Clinical Study Of Posterolateral Fusion Combined With Posterior Decompression In The Treatment Of Severe Lumbar Spinal Stenosis

BackgroundLumbar spinal stenosis(LSS)is a common disease in the department of spine surgery,which mostly occurs in the elderly over 65 years old.LSS refers to the abnormal proliferation of bone or fiber in the lumbar central canal,lateral recess or intervertebral foramen,triggering the narrowing of the spinal canal,thus compressing the dural sac and nerve root and producing a series of clinical symptoms such as low back pain,leg pain and intermittent claudication and so on,which seriously endangers human health.The treatment of LSS is mainly divided into conservative or surgical treatment.For patients who have no symptom amelioration after three months of standard conservative treatment,surgical treatment is the most effective way to remove nerve compression,alleviate symptoms and prevent the deterioration of nerve function.The surgical methods of LSS chiefly contain spinal canal decompression alone or spinal canal decompression combined with lumbar fusion and pedicel screw fixation.Currently,for severe LSS,minimally invasive surgery may have some disadvantages,such as steep learning curve,difficult operation,limited vision,incomplete decompression and so on,therefore,open surgery is the standard way of spinal decompression.For severe LSS with severe stenosis of lumbar central canal and lateral recess,in order to relieve the compression of nerve tissue,a common decompression range in open surgery includes the removal of 2/3 inferior part of the lamina,inferior articular process,and partially hypertrophic and cohesive superior articular process.However,unilateral or bilateral facetectomy over 75% is a potential cause of iatrogenic instability to the lumbar spine.Thus,supplement with lumbar fusion and pedicel screw fixation is necessary.Lumbar circumferential fusion(CF)is one of the most common fusion methods.CF is widely used in LSS because its high fusion rate,as well as the removal of the intervertebral disc to reduce the pressure of the spinal canal.However,CF has many disadvantages,such as larger trauma,longer operation time and more bleeding,and may cause a range of complications such as nerve root injury,cage displacement.In contrast to CF,lumbar posterolateral fusion(PLF)does not involve the anterior and middle columns of the spine and is associated with less trauma and simpler operation.In addition,some patients with severe lumbar spinal stenosis only show degeneration or bulging of the intervertebral disc,which causes mild compression to the dural sac and nerve roots anteriorly,therefore,whether it is necessary to remove the intervertebral disc for decompression of the spinal canal and whether PLF can fulfill solid fusion while preserving the intervertebral disc necessitates further study.Objective1.To assess whether posterior decompression alone can relieve nerve compression and symptoms in the treatment of severe LSS without disc herniation or prolapse.2.To compare the fusion rate of PLF and CF in the treatment of LSS.3.To compare the clinical effects,operation time and bleeding,complications,radiologic results,hospitalization cost of posterior decompression,pedicel screw fixation combined with PLF and discectomy,posterior decompression,pedicel screw fixation combined with CF in the treatment of severe LSS without disc herniation or prolapse,consequently discussing the clinical feasibility,effectiveness and safety of PLF.MethodsResearch type: retrospective research.Research time: from January 2014 to August 2017.Follow-up time: two years.Research subjects: 153 consecutive patients with severe LSS(LSS of grades B to D and lateral recess stenosis of grades 2 to 3)without lumbar disc protrusion or prolapse were recruited into the research,and all patients strictly abided by the inclusion and exclusion criteria.Grouping: All patients were divided into two groups: PLF group(n = 77)and CF group(n = 76).PLF group underwent posterior decompression,pedicle screw fixation combined with PLF,and CF group underwent lumbar discectomy,posterior decompression,pedicle screw fixation combined with CF.Indicator for evaluation conclude:(1)All patients’ genders,ages,surgical segments,surgical areas(unilateral or bilateral),combined diseases and total hospitalization costs were collected through military No.1 system.(2)Clinical results: 10-point Visual Analog Scale(VAS),Japanese Orthopedic Association Score(JOA,lumbar pain score)and Oswestry Disability Index(ODI)preoperatively,3 and 6 months,and 1 and 2 years postoperatively.(3)Postoperative complications.(4)Operation data: duration of operation and surgery blood loss.(5)Radiologic results: change of the involved height of intervertebral space,lumbar lordosis angle pre-and postoperatively at 6 months and 1 and 2 years.Fusion rate postoperatively at 6 months and 1 and 2 years.(6)Hospitalization cost.The two groups were normalized by age,sex,surgical region and level,stenosis degree,comorbidity,preoperative symptom(preoperative VAS,JOA,ODI),preoperative intervertebral space height,and lumbar lordosis(P>0.05).Results1.Clinical resultsCompared with the preoperative values,VAS(back and leg pain)of both groups decreased significantly at all measurement timepoints postoperatively(P < 0.001),but no statistical difference was found between the two groups.Function parameters,ODI and JOA improved significantly postoperatively in both groups compared with the preoperative values(P < 0.001),however,the differences between the two groups were not statistically significant.2.Operation data and hospitalization costThe operation time and blood loss were significantly lower in the PLF group than that in the CF group(P<0.001).The hospitalization cost in PLF group is lower than that in CF group(P<0.001).3.Radiologic resultsAs for the intervertebral space height and lumbar lordosis,both groups showed statistically significant increase at all measurement timepoints compared to their preoperative values(P <0.001),but the CF group showed an obvious increase in these parameters(P <0.05).The fusion rate was 77.92% postoperatively at 6 months,85.71% at the first postoperative year,and 92.21% at the second postoperative year in the PLF group.The corresponding figures were 84.21%,92.11%,and 94.74% in the CF group,showing no significant difference at all measurement timepoints postoperatively between the two groups.The nonunion rate at the last follow-up was 7.79%(6 patients)and 5.26%(4 patients)in the PLF and CF groups,respectively,but no patient had pseudarthrosis.4.Postoperative complicationsThere are eight complications in two groups.PLF group contained one deep surgical site infection(1.3%).The CF group contained two nerve root injury,two deep surgical site infection,one cerebrospinal fluid leakage,one Cage migration,and one Cage subsidence case.Thus,the postoperative complication rate was higher in the CF group than in the PLF group(P <0.05).Conclusions1.For severe LSS without lumbar disc protrusion or prolapse,sole posterior decompression can relieve the nerve compression and ameliorate symptoms.2.For LSS,PLF can prevent and treat degenerative and iatrogenic lumbar instability,which can achieve the same fusion effect as CF.3.In contrast to discectomy,posterior decompression,pedicel screw fixation combined with CF,posterior decompression,pedicel screw fixation combined with PLF successfully achieves the same clinical effects with lesser surgical blood loss,shorter operative time,lower complication rate and lesser hospitalization cost in the treatment of severe LSS(LSS of grades B to D and lateral recess stenosis of grades 2 to 3)without disc herniation or prolapse.