of epidural adhesion decreased significantly in experimental groups. Concerning the fibroblast density evaluated, the scores were significantly lower in experimental group compared with those in non-treatment group. The results of our study demonstrate that PLGA/CS barrier is effective in inhibiting epidural fibrosis and peridural adhesions in post-laminectomy rabbit model.

Effectiveness of the biophysical barriers on the peridural fibrosis of a postlaminectomy rat model: An experimental research

Long term results after surgical treatment of disc herniation have shown that epidural and/or peridural fibrosis formed during the healing process after surgical intervention. We conducted this experimental study to evaluation of the effectiveness of the bioresorbable barriers (ADCON-L and Seprafilm(®) Adhesion Barrier) on formation of the peridural fibrosis in rat model performed laminectomy. Thirty-two male Wistar albino rats 250-350g body weight were distributed into three groups (CONTROL, AL group received ADCON-L; SAB group received Seprafilm(®) Adhesion Barrier). A dorsal laminectomy at L3, L4, L5 was performed, and then except those of the CONTROL group, the experimental material was left on the dura mater. Six weeks later spinal column of all rats was totally removed between the T10 and L5 levels, and peridural fibrosis, and dural adhesions were evaluated histologically and graded. The results were compared statistically by using the chi-square (χ(2)) test. Also three random regions were examined, and the fibroblast cells were counted. The fibroblast count results were statistically analysed by using the One-Way ANOVA test. The variation of histopathological grades was statistically significant regarding the comparison of the all groups obtained from the χ(2) test (χ(2)=16.40; p=0.003). However, the variation in the mean values of the fibroblast count result was not statistically significant obtained from the One-Way ANOVA test (F=2.114; p>0.05). Our study results suggest that Seprafilm(®) Adhesion Barrier and ADCON-L can be effective in reducing the prevalence of the postoperative peridural adhesions in rat laminectomy model. On the other hand, the fibroblast densities of the experimental groups were not different between groups. So, we could say that these materials can act as a foreign body in long term period in rat.

Tetramethylpyrazine and autogenous periosteum to prevent peridural fibrosis and adhesion after laminectomy

Objective To study the effect of Tetramethylpyrazine plus autogenous periosteum on prevention of fibrous scar formation in the epidural space after laminectomy. Methods Forty-eight SD rats were divided randomly into 4 groups.Laminectomy was performed in the segment of lumbar 2.The exposed dura was covered with saline solution (group A),Tetramethyipyrazine(group B),autogenous periostoum(group C)and Tetramethylpyrazine plus autogenous periosteum(group D)respectively.12 weeks postoperatively,evaluation wag based on the gross and histopathological observations,biochemical examination,and bone aiming factor quantitative analysis.Results In modified RydellBalazs score for adhesion toughness,collagen content and modified Nussvuanm score for histology,groups B,C and D were significantly superior to group A(P<0.05)while group D wag significantly superior to groups B and C (P<0.05).TGF-β values in groups C and D were significantly higher than those in groups A and B(P<0.05). Conclusion The combined application of Tetramethylpyrazine plus autogenous periosteum has a better effect on prevention of peridural adhesion after laminectomy than application of just either of the two. Key words: Laminectomy; Dura mater; Tetramethylpyrazine; Periosteum

