Lumbar degenerative disc disease (DDD) encompasses a wide range of disorders ranging from discogenic low back pain, lumbar disc herniation, lumbar spondylolisthesis and secondary lumbar spinal stenosis up to degenerative spondylolisthesis. Different stages of intervertebral disc degeneration determine different clinical manifestations and differences in treatment approaches. The previous technical standard of fusing diseased segments to achieve relief of low back pain is being challenged: fusion suffers from the loss of motor function of the operated segment, accelerated degeneration of neighboring segments, and the irreversibility of the fusion itself [1]. It is in this technical context that non-fusion techniques have emerged, and few clinical studies have been reported in China [2]. We have applied interspinous stabilizers to treat 31 cases of lumbar degenerative disc disease since July 2009, and achieved ideal recent clinical outcomes. The preliminary results of its clinical application are reported as follows. Yu Xiuchun, Department of Orthopedic Diseases, General Hospital of Jinan Military Region Clinical data I. General data: From June 2009 to December 2009, 31 cases of lumbar intervertebral disc degenerative diseases were treated with the application of interspinous stabilizers, among which there were 12 male cases and 19 female cases, with an average age of 53.5 years (31-74 years). There were 7 cases of lumbar disc herniation alone, 8 cases of lumbar disc herniation combined with lumbar instability, 1 case of lumbar disc herniation recurrence after surgery, 4 cases of lumbar stenosis alone, 5 cases of lumbar stenosis combined with lumbar instability, 1 case of lumbar stenosis combined with disc protrusion in the adjacent segment, and 5 cases of lumbar instability alone. Surgical methods and number of cases: intraoperative placement of interspinous stabilizers in 3 cases, simultaneous decompression of the spinal canal in 13 cases, enlargement of the window and nucleus pulposus removal in 12 cases, and internal fixation with bone graft fusion in 3 cases in adjacent segments. Surgical segments and number of cases: 4 cases of simultaneous two-segment (L3/4, L4/5) implantation, 1 case of simultaneous two-segment L4/5, L5/S1 interspace, 2 cases of simple L3/4 interspace implantation, 21 cases of simple L4/5 interspace implantation, 2 cases of dynamic internal fixation of L3/4 fusion L4/5, 1 case of dynamic internal fixation of L5/S1 fusion L4/5. Second, the design, composition and surgical instrumentation of the interspinous stabilizer: the system consists of five parts, namely, the base, the soft sleeve, the fixation wing, the adjustment wing, the fixation screw, etc. (Fig. 1), and each part is made of high-strength titanium alloy material. Surgical instruments consisted of an interspinous ligament stabbing cone, interspinous spacer, No. 6-14 specimen, matrix holder, adjusting wing holder, and hexagonal screw cone (Fig. 2). III.PREOPERATIVE PREPARATION: All patients were routinely subjected to lumbar spine frontal and lateral X-rays, power radiographs, as well as CT and MRI examinations before surgery. The lumbar spine was observed for the presence of spinous process deformity or degeneration, whether the site of degenerative disc disease was consistent with the clinical manifestation, and the stability of the lumbar spine. IV.Surgical method: all patients in this group were operated under epidural anesthesia. The prone position was taken. The surgical site was determined according to the anatomical position. A posterior median incision centered on lumbar 4 and 5 was taken, and the skin and subcutaneous tissues were incised sequentially to reveal the supraspinous ligament. On the basis of protecting the integrity of the supraspinous ligament, the vertebral plates were peeled bilaterally to reveal L4 and 5 or the upper and lower intervertebral spaces according to the condition. The intervertebral plate is firstly enlarged and opened to preserve the structure of the articular process as much as possible. The presence of a herniated disc is explored and the site of the lesion is clamped with a cloth-toweled forceps to observe the presence of lumbar instability. If there is disc herniation or foraminal stenosis, the herniated disc nucleus pulposus tissue is routinely removed and the foramen is enlarged to relieve nerve root compression. After complete hemostasis, the interspinous ligament is punctured with an interspinous puncture device, the interspinous gap is enlarged with an expander, and then the 6-14 specimen molds are placed between the spinous processes one by one, and the stability of the spinal column is restored significantly after the installation as the best. The same model of interspinous stabilizer was chosen to place the fixation wing and matrix between the spinous processes first, and the adjusting wing was fixed on the other side by applying screws (Figure 3). Finally, the spine was probed again for the presence of spinal instability. After repeated rinsing with saline, the incision was closed layer by layer and 1 drain was placed. V. Postoperative treatment: antibiotics were routinely applied for 5-7 days after surgery. The drainage tube was removed 1 day after surgery. 