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

Unilateral versus bilateral pedicle screw fixation with anterior lumbar interbody fusion: a comparison of postoperative outcomes

PURPOSE

To determine of the impact of ALIF with minimally invasive unilateral pedicle screw fixation (UPSF) versus bilateral pedicle screw fixation (BPSF) on perioperative outcomes, radiographic outcomes, and the rates of fusion, subsidence, and adjacent segment stenosis.

METHODS

All adult patients who underwent one-level ALIF with UPSF or BPSF at an academic institution between 2015 and 2022 were retrospectively identified. Postoperative outcomes including length of hospital stay (LOS), wound complications, readmissions, and revisions were determined. The rates of fusion, screw loosening, adjacent segment stenosis, and subsidence were assessed on one-year postoperative CT. Lumbar alignment including lumbar lordosis, L4-S1 lordosis, regional lordosis, pelvic tilt, pelvic incidence, and sacral slope were assessed on standing x-rays at preoperative, immediate postoperative, and final postoperative follow-up. Univariate and multivariate analysis compared outcomes across posterior fixation groups.

RESULTS

A total of 60 patients were included (27 UPSF, 33 BPSF). Patients with UPSF were significantly younger (p = 0.011). Operative time was significantly greater in the BPSF group in univariate (p < 0.001) and multivariate analysis (ß=104.1, p < 0.001). Intraoperative blood loss, LOS, lordosis, pelvic parameters, fusion rate, subsidence, screw loosening, adjacent segment stenosis, and revision rate did not differ significantly between fixation groups. Though sacral slope (p = 0.037) was significantly greater in the BPSF group, fixation type was not a significant predictor on regression.

CONCLUSIONS

ALIF with UPSF relative to BPSF predicted decreased operative time but was not a significant predictor of postoperative outcomes. ALIF with UPSF can be considered to increase operative efficiency without compromising construct stability.

Short-Term Comparison Between Unilateral Versus Bilateral Percutaneous Pedicle Screw Fixation in Short-Level Lateral Lumbar Interbody Fusion-A Prospective Randomized Study

STUDY DESIGN

Prospective randomized controlled trial.

OBJECTIVES

No prospective studies have directly compared clinical and radiographic outcomes of unilateral vs bilateral instrumented lateral lumbar interbody fusion (LLIF) for lumbar degenerative disease (LDD). We compared the short-term radiographic, clinical outcomes, and some complications of the unilateral percutaneous pedicle screw (PPS) (UPS) vs bilateral PPS (BPS) fixation in short-level spinal fusion with LLIF for LDD.

METHODS

This was a prospective randomized controlled study of 33 patients who underwent UPS or BPS fixation after LLIF for LDD; 18 patients were assigned to the UPS group and 15 patients to the BPS group. Clinical outcomes, complication rates, and fusion rates were assessed.

RESULTS

The two groups were similar in age, sex, preoperative diagnosis, and level of surgery. Blood loss, length of hospital stay, and numeric rating scale score one year after surgery did not differ between groups. The operative time was longer in the BPS than UPS group (120.2 vs 88.8 min, respectively; P = .029). Both groups showed improvement in disc height and dural sac in the immediate postoperative computed tomography and magnetic resonance imaging, which did not differ significantly between groups. The subsidence grade and fusion rate did not differ, but cage subsidence was more severe in the UPS than BPS group.

CONCLUSION

Unilateral and bilateral PPS fixation after LLIF yielded similar short-term clinical and radiological outcomes. However, severe cage subsidence was more common in the UPS group, which suggests that BPS fixation after LLIF may be a better choice over the long term.

Comparison of Unilateral versus Bilateral Instrumented Transforaminal Lumbar Interbody Fusion in Lumbar Degenerative Diseases: A Minimum of 5-Year Follow-Up

Background and Objective: There is a paucity of literature comparing unilateral instrumented transforaminal lumbar interbody fusion (UITLIF) with bilateral instrumented TLIF (BITLIF) regarding radiological alignment, including the coronal balance, even though UITLIF might have asymmetric characteristics in the coronal plane. This retrospective study aimed to compare the clinical and long-term radiological outcomes of 1-level UITLIF and BITLIF in lumbar degenerative diseases (LDD) including lumbar spinal stenosis with or without spondylolisthesis (degenerative or spondylolytic). Materials and Methods: Patients who underwent 1-level UITLIF with two rectangular polyetheretherketone (PEEK) cages or BITLIF between November 2009 and June 2016 by four surgeons with ≥5 years of follow-up at a single hospital were included. We compared the clinical and radiological outcomes between the UITLIF and BITLIF. Results: In total, 63 and 111 patients who underwent UITLIF and BITLIF, respectively, were enrolled. The median follow-up was 85.55 months (range: 60-130). The UITLIF group had a significantly shorter operation time (185.0 [170.0-210.0] vs. 225.0 [200.0-265.0], p < 0.001) and lower estimated blood loss (300.0 [250.0-500.0] vs. 550.0 [400.0-800.0], p < 0.001) than the BITLIF group. Regarding the clinical outcomes, there were no significant differences in the intermittent claudication score (p = 0.495) and Kirkaldy-Willis criteria (p = 0.707) at 1 year postoperatively. The interval changes in the local coronal Cobb angle at the index level, L1-S1 lordotic angle, and coronal off-balance from the immediate postoperative radiograph to the last follow-up were not significantly different (p = 0.687, p = 0.701, and p = 0.367, respectively). Conclusions: UITLIF with two rectangular PEEK cages may provide comparable clinical outcomes and radiological longevity including coronal alignment to BITLIF in 1-level LDD. In addition, UITLIF has advantages over BITLIF in terms of operative time and blood loss.

