***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND CONTEXT Few studies have analyzed the results of an interspinous distraction device in patients with lumbar spinal stenosis . It is still unknown whether the outcomes of an interspinous implant are related to the severity of stenosis . PURPOSE To determine the success rate of the Aperius implant and open decompression with the aim of defining better the indications for the two modalities of treatment . STUDY DESIGN Comparison of two cohorts of patients with moderate or severe stenosis treated with the Aperius or by open decompression .  PATIENT SAMPLE The sample comprises 36 patients who had the Aperius implant and 35 who underwent open decompression , both groups followed prospect ively . In the two cohorts , central or lateral stenosis was present in similar proportions , and in both , the patients had pure intermittent claudication or symptoms at rest and on walking . In both groups , preoperative diagnosis was made by magnetic resonance imaging ( MRI ) . OUTCOME MEASURES Patients of both groups were evaluated with the Zurich Claudication Question naire ( ZCQ ) and Oswestry Disability Index . The results were rated as good or poor based on the ZCQ . METHODS The patients of both cohorts were evaluated at 1 month and 3 , 6 , and 12 months after operation , the final follow-up being carried out at least 2 years after surgery . Severity of stenosis was determined based on preoperative MRI scans . In 17 patients of the Aperius group , MRI studies were repeated at the 6-month or final follow-up and compared with the preoperative studies . RESULTS Of the patients in the Aperius group , six had removal of the implant and open surgical decompression at 2 to 17 months after operation ; these patients were considered to have a poor result . At the final follow-up , the result was rated as good in 47 % of all patients who had had the Aperius implant . The percentage of good outcomes was 60 % in moderate stenosis and 31 % in severe stenosis . When considering all not reoperated patients , 57 % had good outcomes ; however , if only the scores in the patient satisfaction domain of the ZCQ were considered , 67 % of these patients were somewhat satisfied with the result of Aperius . No significant relationship was found between patients with pure intermittent claudication and those with leg symptoms also at rest . In 71 % of cases in which preoperative and postoperative MRIs were compared , no significant change in size of the spinal canal was found after operation , whereas in the remaining patients a slight increase in size of the canal was detected . In the open decompression cohort , the results were good in 80 % of cases and poor in 20 % . The outcomes were satisfactory in 69 % of moderate stenosis , with no significant difference with the similar subgroup of the Aperius series . In severe stenosis , the 89 % rate of good results was significantly higher than in the severe Aperius subgroup ( p<.0001 ) . CONCLUSIONS The Aperius interspinous implant is poorly indicated for severe lumbar stenosis , which is significantly improved only in a small minority of cases , whereas decompression procedures ensure high chances of good results . The implant may be indicated for selected patients with moderate stenosis . The outcomes of the Aperius are not influenced by the type of clinical presentation of lumbar stenosis Purpose Interspinous process devices ( IPDs ) are implanted to treat patients with intermittent neurogenic claudication ( INC ) based on lumbar spinal stenosis . It is hypothesized that patients with lumbar spinal stenosis treated with IPD have a faster short-term recovery , an equal outcome after 2 years and less back pain compared with bony decompression . Methods A r and omized design with variable block sizes was used , with allocations stratified according to center . Allocations were stored in prepared opaque , coded and sealed envelopes , and patients and research nurses were blind throughout the follow-up . Five neurosurgical centers ( including one academic and four secondary level care centers ) included participants . 211 participants were referred to the Leiden – The Hague Spine Prognostic Study Group . 159 participants with INC based on lumbar spinal stenosis at one or two levels with an indication for surgery were r and omized into two groups . Patients and research nurses were blinded for the allocated treatment throughout the study period . 