Unilateral Pedicle Screw Fixation Research Articles

Unilateral versus bilateral pedicle screw fixation in short-segment lumbar spinal fusion: a meta-analysis of randomised controlled trials.

We performed this meta-analysis of randomised controlled trials to compare the efficacy and safety of unilateral with bilateral fixation in short-segment lumbar spinal fusion. Predefined terms were used to search electronic databases to identify relevant research. Randomised controlled trials (RCTs) published in English and Chinese during 1990-2015 investigating efficacy and safety of unilateral and bilateral fixation in short-segment lumbar spinal fusion were included. Data of fusion rate, complications, visual analogue scale (VAS), Oswestry Disability Index (ODI), estimated blood loss (EBL) and length of hospital stay were extracted and analysed. Two reviewers independently searched information sources, selected eligible research, analysed data and evaluated risk of bias. Eleven RCTs comprising 756 participants were analysed. There was no significant difference in fusion rate, device-related complication, ODI, VAS and length of hospital stay between bilateral and unilateral groups. The unilateral group had the obvious advantage of reduced blood loss [mean difference (MD) -143.57, 95% confidence interval (Cl) -206.61 to -80.54, P < 0.0001) and operation time (MD -52.72, 95% Cl -73.58 to -31.87, P < 0.00001). Unilateral pedicle screw fixation is equally as effective as bilateral pedicle screw fixation in short-segment lumbar spinal fusion and may reduce operation time and blood loss.

Unilateral Pedicle Screw Fixation is Associated with Reduced Cost and Similar Outcomes in Selected Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion for L4-5 Degenerative Spondylolisthesis.

Study design:Retrospective study of 24 patients who underwent either a bilateral or unilateral TLIF procedure for the treatment of degenerative spondylolisthesis. Objective:To analyze differences in cost and outcome between patients undergoing minimally invasive transforaminal lumbar interbody fusion (mi-TLIF) with unilateral or bilateral pedicle screw fixation for L4-5 degenerative spondylolisthesis.Summary of background data:Lumbar fusion surgeries, including the TLIF procedure, have been shown to be an effective treatment for leg and low back pain caused by degenerative spondylolisthesis. Some studies have shown TLIF surgeries to be cost-effective, but there is still a paucity of data and no consensus. Unilateral TLIFs can provide the same benefits as bilateral TLIFs, but come with additional benefits of a less invasive surgery. Methods:We retrospectively analyzed a consecutive series of patients with L4-5 degenerative stenosis and spondylolisthesis who either received a unilateral or bilateral mi-TLIF, paying particular attention to hospital cost and clinical outcome. Of the 33 patients eligible for analysis, we were able to obtain appropriate clinical and radiographic follow-up data on 24 patients (72.7%), 14 patients who underwent unilateral fixation, and 10 patients who underwent bilateral fixation.Results:The cohorts were similar with regard to age, comorbidities, and demographics. Most patients reported good or excellent results, and there were no significant differences between the cohorts with regard to clinical outcome. There was one interbody graft extrusion in the unilateral cohort that required explantation, but no other hardware failures. Hospital cost was significantly lower in the unilateral cohort, and hardware savings accounted for only part of the difference.Conclusion:Unilateral pedicle screw fixation is an acceptable surgical strategy in patients with stable L4-5 degenerative spondylolisthesis undergoing mi-TLIF. In our series, unilateral fixation led to significant hospital cost savings without compromising clinical or radiographic outcomes.

Transforaminal Lumbar Interbody Fusion with Unilateral Pedicle Screw and Contralateral Percutaneous Transfacet Screw Fixation for the Treatment of Lumbar Degenerative Disorders.