Is unilateral pedicle screw fixation as effective as bilateral pedicle screw fixation in transforaminal lumbar interbody fusion: a meta-analysis of randomized controlled trials

PURPOSE

This meta-analysis aimed to investigate whether unilateral pedicle screw fixation (UPSF) is comparable to bilateral pedicle screw fixation (BPSF) in transforaminal lumbar interbody fusion (TLIF) for lumbar degenerative diseases.

METHODS

Up to September 2022, established electronic literature databases including PubMed, Web of Science, EMBASE, and the Cochrane Library were systematically searched. Randomized controlled trials (RCTs) published in English that compared the efficacy of UPSF versus BPSF in TLIF were included. The methodological quality was evaluated, relevant data was extracted, and suitable meta-analysis was carried out. Data of fusion rate, complications, cage migration, visual analog scale (VAS), and Oswestry Disability Index (ODI), total blood loss (TBL), operation time, and hospital stay were extracted and analyzed. Pooled mean differences and risk ratio (RR) along with 95% confidence intervals (95% CI) were calculated for the results.

RESULTS

Ten RCTs including 614 patients (UPSF = 294, BPSF = 320) were included in our meta-analysis. There were no significant differences in terms of fusion rate, VAS (VAS-BP and VAS-LP), ODI, complications, or hospital stay between UPSF and BPSF groups (P > 0.05, respectively). The UPSF group clearly had the advantage of less blood loss (SMD = -2.99, 95% CI [-4.54, -1.45], P = 0.0001) and operation time (SMD = -2.05, 95% CI [-3.10, -1.00], P = 0.0001). However, UPSF increased cage migration more than BPSF (10.7% vs 4.8%, RR = 2.23, 95% CI [1.07, 4.65],  P = 0.03).

CONCLUSION

According to the findings of this meta-analysis, UPSF is just as effective as BPSF in TLIF and may reduce blood loss and operation time. Nevertheless, UPSF may result in more cage migration than BPSF.

Comparison of electromagnetic and optical navigation assisted Endo-TLIF in the treatment of lumbar spondylolisthesis

Uniportal full endoscopic posterolateral transforaminal lumbar interbody fusion (Endo-TLIF) with percutaneous pedicle screw fixation is a promising, minimally invasive method for the treatment of lumbar spondylolisthesis. However, repeated radiation exposure from X-rays and the steep learning curve remain to be improved.

Outcomes and complications of minimally invasive transforaminal lumbar interbody fusion in the elderly: a systematic review and meta-analysis

OBJECTIVE

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) may be used to treat degenerative spinal pathologies while reducing risks associated with open procedures. As an increasing number of lumbar fusions are performed in the aging United States population, MIS-TLIF has been widely adopted into clinical practice in recent years. However, its complication rate and functional outcomes in elderly patients remain poorly characterized. The objective of this study was to assess complication rates and functional outcomes in elderly patients (≥ 65 years old) undergoing MIS-TLIF.

METHODS

The PubMed, Embase, and Scopus databases were searched for relevant records in accordance with the PRISMA guidelines. Inclusion criteria were peer-reviewed original research; English language; full text available; use of MIS-TLIF; and an elderly cohort of at least 5 patients. Risk of bias was assessed using the ROBINS-I (Risk of Bias in Nonrandomized Studies-of Interventions) tool. Pooled complication rates were calculated for elderly patients, with subgroup analyses performed for single versus multiple-level fusions. Complication rates in elderly compared to nonelderly patients were also assessed. Postoperative changes in patient-reported outcomes, including Oswestry Disability Index (ODI) and visual analog scale (VAS) back pain (BP) and leg pain (LP) scores, were calculated.

RESULTS

Twelve studies were included in the final analysis. Compared to nonelderly patients, MIS-TLIF in elderly patients resulted in significantly higher rates of major (OR 2.15, 95% CI 1.07-4.34) and minor (OR 2.20, 95% CI 1.22-3.95) complications. The pooled major complication rate in elderly patients was 0.05 (95% CI 0.03-0.08) and the pooled minor complication rate was 0.20 (95% CI 0.13-0.30). Single-level MIS-TLIF had lower major and minor complication rates than multilevel MIS-TLIF, although not reaching significance. At a minimum follow-up of 6 months, the postoperative change in ODI (-30.70, 95% CI -41.84 to -19.55), VAS-BP (-3.87, 95% CI -4.97 to -2.77), and VAS-LP (-5.11, 95% CI -6.69 to -3.53) in elderly patients all exceeded the respective minimum clinically important difference. The pooled rate of fusion was 0.86 (95% CI 0.80-0.90).

