***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective The purpose of this study was to assess the clinical and radiological outcomes of minimally invasive transforaminal lumbar interbody fusion ( MI-TLIF ) surgery for degenerative lumbar spine disease . Methods A prospect i ve analysis of 34 consecutive patients who underwent a MI-TLIF using image guidance between July 2008 and November 2010 . The patient group comprised 19 males and 15 females ( mean age 56 ) , 23 of whom had undergone additional reduction of spondylolisthesis . All patients underwent post-operative CT imaging to assess pedicle screw , cage placement and fusion at 6 months . Oswestry Disability Index ( ODI ) scores were recorded pre-operatively and at 6-month follow up . Results 33/34 ( 97.1 % ) patients showed evidence of fusion at 6 months with a mean improvement of 27 on ODI scores . The mean length of hospital stay was 4 days . The mean operative time was 173 min . Complications observed1/34 ( 2.9 % ) suffered a pulmonary embolism and 1/34 ( 2.9 % ) patients developed transient nerve root pain post-operatively . There were no occurrences of infection and no post-operative CSF leaks . Conclusion MI-TLIF offers patients a safe and effective surgical treatment option to treat degenerative lumbar spine disease Study Design : A prospect i ve r and omized study was conducted . Objective : The purpose of this study was to assess the radiographic outcomes of one-level minimally invasive transforaminal lumbar interbody fusion ( MI-TLIF ) with unilateral pedicle screw instrumentation for degenerative lumbar spine disease . Summary of Background Data : MI-TLIF has become an increasingly popular method of lumbar arthrodesis . Recent technological advances in spinal instrumentation have culminated in the development of MI-TLIF with unilateral pedicle screw fixation . However , there are few published studies on radiographic outcomes of the MI-TLIF with unilateral pedicle screw fixation . Methods : A total of 65 patients with one-level degenerative lumbar spine disease were enrolled in this study . Patients were r and omized into the unilateral or bilateral fixation group based on a computer-generated number list . Thirty-one patients ( 17 men and 14 women ; average age , 57.3 y ) were r and omized to the unilateral group ( group A ) and 34 patients ( 16 men and 18 women ; average age , 58.9 y ) to the bilateral group ( group B ) . All patients underwent minimally invasive decompression , interbody fusion , and pedicle screw fixation with the assistance of microscopic tubular retractor system ( METRx-MD ) and Sextant system . All patients were asked to follow-up at 3 , 6 , and thereafter once every 6 months after surgery . The visual analog scale ( VAS ) , Oswestry disability index ( ODI ) , and modified Prolo ( mProlo ) scores were obtained for all patients 24 hours before the operation and at each follow-up visit . The whole lumbar lordosis ( WL ) , the segmental lordosis ( SL ) , fusion level disk space angle , lumbar scoliosis angle , and segmental scoliosis angle were determined before and after surgery on st and ard x-rays . The disk height index ( DI ) and the lumber curvature index ( LI ) were also evaluated . Results : The mean follow-up was 26.6 months , with a range of 18–36 months . All patients showed evidence of fusion at 12 months postoperatively . Statistically , there was no significant difference between the 2 groups in terms of demographic data . The average postoperative VAS , ODI , and mProlo scores improved significantly in each group . No significant differences were found between the 2 groups in relation to VAS , ODI , and mProlo scores at each follow-up time point . There were no significant differences between the 2 groups in relation to WL , SL , disk space angle , lumbar scoliosis angle , segmental scoliosis angle , DI , and LI . There was also no difference between postoperative different follow-up visits in terms of these radiographic parameters in both groups . There was a positive linear correlation between the LI and WL in both groups . Conclusions : One-level unilateral pedicle screw instrumented MI-TLIF provided similar radiologic and clinical outcomes to bilateral pedicle screw instrumented MI-TLIF . This study showed that MIS-TLIF with unilateral pedicle screw fixation would be sufficient in the management of preoperatively stable patients with lumbar degenerative disease STUDY DESIGN A prospect i ve study of 87 patients who underwent unilateral or bilateral pedicle screw fixation .  