To assess the feasibility and efficacy of TLIF with unilateral pedicle screw and contralateral percutaneous lumbar transfacet screw fixation for the treatment of lumbar degenerative disorders. A series of computed tomography (CT) digital images from 60 patients (30 males and 30 females) with L3-S1 segments, were reconstructed in three dimensions using a software named Xelis 3D. Linear and angular measurements of the facets were recorded. Fifty-six patients were divided to either bilateral pedicle screw fixation (BPS) (n=30) or unilateral pedicle screw and contralateral percutaneous transfacet screw fixation (UPFS) (n=26) groups. The operating time, blood loss, length of hospital stay, clinical outcomes, fusion and complication rates were compared between the two groups. The parameters of the facets we recorded were no significant differences between the left and right sides (p > 0.05). No statistically significant differences between males and females were observed, except the maximum width of superior facet at L4 and S1, and length of screw at all levels. Intraoperative parameters, such as operating time, blood loss and postoperative hospital stay had significantly larger in the BPS group than UPFS group (p < 0.05). No significant differences were found between the two groups in clinical results, fusion and complication rates (p > 0.05). Because of the similar clinical outcomes but less operative time, blood loss and length of postoperatively hospital stay, unilateral pedicle screw and contralateral percutaneous lumbar transfacet screw fixation might be an attractive technique compared to bilateral pedicle screw fixation for treating lumbar degenerative disorders with TLIF. Nevertheless differences of the anatomical parameters for the lumbosacral facets fixation between Chinese and Westerners should be noted.

Unilateral versus bilateral pedicle screw fixation for degenerative lumbar diseases: a meta-analysis of 10 randomized controlled trials.

BackgroundThe common and effective treatment for degenerative lumbar diseases is lumbar spinal fusion. Controversy still exists on the choice for instrumentation with spinal fusion procedures. Therefore, we conducted this meta-analysis exclusively of RCTs to compare the clinical outcomes of patients receiving bilateral versus unilateral pedicle screw fixation (PSF).Material/MethodsAfter systematic review of published and unpublished literature, a meta-analysis was conducted to compare the 2 treatment strategies. The methodological quality of the literature was assessed using the PEDro critical appraisal tool.ResultsData synthesis showed less blood loss (P<0.001) and shorter operative time (P<0.001) in patients receiving unilateral PSF compared to bilateral PSF. However, there was no significant difference in fusion rates and functional outcomes between the 2 groups.ConclusionsThe meta-analysis indicated no significant difference in fusion rates and functional outcomes between the 2 treatment procedures, but unilateral PS fixation reduced blood loss and operative time.

Unilateral versus bilateral pedicle screw fixation of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF): a meta-analysis of randomized controlled trials.

BackgroundA few studies focused on unilateral or bilateral pedicle screw (PS) fixation of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) to treat lumbar degenerative diseases have been published. There is still debate over whether one method is superior to another. A systematic review and meta-analysis of randomized controlled trials (RCT) was performed to compare the efficacy of the two methods.MethodsWe searched the established electronic literature databases of MEDLINE, EMBASE, Web of Science and the Cochrane Central Register of Controlled Trials databases for RCTs comparing the unilateral with bilateral pedicle screw fixation of MIS-TLIF. Pooled mean differences (MD) and odds ratios (OR) and with 95% CIs were calculated for the outcomes.ResultsThree RCTs were identified and analyzed. The results showed that there is no significant difference between the two methods in terms of postoperative VAS-BP score (WMD = -0.09; 95% CI: -0.69 to 0.51; P =0.78), ODI (WMD, -0.09; 95% CI -5.85 to 5.67; P =0.98), fusion rate (OR = 2.99; 95% CI 0.55 to 16.38; P = 0.21) or complication rate (OR = 1.61, 95% CI: 0.49 to 5.37; P =0.43). Unilateral pedicle screw fixation was associated with less blood loss (WMD = -87.83; 95% CI: -160.70 to -14.96; P =0.02).ConclusionsThe 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.

Transforaminal lumbar interbody fusion using unilateral pedicle screw fixation plus contralateral translaminar facet screw fixation in lumbar degenerative diseases.