CONCLUSIONS

MIS-TLIF in elderly patients results in a high rate of fusion and significant improvement of patient-reported outcomes, but has significantly higher complication rates than in nonelderly patients. Limitations of this study include heterogeneity in the definition of elderly and limited reporting of risk factors among included studies. Further study of the impact of complications and the factors predisposing elderly patients to poor outcomes is needed.

Effect of percutaneous minimally invasive pedicle screw internal fixation in the treatment of thoracolumbar vertebral fractures and its impact on quality of life

Objectives

To investigate and analyze the effect of percutaneous minimally invasive pedicle screw internal fixation in the treatment of thoracolumbar vertebral fractures and its impact on quality of life.

Methods

Fifty patients with thoracolumbar vertebral fracture admitted to our hospital from January 2015 to December 2018 were selected and divided into two groups according to different treatment regimens. The observation group was treated with minimally invasive percutaneous pedicle screw internal fixation, while the control group was treated with traditional posterior approach open pedicle screw internal fixation. The surgery time, incision length, intraoperative blood loss, postoperative drainage, hospitalization time, ambulation time, fracture healing time and postoperative VAS scores were compared between the two groups. In addition, the cobb angle, the sagittal plane index, and the anterior vertebral height were compared between the two groups before and after surgery, as were the Oswestry Disability Index (ODI) at 1d, 3 months, and 6 months postoperatively.

Results

The surgery time, incision length, postoperative pain level, postoperative drainage and intraoperative blood loss of the observation group were less than those of the control group (P<0.05). The postoperative Cobb angle of the two groups decreased, the sagittal plane index as well as the anterior vertebral height increased (P<0.05). The Oswestry index of the observation group was better than that of the control group at one day and three months postoperatively, with a statistical significance between the two groups (P<0.05). The complication rate of the observation group was significantly lower than that of the control group (P<0.05).

Conclusion

Percutaneous minimally invasive pedicle screw internal fixation is safer than the traditional open pedicle screw internal fixation, and it is more worthy of clinical promotion.

Comparison of the Unilateral and the Bilateral Pedicle Screw Fixation without Using an Interbody Cage: Randomized Clinical Trial

BACKGROUND: Lumbar spine instability is one of the main causes of low back pain and has become more prevalent in recent years. Bilateral pedicle screw fixation is used to perform posterior lumbar stabilization, which is complemented by the installation of an interbody cage. AIM: The aim of the study was evaluating of the results of unilateral and bilateral pedicle screw fixation without using of an interbody cage. METHODS: A prospective randomized study of 96 patients was carried out. Forty-seven patients were assigned to the group of the unilateral pedicle screw fixation versus 49 patients were moved to the group of the bilateral pedicle screw fixation of the lumbar spine. Of the 96 patients, 80 patients eventually were included in the study. However, seven patients in the first group and nine patients were lost to follow-up. Surgery timing, blood loss volume, clinical outcomes (scores on the Oswestry disability index [ODI], EQ-5D and visual analogue scale [VAS]) were evaluated in 6–12 months after surgical treatment. All the patients included in this study underwent functional and control computed tomography in 12 months after surgery. RESULTS: Both groups showed a significant improvement in VAS, EQ-5D, and ODI in 1 year after surgical treatment. The two groups significantly differed in the surgery timing (unilateral – 90.2 min; and bilateral – 129.4 min) and blood loss volume (unilateral – 152.7 ml; and bilateral – 230.1 ml), p < 0.05. CONCLUSIONS: Unilateral and bilateral pedicle screw fixation showed similar clinical results, while results in both types of fixation differed in slight manner. However, the duration of surgical treatment and intraoperative blood loss volume proved to be lower for the unilateral fixation group, which indicates that the use of the unilateral fixation can be the choice of performing posterior stabilization at a single-level instability of the spine without using an interbody cage.

Understanding the Future Prospects of Synergizing Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery with Ceramics and Regenerative Cellular Therapies

Transforaminal lumber interbody fusion (TLIF) is the last resort to address the lumber degenerative disorders such as spondylolisthesis, causing lower back pain. The current surgical intervention for these abnormalities includes open TLIF. However, in recent years, minimally invasive TLIF (MIS-TLIF) has gained a high momentum, as it could minimize the risk of infection, blood loss, and post-operative complications pertaining to fusion surgery. Further advancement in visualizing and guiding techniques along with grafting cage and materials are continuously improving the safety and efficacy of MIS-TLIF. These assistive techniques are also playing a crucial role to increase and improve the learning curve of surgeons. However, achieving an appropriate output through TLIF still remains a challenge, which might be synergized through 3D-printing and tissue engineering-based regenerative therapy. Owing to their differentiation potential, biomaterials such as stem/progenitor cells may contribute to restructuring lost or damaged tissues during MIS-TLIF, and this therapeutic efficacy could be further supplemented by platelet-derived biomaterials, leading to improved clinical outcomes. Thus, based on the above-mentioned strategies, we have comprehensively summarized recent developments in MIS-TLIF and its possible combinatorial regenerative therapies for rapid and long-term relief.