80 participants received an IPD  and 79 participants underwent spinal bony decompression . The primary outcome at long-term ( 2-year ) follow-up was the score for the Zurich Claudication Question naire . Repeated measurement analyses were applied to compare outcomes over time . Results At two years , the success rate according to the Zurich Claudication Question naire for the IPD group [ 69 % ( 95 % CI 57–78 % ) ] did not show a significant difference compared with st and ard bony decompression [ 60 % ( 95 % CI 48–71 % ) p value 0.2 ] . Reoperations , because of absence of recovery , were indicated and performed in 23 cases ( 33 % ) of the IPD group versus 6 ( 8 % ) patients of the bony decompression group ( p < 0.01 ) . Furthermore , long-term VAS back pain was significantly higher [ 36 mm on a 100 mm scale ( 95 % CI 24–48 ) ] in the IPD group compared to the bony decompression group [ 28 mm ( 95 % CI 23–34 ) p value 0.04 ] . Conclusions This double-blinded study could not confirm the advantage of IPD without bony decompression over conventional ‘ simple ’ decompression , two years after surgery . Moreover , in the IPD treatment arm , the reoperation rate was higher and back pain was even slightly more intense compared to the decompression treatment arm OBJECT To assess the safety and efficacy of the DIAM implant , the authors compared the mean 12-month outcomes in patients who underwent lumbar surgery with DIAM placement  and in those who underwent lumbar surgery only . METHODS Of 62 patients who underwent simple lumbar surgery ( laminectomy and /or microdiscectomy ) in a 24-month period , 31 underwent concomitant surgical placement of a DIAM interspinous process spacer  ( 33 devices total ) . Radiographic imaging , pain scores , and clinical assessment s were obtained postoperatively to a mean of 12 months ( range 8 - 25 months ) . Patients who did not undergo implantation of an interspinous process spacer ( Group C ) were compared with and stratified against patients who underwent placement of a DIAM implant ( Group D ) . In Group D , no statistically significant differences were noted in anterior or posterior disc height when comparing patients pre- and postoperatively . Compared with Group C , a relative kyphosis of less than 2 degrees was noted on postoperative images obtained in Group D. No statistically significant differences in visual analog scale ( VAS ) pain scores or MacNab outcomes were noted between Groups C and D at a mean of 12 months of follow up . Complications in Group D included three intraoperative spinous process fractures and one infection . CONCLUSIONS After simple lumbar surgery , the placement of a DIAM interspinous process spacer did not alter disc height or sagittal alignment at the mean 12-month follow-up interval . No adverse local or systemic reaction to the DIAM was noted . No difference in VAS or MacNab outcome scores was noted between the groups treated with or without the DIAM implants , particularly when the DIAM was used to alleviate low-back pain Study Design . Prospect i ve r and omized controlled study . Objective . To compare the outcome of indirect decompression by means of the X-Stop ( Medtronics Inc. , Minneapolis , MN ) implant with conventional decompression in patients with neurogenic intermittent claudication due to lumbar spinal stenosis . Summary of Background Data . Decompression is currently the “ gold st and ard ” for lumbar spinal stenosis but is afflicted with complications and a certain number of dissatisfied patients . Interspinous implants have been on the market for more than 10 years , but no prospect i ve study comparing its outcome with decompression has been performed . Methods . After power calculation , 100 patients were included : 50 in the X-Stop group and 50 in the decompression group . Patients with symptomatic 1- or 2-level lumbar spinal stenosis and neurogenic claudication relieved on flexion were included .  X-Stop operations were performed under local anesthesia . The mean patient age was 69 ( 49–89 ) years , and the male/female distribution was 56/44 . Minimal dural sac area was in all cases except two 80 mm2 or less . The noninferiority hypothesis included 6 , 12 , and 24 months of follow-up , and included . intention-to-treat as well as as-treated analyses . The primary outcome meansure was the Zürich Claudication Question naire , and the secondary outcome measures was the visual analogue scale pain , Short-Form 36 ( SF-36 ) , complications , and reoperations . Results . The primary and secondary outcome measures of patients in both groups improved significantly . The results were similar at 6 , 12 , and 24 months and at no time point could any statistical difference between the 2 types of surgery be identified . Three patients ( 6 % ) in the decompression group underwent further surgery , compared with 13 patients ( 26 % ) in the X-Stop group ( P = 0.04 ) . Results were identical in intention-to-treat and as-treated analyses . Conclusion . For spinal stenosis with neurogenic claudication , decompressive surgery as well as X-Stop are appropriate procedures . Similar results were achieved in both groups , however , with a higher number of reoperations in the X-Stop group . Patients having X-Stop removal and decompression experienced results similar to those r and omized to primary decompression . Level of Evidence : Study Design . R and omized clinical trial with 2-year follow-up . Objective . To compare the cost-effectiveness of X-stop to minimally invasive decompression in patients with symptomatic lumbar spinal stenosis . Summary of Background Data . Lumbar spinal stenosis is the most common indication for operative treatment in elderly . Although surgery is more costly than nonoperative treatment , health outcomes for more than 2 years were shown to be significantly better . Surgical treatment with minimally invasive decompression is widely used . X-stop is introduced as another minimally invasive technique showing good results compared with nonoperative treatment . Methods . We enrolled 96 patients aged 50 to 85 years , with symptoms of neurogenic intermittent claudication within 250-m walking distance and 1- or 2-level lumbar spinal stenosis , r and omized to either minimally invasive decompression or X-stop .  Quality -adjusted life-years were based on EuroQol EQ-5D . The hospital unit costs were estimated by means of the top-down approach . Each cost unit was converted into a monetary value by dividing the overall cost by the amount of cost units produced . The analysis of costs and health outcomes is presented by the incremental cost-effectiveness ratio . Results . The study was terminated after a midway interim analysis because of significantly higher reoperation rate in the X-stop group ( 33 % ) . The incremental cost for X-stop compared with minimally invasive decompression was & OV0556;2832 ( 95 % confidence interval : 1886–3778 ) , whereas the incremental health gain was 0.11 quality -adjusted life-year ( 95 % confidence interval : −0.01 to 0.23 ) . Based on the incremental cost and effect , the incremental cost-effectiveness ratio was & OV0556;25,700 . Conclusion . The majority of the bootstrap sample s displayed in the northeast corner of the cost-effectiveness plane , giving a 50 % likelihood that X-stop is cost-effective at the extra cost of & OV0556;25,700 ( incremental cost-effectiveness ratio ) for a quality -adjusted life-year . The significantly higher cost of X-stop is mainly due to implant cost and the significantly higher reoperation rate . Level of Evidence : Purpose Percutaneous interspinous st and -alone spacers offer a simple and effective technique to treat lumbar spinal stenosis with neurogenic claudication . Nonetheless , open decompressive surgery remains the st and ard of care . This study compares the effectiveness of both techniques and the validity of percutaneous interspinous spacer use . Methods Forty-five patients were included in this open prospect i ve non-r and omized study , and treated either with percutaneous interspinous st and -alone spacers ( Aperius ® ) or bilateral open microsurgical decompression at L3/4 or L4/5 . Patient data , operative data , COMI , SF-36 , PCS and MCS , ODI , and walking distance were collected 6 weeks , 3 , 6 , 9 , 12 , and 24 months post-surgery . Results Group 1 ( n = 12 ) underwent spacer implantation , group 2 ( n = 33 ) open decompression . Five patients from group 1 required implant removal and open decompression during follow-up ( FU ) ; one patient was lost to FU . From group 2 , seven patients were lost to FU . Remaining patients were assessed as above . After 2 years , back pain , leg pain , ODI , and quality of life improved significantly for group 2 . Remaining group 1 patients ( n = 6 ) reported worse results . Walking distance improved for both groups . Conclusion Decompression proved superior to percutaneous st and -alone spacer implantation in our two observational cohorts . Therapeutic failure was too high for interspinous spacers Study Design . A r and omized , controlled , prospect i ve multicenter trial comparing the outcomes of neurogenic intermittent claudication ( NIC ) patients treated with the interspinous process decompression system 
    Output:
    
There was no significant difference in VAS back pain , leg pain or ODI scores for st and alone interspinous process device ( IPD ) vs. bony decompression .
IPD as an adjunct to decompression had comparable patient-reported scores , complications and reoperation rates to decompression alone .
Current evidence indicates no superiority for mid- to long-term patient-reported outcomes for IPD compared with traditional bony decompression , with lesser surgical complications but at the risk of significantly higher reoperation rates and costs