Background:Transforaminal lumbar interbody fusion (TLIF) has been used in lumbar degenerative diseases. Some researchers have applied unilateral fixation in TLIF to reduce operational trauma without compromising the clinical outcome, but it is always suspected biomechanically unstable. The supplementary contralateral translaminar facet screw (cTLFS) seemed to be able to overcome the inherent drawbacks of unilateral pedicle screw (uPS) fixation theoretically. This study evaluates the safety, feasibility and efficacy of TLIF using uPS with cTLFS fixation in the treatment of lumbar degenerative diseases (LDD).Materials and Methods:50 patients (29 male) underwent the aforementioned surgical technique for their LDD between December 2009 and April 2012. The results were evaluated based on visual analogue scale (VAS) of the leg and back, Japanese Orthopedic Association (JOA) score and Oswestry Disability Index (ODI) were recorded. The radiographic examinations in form of X-ray, computed tomography (CT) or magnetic resonance imaging was done preoperatively and 1 week, 3 months, 6 months, 12 months and 24 months postoperatively. The student t-test was used for comparison between the preoperative values and postoperative counterparts. P < 0.05 was considered to be statistically significant.Results:Among 50 patients, 22 received one level fusion and 28 two level's, with corresponding operation time and estimated blood loss being approximately 90 min, 150 ml and 120 min, 200 ml, respectively. No severe complications happened perioperatively. The mean VAS (back, leg) scores dropped from (7.6, 7.5) preoperatively to (2.1, 0.6) at 12 months’ followup, ODI from 49.1 preoperatively to 5.6 and JOA score raised from 10.6 preoperatively to 28.5, all P < 0.001, suggesting of good clinical outcome. From the three-dimensional reconstructed CT, 62 out of 70 segments displayed solid fusion with fusion rate of 88.6% at 12 months postoperatively.Conclusions:TLIF using uPS fixation plus cTLFS fixation is a safe, feasible and effective technique in the treatment of one or two level lumbar degenerative diseases short termly.

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with unilateral pedicle screw fixation in treatment of one-level lumbar degenerative disease

Objective To explore the clinical and radiographic outcomes of minimally invasive transforarninal lumbar interbody fusion (MIS-TLIF) with unilateral pedicle screw fixation in treatment of one-level lumbar degenerative disease.Methods A total of 65 patients suffered from one-level lumbar degenerative disease between October 2009 and December 2011.They were divided into 2 groups according to different fixation ways.31 patients were given MIS-TLIF with unilateral pedicle screw fixation.The other 34 patients were given MIS-TLIF with bilateral pedicle screw fixation.Microscopic tubular retractor system (METRxMD) and Sextant system were used in all the procedures of treatment.The whole lumbar lordosis (WL),the segmnental lordosis (SL),fusion level disc space angle,lumbar scoliosis angle,and segmental scoliosis angle were measured pre and post operation according to standarded X-rays.The disc height index (DI) and the lumber curvature index (LI) were also evaluated.The Oswestry disability index (ODI) score and visual analog scale (VAS) pain score data were obtained from all the patients pre-operation and during each following-up procedure.Results All the patients were well followed up 18 months to 36 months(average 26.6 months).All the 65 patients were proved to achieve bone fusion in 12 months post-operation.The ODI and VAS scores post-operation improved significantly in each group,but showed no significant difference between the 2 groups.Likewise,there were no significant differences between the 2 groups in datas of WL,SL,fusion level disc space angle,lumbar scoliosis angle,segmental scoliosis angle,DI,and LI.But there was a positive linear correlation between the LI and WL in the 2 groups.Conclusion MIS-TLIF with unilateral pedicle screw fixation is as good as MIS-TLIF with bilateral pedicle screw fixation in patients of one-level lumbar degenerative disease. Key words: Lumbar Vertebrae; Surgical procedures, minimally invasive; Spinal fusion

Treatment of unstable thoracolumbar fractures through short segment pedicle screw fixation techniques using pedicle fixation at the level of the fracture: a finite element analysis.

