***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND CONTEXT Intraoperative reduction of low- grade lumbar spondylolisthesis ( LGLS ) remains disputed . There is currently no published data comparing midterm outcomes of reduction versus in situ fusion . PURPOSE This study aim ed to compare mid-term clinical , radiological , and perioperative outcomes for reduction versus in situ fusion in LGLS with neurogenic symptoms . STUDY DESIGN / SETTING A retrospective review of prospect ively collected spine registry data in a single institution was carried out . PATIENT SAMPLE All patients who underwent minimally invasive transforaminal lumbar interbody fusion ( MIS TLIF ) for LGLS with neurogenic symptoms with a minimum 5-year follow-up comprised the patient sample . OUTCOME MEASURES Self-reported measures were Oswestry Disability Index , North American Spine Society Neurogenic Symptom Score , Health Outcomes Survey Short Form-36 score , and Numerical Pain Rating Scale ( back and leg pain ) . Radiological outcomes were fusion grading , adjacent segment degeneration ( ASD ) , and implant failure or loosening . Perioperative outcomes were fluoroscopic time , operative time , intraoperative blood loss , opioid analgesia usage , time to ambulation , duration of hospitalization , and complication rate . Functional outcomes were patient satisfaction rate and rate of return to full function . METHODS A retrospective review was performed on prospect ively collected registry data of patients undergoing MIS TLIF for LGLS with neurogenic symptoms , from 2004 to 2009 . The operative technique and postoperative protocol were st and ardized . Two groups were formed based on complete reduction of the spondylolisthesis ( reduction group [ RG ] ) or the lack thereof ( non-reduction group [ NRG ] ) in the immediate postoperative radiograph . Outcomes at baseline , 6 months , 2 years , and 5 years postsurgery were compared . RESULTS There were 56 patients included ( RG=30 , NRG=26 ) . The two groups had comparable baseline characteristics : demographics , body mass index , spondylolisthesis etiology , spinal level involved , bone graft and bone morphogenetic protein used , and all self-reported outcome measures . Perioperative outcomes were not significantly different . The early complication rate ( RG=3.3 % , NRG=19.2 % , p=.086 ) and late complication rate ( RG=10 % , NRG=23.1 % , p=.184 ) were similar . All patients achieved Bridwell grade 1 fusion from 2 years onward . Adjacent segment degeneration rate at 5 years was similar ( RG=10 % , NRG=0 % , p = NS ) . Both groups showed significant postoperative improvement in all self-reported measures with no significant differences between the two groups at all follow-up points . Functional outcomes were equivalent . CONCLUSIONS Intraoperative reduction does not improve outcomes in LGLS with neurogenic symptoms after MIS TLIF . Adequate decompression and solid fusion are likely the keys to good mid-term outcomes BACKGROUND Management of degenerative spondylolisthesis with spinal stenosis is controversial . Surgery is widely used , but its effectiveness in comparison with that of nonsurgical treatment has not been demonstrated in controlled trials . METHODS Surgical c and i date s from 13 centers in 11 U.S. states who had at least 12 weeks of symptoms and image-confirmed degenerative spondylolisthesis were offered enrollment in a  r and omized cohort or an  observational cohort . Treatment was st and ard decompressive laminectomy ( with or without fusion ) or usual nonsurgical care . The primary outcome measures were the Medical Outcomes Study 36-Item Short-Form General Health Survey ( SF-36 ) bodily pain and physical function scores ( 100-point scales , with higher scores indicating less severe symptoms ) and the modified Oswestry Disability Index ( 100-point scale , with lower scores indicating less severe symptoms ) at 6 weeks , 3 months , 6 months , 1 year , and 2 years . RESULTS We enrolled 304 patients in the r and omized cohort and 303 in the observational cohort . The baseline characteristics of the two cohorts were similar . The one-year crossover rates were high in the r and omized cohort ( approximately 40 % in each direction ) but moderate in the observational cohort ( 17 % crossover to surgery and 3 % crossover to nonsurgical care ) . The intention-to-treat analysis for the r and omized cohort showed no statistically significant effects for the primary outcomes . The as-treated analysis for both cohorts combined showed a significant advantage for surgery at 3 months that increased at 1 year and diminished only slightly at 2 years . The treatment effects at 2 years were 18.1 for bodily pain ( 95 % confidence interval [ CI ] , 14.5 to 21.7 ) , 18.3 for