The Role Of Adjacent Spinous Process-Ligament Complex In Preventing Adjacent Segment Degeneration After Lumbar Fusion

Objective:To observe and analyse the role of adjacent spinous process-ligament complex structures in preventing adjacent segment degeneration after lumbar fusion and the effects of the surgery with different spinal canal decompression surgery.Methods:The clinic data of120patients from1998to2006with lumbar degenerative diseases in L4-5were analyzed, which involved84men and46women,whose symptoms lasting for three months to28months,14months on average.Patients were followed up for5to7years,6.2years on average. The causes of degenerative lumbar disease were lumbar disc herniation in64patients degenerative, lumbar segmental instability in24patients, and spinal stenosis in32. Symptoms included low-back pain in110patients (91.7%) and leg pain in102(85%).The120patients were randomly divided into A, B, C three groups, each group of40patients. The patients in Group A were removed articular process with L4-5interbody fusion while reserved the posterior spinous process, interspinous ligament and supraspinous ligaments.The patients in group B were removed the lower half of L4lamina, spinous process along with the upper part of L5lamina, spinous process with L4-5interbody fusion. The patients in group C were doing the complete L4laminectomy with L4-5interbody fusion. To confirm the presence of degenerative changes of the superior adjacent disc,the disc height using the standing lateral plain radiography, the dynamic intervertebral space angulation and the displacement of the vertebral body at L3-L4, the lordosis angle of L1/S1using Cobb’s method were measured respectively at preoperation,postoperation and at the time of the last follow up.As for clinical results, the JOA score were used to evaluate patient outcomes before and after surgery and at the last follow-up.Differences observed between the three groups were analyzed using the Statistical Package for the Social Sciences version10.0(SPSS, Chicago, IL, USA).A p<0.05was considered significant.Results:1.The original operative segment has been integrated after three months from X-ray plain radiography, no pseudarthrosis, fixation loosening or breakage.2. The upper adjacent segment L3-4segment were observe occurance of the adjacent segment degeneration at the time of the last follow up in24patients, including the disc decreased height of intervertebral space, the displacement of the vertebral body at L3-L4and the increased dynamic intervertebral space angulation between L3-L4increases. There were3cases in Group A,4cases in Group B and17cases in group C among these patients.There was no statistical difference (P>0.05)in occurance of the adjacent segment degeneration between group A and group B at the time of the last follow up but significant statistical difference between group A and C (P<0.05)or group B and C (P<0.05). There were7cases recuring low-back pain or neurological symptoms in lower limbs including leg pain and symptoms of spinal stenosis among the17patients in Group C who were observed occuranee of the adjacent segment degeneration from radiography.The7patients with neurological symptoms were given the second surgery. The incidence of reoperation for adjacent segment degeneration in group C was significantly higher than that in group A and group B.3.JOA score of patients in the three groups after three months significantly improved, and there is no statistical difference in JOA score between the three groups (P>0.05). Compared to group A and B, there is statistical difference in JOA score of Group C (P<0.05)and the JOA score decreased significantly at final follow-up. Conclusions:1.The destruction of the integrity of spinous process-ligament complex or removal of it in lumbar fusion surgery may lead to the increased incidence of serious adjacent segment degeneration and thus induce clinical symptoms.2. Keeping the integrity of lumbar spinous process-ligament complex in lumbar fusion surgery for treatment of lumbar degenerative disease can effectively decrease the incidence of ASD,maintain postoperative long-term efficacy, prevent iatrogenic spinal stenosis and decrease the risk of further surgical intervention.