OBJECTIVES To determine whether unilateral pedicle screw fixation is comparable with bilateral fixation in one- or two-segment lumbar spinal fusion . SUMMARY OF BACKGROUND DATA Clinical results for unilateral variable screw placement instrumentation in isolated L4-L5 fusion have been reported to be as good as those for bilateral instrumentation . However , unilateral instrumentation may not be recommended for multilevel fusion . METHODS Eighty-seven patients were assigned to either unilateral ( n = 47 ) or bilateral ( n = 40 ) pedicle screw instrumentation groups  . Two kinds of pedicle screw system ( Moss Miami , DePuy , Warsaw , IN , and Steffee VSP , AcroMed , Clevel and , OH ) were used . Operating time , blood loss , duration of hospital stay , clinical outcomes , fusion rates , complication rates , and medical expenses were studied and tested with independent sample t test and chi2 test . RESULTS There were no significant differences between the two groups in blood loss , clinical ly satisfactory results , fusion rate , and complication rate . There were significant differences in duration of operating time , duration of hospital stay , and medical expenses . The number of fusion segments or kinds of instrumentation did not affect the fusion rate or clinical outcomes . CONCLUSIONS Unilateral pedicle screw fixation was as effective as bilateral pedicle screw fixation in lumbar spinal fusion independent of the number of fusion segments ( one or two segments ) or pedicle screw systems . Based on the results of this study , unilateral fixation could be used in two-segment lumbar spinal fusion OBJECT Clinical and radiographic results were assessed to determine the clinical outcomes and fusion rate in eight consecutive patients selected for minimally invasive transforaminal lumbar interbody fusion ( TLIF ) in which a percutaneous pedicle screw system was used unilaterally . METHODS Eight patients underwent one-level , minimally invasive TLIF  in which a percutaneous pedicle screw system was used only on the side where facets were removed for interbody access . Clinical , economic , functional , and radiographic data were recorded preoperatively and at 6 months postoperatively . The mean 6-month change in the modified Prolo Scale score was 7 , and osseous interbody bridging assessed on coronal and sagittal computerized tomography studies was seen in all patients . CONCLUSIONS The use of unilateral percutaneous pedicle screw instrumentation for the minimally invasive TLIF procedure provides excellent clinical results and is an option in selected patients OBJECT Minimally invasive transforaminal lumbar interbody fusion ( MIS-TLIF ) is used to treat a wide variety of lumbar degenerative disorders . Although there are some reports showing efficacy of unilateral instrumentation during MIS-TLIF , a controlled r and omized prospect i ve study has not been done . METHODS Forty-one patients were r and omly assigned to receive either bilateral or unilateral instrumentation following 1-level unilateral MIS-TLIF .  Four patients were lost to follow-up in the unilateral group and 1 patient was lost to follow-up in the bilateral group . Preoperative and postoperative scores on a visual analog scale ( VAS ) for back pain and leg pain ( VAS-BP and VAS-LP , respectively ) , Oswestry Disability Index ( ODI ) , and 36-Item Short Form Healthy Survey version 2 ( SF-36v2 ) were collected . Additionally , preoperative and postoperative segmental Cobb angles and radiographic evidence of fusion were analyzed . RESULTS There was no statistically significant difference in baseline demographic characteristics between the 2 groups . The VAS-BP , VAS-LP , ODI , and SF-36v2 physical component scores improved significantly after surgery in both groups ( p < 0.05 ) ; there was no statistically significant between-groups difference in the degree of improvement . Blood loss was significantly higher in the bilateral instrumentation group and hospital stay was longer in the unilateral instrumentation group . There was no statistically significant between-groups difference with respect to change in segmental lordosis or fusion rate . The average duration of follow-up was 12.4 months for the bilateral instrumentation group and 11.4 months for the unilateral instrumentation group . CONCLUSIONS Clinical and radiographic outcomes of unilateral and bilateral instrumentation for unilateral MISTLIF are similar 1 year after surgery BACKGROUND CONTEXT Current surgical trends increasingly emphasize the minimization of surgical exposure and tissue morbidity . Previous research question ed the ability of unilateral pedicle screw instrumentation to adequately stabilize posterior fusion constructs . No study to date has addressed the effects of reduced posterior instrumentation mass on interbody construct techniques . Unilateral surgical exposure for transforaminal lumbar interbody fusion ( TLIF ) allows ipsilateral pedicle screw placement . Theoretically , percutanous contralateral facet