physical function ( 95 % CI , 14.6 to 21.9 ) , and -16.7 for the Oswestry Disability Index ( 95 % CI , -19.5 to -13.9 ) . There was little evidence of harm from either treatment . CONCLUSIONS In nonr and omized as-treated comparisons with careful control for potentially confounding baseline factors , patients with degenerative spondylolisthesis and spinal stenosis treated surgically showed substantially greater improvement in pain and function during a period of 2 years than patients treated nonsurgically . ( Clinical Trials.gov number , NCT00000409 [ Clinical Trials.gov ] . ) Objective We prospect ively compared surgical reduction or fusion in situ with posterior lumbar interbody fusion ( PLIF ) for adult isthmic spondylolisthesis in terms of surgical invasiveness , clinical and radiographical outcomes , and complications . Methods From January 2006 to June 2008 , 88 adult patients with isthmic spondylolisthesis who underwent surgical treatment in our unit were r and omized to reduced group ( group 1 , n = 45 ) and in situ group  ( group 2 , n = 43 ) , and followed up for average 32.5 months ( range 24–54 months ) . The clinical and radiographical outcomes were compared between the two groups . Results The average operative time and blood loss during surgery showed insignificant difference ( p > 0.05 ) between two groups . The radiological outcomes were significantly better in group 1 , but there was no significant difference between two groups of clinical outcomes , depicting as VAS , ODI , JOA and patients ’ satisfaction surveys . Incident rate of surgical complications was similar in two groups , but in group 1 the complication seemed more severe because of two patients with neurological symptoms . Conclusions For the adult isthmic spondylolisthesis without degenerative disease in adjacent level , single segment of PLIF with pedicle screw fixation is an effective and safe surgical procedure regardless of whether additional reduction had been conducted or not . Better radiological outcome does not mean better clinical outcome Background In instrumented posterolateral fusion reduction of a spondylolisthesis is appealing on theoretical grounds since this may lead to indirect decompression of the entrapped nerve roots . However , there is no consensus in the literature whether a beneficial effect of reduction on outcome can be expected . The objective of the current study was to evaluate whether a correlation between the extent of listhesis reduction and clinical improvement could be established . Methods From two ongoing prospect i ve studies 72 patients with a single-level instrumented posterolateral lumbar fusion for low- grade spondylolisthesis ( isthmic/degenerative 51/21 ) were evaluated . Radiographs and clinical outcome scores were available at baseline , 6 weeks and 1 year after surgery . Changes in neuroforaminal morphology were measured on calibrated radiographs . These changes in radiographic parameters were correlated to clinical outcome ( Visual Analogue Score ( VAS ) leg pain , Oswestry Disability Index ( ODI ) ) . Fusion status was assessed on Computed Tomography-scan at one year . Results A mean spondylolisthesis of 25 percent was reduced to 15 percent at 6 weeks with some loss of reduction to 17 percent at one year . The VAS and ODI significantly improved at both time intervals after surgery ( p < 0.001 ) . No significant correlations could be established between the extent of slip reduction and improvement in VAS or ODI ( Pearson ’s correlation −0.2 and 0.07 respectively at one year ) ; this also accounted for the other radiographic parameters . A fusion rate of 64 percent was seen on CT-scan . Conclusions Clinical outcome was not related to the obtained radiographic reduction of the slipped vertebra in patients with a lumbar fusion for low grade spondylolisthesis . Loss of reduction or non-union on CT-scans had no effect on the clinical outcome . Reduction of a low- grade spondylolisthesis in spinal fusion is appealing , however , there is no evidence that it positively affects clinical outcome on the short term . Trial registration IS RCT BACKGROUND CONTEXT In situ fusion is the gold st and ard method of treatment of spondylolisthesis . There is no study in the literature evaluating the effect of sagittal contour realignment on clinical outcomes in comparison with the addition of anterior slippage reduction . PURPOSE The correction of sagittal plane vs. reduction with instrumentation in the patients with low or high dysplastic spondylolisthesis . STUDY DESIGN / SETTING A prospect i ve r and omized study in patients treated with the same surgical team at the same center . PATIENT SAMPLE 40 patients , 20 with low and 20 with high dysplastic spondylolisthesis ( mean age : 33.1+/-10.6 ; average follow-up : 37.9+/-11.9 Mo. ) . OUTCOME MEASURES The extent of displacement , lumbosacral angle values , lumbar sagittal contours , correction rates , JOA scores , SRS-22 question naire were evaluated preoperatively , postoperatively , and at the final visit . Fusion rates , complications and quality of fusion were recorded . METHODS 4 groups of patients were generated . Only posterolateral fusion , neural decompression , and sagittal plane correction with posterior instrumentation using 3rd generation instrumentation system transpedicular screws was accomplished in 20 patients ( low dysplastic : 10 patients , high dysplastic : 10 patients ) . Additional reduction of anterior slippage was done in the remaining 20 patients ( low dysplastic : 10 patients , high dysplastic : 10 patients ) . RESULTS No statistically significant difference was found between low vs. high dysplastic patients and between patients with sagittal contour realignment vs. patients with additional anterior slippage reduction ( p>0.05 ) . The correction rates for displacement were statistically similar at the final visit . Postoperative and final JOA and SRS scores were similar between in situ fusion and reduction groups ( p>0.05 ) . A solid fusion mass of 77.5 % was achieved in both groups . CONCLUSIONS A high percentage of fusion was achieved with posterolateral in situ fusion with or without reduction ; and an additional reduction procedure did not have a statistically detectable impact on clinical outcomes . Successful fusion and neural decompression were the most important parameters that have an impact on clinical outcomes in patients with developmental spondylolisthesis , irrespective of the extent of preoperative displacement and the type of listhesis Background spondylolisthesis is a condition in which a vertebra slips out of the proper position onto the bone below it as a result of pars interarticularis defect . The slipped segment produces abnormal positioning of the vertebrae in relation to each other along the spinal column and causes mechanical back pain and neural breach . Material s and methods A r and omized and double blinded study consisted of 41 patients aged 36 - 69 years ( 18 females and 28 males ) treated for symptomatic spondylolisthesis between December,2006 and December , 2009 . All patients were r and omly distributed into two groups I and II . Twenty patients were in Group I ; they underwent reduction of the slipped vertebrae by using Reduction-Screw Technique and posterior lumbar interbody fixation ( PLIF ) . Group II consisted of twenty one patients who underwent only surgical fixation ( PLIF ) without reduction . All patients in this study had same pre and post operative management . Results only one case had broken rod in group I that required revision . Superficial wound infection was experienced in two patients and one patient , from group II , developed wound hematoma . The outcome in both groups was variable on the short term but was almost the same on the long term follow up . Conclusions urgical management of symptomatic low grade spondylolisthesis should include neural decompression and surgical fixation . Reduction of slipped vertebral bodies is unnecessary as the ultimate outcome will be likely similar BACKGROUND CONTEXT The role of surgical correction of sagittal plane deformity in cases of lytic spondylolisthesis remains controversial . While some early evidence is emerging of the possible short- and long-term benefits of restoring spinal balance , many surgeons have been concerned about the associated risks . The insert- and -rotate posterior lumbar interbody fusion ( PLIF ) technique , first described by Jaslow in 1946 , may enable surgeons to safely and effectively correct sagittal balance through a single posterior approach . PURPOSE To determine whether the focal kyphosis and subluxation associated with a lytic lumbosacral spondylolisthesis can be safely and effectively corrected using a single-stage posterior distraction/reduction technique and insert- and -rotate interbody fusion spacers . STUDY DESIGN / SETTING A prospect i ve , single cohort , observational study of the clinical outcomes and retrospective radiological review , in a series of 18 consecutive patients with lytic spondylolisthesis Grade s I to IV , operated between September 2000 and December 2002 . PATIENT SAMPLE Mean age of 50.2 years ( range 
    Output:
    
Conclusions On the basis on this review , arthrodesis after reduction of low- grade spondylolisthesis potentially reduced vertebral slippage .
Reduction was neither associated with a longer operative time nor more blood loss .
There was no significant difference in the outcomes between reduction and arthrodesis in situ group .