ObjectiveTo compare the von Mises stresses of the internal fixation devices among different short segment pedicle screw fixation techniques to treat thoracic 12 vertebral fractures, especially the mono-segment pedicle screw fixation and intermediate unilateral pedicle screw fixation techniques.MethodsFinite element methods were utilised to investigate the biomechanical comparison of the four posterior short segment pedicle screw fixation techniques (S4+2: traditional short-segment 4 pedicle screw fixation [SPSF]; M4+2: mono-segment pedicle screw fixation; I6+2: intermediate bilateral pedicle screw fixation; and I5+2: intermediate unilateral pedicle screw fixation).ResultsThe range of motion (ROM) in flexion, axial rotation, and lateral bending was the smallest in the I6+2 fixation model, followed by the I5+2 and S4+2 fixation models, but lateral bending was the largest in the M4+2 fixation model. The maximal stress of the upper pedicle screw is larger than the lower pedicle screw in S4+2 and M4+2. The largest maximal von Mises stress was observed in the upper pedicle screw in the S4+2 and M4+2 fixation models and in the lower pedicle screw in the I6+2 and I5+2 fixation models. The values of the largest maximal von Mises stress of the pedicle screws and rods during all states of motion were 263.1 MPa and 304.5 MPa in the S4+2 fixation model, 291.6 MPa and 340.5 MPa in the M4+2 fixation model, 182.9 MPa and 263.2 MPa in the I6+2 fixation model, and 269.3 MPa and 383.7 MPa in the I5+2 fixation model, respectively. Comparing the stress between different spinal loadings, the maximal von Mises stress of the implants were observed in flexion in all implanted models.ConclusionAdditional bilateral pedicle screws at the level of the fracture to SPSF may result in a stiffer construct and less von Mises stress for pedicle screws and rods. The largest maximal von Mises stress of the pedicle screws during all states of motion were observed in the mono-segment pedicle screw fixation technique.

Unilateral versus bilateral pedicle screw instrumentation for single-level minimally invasive transforaminal lumbar interbody fusion

Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has become an increasingly popular method of lumbar arthrodesis. However, there are few published studies comparing the clinical outcomes between unilateral and bilateral instrumented MIS TLIF. Sixty-five patients with degenerative lumbar spine disease were enrolled in this study. Thirty-one patients were randomized to the unilateral group and 34 to the bilateral group. Recorded demographic data included sex, age, preoperative diagnosis, and degenerated segment. Operative time, blood loss, hospital stay length, complication rates, and fusion rates were also evaluated. The Oswestry Disability Index (ODI) score and Visual Analog Scale (VAS) pain score data were obtained. All patients were asked to follow-up at 3 and 6months after surgery, and once every 6months thereafter. The mean follow-up was 26.6months (range 18–36months). The two groups were similar in sex, age, preoperative diagnosis, and operated level. The unilateral group had significantly shorter operative time, lower blood loss, and shorter hospital time than the bilateral group. The average postoperative ODI and VAS scores improved significantly in each group. No significant differences were found between the two groups in relation to ODI and VAS. All patients showed evidence of fusion at 12months postoperatively. The total fusion rate, screw failure, and general complication rate were not significantly different. Results showed that single-level MIS TLIF with unilateral pedicle screw fixation would be sufficient in the management of preoperatively stable patients with lumbar degenerative disease. It seems that MIS TLIF with unilateral pedicle screw instrumentation is a better choice for single-level degenerative lumbar spine disease.

Treatment of thoracolumbar fractures by unilateral pedicle screw fixation plus short segment pedicle screw through para-vertebral muscles

A total of 33 non–neurological symptoms patients with thoracolumbar fractures underwent unilateral pedicle screw fixation plus short segment pedicle screw through para–vertebral muscles. Preoperative computed tomography (CT) scan showed one side pedicle was complete. The average follow–up period was 22 (12–40) months. There was no internal fixation failure. The posterior paraspinal approach for unstable thoracolumbar fractures, retaining posterior ligament complex and fixation by unilateral pedicle screw fixation through the pedicle of fractured vertebra, is both safe and effective for thoracolumbar fractures. Key words: Surgical procedures, operative; Spinal fractures

Finite element analysis of minimal invasive transforaminal lumbar interbody fusion.