The technical feasibility and preliminary results of minimally invasive endoscopic-TLIF based on electromagnetic navigation: a case series

Background

Uniportal full endoscopic posterolateral transforaminal lumbar interbody fusion (Endo-TLIF) with percutaneous pedicle screw fixation is a promising, minimally invasive method for the treatment of lumbar spondylolisthesis. However, repeated radiation exposure from X-rays and the steep learning curve remain to be improved.

Methods

This retrospective study explored the effects of electromagnetic navigation on improving Endo-TLIF with percutaneous pedicle screw fixation. Clinical information from 42 patients who had received Endo-TLIF with percutaneous pedicle screw fixation from May 2019 to November 2020 was analyzed retrospectively. The procedures were assisted under electromagnetic navigation. The rate of adjustment for guide wires, frequency of X-ray exposure, operative time, accuracy of pedicle screw location, and clinical outcomes were recorded.

Results

The mean follow-up for 42 patients was 11.9 ± 3.1 months. The mean age of the patients was 56.1 ± 9.26 years, with a female/male ratio of 25:17. According to postoperative CT scans and 3D reconstructions, the excellent and good rate of pedicle screws was 96.4%. The rate of adjustment for guide wires under the assistance of electromagnetic navigation was 1.78%, and the frequency of X-ray exposure was 8.27 ± 1.83. The operative time was 167.25 ± 28.16 min, including the duration of guide wire insertion (14.63 ± 5.45 min) and duration of decompression and cage placement (75.43 ± 13.97 min). The duration of hospitalization after operation was 2.59 ± 1.16 days. The preoperative VAS score was 7.51 ± 1.91, and the preoperative ODI was 82.42 ± 8.7%. At the last follow-up, the VAS score was 2.09 ± 0.59, and the ODI was 11.09 ± 3.2%. There were statistically significant improvements in the VAS score and ODI in all patients at the follow-up (p < 0.05).

Conclusions

Electromagnetic navigation can provide accurate positioning and guidance in real time, which improves the surgical efficiency of percutaneous pedicle screw placement and endoscopic decompression in Endo-TLIF with reduced radiation exposures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01148-9.

Residual leg numbness after endoscopic discectomy treatment of lumbar disc herniation

Background

Transforaminal endoscopic discectomy was popular in the treatment of lumbar disc herniation. Previous study focuses on the leg pain of disc herniation, and little study concern the residual leg numbness after surgery. The purposes of this study were to evaluate the clinical outcomes of transforaminal endoscopic discectomy in the treatment of lumbar disc herniation with leg pain and numbness.

Methods

Patients with one level lumbar disc herniation who had transforaminal endoscopic lumbar discectomy from June 2016 to July 2019 were categorized into two groups according to the leg numbness. 293 patients initially fulfilled the study criteria, and 27 patients were lost to follow-up. Of the remaining 266 patients available for analysis, 81 cases with leg numbness and pain (A group), and 185 cases with leg pain (B). Endoscopic transforaminal lumbar discectomy was performed, and the clinical outcomes of blood loss, operation times, hospital stay days, pain (Visual Analog Scale, VAS-pain), numbness (VAS-numbness), functional disability (Oswestry Disability Index, ODI), and the disk height and intervertebral foramen height were recorded.

Results

All patients with pain and numbness pre-operation in group A, complain of leg numbness during or just after walking or standing not diminished after surgery in group A, and no one complain numbness after surgery in group B. The pain index and ODI score were better than preoperational in all patients (P < 0.01), and no significant difference between two groups (P > 0.05). The postoperative disk and foramen height were no significant difference compare to preoperative in all patients (P > 0.05), and no significant difference between two groups (P > 0.05). The leg numbness symptoms last longer in central disc herniation patients (10.4 ± 2.2 months) than in paracentral (6.3 ± 2.1 months) and foraminal disc herniation patients (5.6 ± 2.3 months) after surgery (P < 0.01).

Conclusions

Based on the results of this study, transforaminal endoscopic lumbar discectomy was effective and safe procedures in the treatment of disc herniation with leg pain and numbness. The leg numbness symptoms last longer in central disc herniation patients than in paracentral and foraminal disc herniation patients after surgery.

Unilateral versus bilateral pedicle screw fixation in lumbar fusion: A systematic review of overlapping meta-analyses

OBJECTIVES

To carry out a systematic review on the basis of overlapping meta-analyses that compare unilateral with bilateral pedicle screw fixation (PSF) in lumbar fusion to identify which study represents the current best evidence, and to provide recommendations of treatment on this topic.

METHODS

A comprehensive literature search in PubMed, Embase, and the Cochrane Library databases was conducted to identify meta-analyses that compare unilateral with bilateral PSF in lumbar fusion. Only meta-analyses exclusively covering randomized controlled trials were included. Study quality was evaluated using the Oxford Levels of Evidence and Assessment of Multiple Systematic Reviews (AMSTAR) instrument. Then, the Jadad decision algorithm was applied to select the highest-quality study to represent the current best evidence.

