| Background:Wallis and Coflex interspinous dynamic stabilization systems are most widely used and reported in China.However,there are still controversies on the mid-and long-term survial rate,safety,effectiveness and indicatons of the two devices.Objective:This retrospective cohort study aim to analyze the mid-and long-term efficacy of the Wallis and Coflex dynamic stabilization system in the treatment of lumbar degenerative disc disease and compare the complications,reoperation and survival rate of different indications.The following comparative studies were also performed:1.Discectomy with or without the Wallis implant in the treatment of primary lumbar disc herniation;2.The differences and similarities of clinical and radiological outcomes between the two interspinous implants.We performed this study to find the best surgical indications,to analyze the causes and solution of surgical complications and reoperation,for the aim to provide the clinical evidence for proper application of the interspinous dynamic stabilization system.Methods:From May 2008 to March 2013,patients received surgeries for treatment of lumbar degenerative disc disease and followed up for more than 5 years in the department of Orthopedics,Guangdong General Hospital were included in our study.This study consists four parts.Part one and part two expatiate the mid-and long-term efficacy and survival analysis of Wallis and Coflex interspinous dynamic stabilization system respectively for treatment of lumbar degenerative disc diseases(include lumbar disc herniation,lumbar spinal stenosis and degenerative lumbar spondylolisthesis<I°).126 patients treated with lumbar posterior decompression or discectomy combined with the Wallis system and 183 patients with the Coflex system.Surgical indications,preoperative and postoperative Visual Analogue Scale(VAS),Japanese Orthopedics Association(JOA)and Oswestry Disability Index(ODI)scores,perioperative complications and reoperation were evaluated.Kaplan-Meier survival analysis was used to evaluate the mid-and long-term survival rate of the device.Part three is a retrospective cohort study comparing patients underwent posterior lumbar discectomy with(Wallis group,36 patients)and without(Control group,36 patients)for treatment of primary lumbar disc herniation.The VAS,JOA and ODI were scored to evaluate the clinical efficiency.The intervertebral disc height(DH),range of motion(ROM),intervertebral angle(IVA)of the operative segements were recorded to assess the biomechanical change before and after operation.Perioperative complications were also evaluated.Part four is a retrospective cohort study comparing Wallis(Wallis group,52 patients)and Coflex(Coflex group,52 patients)implant in the treatment of L4/5 single-segment lumbar spinal stenosis associated with or without lumbar disc herniation.VAS,JOA and ODI scores were used to evaluate postoperative pain and functional improvement.Lumbar lordosis(LL),DH,ROM,IVA were measured and compared before and after surgery.Perioperative complication and reoperation rate were also analyzed.Results:Part one:Among the 126 patients with Wallis implant,there were 12 cases of lumbar spinal stenosis,56 cases of lumbar disc herniation,9 cases of lumbar spondylolisthesis and 49 cases of lumbar stenosis associated with disc herniation.The mean follow-up time was 93.04±12.24 months.At final follow-up,all the patients had better VAS,JOA and ODI scores than those before surgery(P<0.05).The overall complication rate of Wallis was 11.9%(15/126),including prosthesis burst,spinous fracture,recurrent disc herniation of index or adjacent segment,superficial wounds infection and unexplainable lower back pain.The total reoperation rate was 6.3%(8/126).Patients with lumbar disc herniation had the highest complication rate of 17.9%(10/56)and reoperation rate of 10.7%(6/56),while patients with lumbar spinal stenosis had no complications and reoperation.The overall 5-year survival rate was 98.4%(124/126)and 7-year survival rate was 97.6%(123/126).Three patients with removal of the device were preoperatively diagnosed as lumbar disc herniation,with a 5-year survival rate of 96.4%(54/56)and a 7-year survival rate of 94.6%(53/56),lower than the other indications.Part two:Among the 183 patients with Coflex implant,21 cases were diagnosis as lumbar spinal stenosis,57 as lumbar disc herniation,10 as lumbar spondylolisthesis,and 95 as lumbar stenosis associated with disc herniation.The mean follow-up time was 83.61±15.12 months.At final follow-up,all the patients had better VAS,JOA and ODI scores than those before surgery(P<0.05).The overall complication rate of Coflex was 8.2%(15/183),including implant rupture,spinous fracture,recurrent disc herniation of index or adjacent segment,superficial wound infection and unexplainable lower back pain.The reoperation rate was 5.5%(10/183).Patients with lumbar disc herniation had the highest complication rate of 10.5%(6/57)and reoperation rate of 8.8%(5/57).The 5-year and 7-year overall survival rate was 97.3%(178/183).No significant difference was found among differernt indications(P>0.05),but patients with lumbar disc herniation had a slightly lower survival rate of 94.7%(54/57).Part three:The mean follow-up time was 84.35±10.41 months.Wallis group had better VAS,JOA and ODI scores than the control group at 2 years postoperatively(P<0.05),however,no significant difference was found between the 2 groups at final follow-up postoperatively(P>0.05).At final follow-up,the DH of the Wallis group was significantly higher than that of the control group(P<0.05),and the ROM was significantly smaller(P<0.05),but no significant difference was found between the two groups in IVA(P>0.05).In the Wallis group,2 patients had recurrent disc herniation at the operative and adjacent segments respectively,and 1 patient had wound infection.In the control group,3 cases had recurrent disc herniation and 1 case had intraoperative dural tear.Part four:The mean follow-up time was 83.66±13.94 months.The VAS,JOA and ODI scores of the two groups were significantly improved compared with those before surgery(P<0.05)and no significant difference was found between the two groups(P>0.05).The DH of L4/5 did not change(P>0.05)while the ROM of L4/5 at final follow-up was significantly smaller(P<0.05)comparing with that before surgery.The IVA of L4/5 segment in Wallis group did not change at final follow-up(P>0.05),while decrease(P<0.05)in Coflex group and smaller(P<0.05)than that of Wallis group.At final follow-up,no significant difference(P>0.05)was found in LL of both groups compared with that before surgery.There was also no significant difference(P>0.05)in the DH,IVAof L3/4,L5/S1 and ROM of L5/S1 compared with that before surgery,but the ROM of L3/4 segment in Wallis group was significantly lower(P<0.05).There was no difference in complication and reoperation rate between the two groups(P>0.05).Conclusion:1.Wallis and Coflex implant had relatively low survival rate,high complication and reoperation rate for treatment of lumbar disc herniation comparing with the other indications.They may not be able to prevent recurrent disc herniation and adjacent segment degeneration.Discectomy combined with the Wallis implant was not beneficial for pain relief or lumbar function improvement compared to lumbar discectomy alone,although the Wallis implant was associated with the maintenance of intervertebral disc height and limited range of motion of the spine.So both implants should be cautiously used in patients with lumbar disc herniation.2.Both implants achieved the same mid-and long-term efficacy and had similar complication and reoperation rate in the treatment of lumbar spinal stenosis.They had similar radiological change but Coflex may decrease segmental lordosis.The indications of Wallis and Coflex should be chosen according to their different characteristics to achieve better clinical outcome.3.Both implants had the risk of complications and reoperation,however,they may achieve good mid-and long-term efficancy and high survial rate with proper choice of indications. |
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