Mitomycin C-induced fibroblast apoptosis and mechanism

Objective To elucidate the mitomycin C (MMC) -induced apoptosis of fibroblasts and the mechanism. Methods The cultured fibroblasts were exposed for 12 h to 0-0. 3 g/L MMC, respectively. The cell proliferation was measured by CCK-8 assay and apoptotic cell death was analyzed by Ho-echst33342 stain on the fisherbrand covergla. The expression of Caspase-3 and the activation of p-ERK1/2, p-Akt were detected by Western blotting. Results Treatment of fibroblasts with MMC induced a significant decrease in proliferation. With the increases of MMC from 0. 001-0. 2 g/L MMC, Hoechst 33342 staining displayed nuclei with abnormal morphologies: bean-shaped nuclei with highly condensed chromatin or nuclei with irregular clumps of dense chromatin. 0.2g/L MMC, 100 nmol/L PD98059 (ERK kinase inhibitor) , 100 nmol/L LY294002 (AKT kinase inhibitor) induced a significant increase of Caspase-3 as compared with control group, accompanied by an increase in cell apoptosis. 0.2 g/L MMC, PD98059, LY294002 caused decrease of p-ERKl/2 and p-Akt. Conclusion 0. 2 g/L MMC can induce fibroblast apoptosis by reducing the phosphorylation of p-ERKl/2 and p-Akt, resulting in the increase in the Caspase-3 expression. MMC can inhibit fibroblast proliferation and induce its apoptosis, which may be one of mechanisms by which MMC prevents peridural adhesion after laminectomy. Key words: Fibroblast; Mitomycin C; Apoptosis

Repair of the Canine Vertebral Lamina With a Combination of Autologous Micromorselized Bone and Poly-Lactic Acid Gel After a Total Laminectomy

The complications of a total laminectomy can include epidural scar adhesion, secondary vertebral canal stenosis and lumbar instability. The aim of this study was to assess the ability of a combination of autologous micromorselized bone and polylactic acid (PLA) gel to stimulate bone repair within canine vertebral lamina defects, as well as to prevent peridural adhesion following a laminectomy. Twenty dogs underwent a L1, L3 and L5 laminectomy after a pre-computed tomography examination. The 60 laminectomies were divided into 4 groups, and underwent the following treatments: Group A were treated with a combination of autologous micromorselized bone and PLA gel (n = 16); Group B were treated with micromorselized bone only (n = 16); Group C with PLA gel only (n = 14); and Group D were left untreated as they were the blank controls (n = 14). Vertebral laminae were harvested at 4th and 8th weeks, and examined by computed tomography and histological staining. Significant bone regeneration was observed at 4 and 8 weeks in Groups A and B, although the newly formed bone in the latter group was more irregular in shape. Spinal canal cross-sectional areas in Group B decreased as compared with those in Group A(p < 0.05), and the degree of peridural adhesion in Groups A and C was significantly lower compared with Groups B and D (p < 0.05). These findings indicate that a combination of micromorselized bone and PLA gel may provide a better strategy for the treatment of spinal stenosis.

Empirical study of autogenous dermal grafts in the prevention of epidoral fiSrosis and adhesions

Objective To investigate the ability of auto-dermis grafts in the prevention of epidural fibrosis and adhesions, and provide reference for clinical application. Methods Five Tibet mini-pigs were used and laminectomy was performed in lumbar 2 and 4 segment. Dura was exposed and covered with auto-genous dermis grafts in lumbar 2 (the experimental group), without grafts in lumbar 4 (the autogeoous blank group). The specimens were observed grossly and histologically at 2, 4, 6, 8 and 10 weeks postoperatively. Epidural scar amount and adhere range was evaluated by modified Robertson scoring method and analyzed by SPSS 13.0. No sear and adhesion, 0 point; small amount scar and light-range adhesion, 1 point; medium sear and midrange adhesion, 2 pionts; bulk scar ang high-range adhesion, 3 pionts. Results All grafted dermis survived and thicken obviously than dermis in body surface (P< 0.05). Hair growth, sebaceous gland cyst and sweat cystogenesis were not observed. A larvaceous dissection abruption plane, little cicatricial tis-sue and adhesions rarefaction between dermis and dura were observed in the experimental group. Massive ei-catricial tissue from erector spinae filled in cavitas epiduralis was observed and dura was separated difficult-ly from cicatricial tissue in the autogeous blank group. Epidural scar amount and adhesion range in the ex-perimental group was significantly lower than the blank group (P< 0.05). Conclusion Dermis is a kind of favourable biomaterial with restraining cicatrisation and isolation barrier. Autogenous dermis grafts has the best effect on preventing peridural cicatrisation and adhesion after laminectomy. Key words: Dermis; Transplantation, autologons; Dura mater

