Clinical Effect Evaluation Of Cortical Bone Trajectory Screw Fixation Combined With Facet Fusion In The Treatment Of Lumbar Degenerative Diseases

BackgroundLumbar degenerative disease(LDD)is a common cause of low back and leg pain in middle-aged and elderly people.The onset of LDD is slow and the course of disease is long.In severe cases,symptoms such as low back and leg pain,intermittent claudication and neurological dysfunction can occur,which deeply affects the normal work and life.For the patients with nerve compression symptoms and no responding to conservative treatment,surgical treatment may be inevitable.Lumbar interbody fusion is a common option for the treatment of lumbar degenerative diseases.It is often combined with pedicle screw(PS)internal fixation system which can supply biomechanical stability for fusion.Among them,posterior lumbar interbody fusion(PLIF)and transforaminal lumbar interbody fusion(TLIF)are widely used lumbar fusion methods that can achieve high fusion rate,and effectively restore the height of lumbar intervertebral space and normal lumbar alignment.However,PLIF procedure is more invasive,because dural sac and nerve root are violated more during operation,the risk of iatrogenic neural element injury may be higher.TLIF,which take foramen as working corridor,can reduce nerve roots irritation,although it has the advantages of minimally invasive,but it has high technical requirements,long operation time,more intraoperative bleeding,high incidence of postoperative complications.The mainstream lumbar fusion procedures have shortcomings to some extent.So it has been becoming the goal of spine surgeons to minimize the surgical injury to achieve better treatment effect.Facet fusion(FF)is a relatively safe,minimally invasive,simple and inexpensive spinal fusion method for the treatment of lumbar degenerative diseases.Biomechanical and clinical studies have shown that FF can achieve similar results as intervertebral fusion.At present,the facet fusion mostly adopts V-shaped groove made with bur,and then filled with autogenous cancellous bone graft.FF has the advantage of narrow gap for creeping substitute,less invasive,less bone graft needed,and high fusion rate.Cortical bone trajectory(CBT)is a novel lumbar fixation trojectory first proposed by Santoni in 2009.Compared with the traditional pedicle screw,CBT screw can provide stronger anti-axial pullout purchase and anti-torsion force.At the same time,the unique angle of CBT screw head tilt and extraversion avoids the important neurovascular tissue,with less invasive and less complications.At present,there are few reports about CBT screw fixation combined with facet fusion in the tyeatment of lumbar degenerative diseases.Therefore,we conducted this study to investigate the clinical effect of cortical bone trajectory screw fixation combined with facet fusion,and evaluate its safety,efficacy and feasibility.ObjectiveThe clinical data of four groups of patients(CBT+FF group,PS+FF group,CBT+TLIF group,PS+TLIF group)were retrospectively analyzed to assess the clinical effect of CBT screw fixation combined with FF,compare and probe whether CBT screw fixation combined with FF has advantages compared to other fixation and fusion methods,evaluate its safety and efficacy,in order to document option of surgical treatment.Materials and methodsA total of 167 consecutive patients with grade I single level degenerative lumbar spondylolisthesis or one level lumbar spinal stenosis who underwent FF or TLIF from January 2013 to September 2019 in Department of spine surgery,Second Hospital of Shandong University were enrolled and retrospectively analyzed.Four groups of patients had low back and leg pain,with or without neurogenic intermittent claudication before operation.They all received conservative treatment,and were poor for more than 3 months.After operation,they were routinely treated with dehydration,detumescence and neurotrophic drugs.24 hours after operation,they began to guide patients to exercise their back muscles in bed.When the postoperative drainage volume was less than 50ml/day,the drainage tube was removed.Three days after operation,the patients were asked to get out of bed under the protection of lumbar brace and gradually increase the amount of ambulating.All patients underwent detailed history collection,physical examination,X-ray,CT scan+three-dimensional reconstruction and MRI examination before operation.All patients were followed up for at least 1 year and their data was complete.The patients were divided into four groups according to different fixation and fuusion methods:experimental group(group A):CBT screw combined with facet fusion group;Control group:PS screw combined with facet fusion group(group B),CBT screw combined with TLIF group(Group C),PS screw combined with TLIF group(Group D).The perioperative variables were analyzed retrospectively:operation time,intraoperative blood loss,postoperative complications and reoperation.The complications