The Application Value Of Coflex Interspinous Process Device In The Treatment Of Degenerative Lumber Spinal

Background:Lumbar spinal stenosis (LSS) is caused by the stenosis of the middle of the lumbar spinal canal or lateral recess and intervertebral foramen. Nowadays it have been recognised that nerve compression and blood circulation obstacle is responsible for its symptoms, namely lower limb radiative pain, neurogenic intermittent claudication, or back pains. Degenerative lumber spinal stenosis(DLSS) is a special type of LSS. It is a common degenerative disease of elderly.The current treatment for degenerative lumbar spinal stenosis includes conservative treatment and operation treatment. For three months of conservative treatment ineffective, surgery is recommended. Currently the most often used surgical approach in clinical is spinal decompression and interbody fusion with pedicle screw fixation. However, the adjacent segment pathology (ASP) after the interbody fusion surgery is a common seen complications in long-term follow-up. Because of its serious impact on the rehabilitation process and the long-term quality of life of patients, it may be one of the most serious complications. It even make patients doubt about the effectiveness of treatment. At present, there are several factors be consider as the reason for the occurrence of ASP:the destruction of the posterior column structure on the adjacent segment after lumbar decompression and fusion fixation process; increased range of motion (ROM) of the adjacent segment; increased pressure in the adjacent segment; facet joint hyperplasia. The performance of the radiology imaging includes signal changes in MR of the adjacent lumbar intervertebral disc, inter-discs space narrowing, hyperplasia of facet joint or posterior marginal of lumbar veterbra, lumbar spine instability or spondylolisthesis. All these changes may lead to stenosis of the lumbar spinal canal. To avoid the ASP after interbody fusion surgery, a dynamic un-fusion fixation system develops in the present days. One most representative product of this system is an internal fixation device between spinal spinous. Its called Coflex inter-spinous fixation system. Sinces developed in 1994 by Samani, the Coflex system is gradually being widely used in hospital. The Coflex system can reduce soft tissue compression of the Spinal Canal, and thus can reduce the stenosis of corresponding segment of spinal canal. It can also reduce the pressure of the segment which has been in the process of degenerating. However, it is controversial nowadays that whether the Coflex system has an effect on treating lumbar spinal stenosis with safety. On the one hand, a simple operation approach and minimally invasive is the advantage of Coflex system. On the other hand, the revision rate and a higher cost are still being considered. Therefore, the indication of Coflex inter-spinous fixation surgery must be very strict. LSS with slight symptom, especially symptoms caused by lumbar extension, is one of the indications. At presents, it had been proved that the Coflex system surgery can achieve equal clinical effect as the traditional lumbar interbody fusion approach. But a medium-long term follow-up still need to be done.Abjectives:To summarize the results of adjacent segmental pathology and quality of life of patients after the treatment of degenerative lumbar spinal stenosis with the Coflex interspinous process device.And evaluate the clinical application value ofthe Coflex interspinous process deviceMethods:Follow up all LSS patients in our ward between April 2007 to March 2010. The include criteria are as follow:1.There is a clear symptom of intermittent claudication, may be or not associated with low back pain or lower limb radiative pain, and the conservative treatment is noneffective; 2. X-ray and MRI scan proved lumbar spinal stenosis of L4/5; 3. May combined with a lumbar disc herniation or spondylolisthesis in grade I or not. The exclude criteria are as follow:1. History of Lumbar Spine Surgery, lumbar trauma or infections or other disease such as kyphosis or rheumatoid arthritis; 2. No spondylolisthesis higher than grade I in the corresponding segment; 3. No spondylolisthesis or instability in the adjacent segments; 4. Severe Osteoporosis. Eventually there were 115 cases included. These patients were randomly, single blind allocated in a Coflex group and fusion group. All patients take X-ray and MRI scan pre-operatively. In the follow-up, we collect data of the operation time, intra-operative blood loss, volume of drainage after surgery, extubation time, ambulation time and inpatient days. The Japanese Orthopedic Association(JOA)scores, visual analogue scale(VAS)scores, Oswestry disability index(ODl) scores and SF-36 scores questionnaire is done before the surgery and in the last follow-up to evaluate the clinical effect. In the radiological image, we measure the change of inter-disc height, ROM of adjacent segments. Pfirrmann grading was done by 2 independent physicians to evaluate the degeneration of adjacent segment. The final outcome of the measurement is an average value. And the grading was done by that 2 physicians at the same time, or by another physician if there was a controversy between that 2 physicians. Complications were also recorded.Results:There were 54 cases in Coflex group:33 males,21 females, the average age is 54.6 (45-70).61 cases in fusion group:38 males,23 females, the average age is 61.9 (50-75). The follow-up was end if there needs a revision surgery. In the last follow-up there were 49 cases in Coflex group and 57 in fusion group. The average follow-up were 7.02±0.34 years in Coflex group and 7.62±0.18 years in fusion group. Coflex group show advantages in the operation time, intra-operative blood loss, volume of drainage after surgery, extubation time, ambulation time and inpatient days (P<0.001). At final follow-up, JOA, ODI, VAS and SF-6 score were improved after surgery in the two groups, with statistical difference (P<0.01), no statistical difference between the two groups (P>0.05). The intervertebral heights of adjacent segments were decreased at final follow-up and intervertebral motions were increased in two groups. The range of loss of intervertebral height of adjacent segments was greater in the fusion group, with statistical difference (P<0.01) between the two groups. The range of increase of intervertebral motion of adjacent segments was no statistical difference (P<0.01) between the two groups. At final follow-up, adjacent segment disc Pfirrmann grading progressed in both 2 groups. The degeneration is more obviously in the distal adjacent segments, with grade V discs in some cases. And this changes in Pfirrmann grading is more obviously in the fusion group, with statistically difference (P<0.05) between the two groups. There were 5 cases needed revision surgery in Coflex group. One patient suffered a radiological and clinical spinal spinous fracture 6 months after the first surgey. Three cases with recurrence of lumbar disc herniation. One case with clinical adjacent segment pathology. No cases show loosen fixation of Coflex devices or broken devices after surgery.4 cases needed revision surgery in fusion group and three of them caused by clinical adjacent segment pathology. The rate of reoperation for adjacent segment pathology is 1.9% and 4.9% in coflex group and fusion group respectively (P>0.05),and the total rate of reoperation were 9.3% and 6.6% respectively (P>0.05)Conclusion:Showing advantages in the operation time, intra-operative blood loss, volume of drainage after surgery, extubation time, ambulation time and inpatient days, the Coflex system may help to decreased the rate of surgical relative complication with an earlier postoperative rehabilitation. By saving medical resources, Cofelx system is more effective. At final follow-up, JOA, ODI, VAS and SF-6 score were improved after surgery in the two groups without statistical difference between the two groups. In this scales Coflex system have an equal clinical effect as fusion surgery. Adjacent segment disc Pfirrmann grading progressed more obviously in the fusion group. Although the rate of reoperation show no differences between two groups, the image changing of adjacent segment may still needs attention. A longer follow-up must be done. In all, Coflex non-fusion technology and fusion technology can both achieve good clinical curative effect in the treatment of degenerative lumbar spinal stenosis at midterm and long-term follow-up, but the Coflex group achieved less bleeding, smaller trauma, quicker recovery. Coflex interspinous process device can maintain the adjacent segments intervertebral height and delay the adjacent segment disc degeneration. In the Coflex group, the rate of reoperation for adjacent segment pathology was lower, but the total reoperation rate is higher, all of them have no statistically difference. The clinical application value of Coflex interspinous process device is under conducted by long-term follow-up observation.