The purpose of our study is to develop and validate three-dimensional finite element models of transforaminal lumbar interbody fusion, and explore the most appropriate method of fixation and fusion by comparing biomechanical characteristics of different fixation method. We developed four fusion models: bilateral pedicle screws fixation with a single cage insertion model (A), bilateral pedicle screws fixation with two cages insertion model (B), unilateral pedicle screws fixation with a single cage insertion model (C), and unilateral pedicle screws fixation with two cages insertion model (D); the models were subjected to different forces including anterior bending, posterior extension, left bending, right bending, rotation, and axial compressive. The von Mises stress of the fusion segments on the pedicle screw and cages was recorded. Angular variation and stress of pedicle screw and cage were compared. There were differences of Von Mises peak stress among four models, but were within the range of maximum force. The angular variation in A, B, C, and D decreased significantly compared with normal. There was no significant difference of angular variation between A and B, and C and D. Bilateral pedicle screws fixation had more superior biomechanics than unilateral pedicle screws fixation. In conclusion, the lumbar interbody fusion models were established using varying fixation methods, and the results verified that unilateral pedicle screws fixation with a single cage could meet the stability demand in minimal invasive transforaminal interbody fusion.

Lumbar spine stability after combined application of interspinous fastener and modified posterior lumbar interbody fusion: a biomechanical study

Posterior lumbar interbody fusion (PLIF) and internal fixation are commonly performed for the treatment of lower back pain due to lumbar spinal degeneration. We have developed a novel interspinous fixation device, the interspinous fastener (ISF) for potential use in the surgical management of degenerative spinal disease. The aim of this study was to assess the in vitro biomechanical characteristics of calf lumbar spine specimens after ISF fixation with modified PLIF. Ten lumbar spine (L3-L6) specimens from ten fresh calf cadavers (8-10weeks of age) were used. Each specimen underwent sequential testing for each of the following four groups: no instrumentation (INTACT); interspinous fusion device fixation+PLIF (ISF); unilateral pedicle screw and titanium rod fixation+PLIF (UPS); bilateral pedicle screw and titanium rod fixation+PLIF (BPS). Outcome measures included angular range of motion (ROM) during unloaded and loaded (8Nm) flexion, extension, left bending, right bending, left torsion and right torsion. For all unloaded and loaded assessments, ROM was significantly higher in the INTACT group compared with all other groups (P<0.05). Similarly, ROM was significantly higher in the UPS group (indicating decreased stability) compared with the ISF and BPS groups (P<0.05). The only significant difference between the ISF and BPS groups was in the ROM with unloaded extension (higher in the BPS group, P=0.006). We found that ISF fixation with PLIF of the lower lumbar spine provided biomechanical stability that was equivalent to that associated with bilateral pedicle screw/rod fixation with PLIF. The ISF shows potential as an alternative means of fixation in the surgical management of degenerative spinal disease.

Comparison of unilateral versus bilateral pedicle screw fixation in degenerative lumbar diseases: a meta-analysis

Traditionally, lumbar spinal surgery is performed with bilateral pedicle screw fixation to provide stability as the fusion heals. However, many studies have reported that unilateral pedicle screw fixation is as effective as bilateral constructs. To compare the clinical outcomes, complications, and surgical trauma between the two techniques for treatment of degenerative lumbar diseases, we conducted a meta-analysis. We searched MEDLINE, EMBASE, PubMed, Google Scholar, and Cochrane databases for relevant controlled studies up to August 2013 that compared unilateral with bilateral fixation for the treatment of degenerative lumbar diseases. We independently performed title/abstract screening and full-text screening. A random effects model was used for heterogeneous data; otherwise, a fixed effect model was used, pooling data using mean difference (MD) for continuous outcomes and odds ratio (OR) for dichotomous outcomes. A total of 12 articles (865 participants) were eligible. Overall, there were significant differences between the two groups for blood loss (MD=-171.73, 95% CI=-281.70 to -61.76; p=0.002), operation time (MD=-66.02, 95% CI=-115.52 to -16.51; p=0.009), and fusion rate (OR=0.50, 95% CI=0.26-0.96; p=0.004). However, there were no significant differences in hospital stay (MD=-4.44, 95% CI=-13.37 to 4.50), ODI (MD=-0.09, 95% CI=-0.59 to 0.42; p=0.74), JOA (MD=0.18, 95% CI=-0.77 to 1.14; p=0.71), VAS (MD=-0.04, 95% CI=-0.16 to 0.08; p=0.49), SF-36 (PF: MD=-1.11, 95% CI=-4.38 to 2.17, p=0.51; GH: MD=1.22, 95% CI=-2.17 to 4.60, p=0.48; MH: MD=-0.22, 95% CI=-3.83 to 3.38, p=0.90) and complications (OR=1.15, 95% CI=0.72-1.85; p=0.56). This meta-analysis shows that there was significantly less blood loss in unilateral group and less operating time; however, the fusion rate was significantly higher in the bilateral group. The outcomes of hospital stay, ODI, JOA, VAS, SF-36 score, and complications are similar in the two groups.