screw placement could provide supplemental construct support without additional surgical exposure . PURPOSE Identify the biomechanical effects of reduced spinal fusion instrumentation mass on interbody construct stability . STUDY DESIGN An in vitro biomechanical study using human lumbar spines comparing stability of TLIF constructs augmented by : ( 1 ) bilateral pedicle screw fixation , ( 2 ) unilateral pedicle screw fixation , or ( 3 ) a novel unilateral pedicle screw fixation supplemented with contralateral facet screw construct . METHODS Seven fresh frozen human cadaveric specimens were tested in r and om construct order in flexion/extension , lateral bending , and axial rotation using + /-5.0 Nm torques and 50 N axial compressive loads . Analysis of torque rotation curves determined construct stability . Using paired statistical methods , comparison of construct stiffness and total range of motion within each specimen were performed using the Wilcoxon signed ranks test with a Holm-Sidák multiple comparison procedure ( alpha=0.05 ) . RESULTS In flexion/extension , lateral bending , and axial rotation , there were no measurable differences in either stiffness or range of motion between the st and ard bilateral pedicle screw and the novel construct after TLIF . After TLIF , the unilateral pedicle screw construct provided only half of the improvement in stiffness compared with bilateral or novel constructs and allows for significant off-axis rotational motions , which could be detrimental to stability and the promotion for fusion . CONCLUSIONS All tested TLIF constructs with posterior instrumentation decreased segmental range of motion and increased segmental stiffness . While placing unilateral posterior instrumentation decreases overall implant bulk and dissection , it allows for significantly increased segmental range of motion , less stiffness , and produces off-axis movement . The technique of contralateral facet screw placement provides the surgical advantages of unilateral pedicle screw placement with stability comparable to TLIF with bilateral pedicle screws OBJECTIVE Percutaneous spinal instrumentation techniques may be helpful to reduce approach-related morbidity inherent to conventional open surgery . This article reports technique , clinical outcomes , and fusion rates of percutaneous transforaminal lumbar interbody fixation ( pTLIF ) . Results are compared with those of mini-open transforaminal lumbar interbody fixation ( oTLIF ) using a muscle splitting ( Wiltse ) approach . METHODS  pTLIF was performed in 43 patients with single-level and 10 patients with bi- or multilevel lumbar discopathy or degenerative pseudolisthesis result ing in axial back pain and claudication , pseudoradicular , or radicular symptoms .  Decompression , discectomy , and interbody cage insertion were performed through 18-mm tubular retractors followed by percutaneous pedicle screw-rod fixation . Clinical outcome was assessed by early postoperative pain scores ( visual analog score ) and st and ardized functional outcome question naires ( American Academy of Orthopedic Surgeons lumbar spine and Rol and -Morris low back pain score ) . Fusion rates were assessed by thin-slice computed tomographic scan at 16 months . Clinical outcome , time in the operating room , intraoperative blood loss , and postoperative access-site pain were compared with an institutional reference series of 67 oTLIF procedures . RESULTS Excellent and good clinical results were obtained in 46 ( 87 % ) out of 53 patients at 16 months . The time spent in the operating room was equivalent and the blood loss reduced compared with oTLIF ( P < 0.01 ) . There was no morbidity related to instrumentation . Postoperative pain was significantly lower after pTLIF after the second postoperative day ( P < 0.01 ) . The overall clinical outcome was not different from oTLIF at 8 and 16 months . CONCLUSION pTLIF allows for safe and efficient minimally invasive treatment of single and multilevel degenerative lumbar instability with good clinical results . Further prospect i ve studies investigating long-term functional results are required to assess the definitive merits of percutaneous instrumentation of the lumbar spine OBJECT Posterior lumbar interbody fusion ( PLIF ) has been shown to be effective in the treatment of axial low-back pain . Minimally invasive spine surgery for arthrodesis has several advantages , including quicker patient recovery , less postoperative pain 
    Output:
    
Conclusions The existing evidence indicate that no superiority exists between the two fixation methods of MIS-TLIF in terms of functional outcome , fusion rate and complication rate , in spite of that unilateral pedicle screw fixation can achieve less blood loss than bilateral fixation