| Objective The spinal surgeons around the world have performed a lot of different surgeries on the patients with lumbar instability .The philosophy on how to chose certain kind of surgery was based on their own understanding of the pathology of lumbar instability. Posterior lateral fusion(PLF), posterior lumbar inetrbody fusion(PLIF),anterior lumbar interbody fusion(ALIF),and transforaminal lumbar interbody fusion(TLIF) were widely applied by the surgeons. There still were some questions should be answered in those surgeries such as how to maintain the stability of the spine , how to increase the success rate of fusion ,how to improve the quality of the patients life, and so on. The purpose the present investigation was to compare the clinical outcome of three kinds of lumbar spinal fusion based on the Oswestry distability index(ODI) and the visual ananlogue scale(VAS). The following surgeries were included in this study.(1)pedicle screw fixation and posterior lateral fusion;(2)pedicle screw fixation and posterior lumber interbody fusion;(3)pedicle screw fixation and posterior lumbar interbody fusion with cages.Methods There were 91 patients in the study, including 42 males and 49 females. Their age was from 27 years to 68 years and the average was 55.6 years. There were 43 cases with degenerative low lumbar spinal instability. The distance of lumbar body slipping at flextion were more than eight percent of the body, at extension, more than nine percent. And there were 32 cases with spondylolisthesis including 11 cases with lateral spondylolysis,and 21 cases with bilateral spondylolysis. According to Meyerding scale of spondylolisthesis, 12 cases were considered as the first degree, 18 cases the second degree. Also, there were 16 patients with low back failure syndrome. All of the 91 patients were divided into three treatment groups randomly. The distribution of the surgery and the segment fused was following:Degenertive LLSI Spondylisthesis Low back failure syndromSurgical technigue The edidural anesthesia was applied in most of the patients, the general anesthesia was for the patients with low back failure syndrome. Patient was prone on the operating table with both iliac area supported by soft pads in order to reduce the abdominal pressure and to decrease the bleeding introoperatively.The posterior approach through a posterior longitudinal incision in middleline provides direct access to the spinous processes,lamina, and facets. The bilateral facets were exposed widely, the soft tissue around the lamina was dissected with a long-hand curette. The lamina was cut off with a sharp osteotome. The one-third parts of the upper facet and the two-thirds part of low facet were chiseled off so that the diameter of the spinal canal were enlarged, and the lateral part of disc would be exposed easily. For the patients with spondylolisthesis the whole facet should be cut off as much as possible. This process was very important for the exposing the surgical field and the reduction of the slipped body. Also, this process made the posterior column of the spine separated into two parts. The proliferated soft tissue at the spondylolysis area would be removed as much as possible. At the same time, the bilateral nerve roots should be decompressed and get freed. For the patients with low back failuresyndrome, a sharp osteotome would be used to enlarge the spinal canal because of the severe adhesion occured after the primary surgery . The compression from the disc and osteophytes were removed.The laminectomy should be extended laterally (and superiorly and inferiorly )to expose safely and completely the lateral aspect of the nerve root and to visualize its contact with the offending disc material. A thin instrument was used to separate the anterior surface the nerve root dura from the floor of the sp inal canal. Removal of significant portions of the intervertebral facet was usually necessary to expose disc area for interbody fusion.For the pedicle screw fixation, the starting hole was at the intersection of a line drawn transversely through the midportion of the transverse process and vertically through the facet joints. These screws were placed roughly parallel to the end plate and down the axis of the pedicle. The superior bit should be started somewhat more inferior and laterally and aimed slightly up toward the end plate of L4 to avoid impingement on the L3-L4 facet joint just rostral to the starting point. The L5 screw usurally was perpendicular to the floor or slightly inclined inferiorly again to follow the axis at the end plate of L5. The SI screw was roughly parallel to the SI end plate approximately 1 cm distal to it,oriented approximately 15-20 degrees caudally to achieve this angulation.Generally, the hole for S1 screw should be perforated through the apposite cortex of S1 body to give more holding strength of the screw. The prebented rods were placed into the screws and the nuts were tightened slightly and then distracted along the rod with a spreader until the bodies had been returned to their anatomically correct location.There were three types of lumbar instrumented fusions used in the investigation.A. Postlateral lumbar spinal fusion.The parts of bone from the laminectomy and the posterior iliac crest were preserved as bone graft. The graft material was then placed in the rough bed of the transverse processes to the ala of the sacrum bilaterally.B. Posterior lumbar interbody fusion. The dura sac and nerve roots were retracted gently towards the midline to expose the interbody space. The disc materials should be removed as much as possible bilaterally, but the end plate should keep intacted.The post iliac crest was chiseled as graft and inserted into the interbody space properly.The bone graft with three-planed cortex was prefered. The graft should be a little bit shorter than the body at sagital plane. The two body which would be fused should be compressed against the bone graft to make sure its position not be changed with the spinal movement.C. Posterior lumbar interbody fusion with cages. The posterior area of the interbody space were carefully exposed by retraction the dura, a rectangular incision on the posterior longitudinal ligament and the annulas was performed bilaterally using a No. 15 knife blade on a long thin handle. The disc was extensively excised using a rongeur or a curette. When verifying that the nerve root and the dural sac were protected. The guide protector was slided into the disc space. Through this protector the reamer was ulilized to drill the disc materials out.A minimum of three reaming processes were needed to adequately extract the cartilage and disc debris. A proper cage packed with cancellous bone graft was screwed through the guide protector down to the level of the preset stop. These processes should be carried out in the opposite side.The portion of the cage with large holes might be properly embedded in the end plates of the bodies. At this stage, the nuts of the pedicle screws were slightly loosed again in order to guarantee the two cages fit the intervertebral space correctly and firmly. Closed suction drainage system was employed.All the patients encountered the various lumbar fusion would be encouraged to carry a brace for walking 4 weeks postoperatively. Progressive rehabilitative therapy was then administered.Results All of the patients from the three groups were followed up for 12-24 months, average 16 months.In the 86 patients with nerve root or caudal equina compression, 82 patients had improved motor function or resolution of radicular pain. The patients with low back pain were improved significantly.The effectiveness of three fusions on lumbar stability... |
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