RESULTS

A total of 9 studies with Level II of evidence fulfilled the eligibility criteria and were included. The scores of AMSTAR criteria for them varied from 5 to 9 (mean 7.78). The current best evidence detected no significant differences between unilateral and bilateral PSF for short-segment lumbar fusion in the functional scores, length of hospital stay, fusion rate, and complication rate. However, unilateral PSF involved a remarkable decrease in operative time and blood loss but increase of cage migration when compared with bilateral PSF.

CONCLUSIONS

According to this systematic review, unilateral PSF is an effective method of fixation for short-segment lumbar fusion, has the advantages of reduced operative time and blood loss over bilateral PSF, but increases the risk of cage migration.

Minimally invasive surgical techniques for the therapy of far lateral disc herniation in middle-aged and elderly patients

To examine the clinical results of different minimally invasive techniques for the therapy of far lateral disc herniation in middle-aged and elderly patients. An endoscopic approach (percutaneous endoscopic lumbar discectomy; PELD), MIS-TLIF combined with contralateral translaminar screw (MIS-TLIF CTS), and MIS-TLIF combined with bilateral pedicle screws (MIS-TLIF BPS) were evaluated via a retrospective chart review. Data from 74 consecutive middle-aged and elderly patients with far lateral disc herniation were analyzed. All patients underwent surgery; 19 with PELD, 24 with MIS-TLIF CTS, and 31 with MIS-TLIF BPS. Clinical data included the length of the incision, duration of the operation, estimated blood loss, hospitalization time, operation cost, recurrence rate, and fusion rate. Preoperative and postoperative patient outcomes including the VAS, ODI scores and MacNab criteria were assessed and recorded. The mean follow-up time was 26.4 months (range from 14 to 46 months). Compared with the internal fixation groups, the length of the incision, duration of operation, estimated blood loss, and hospitalization time were obviously lower in the PELD group. The difference in operation cost among the three methods was statistically significant. The postoperative VAS scores for LBP and LP decreased significantly as compared with those recorded preoperatively. The postoperative ODI scores were lower than those recorded preoperatively. MacNab criteria rating excellent, good and fair results were in 27, 37 and 10 patients, respectively. Conclusion: PELD, MIS-TLIF CTS, and MIS-TLIF BPS are all effective minimally invasive techniques for the therapy of single segment far lateral lumbar disc herniation in middle-aged and elderly patients. PELD had a shorter operation time and less surgical trauma, being a less invasive and more economical method; however, there was no recurrence of disc herniation after fixation. Compared with MIS-TLIF BPS, MIS-TLIF CTS obtained a similar clinical effect and certain costs were saved.

Cage migration after unilateral instrumented transforaminal lumbar interbody fusion and associated risk factors: a modified measurement method

Objective

In this retrospective study, a modified measurement method was used to analyze cage migration during follow-up after unilateral instrumented transforaminal lumbar interbody fusion (TLIF) and identify associated factors.

Methods

We retrospectively evaluated 75 patients who had been treated with unilateral instrumented TLIF. Cage migration was quantitatively defined as anterior–posterior or lateral displacement of the cage.

Results

Five patients had significant cage migration (6.7%), but none developed severe neural symptoms during follow-up or underwent reoperation. The cages tended to migrate posteriorly or toward the side of surgery. The initial cage position and patient age were strongly associated with migration. Migration was less frequent when the cages were initially placed closer to the side of surgery. Patients of advanced age were more likely to develop anterior–posterior migration than were young patients.

Conclusion

Cage migration is related to the initial position of the cage. Particular attention is required when performing unilateral instrumented TLIF in patients of advanced age because they are most likely to develop cage migration. Quantification of cage migration is an effective method of exploring the associated factors.

Comparison of the efficacy of MIS-TLIF combined with unilateral or bilateral internal fixation on single-segment lumbar degenerative diseases

In this study, to compare the efficacy of minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) combined with unilateral or bilateral internal fixation for the treatment of single-segment lumbar degenerative diseases, patients with single-segment lumbar degenerative diseases treated with MIS-TLIF combined with unilateral or bilateral internal fixation in Rehabilitation Center, Gansu Province Hospital from January 2014 to November 2015 were retrospectively enrolled, and the related data of 85 patients with 2-year follow-up were obtained. The patients were divided into unilateral group (40 cases) and bilateral group (45 cases) according to the method of internal fixation, and the Oswestry dysfunction index (ODI), visual analogue scale (VAS), lumbar lordosis angle, surgical segmental lordosis angle, lumbar scoliosis angle, surgical segmental scoliosis angle, lumbar lordosis index (LI), intervertebral height index (IHI), fusion rates, and serum inflammatory factors, including C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor alpha (TNF-α), were calculated to evaluate the efficacy of these two surgical methods. The results showed that the VAS and ODI of the two groups at 1 month, 6 months after surgery, and the last follow-up were significantly improved when compared with those before surgery ( P < 0.05). However, there were no significant differences in VAS and ODI between the two groups at preoperative, 1 month, 6 months after surgery, and the last follow-up ( P > 0.05). The lumbar lordosis and LI decreased at 1 month, 6 months, and the last follow-up ( P < 0.05), while the IHI increased when compared with that before surgery ( P < 0.05). Besides, no significant differences were observed in lumbar lordosis, LI, and IHI between the two groups at preoperative, 1 month, 6 months after surgery, and final follow-up ( P > 0.05). In addition, the fusion rates between these two groups had no significant difference ( P > 0.05). The levels of serum CRP, IL-6, and TNF-α at 12 and 24 h after operation in the two groups were higher than those before operation ( P < 0.05), but there was no significant difference in the levels of serum CRP, IL-6, and TNF-α between the two groups at 12 and 24 h after operation ( P < 0.05). In addition, none of the patients of both groups had permanent nerve injury, incision infection, and other complications. These results showed that MIS-TLIF combined with unilateral or bilateral percutaneous internal fixation technique causes less damage to the body tissues of patients with single-segment lumbar degenerative diseases, and they were considered to have similar clinical effects and imaging.