5-7 days after surgery, get out of bed with a waist cuff and start the functional exercise of lumbar and dorsal muscles. The lumbar spine front and side films were taken routinely 2 weeks after the operation to observe the position of interspinous stabilizers. 3 months later, the lumbar girdle was removed to start a normal life, and then followed up every 3 months. VI. Clinical efficacy evaluation criteria: all patients were evaluated for clinical efficacy before and 3 months after surgery. The lower back pain JOA score was observed and recorded by the non-operator using a form-filling method. At the same time, the imaging data were compared and analyzed before and after surgery (will be reported separately). VII. Statistical analysis The data were statistically analyzed using SPSS software (version 10.0, SPSS Inc, Chicago, IL, USA). All observations were analyzed using paired t-test with a confidence level of P<0.05. Results All patients in this group successfully completed the surgery. The average operation time was 65 minutes (45-90 minutes), the time for placing the interspinous fixator was 10-15 minutes, intraoperative bleeding was 50 ml-300 ml, and there was no intraoperative or postoperative blood transfusion.Of the 31 patients, 28 underwent enlarged-open disc nucleus pulposus removal followed by interspinous fixator fixation (Fig. 4), and 3 patients underwent interspinous stabilizer fixation alone.23 fixed a single-segment, 5 In 23 cases, single-segment fixation was performed, in 5 cases, double-segment fixation was performed (Figure 5), and in 3 cases, single-segment fixation was performed together with fusion of adjacent segments; in this group, 1 patient underwent simultaneous L5S1 interspinous fixation due to intraoperative findings of concomitant L5S1 interspinous instability and a larger S1 spinous process in this patient (Figure 6). No complications such as dural tear, sphenoid fracture, intraoperative internal fixation breakage, nerve injury, or incision infection occurred. All patients received regular follow-up for an average of 7 months (4-10 months). No complications such as displacement or loosening of the interspinous stabilizer, spinous process fracture, or lumbar kyphosis deformity have occurred so far. All the patients' symptoms were significantly improved after the operation, and there was a statistically significant difference in the JOA score for lower back pain compared with the preoperative period (12.84±3.65 preoperatively and 20.55±3.41 3 months after the operation, P<0.01), with an improvement rate of 47.5%. DISCUSSION Principles and mechanisms of clinical application of interspinous stabilizers: Lumbar degenerative disease can be divided into three clinical stages: early dysfunction, instability, and terminal stabilization [3]. In the first two phases, acute or progressive intervertebral disc injury leads to loss of rigidity of the segment, decreased stability, and stress concentration in the posterior part of the intervertebral disc leads to rupture of the annulus fibrosus, followed by loss of the nucleus pulposus, decrease in the height of the intervertebral disc, and hyperplasia of the lesser joints and the ligamentum flavum. Clinical manifestations range from initial discogenic low back pain and disc herniation to spinal stenosis and degenerative slip. Conventional surgical treatment relieves compression by removing the diseased disc and enlarging the neural root canal, and is often supplemented by interbody fusion when degenerative instability exists to stop the progression of the lesion. Studies have shown that the incidence of degeneration ranges from 25% to 45% after interbody fusion with increased compensatory motion and loading of its adjacent segments [4]. A dynamic stabilization system that is reversible and preserves the motor function of the diseased segment while increasing its mechanical stability has become a hot topic of clinical research for mild and moderate degenerative diseases [5]. Such systems can be divided into two main categories: those using pedicle screw fixation and those relying on interspinous fixation. Our clinical application of interspinous internal fixator belongs to the latter category. Currently, there are four types of dynamic interspinous stabilization systems: Wallis system, DIAM system, Coflex system, and X-Stop system.Wilke HJ et al[6] compared the effects of the four systems on the three-dimensional flexion-extension mobility of the spine and the pressure in the spinal canal through in vitro experiments, and concluded that the interspinous implants have a similar effect on the flexion-extension mobility and the stabilization reduces the pressure of the spinal canal in the backward-extension mobility but not on the flexion-extension mobility, and the stabilized interspinous implant has a similar effect on the flexion-extension mobility. Sobottke R et al.