Experimental study of reservation flaval ligament on prevention of peridural adhesion after operation on lumbar disc

Through an experiment in rabbits, to evaluate the role of reservation flaval ligament using different methods to prevent the epidural adhesion by observing the morphological changes and provide experiment evidences for clinic. 45 adult rabbits were divided into three groups: Group A (treated with no reservation of flaval ligament), Group B (treated with reserving half flaval ligament), and Group C (treated with reserving the complete flaval ligament). Every group has 15 rabbits. At the 2nd, 4th and 8th weeks, the samples were obtained for gross observation, histological examinations, and the images were analysed by computer. The data were processed using SPSS11.5. Gross Observation and Histological Examinations, at the 2nd, 4th and 8th postoperative week, there was significant difference between the group A, B and C (gross observation: F2w=4.660, F4w=8.591, F8w=31.858, P<0.05; histological examinations: F2w=5.190, F4w=9.561, F8w=34.658, P<0.05). Images analysis: the difference was very significant in the groups at 2nd, 4th and 8th weeks (F2w=30.783, F4w=47.350, F8w=25.544, P<0.01). With time passing, the ratio became larger and larger in the same group. Reserving the complete flaval ligament can significantly prevent the peridural adhesion from the back as a barrier, and can reduce the adhesion formed.

Comparison of a Caprolactone/Lactide Film (Mesofol) to Two Polylactide Film Products as a Barrier to Postoperative Peridural Adhesion in an Ovine Dorsal Laminectomy Model

Experimental study. To evaluate and compare the performances of 2 bioresorbable products, Mesofol (a caprolactone/lactide film) and Lactosorb (a polylactide film), as barriers to postoperative peridural adhesions and fibrosis. Postoperative peridural adhesions from scar tissue may be an inciting cause of chronic pain and dysfunction in "failed back" syndrome. Many biocompatible products and drugs, as well as autografts have been tested as antiadhesion barriers with varying success. The bioresorbable film products were used to cover large laminectomy defects in 11 sheep. Three laminectomy defects were created, with 2 randomly assigned treatment sites and 1 control site in each animal. A tear was created in the dura allowing cerebrospinal fluid leakage to assess for impaired dural healing. Performance of the film barriers was assessed at 10 weeks postoperative by gross scar and tenacity scoring by 3 blinded, independent observers in 7 animals. Histology was performed in 4 animals. New Methylene blue dye myelography and magnetic resonance imaging were performed to assess for cerebrospinal fluid leakage. Magnetic resonance imaging was also used to evaluate the imaging characteristics of adhesions. All 3 products evaluated showed a benefit to prevention of postoperative peridural adhesion; the performance of Mesofol was deemed superior to either of the 2 Lactosorb products. The handling characteristics of all products were compatible with clinical usage. Impairment to healing of dural tears or active inflammation was not identified with any product. The results of this investigation support previous studies on the benefit of polylactide film barriers, like Lactosorb, for reducing peridural adhesion following spinal surgery. The performance of Mesofol in this investigation suggests that it may provide improved antiadhesion properties in comparison to the polylactide products. Safety issues related to impaired dural healing was not identified in either product.

