| Background and Objection:The human spine activity and pressure on the disc have undergone tremendous changes in the course of human evolution, in which human’s activity changed from the crawling to walking upright. Its high morbidity, severe or even complete loss of the ability to live a normal life, the lumbar degenerative disease has became one of the common and frequent disease which affect human’s health in all over the world. Lumbar disc herniation (Lumbar disc herniation, LDH) is most common lumbar degenerative disease, and the following is degenerative lumbar spinal stenosis and lumbar instability. The World Health Organization (WHO) recognized LDH as one of ten most common diseases which affecting the human’s quality of life. Disc herniation has complex etiology, varying clinical manifestations, and many different treatments. Although surgery in relieving symptoms, control disease progression and improve quality of life has important value, but traditional surgery caused damage the structural integrity of the spine, often raises other problems. Whether doctors or patients have been looking for a little trauma operation and be able to achieve a therapeutic effect of the all traditional surgery methods. With the development of science and technology? the equipment and special devices are also more and more advanced for the treatment of this disease. Lumbar discectomy endoscopic assisted treatment of lumbar disc herniation is the demonstration that the application of science and technology advanced in the medical field, where under microscopic discectomy (microendoscopic disectomy, MED) is the most representative one of the minimally invasive techniques. Although MED is minimally invasive surgery, adhesions of dural and nerve root with surrounding tissue are a major reason for poor outcome after the operation, and even lead to new problems. This phenomenon has been recognized by spine surgeon. For to reduce or prevent such adhesions or scar formation, the researchers have been exploring for many years. Using microsurgical or minimally invasive surgical techniques to reduce the wound and attempt to use the various anti-adhesion mebrane is the main means for such prevention, but the result was unsatisfactory. Micro-surgery or minimally invasive surgery to reduce scarring adhesion is now readily apparent, but does not completely prevent it. So, the researchers put more eyes on a variety of materials and drugs to prevent scarring. In 1974, LaRocca put gelatin sponge attached to the exposed spinal epidural to prevent nerve root and dural adhesions, and declare that the sponge can be absorbed after 5 weeks, and can effectively prevent adhesion of epidural and nerve root. But some other researchers come to the opposite conclusion that the gelatin sponge have a pore structure, the vampire can achieve hemostasis purposes, but just a lot of scar easily lead generation, more likely to cause adhesion. Some researchers try to use the collagen sponge, PTFE material or steroids, or Salvia sodium hyaluronate gel, these methods can be effective in preventing a lot of scarring but has not yet formed a final conclusion. Biomaterials because the immune compatibility, has been widely used as the preferred way. such as some scholars use autologous or allogeneic fascia piece, adipose tissue vascularized or some biosynthetic material, but clinical effects are imprecise. It has been verified that the epidural fat presenting the meager to sustain the dural sac and nerve root activity is important, adhesions after surgery because of the destruction of the layer of fat. this fat retention organization is the key to the prevention of adhesions, but it is often difficult to retain during the surgery, f he retain of the epidural fat dependent on the presence of its outer LF. so researchers turn their attention to study the LF. LF is attached to the adjacent upper and lower lamina, starting at the C 2 and stop at S1. The ligament flavum (LF) is a yellow elastic ligamentous structure that connects the laminae of the adjacent vertebrae in the vertebral canal. The superior margin of LF attaches to the underside of the upper lamina and the inferior margin of LF attaches to the upside of the inferior lamina. In addition. LF attaches the zygapophyseal capsules laterally and medially fuses with the interspinous ligament. Under normal situations, the LF was tense, only when extreme hyperextension relaxation. Such kind structure can prevent the LF in the normal physiological state oppress dural sac. It has been reported that the dural sac and nerve root package in fatty tissue which can prove an, in the spine, nerve root and dural sac can smoothly slide in this semi-liquid surrounding conditio. LF addition to maintaining the stability of the spine functions, but also to protect the existence of these adipose tissue, nerves and dural sac kept within a certain range of activity. In this study, both clinical and experimental animal studies in order to verify the viewpoint that the preserving of LF can prevent the adhesions of dural sac and nerve root with the surrounding tissue.Methods and materials:From March 2014-- March 201584 cases who underwent a unilateral single-level lumbar microendoscopic discectomy in our hospital were included in this study. The inclusion criteria were as follows:first lumbar surgery; main symptom of low back pain with radiating pain in the lower limbs; positive for straight leg raising test; a lesion of a single nerve root identified by electromyography; computed tomography correlated with single-level disc herniation; and no response to at least 2 weeks of conservative treatment. Patients with double nerve root involvement, stenosis, lumbar instability syndrome, cauda equina syndrome, multilevel or far lateral disc herniation, L2-3 or above disc herniation and scoliosis were excluded. According to the LF was preserved or not, the cases were divided into two groups.54 cases was preserved successfully (A group), and 34 cases droped out (group B), all patients were followed up for 6-26 (means 15 months), the operation clinical outcome was evaluated 3 month and 1 year after the operation and review of CTto evaluate epidural adhesions. Demographic and clinical characteristics of patients were collected:age, gender, duration of disease, area of the interlaminar space, disc level and