Device solutions for a challenging spine surgery: minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)

INTRODUCTION

Lumbar interbody fusion remains a mainstay in the treatment of degenerative spinal pathology. Interbody devices are often used in an attempt to improve fusion rates and outcomes. Minimally invasive techniques lend unique advantages, but are challenging and often plagued with complications. Specifically, minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has a steep learning curve and there is a lack of concise information on solutions to optimize outcomes.

AREAS COVERED

This review details an appropriate surgical technique of MIS TLIF and includes an overview of the components that go into a successful procedure. A thorough literature search of the PubMed database was completed to provide a comprehensive analysis of the interbody devices, posterolateral fixation, and osteobiologics.

EXPERT OPINION

MIS TLIFs have demonstrated successful clinical and radiographic outcomes and have become a mainstay for treating various degenerative lumbar pathologies. As minimally invasive techniques continue to evolve, devices and biologics will continue to expand the indications for MIS TLIFs and will optimize long-term outcomes.

Assessment of Paraspinal Muscle Atrophy Percentage after Minimally Invasive Transforaminal Lumbar Interbody Fusion and Unilateral Instrumentation Using a Novel Contralateral Intact Muscle-Controlled Model

Study Design

Retrospective comparative clinical study.

Purpose

This study aimed to assess paraspinal muscle atrophy in patients who underwent minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) and unilateral pedicle screw fixation using a novel contralateral intact muscle-controlled model.

Overview of Literature

The increased incidence of paravertebral lumbar muscle injuries after open techniques has raised the importance of implementing minimally invasive spine surgical techniques using tubular retractors and minimally invasive screw placement. The functional cross-sectional area (FCSA) represents the lean muscle mass; furthermore, FCSA is a useful marker of the contractile ability of a muscle following a spine surgery. However, the benefits of unilateral fixation and MI-TLIF on paraspinal muscles have not been defined.

Methods

We performed a retrospective imagenological review on eleven patients who underwent unilateral MI-TLIF and unilateral transpedicular screw lumbar placement. FCSAs of the multifidus and erector spinae were measured 1 year after surgery at adjacent levels and were compared to the contralateral intact muscles. Measurement differences between the surgical and nonsurgical sites were compared. The interobserver reliability was calculated using an intraclass correlation coefficient.

Results

The mean FCSA at the surgical site was 20.97±5.07 cm² at the superior level and 8.89±2.87 cm² at the inferior level. The mean FCSA at the contralateral nonsurgical site was 20.15±5.95 cm² at the superior level and 9.20±2.66 cm² at the inferior level was. The superior and inferior FCSA measurements showed no significant difference between the surgical and nonsurgical sites (p=0.5, p=0.922, respectively).

Conclusions

Using a mini-open tubular approach through the sulcus between the longissimus and iliocostalis, MI-TLIF and unilateral pedicle screw instrumentation produced minimal paraspinal muscle damage at the superior and inferior adjacent levels.

Effect of cage design, supplemental posterior instrumentation and approach on primary stability of a lumbar interbody fusion - A biomechanical in vitro study

BACKGROUND

There are various techniques and approaches for lumbar interbody fusion differing in access, cage type and type of supplemental posterior instrumentation. While a transforaminal access usually includes a hemifacetectomy, the facet joint can be preserved with a more lateral extraforaminal access. The supplemental posterior instrumentation required for both fusion techniques is still debated. The purpose of the present study was to compare primary stability of the two accesses for two different cage types with none, unilateral and bilateral supplemental posterior instrumentation.

METHODS

Six monosegmental lumbar functional spinal units (FSUs) were included in each of the two groups, and subjected to a flexibility test. As cages, a newly designed cage was compared to a standard cage in the following states: (a) native, (b) stand-alone cage, (c) bilateral internal fixator, (d) unilateral internal fixator, (e) unilateral facetectomy+bilateral internal fixator, (f) unilateral facetectomy+unilateral internal fixator and (g) unilateral facetectomy with stand-alone cage. For comparison the range of motion was normalized to the native state and the effects of the facetectomy, cage type, and supplemental instrumentation was compared.

FINDINGS

Within the subject comparison showed a significantly higher flexibility for the unilateral facetectomy in all motion directions (p<0.001). In between subject comparison showed a significant effect of cage type on flexibility in flexion/extension (p=0.002) and lateral bending (p=0.028) but not in axial rotation (p=0.322). The type of supplemental posterior fixation had a significant effect on the flexibility in all motion directions (stand-alone>unilateral fixator>bilateral fixator).