included iatrogenic nerve injury,cerebrospinal fluid leakage,surgical site infection and internal fixation related complications(such as pedicle screw loosening or breakage).Visual analogue scale(VAS)and Oswestry disability index(ODI)were used to evaluate the improvement of symptoms preoperatively and at 1 week,3 months and 12 months postoperatively.Imaging evaluation:at the follow-up of 3 days,6 months and 12 months after operation,the anteroposterior and lateral films of lumbar spine and CT scan+three-dimensional reconstruction were taken to evaluate the fusion status of intervertebral fusion or facet joint fusion,and to know whether the screws were loose,fallen off,displaced or broken.The fusion standard of TLIF group was that continuous trabeculae between adjacent vertebral bodies and through the interbody fusion cage could be seen on CT scan.If there was no continuous trabeculae,it was not fused.CT imaging evaluation criteria of facet fusion:Grade Ⅰ is complete bone continuity covering the whole facet;In grade Ⅱ,there was continuous but incomplete bone between facets;In grade Ⅲ,there was uncertain bony continuity between facets;Grade Ⅳ is obvious nonunion between facets.The standard of facet fusion was unilateral or bilateral gradeⅠ or Ⅱ fusion.ResultA total of 167 patients(92 females and 75 males)with an average age of 55.87±7.31 years old were included in this study,including 35 cases in group A,41 cases in group B,39 cases in group C and 52 cases in Group D.The follow-up time was 12-40 months(mean 17.3±6.6months).There was no significant difference in age,gender,symptom distribution and surgical segment among the four groups(P>0.05).There was no significant difference in preoperative VAS and ODI scores among the four groups(P>0.05).However,the postoperative VAS and ODI scores were significantly lower than those before surgery.The VAS score for low back pain 1 week after operation of group A and group C were 2.14±0.73 and 2.141±0.79 respectively,which were significantly lower than group B and D(2.78±0.94、3.06±0.85),the difference was statistically significant(PAB=0.001,PAD=0.000,PBC=0.049,PCD=0.000).The VAS score of low back pain in group A was lower than that in group C,but the difference was not statistically significant(PAC=0.171);The VAS score of group A was 1.11±0.76 at 3 months after operation,which was significantly lower than that in group B and D(1.51±0.87、1.62±0.84),the difference was statistically significant(PAB=0.045,PAD=0.008);The ODI score of group A was 16.1±6.4 at one week after operation,which was significantly lower than that in group B,C and D(21.2±6.5、20.1±5.7、23.3±5.8),the difference was statistically significant(PAB=0.000,PAC=0.005,PAD=0.000);The ODI score of group A was 10.9±3.6 at 3 months after operation,which was significantly lower than group B,C and D(13.3±3.1、13.2±3.2、13.7±3.0),The difference was statistically significant(PAB=0.001,PAC=0.002,PAD=0.000);There was no significant difference in VAS score of low back pain at lyear after operation,VAS score of leg pain at 1 week,3 months and 1 year after operation,and ODI score at 1 year after operation among the four groups(P>0.05).The operation time of group A and B was 91.14±26.98 min and 102.44±28.64 min,which were significantly lower than those in group C and D(141.92±32.84mim、159.23±31.74min),and the operation time of group C was significantly shorter than that of group D(P<0.05),the difference was statistically significant(PAC=0.000,PAD=0.000,PBC=0.000,PBD=0.000,PCD=0.008),but there was no statistic difference between group A and B(PAB=0.107),The intraoperative blood loss in group A and B was 131.43±62.21ml and 151.46±60.94ml respectively,which were significantly lower than those in group C and D(224.87±67.63ml、294.71±66.33 ml),the difference was statistically significant(PAC=0.000,PAD=0.000,PBC=0.000,PBD=0.000),the intraoperative blood loss in group C was significantly lower than that in group D(PAB=0.179),there was no significant difference between group A and B.At 1-year follow-up,the fusion rate of group A was 94.3%(33/35);Group B:95.1%(39/41);Group C:97.4%(38/39);Group D:96.2%(50/52),the difference was not statistically significant(P=0.914).Up to the last follow-up,1 case of infection occurred in group A;In group B,there was 1 case of infection and 1 case of screw loosening;In group C,there was 1 case of cerebrospinal fluid leakage and 1 case of iatrogenic nerve injury;In group D,there were 1 case of infection,2 cases of nerve injury and 1 case of screw loosening;There was no significant difference in complications(P>0.05).No patients in the four groups need revision surgery.ConclusionsCortical bone trajectory screw fixation combined with FF has achieved good clinical results.Compared with the traditional fusion,The present procedure is simple,and with shorter operation time,faster the postoperative recovery,and equivalent fusion rat.It is a less invasive,less damanding operation method for the treatment of lumbar degenerative diseases.