position of disc herniation. The duration of disease was the period between the date of first appearance of low back pain with radiating pain in the lower limbs in patients and the date of this treatment. The images of interlaminar space from the anteroposterior view were taken using X-ray technique (plain films). Then these images were input into computers and the area of interlaminar space was calculated according to the original scale in X-ray films using efilm workstation software (Merge Healthcare Co Ltd, Chicago, IL, USA). All protrusion of lumbar intervertebral disc occurred in the lumbar spinal canal and two types of disc herniation position wasere found among included patients:central type and post-lateral type. Clinical outcomes for each patient were assessed by Oswestry disability index (ODI) and visual analog scale (VAS). Patients were evaluated for their ability to function using ODI with the range of 0-50 (a score of 50 indicates very poor function and lower scores indicate better function). Patients were asked to discrib their pain using a 0-10 scale. These clinical data were obtained pre-postoperatively and 3 and 12 months postoperatively. In addition, patients with successful preservation of LF and those without LF were compared for the fibrosis formation using computed tomographic scans with IDR (Irregular Dural sac Ratio, IDR) for dural sac adhesions were scored:less than or equal to 25% 1 scor, more than 25% but less than or equal to 50% 2 scor. more than 50% but less than or equal to 75% 3 scor, more than 75% 4 scor. Statistical analyses were performed using SPSS 19.0 software (SPSS Inc., Chicago, IL, USA). The results were presented as mean means±standard deviation (S.D.). Characteristics of the included participants underwent lumbar microendoscopic discectomy with or without LF were compared using t-test for means (paired t-tests for intra-group comparison and independent sample t-tests for inter-group comparison) and chi-square test for proportions. Logistic regression models were constructed to determine the odds ratios (OR) and 95% confidence intervals (CI) for putative correlation factors which were associated with the preservation of LF. A P value of<0.05 was considered significantly different.The second part (experimental study):1) experimental animals (4-6 months old New Zealand white rabbits) weighing 1000-1500g, using a random number table were randomly divided into two groups:A group (LF resection group) and group B (LF preserve group),20 animals in each group. The animals were feed with free diet in cage respectively and the experimental period is 12 weeks.12 weeks after surgery animals were sacrificed to observe the situation and epidural scar tissue formation.2) Operation L4,5 laminectomy. Take L4,5 incision, about 2.5 cm, cut the skin, subcutaneous tissue, stripped sacral spine muscle to expose the L4,5 lamina, cut off the spinous process by a micro-laminectomy rongeur. The LF was removed in group A and was preserved in group B.3)Observations①Gross observation:observe the dura, nerve root adhesions, and the adhesions were divided into 4 degree:0, and the dura no tissue adhesion; 1, sparse and scattered adhesions, scar tissue can be blunt dissected easily; 2, the scar more extensive and dense; 3, extensive adhesions, dense scar and dura mater can not blunt dissection. ② Histological observation:.0:No visible scar, a small amount of fibrous tissue around the dura; 1:There are more dense collagen fibers surrounding dura; 2:a large number of dense collagen fibers surrounding dura or nerve roots, or scar to invade the nerve root, or scarring embedded in the spinal canal, dural sac or spinal cord; 3:with compression deformation.Results:The first part (clinical research):82 cases of attempts to protect the LF,52 cases successful preserved and 32 case droped out, the success rate is 61.90%. The average age of two group is 33.1±5.8 years and 43.1±1.8 years respectively, there is no significantly difference between the two groups. The disease course of two groups is 4.36±2.5 and 17.1±.8 months respectively, there is no significantly difference between the two groups. It is to say that the patient with young and short disease duration easy to retain the ligamentum flavum. Average operation time is 49.1±10.0 and 50.0±7.3 minutes respectively and there is no significantly difference between the two groups. The bleeding lose of the two group is 74.5±15.8 and 79.3 ±10.2 ml/cases and without the remarkable difference by t test. Average interlaminar size in group A is 3.9± 0.5 and 2.9+0.8 cm2, the average area of the laminar space was also significantly larger inpatients with preservation of LF than patients without preservationof LF (P= 0.001). The pathological classification and sex composition of the two groups were tested by chi square test, and P value was greater than 0.05, which showed that the pathologic classification and gender had no effect on the preserving LF. Before and after operation, the VAS and ODI scores were significantly different (p<0.05), but there was no difference at 3 months and 1year after operation. CT scan were performed at 3 months after operation, which show that the IDR scar is significantly difference between the two groups. The epidural adhesion in ligament preserving group is significantly lighter than unpreserved group.Conclusion:The patients with small age, short course of disease and large interlamina space is more likely to preserve ligament flavumum during MED operation. There was no correlation between the pathologic classification of lumbar disc herniation and ligament flavum preservation, and the amount of blood loss and operation time has not been affected. Whther the LF was preserved or not, all the operation outcome is good at the twelfth month in the follow-up. But the VAS remission rate in the preserving group is better than the no preserving group. Preserving LF group IDR score was significantly better than the not preserving group, which consistent with the clinical outcome. The CT image Irregular Dural sac Ratio (IDR) is reliability index for evaluateing dural adhesion with the surrounding tissue. The microscopy histological study showed that the preserving of the LF was effective in preventing the adhesion of Dural sac with the surrounding tissues. |
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