INTERPRETATION

Cage design and approach type are affecting the primary stability of lumbar interbody fusion procedures while the type of posterior instrumentation is the most influencing factor.

Minimally invasive transforaminal lumbar interbody fusion versus open transforaminal lumbar interbody fusion: a technical description and review of the literature

BACKGROUND

Minimally invasive spine surgery (MISS) has been increasingly advocated during the last decade with new studies being reported every year. Minimally invasive spine procedures, such as minimally invasive transforaminal interbody fusion (MI-TLIF), have been introduced to reduce approach-related muscle trauma, to minimise blood loss, and to achieve faster wound healing, quicker ambulation and earlier patient discharge.

METHODS

The aim of this article was to give a comprehensive review of the available English literature comparing open TLIF with MI-TLIF techniques published or available online between 1990 and 2014 as identified by an electronic database search on http://www.ncbi.nlm.nih.gov/pubmed . Fourteen relevant studies comparing MI-TLIF and open TLIF cohorts could be identified.

RESULTS AND CONCLUSION

MI-TLIF seems to be a valid alternative to open TLIF. Both methods yield good clinical results with similar improvements of Oswestry Disability Index (ODI) and visual analogue scale (VAS) on follow-up. There seems to be no significant differences in clinical outcome and fusion rates on comparison. These results are consistent throughout all reported studies in this review. The most pronounced benefits of MI-TLIF are a significant reduction of blood loss, shorter lengths of hospital stay (LOHS) and lower surgical site infection rates. On the downside, MI-TLIF seems to be associated with significantly higher intraoperative radiation doses, a shallow learning curve, at least in the beginning, longer operating times and potentially more frequent implant failures/cage displacements and revision surgeries.

Unilateral versus bilateral pedicle screw fixation with posterior lumbar interbody fusion for lumbar degenerative diseases: A meta-analysis

BACKGROUND

Both unilateral pedicle screw fixation with posterior lumbar interbody fusion (PLIF) and bilateral pedicle screw fixation with PLIF are used to treat lumbar degenerative diseases (LDD). However, which one is a better treatment for LDD remains considerable controversy. Therefore, the focus of this meta-analysis was to assess the merits and shortcomings of efficacy of these 2 surgical procedures for LDD.

METHODS

An extensive search of literature was performed in Pubmed/MEDLINE, Embase, CNKI, and WANFANG databases on unilateral versus bilateral pedicle screw fixation with PLIF fusion for LDD, from January 2007 to January 2017 and language was restricted to Chinese or English. The following variables were extracted: blood loss, operation time, length of hospital stay, Japanese Orthopedic Association (JOA) scores, visual analog scale (VAS) and Oswestry disability index (ODI) scores, fusion rate, total complications, infection, dural injury, and nerve injury. Data analysis was conducted with RevMan 5.3 and STATA 12.0.

RESULTS

A total of 11 studies containing 844 patients were included in our study. The results showed that unilateral is better than bilateral pedicle screw fixation with PLIF in blood loss (P < .00001), operation time (P < .00001), the length of hospital stay (P = .003), and the final follow-up ODI scores (P = .04). However, there are no significant differences in JOA, VAS, and preoperative ODI scores. There are also no significant differences in fusion rate and complications (all P > .05).

CONCLUSION

Based on our meta-analysis, our results suggest that both unilateral pedicle screw fixation with PLIF and bilateral pedicle screw fixation with PLIF for LDD have effective results in clinical outcomes. Both 2 methods may result in clinical improvement and similar outcomes of fusion rate and complications; However, compared with bilateral fixation, unilateral fixation produces more satisfactory efficacy in the blood loss and the operation time.

Comparison between Minimally Invasive Transforaminal Lumbar Interbody Fusion and Conventional Open Transforaminal Lumbar Interbody Fusion: An Updated Meta-analysis

Background:

The previous studies agree that minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has better function outcomes, less blood loss, and shorter hospital stay, when compared to open-TLIF. However, there are no significance differences on operative time, complication, and reoperation rate between the two procedures. This could be from less relative literatures and lower grade evidence. The further meta-analysis is needed with more and higher grade evidences to compare the above two TLIF procedures.

Methods:

Prospective and retrospective studies that compared open-TLIF and MIS-TLIF were identified by searching the Medline, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang, and VIP database (the literature search comprised Medical Subject Heading terms and key words or Emtree term). The retrieval time ranged from the date when the database was founded to January 2015. Pooled risk ratios (RRs) and weighted mean differences (WMDs) with 95% confidence intervals were calculated for the clinical outcomes and perioperative data.