[7] found that the height, width, and cross-sectional area of the intervertebral foramina improved better after X-Stop implantation than DIAM and Wallis, and suggested that interspinous stabilizers do not exacerbate mild anterior displacement of the vertebral body. The interspinous stabilizer we used in our clinic is similar to the X-Stop system. It is designed to be placed between the spinous processes to prevent posterior extension of the diseased segment and to allow flexion, axial rotation, and lateral bending, thus preventing irritation of the neural structures of the diseased segment caused by postural changes. It is placed intraoperatively between the supraspinous ligament and the ligamentum flavum, whose wings prevent anterior translation, and the supraspinous ligament, which shields the device from posterior translation. It distributes the intervertebral pressure, keeping the spine in a mildly flexed position and allowing the patient to retain a relatively normal position rather than hyperflexion. Biomechanical studies [8] have found that lumbar extension after placement of an interspinous stabilizer increases the area of the spinal canal by 18%, the contact area of the small joints by 50%, the diameter of the spinal canal by 10%, the area of the neural root canals by 25%, and the diameter of the neural root canals by 41%, while the spinal canals and neural root canals of the neighboring segments are unaffected. At the same time, it does not change the stress of the small joints in the neighboring segments and cause disorders or accelerate the degeneration of the small joints in the neighboring segments [9]. In addition, it was found to significantly reduce the pressure in the intervertebral disc of the inserted segment without affecting the pressure in the neighboring intervertebral discs [10]. These results provide a scientific rationale for the clinical use of interspinous stabilizers in the treatment of lumbar degenerative diseases. If the indications are clear and fusion is not necessary, dynamic interspinous stabilization is a good choice. Clinical indications for interspinous stabilizers: In general, the procedure is suitable for patients with degenerative disc disease who have been ineffective in conservative treatment but appear to be over-treated by interbody fusion. (1) Site: It is mainly applied to lesions in the non-L5S1 interspace, with L3/4 and L4/5 being the best. Only 1 of the 31 patients in this group underwent simultaneous L5S1 interspace fixation due to intraoperative findings of concomitant L5S1 interspace instability and a larger S1 spinous process in this patient, and no discomfort was seen in the 9 months of postoperative follow-up. (2) Patients with giant disc herniation, recurrent disc herniation, and a tendency to instability on preoperative examination. The traditional treatment could remove the nucleus pulposus alone, leaving the segment with obvious unstable tendency; at this time, the choice of interspinous stabilizer surgery for the protection of this segment was very appropriate, and it also reserved the opportunity for interbody fusion in the future. In this group, there were 7 cases of simple lumbar disc herniation, 8 cases of lumbar disc herniation combined with lumbar instability, 1 case of postoperative recurrence of lumbar disc herniation, and 1 case of lumbar disc herniation combined with spinal stenosis of adjacent segments. These patients accounted for 54.8% of the operations in this group, indicating that for lumbar disc herniation, especially patients with combined intervertebral instability, is the main indication for this operation. (3) Senegas advocated that intervertebral discogenic low back pain can be supported by using the interspinous stabilizer system to reduce the load and promote intervertebral disc healing [9], and we have not yet applied this method to this group of patients. (4) Studies have shown [10] that posterior interspinous bracing devices can play a role in enlarging the area of the spinal canal and the height of the intervertebral foramina similar to interspinous fusion devices, and thus can be used in the treatment of lumbar spinal stenosis. In our group, there were 4 cases of simple lumbar spinal stenosis, 5 cases of lumbar spinal stenosis combined with lumbar spinal instability, and 1 case of lumbar spinal stenosis combined with disc herniation in adjacent segments, in which we carried out nucleus pulposus removal in 1 patient, and 9 patients underwent simple decompression of the nerve root canal with the simultaneous application of interspinous stabilizer, and this type of patients accounted for 32.3% of the operations in our group. (5) To prevent degenerative lesions in the adjacent segments of the fused segments, three cases of dynamic internal fixation of the adjacent segments were performed in this group due to instability of the adjacent segments during the operation by implant fusion of the diseased segments with simultaneous application of interspinous stabilizers, two cases of L3/4 fusion of L4/5 interspinous fixation, and one case of L5/S1 fusion of L4/5 interspinous fixation. About this point is still controversial [11], we believe that this is a very ideal surgical approach, not only to achieve the stability of unstable segments, but also to prevent the degenerative changes of adjacent segments to lay the foundation for the prevention of degenerative changes, especially intraoperative found that adjacent segments have a tendency to instability should be recommended for the clinical application of this surgical approach. (6) Degenerative lumbar instability: Verhoof et al [11] chose 12 patients with lumbar spinal stenosis and degenerative vertebral body slippage to be given interspinous stabilizers, and 4 cases had no symptomatic relief after surgery, and 3 cases had symptomatic aggravation 1 year later, and there was no significant improvement on X-ray and MRI. 7 