A comparison of the effectiveness of mitomycin C and 5-fluorouracil in the prevention of peridural adhesion after laminectomy

The effectiveness of the topical application of mitomycin C (MMC) or 5-fluorouracil (5FU) in preventing peridural adhesion after laminectomy was compared in this study. Laminectomies were performed at L-1 in 30 rats. Cotton pads soaked with 0.1 mg/ml MMC, 25 mg/ml 5FU, or 9 mg/ml saline (control) were applied to the operative sites. To evaluate neurological deficits pre- and postoperatively, somatosensory evoked potentials were monitored and the Basso-Beattie-Bresnahan locomotion test was performed. Four weeks postlaminectomy the rats were killed, and peridural scar adhesion was evaluated histologically. The level of hydroxyproline, the area of peridural scar tissue, and the number of fibroblasts were determined. The degree of peridural adhesion was classified according to the Rydell standard. No obvious adhesion formed in the rats in the MMC group, but severe peridural adhesions were found in those in the 5FU and control groups. The content of hydroxyproline, the area of peridural scar tissue, and the number of fibroblasts in the MMC group were significantly lower than those in the 5FU and control groups. The topical application of MMC rather than 5FU may be a successful method of preventing postlaminectomy peridural adhesions.

A comparison of the effectiveness of mitomycin C and 5-fluorouracil in the prevention of peridural adhesion after laminectomy

A comparison of the effectiveness of mitomycin C and 5-fluorouracil in the prevention of peridural adhesion after laminectomy

Experimental Rabbit Hemilaminotomy Model in the Evaluation of Peridural Fibrosis: A Minimally Invasive Peridural Fibrosis Model

The neuronal adhesions of newly synthesized scar tissue to dura mater after spinal peridural operations represent an unsolved problem in neurosurgical practice. This experimental study was planned to compare the success of a rabbit hemilaminotomy procedure with the total laminectomy model in the evaluation of peridural fibrosis in terms of proposing a lesser invasive peridural adhesion model. Fourteen New Zealand white rabbits were used in this experiment. Laminectomy was performed in one level, and hemilaminotomy was done in another level. Four weeks after operation the rabbits were sacrificed by perfusion with 10 % neutral buffered formalin solution. The lumbar spines were removed and immersed in 10 % neutral buffered formalin for approximately 24 hours. Then each specimen was decalcified in 5 % formic acid for approximately 3 weeks. Specimens were cut coronally for gross inspection. Two blocks of tissue were taken from each laminectomy site to be processed and embedded in paraffin. In seven (50 %) of the laminectomy sites of the rabbits, fibrous tissue penetrated the spinal canal through the laminectomy defect and produced neural compression (Grade III). Eight (57 %) hemilaminotomy sites were in Grade III fibrosis. There was no difference between laminectomy and hemilaminotomy in regard to the dural adhesions. In this experimental study, we modified the rabbit total laminectomy model by using a hemilaminotomy procedure in the study of peridural scar formation. The authors conclude that this procedure is more simple, reliable, and lesser invasive than the total laminectomy model.

Reduction in experimental peridural adhesion with the use of a crosslinked hyaluronate/collagen membrane

The research goals were to fabricate a crosslinked hyaluronate (HA)/collagen membrane and study its efficacy in preventing peridural adhesion. Different weight ratios of HA/collagen membranes crosslinked with carbodiimide were tested for biocompatibility and biodegradability first. Forty-eight adult New Zealand white rabbits underwent an L6 laminectomy. Sixteen rabbits each received a weight ratio of HA/collagen = 60/40 membrane (Membrane A) or a 40/60 membrane (Membrane B) on the exposed dura. The last 16 rabbits received no treatment and served as controls. No adverse reaction of the membranes was noted. Magnetic resonance images revealed a hyposignal space between the dura and the scar tissues at Membrane B-treated laminectomy site 3 months after surgery. Histological examination showed that the amount of scarring decreased with time in all groups. Amount of scarring decreased significantly at laminectomy sites treated with either membrane. Compared with the control group, the extent of peridural adhesion decreased significantly in the Membrane B-treated group at 3 months after surgery; while it decreased substantially, but not significantly, in the Membrane A-treated group. The carbodiimide-crosslinked HA/collagen membrane is a safe and effective antiadhesive material in vivo. When placed onto the laminectomy site, the membrane with a weight ratio of HA/collagen = 40/60 appears to reduce peridural scar adhesion.