Biomechanical stability of different bisegment fixation methods for lumbar spine

Objective To compare the biomechanical stability of different bisegment fixation methods for the lumbar spine.Methods Six adult cadaveric lumbar spines (L2-S1) were selected and fixed progressively with different fixation methods at L3/4-L4/5.The specimens were divided into five groups,Group A (normal specimen group),Group B (unilateral translaminar facet screw fixation + interbody cage fusion),Group C (unilateral pedicle screw fixation + interbody cage fusion),Group D (unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation + interbody cage fusion) and Group E (bilateral pedicle screw fixation + interbody cage fusion).After loading on the fixed segments in each group,range of motion (ROM),stability index,axial displacement as well as stiffness were measured and compared.Results Compared with normal specimen group,the four fixation modes reduced the ROM of L3/4-L4/5 in different directions and increased the stability and stiffness of the spine.Whereas,the reduced range of motion in different directions as well as axial displacement,increased stability index and enhanced stiffness varied among the groups.But in pair comparison,the difference was insignificant between Groups B and C and between Groups D and E (P ＞ 0.05).A significant difference was found in between Groups D and B,between Groups D and C,between Groups E and B and between Groups E and C (P ＜ 0.05).Conclusion Unilateral translaminar facet screw fixation combined with contralateral pedicle screw fixation + interbody cage fusion can be a favorable choice for bisegmental fixation and fusion of lumbar spine. Key words: Spinal injuries ; Fracture fixation, internal; Biomechanics

A Systematic Review and Meta-Analysis of Unilateral versus Bilateral Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion

BackgroundTransforaminal lumbar interbody fusion (TLIF) has become one of the most widely used procedures for lumbar spinal disorders. However, it is still unclear whether TLIF with unilateral pedicle screw (PS) fixation is as effective as that with bilateral PS fixation. We performed a meta-analysis of the literatures and aimed to gain a better understanding of whether TLIF with unilateral PS fixation was safe and effective for lumbar diseases.Methodology/Principal FindingsWe systematically searched Ovid, Springer, and Medline databases for relevant randomized controlled trials (RCTs) that compared the clinical and radiological outcomes of unilateral versus bilateral PS fixation in TLIF. Risk of bias in included studies was assessed using the Cochrane Risk of Bias tool. We generated pooled risk ratios or weighted mean differences across studies. According to our predefined inclusion criteria, seven RCTs with a total of 441 patients were included in this study. Baseline characteristics were similar between the unilateral and bilateral groups. Our meta-analysis showed that no significant difference was detected between the two groups in terms of postoperative clinical function, fusion status, reoperation rate, complication rate, and hospital stay (p>0.05). Pooled estimates revealed that the unilateral group was associated with significantly reduced implant cost, operative time and blood loss (p<0.05).Conclusions/SignificancesOur meta-analysis suggested TLIF with unilateral PS fixation was as safe and effective as that with bilateral PS fixation for lumbar diseases in selected patients. Despite these findings, our meta-analysis was based on studies with small sample size and different study characteristics that might lead to the inconsistent results such as various functional outcomes among the included studies. Therefore, high-quality randomized controlled trials with larger sample size are also needed to further clarify these issues and to provide the long-term outcomes.

Unilateral instrumented fixation for cervical dumbbell tumors.