cases (58%) were reoperated with fusion, and he concluded that the proposed interspinous stabilizers were not suitable for patients with combined degenerative vertebral body slippage. lumbar stenosis patients with lumbar spondylolisthesis. There were 8 cases of lumbar disc herniation combined with lumbar instability, 5 cases of lumbar spinal stenosis combined with lumbar instability, and 5 cases of lumbar instability alone. During the operation, only 3 patients did not undergo decompression of the spinal canal due to the absence of nerve compression symptoms before the operation, and the rest of the patients underwent decompression of the spinal canal or nucleus pulposus removal of the intervertebral discs, and all of them had satisfactory clinical outcomes after the operation. Therefore, we believe that for patients without nerve compression symptoms, despite the presence of lumbar instability imaging signs, simple interspinous stabilizer placement surgery can be performed; otherwise, interspinous stabilizer placement surgery should be performed at the same time as decompression of the radicular canal or nucleus pulposus removal of the intervertebral disc, or else the clinical efficacy of the surgery will be affected. Clinical efficacy and complications of interspinous stabilizers: A study by Kuchta et al [12] found that the mean VAS score decreased from 61.2% preoperatively to 39% at 6 weeks postoperatively, and to 39% at 24 months postoperatively. only 8 out of 175 cases had unsatisfactory postoperative results and were removed from the X-Stop and minimally invasive decompression was performed. The results of X-Stop were not only satisfactory in the short term, but also in the 2-year follow-up.Siddiqui et al[13] found that 54% of the patients had a significant improvement in clinical symptoms, 33% had a significant improvement in physical function, 71% were satisfied with the results, and 29% had a recurrence of intermittent claudication at 1 year postoperatively. This study suggests that the short-term efficacy of the X-Stop is good, but the results have not yet been demonstrated in a multicenter, clinically randomized study.Zucherman et al [14] reached similar conclusions as Kuchta et al [12] in a 2-year follow-up study of the patients they treated, with a satisfaction level of 73.1% and a reoperation rate of 6% for the patients who had the X-Stop inserted. In our group of 31 patients with an average follow-up of 7 months, the preoperative JOA score was 12.84±3.65, and 3 months after the operation was 20.55±3.41, which was significantly different from the preoperative period (P<0.01), and all the patients' symptoms improved significantly after the operation, and the rate of improvement of lower back pain was 47.5%. Therefore, we believe that the near-term efficacy of this surgery is very satisfactory. It is difficult to evaluate the long-term efficacy due to the follow-up time of our group. Complications of this procedure have been reported less frequently, and in the 69 patients treated by Barbagallo et al [15], a total of 8 complications occurred: 4 dislocations and 4 spinous process fractures, including 2 spontaneous spinous process fractures (both with L4 bi-segmental implantation). Barbagallo [16] proposed the "sandwich phenomenon", i.e., the presence of spontaneous fractures of the spinous processes (L4) after insertion of a bi-segmental X-Stop implant, which may be related to anatomical variations. The cause may be related to anatomical variations. In the event of a fracture of the spinous process, placement of the X-Stop device will result in failure. Complications related to the interspinous stabilizer have not occurred in our group. However, we believe that the prevention of spinous process fracture is the key to the success of this procedure, and the following measures should be taken: carefully analyze the relevant preoperative imaging data to understand the size of the spinous process of the diseased segment and whether there is any variance; the intraoperative operation should be gentle, especially in the process of opening the interspinous process and placing the specimen, and can be used to help the operator to operate with the help of a cloth cloth forceps to lift the upper and lower spinous process, and the use of violent surgery is strictly prohibited. If the patient has lumbar osteoporosis before the operation, the operation should be more gentle; if there is spinal stenosis or disc herniation in the adjacent segment, the continuity of the vertebral plate and the structural integrity of the articular process should be preserved as much as possible in order to relieve the nerve root compression or remove the herniated nucleus pulposus as a criterion. In conclusion, the interspinous stabilizer, as a non-fusion interspinous decompression device, is a new and effective method of treating lumbar degenerative diseases, with simple operation process, little tissue damage, no need for implantation and fusion, no possibility of nerve root injury, and at the same time, it will not cause degenerative changes in the adjacent segments, so it has a good prospect of application in the clinical aspect. However, the long-term efficacy of this surgical approach is still to be further observed and evaluated with the increasing number of cases and the prolongation of the follow-up period.