Toward optimal tissue sealants for neurosurgery: use of a novel hydrogel sealant in a canine durotomy repair model.

Watertight dural repairs are difficult to achieve, and cerebrospinal fluid leakage causes complications and extends hospital stays. Therefore, a novel synthetic hydrogel film was evaluated as an adjunct to dural closure in a canine model. The self-polymerizing, absorbable, and biocompatible hydrogel was sprayed onto tissue and formed a flexible, adherent sealant. A 2-cm incision of cranial dura and arachnoid was created in 26 adult dogs and loosely repaired. Hydrogel was applied over the 2-mm dural gap in 13 dogs; 13 control dogs received no hydrogel application. All dogs remained neurologically intact. Valsalva tests conducted at 1, 4, 7, and 56 days were associated with mean leakage pressures (+/- standard error of the mean) of 5 +/- 0, 5 +/- 0, 7 +/- 2, and 13 +/- 8 cm H(2)O in the controls and of 53 +/- 2, 37 +/- 11, 42 +/- 6, and 48 +/- 4 in the treated animals (P = 0.001, 0.053, 0.010, 0.035, respectively, at each time point; one-tailed t test). Histopathological analysis revealed minimal changes. The hydrogel-treated animals exhibited normal progression of dural healing, no dural adhesions, and no underlying effects on the brain. Although dural healing progressed normally, the control animals displayed marked peridural adhesions. The results of this in vivo study suggest that hydrogels, such as that used here, may significantly decrease cerebrospinal fluid leakage, thereby increasing the safety and effectiveness of dural closure in patients and facilitating surgical reexploration.

The prevention of peridural adhesions: A comparative long-term histomorphometric study using a biodegradable barrier and a fat graft

We studied peridural fibrosis in 16 dogs after laminectomies at the L2, L4 and L6 levels. They received either a free fat graft, a biodegradable mechanical barrier (polyethylene oxide (PEO)/polybutylene terephthalate (PBT) copolymer), or no treatment. The animals were killed after 4, 12, 26 and 52 weeks. Histomorphometry showed extensive and consistent peridural fibrosis in control and PEO/PBT groups. Fat grafts produced significantly less fibrous tissue, but the presence of the fat graft in the bony defect prevented closure. Degradation of the PEO/PBT barrier resulted in the formation of more fibrous tissue. We conclude that up to one year a free fat graft is effective in reducing the amount of peridural scarring.

A histological study on polyactive� for the prevention of peridural adhesions after spinal surgery: an experimental study in dogs with a 3 months follow-up

In the present study the potential of Polyactive® bilayer sheets in the prevention of scar tissue formation after spinal surgery was investigated. Eight adult beagle dogs underwent 3 laminectomies at three levels (L2, L4 and L6). According to a randomized implantation schedule a Polyactive® sheet or autogenous fat graft was placed in the defect. The third site served as a control without implant. After 4 or 12 weeks (4 dogs per period) the dogs were sacrificed and histological sections were prepared. The Polyactive® treated defects showed partial closure by newly formed bone. The Polyactive® was encapsuled by a thin fibrous tissue layer. Ventral to the defect, dense fibrous tissue was present which was separated from the dura by the Polyactive® sheet in all cases. In some cases fibrous tissue was present between the implant capsule and the dura. In the fat graft group there were no signs of closure of the defect but most sites showed fibrous tissue at the edges of the graft, which was in 4 sites continous with the dura mater. Fibrosis and degeneration of the fat grafts were seen. All control defects showed partial closure by newly formed bone, and ventral to the defect extensive fibrous tissue, which was in 50% continous with the dura mater. Other sections showed loose connective tissue in contact with the dura mater. It is concluded that Polyactive® has a potential as a mechanical barrier in the prevention of adhesions between the dorsal spinal muscles and the dura mater.