PurposeThe purpose of this study was to describe the radiological outcomes in patients with unilateral instrumented fixation for cervical dumbbell tumors.Patients and methodsFourteen consecutive individuals were included in the present study. We included Eden type II and III tumors in this cohort study and analyzed fixed segment fusion rates, screw failure with multiplanar reconstruction computed tomography (CT) scan radiographs and lateral radiographs with flexion-extension dynamic views, and immediate postoperative and last follow-up radiographs after surgery.ResultsThe mean follow-up was 105.4 months. There were six men and eight women ranging in age from 32 to 70 years (mean age, 48 years). Twenty pedicle screws (PSs) and 11 lateral mass screws (LMSs) were used in total. There were seven patients with only PSs, four with only LMSs, and three with PSs at C2 and LMSs at C3. PS misplacement occurred in three screws of insertions including two screws with grade 1 misplacement and one screw with grade 2 misplacement, and no grade 3 misplacement occurred. All screws breached the lateral wall with no apparent superior or inferior misplacement. None of the LMSs were misplaced. Fortunately, no complication could be directly attributed to screw insertion. Radiological evidence showed that all patients achieved successful fusion with no screw loosening or breakage. However, two patients who received only LMS fixation had degenerative spondylolisthesis at the upper fusion segment at the last follow-up.ConclusionsGrade 2 PS misplacement occurred in one screw of insertions. Unilateral pedicle screw fixation for cervical dumbbell tumors is a useful surgical method that can successfully fuse vertebrae with good postoperative alignment.

Bilateral decompression using a unilateral pedicle construct for lumbar stenosis

To determine the effectiveness of bilateral decompression via a unilateral approach using unilateral pedicle screw fixation for two-level lumbar stenosis with instability. Between October 2006 and October 2010, 98 patients (61 men and 37 women) who had reached the three-year follow-up interval were treated with unilateral pedicle screw fixation at the authors' institution. All patients underwent two-level transforaminal lumbar interbody fusion (TLIF), and the mean age was 59.6years (range, 40-72). Visual analog scale (VAS) scores and Oswestry Disability Index (ODI) were used to assess the pre-operative and postoperative clinical results. Fusion status, the disc space height, and the whole lumbar lordotic angle were analysed for the radiological evaluation. The ODI scores decreased significantly in both early and late follow-up evaluations and the visual analog scale (VAS) score demonstrated significant improvement in late follow-up (P < 0.01). The disc space height (P < 0.05) and the whole lumbar lordotic angle (P < 0.05) were increased at the final follow-up. Successful fusion was achieved in all patients. Bilateral decompression via a unilateral approach using unilateral pedicle screw fixation for two-level lumbar stenosis with instability, which can maintain the lumbar lordosis and the disc space height, is an effective and less invasive method than with bilateral constructs.

Comparison of unilateral versus bilateral pedicle screw fixation in lumbar interbody fusion: a meta-analysis

This is a meta-analysis to compare the clinical results between unilateral and bilateral pedicle screw (PS) fixation in lumbar interbody fusion. We included published studies with no language and year restrictions. The criteria which Koes et al. designed in 1995 were used to evaluate the risk of bias of the included studies. All data were analyzed by Review Manager 5.1. The primary outcomes included fusion rate and screw complications, and the secondary outcomes were operative time, blood loss, and hospital time. A total of five prospective studies with 407 patients were included in the current meta-analysis, and four of them were randomized controlled trials. There was no significant difference between unilateral PS fixation and bilateral PS fixation group in fusion rate and screw complications (fusion rate: OR 0.54, Z=1.33, P=0.18, I (2)=0%; screw complications: OR 1.45, Z=0.71, P=0.48; I (2)=44%). In the secondary outcomes, the operative time (Z=3.35, P=0.0008; I (2)=95%) and blood loss (Z=4.35, P<0.0001; I (2)=98%) was significantly higher in bilateral PS fixation group than in unilateral PS fixation group. Besides, no significant difference was found in hospital time (Z=1.19, P=0.24; I (2)=99%). In our meta-analysis, we found that unilateral PS fixation in lumbar fusion was as effective as bilateral PS fixation for lumbar degenerative diseases without major instability, no significant difference was found in hospital time, fusion rate and screw complications. In terms of operative time and blood loss, unilateral PS fixation even produced better results.

Unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach compared with conventional bilateral pedicle screw fixation for single-segment degenerative lumbar instability: a prospective randomized study

Treatment of patients with single-segment degenerative lumbar instability using unilateral pedicle screw fixation can achieve stability and fusion rates similar to those of bilateral pedicle screw fixation. The aim of this study was to analyze the clinical outcome of using unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach to treat single-segment degenerative lumbar instability. Thirty-nine consecutive patients with single-segment, low-grade, degenerative lumbar instability were randomly assigned to treatment with either unilateral (n = 20) or bilateral (n = 19) pedicle screw fixation. In the unilateral group, patients underwent unilateral posterior lumbar interbody fusion (PLIF) and ipsilateral pedicle screw fixation through a tubular retractor via the Wiltse approach. In the bilateral group, patients underwent modified bilateral PLIF with bilateral pedicle screw fixation via the posterior midline approach. During follow-up, patients were evaluated using a visual analog scale (VAS), the Japanese Orthopaedic Association (JOA) score, and the Oswestry Disability Index. The unilateral group had a shorter operative duration (p < 0.05) and less blood loss (p < 0.001). All patients completed more than 2 years of follow-up (mean 36 months). In general, the time trends in improvement on the VAS and JOA differed slightly between the groups through 2 years, but no significant difference in back pain VAS score or leg pain VAS score was found between these 2 groups at the 2-year follow-up. Complete bone fusion was shown on CT in all patients at the 2-year follow-up. Unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach appears to be as safe and effective as bilateral pedicle screw fixation for the treatment of single-segment degenerative lumbar instability.

Clinical sequelae after rhBMP-2 use in a minimally invasive transforaminal lumbar interbody fusion

Background contextRecent reports of postoperative radiculitis, bone osteolysis, and symptomatic ectopic bone formation after recombinant human bone morphogenetic protein-2 (rhBMP-2) use in transforaminal lumbar interbody fusions (TLIFs) are a cause for concern. PurposeTo determine the clinical and radiographic complications associated with BMP utilization in a minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) environment. Study design/settingRetrospective clinical case series at a single institution. Patient sampleFive hundred seventy-three consecutive patients undergoing an MIS-TLIF. Outcome measuresReoperation rates and total costs associated with complications of rhBMP-2 use and pseudarthrosis. MethodsA retrospective review of 610 consecutive patients undergoing an MIS-TLIF (2007–2010) by a single surgeon at our institution was performed (mean age 48.7 years, range 26–82 years). All patients underwent an MIS laminectomy with bilateral facetectomy, single TLIF cage, unilateral pedicle screw fixation, and 12 mg (large kit) or 4.2 mg (small kit) of rhBMP-2. The BMP-2 collagen-soaked sponge was placed anteriorly in the disc space, followed by local bone graft, and then the cage was filled only with local bone and no BMP-2. Patients were evaluated at 6 months and 1 year with computed tomography (CT) scan. Those demonstrating neuroforaminal bone growth, osteolysis/cage migration, or pseudarthrosis were reviewed, and cost data including direct cost/procedure for both index and revision surgeries were collected. ResultsOf the 573 patients, 10 (1.7%) underwent 15 additional procedures based on recalcitrant radiculopathy and CT evidence of neuroforaminal bone growth, vertebral body osteolysis, and/or cage migration. Thirty-nine patients (6.8%) underwent reoperation for clinically symptomatic pseudarthrosis. Bone overgrowth was associated with nerve impingement and radiculopathy in all 10 patients (small kit, n=9; large kit, n=1). Osteolysis and cage migration occurred in 2 (20%) of these same 10 patients. Average total costs were calculated per procedure ($19,224), and the costs for reoperation equaled $14,785 per encounter for neuroforaminal bone growth and $20,267 for pseudarthrosis. ConclusionsSymptomatic ectopic bone formation, vertebral osteolysis, and pseudarthrosis are recognized complications with the use of rhBMP-2 in MIS-TLIFs. Potential causes include improper dosage and a closed space that prevents the egress of the postoperative BMP-2 fluid collection. Management of these complications has a substantial cost for the patient and the surgeon and needs to be considered with the off-label use of rhBMP-2.