Results:

Twenty-four studies (n = 1967 patients) were included in this review (n = 951, open-TLIF, n = 1016, MIS-TLIF). MIS-TLIF was associated with a significant decrease in the visual analog score (VAS)-back pain score (WMD = −0.44; P = 0.001), Oswestry Disabilities Index (WMD = −1.57; P = 0.005), early ambulation (WMD = −1.77; P = 0.0001), less blood loss (WMD = −265.59; P < 0.00001), and a shorter hospital stay (WMD = −1.89; P < 0.0001). However, there were no significant differences in the fusion rate (RR = 0.99; P = 0.34), VAS-leg pain (WMD = −0.10; P = 0.26), complication rate (RR = 0.84; P = 0.35), operation time (WMD = −5.23; P = 0.82), or reoperation rate (RR = 0.73; P = 0.32).

Conclusions:

MIS-TLIF resulted in a similar fusion rate with better functional outcome, less blood loss, shorter ambulation, and hospital stay; furthermore, it did not increase the complication or reoperation rate based on the existing evidence.

Surgical techniques for lumbo-sacral fusion

Lumbo-sacral (L5-S1) fusion is a widely performed procedure that has become the reference standard treatment for refractory low back pain. L5-S1 is a complex transition zone between the mobile lordotic distal lumbar spine and the fixed sacral region. The goal is to immobilise the lumbo-sacral junction in order to relieve pain originating from this site. Apart from achieving inter-vertebral fusion, the main challenge lies in the preoperative determination of the fixed L5-S1 position that will be optimal for the patient. Many lumbo-sacral fusion techniques are available. Stabilisation can be achieved using various methods. An anterior, posterior, or combined approach may be used. Recently developed minimally invasive techniques are gaining in popularity based on their good clinical outcomes and high fusion rates. The objective of this conference is to resolve the main issues faced by spinal surgeons in their everyday practice.

Finite Element Analysis of a New Pedicle Screw-Plate System for Minimally Invasive Transforaminal Lumbar Interbody Fusion

PURPOSE

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is increasingly popular for the surgical treatment of degenerative lumbar disc diseases. The constructs intended for segmental stability are varied in MI-TLIF. We adopted finite element (FE) analysis to compare the stability after different construct fixations using interbody cage with posterior pedicle screw-rod or pedicle screw-plate instrumentation system.

METHODS

A L3-S1 FE model was modified to simulate decompression and fusion at L4-L5 segment. Fixation modes included unilateral plate (UP), unilateral rod (UR), bilateral plate (BP), bilateral rod (BR) and UP+UR fixation. The inferior surface of the S1 vertebra remained immobilized throughout the load simulation, and a bending moment of 7.5 Nm with 400N pre-load was applied on the L3 vertebra to recreate flexion, extension, lateral bending, and axial rotation. Range of motion (ROM) and Von Mises stress were evaluated for intact and instrumentation models in all loading planes.

RESULTS

All reconstructive conditions displayed decreased motion at L4-L5. The pedicle screw-plate system offered equal ROM to pedicle screw-rod system in unilateral or bilateral fixation modes respectively. Pedicle screw stresses for plate system were 2.2 times greater than those for rod system in left lateral bending under unilateral fixation. Stresses for plate were 3.1 times greater than those for rod in right axial rotation under bilateral fixation. Stresses on intervertebral graft for plate system were similar to rod system in unilateral and bilateral fixation modes respectively. Increased ROM and posterior instrumentation stresses were observed in all loading modes with unilateral fixation compared with bilateral fixation in both systems.

CONCLUSIONS

Transforaminal lumbar interbody fusion augmentation with pedicle screw-plate system fixation increases fusion construct stability equally to the pedicle screw-rod system. Increased posterior instrumentation stresses are observed in all loading modes with plate fixation, and bilateral fixation could reduce stress concentration.

Minimally Invasive Unilateral vs. Bilateral Pedicle Screw Fixation and Lumbar Interbody Fusion in Treatment of Multi-Segment Lumbar Degenerative Disorders

Background

The choice for instrumentation with minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in treatment of degenerative lumbar disorders (DLD) remains controversial. The goal of this study was to investigate clinical outcomes in consecutive patients with multi-segment DLD treated with unilateral pedicle screw (UPS) vs. bilateral pedicle screw (BPS) instrumented TLIF.

Material/Methods

Eighty-four consecutive patients who had multi-level MIS-TLIF were retrospectively reviewed. All data were collected to compare the clinical outcomes between the 2 groups.

Results

Both groups showed similar clinical function scores in VAS and ODI. The two groups differed significantly in operative time (P<0.001), blood loss (P<0.001), and fusion rate (P=0.043), respectively.

Conclusions

This study demonstrated similar clinical outcomes between UPS fixation and BPS procedure after MIS-TLIF for multi-level DLD. Moreover, UPS technique was superior in operative time and blood loss, but represented lower fusion rate than the BPS construct did.

Biomechanical analysis of an expandable lateral cage and a static transforaminal lumbar interbody fusion cage with posterior instrumentation in an in vitro spondylolisthesis model

OBJECTIVE

Insufficient biomechanical data exist from comparisons of the stability of expandable lateral cages with that of static transforaminal lumbar interbody fusion (TLIF) cages. The purpose of this biomechanical study was to compare the relative rigidity of L4-5 expandable lateral interbody constructs with or without additive pedicle screw fixation with that of L4-5 static TLIF cages in a novel cadaveric spondylolisthesis model.

METHODS

Eight human cadaver spines were used in this study. A spondylolisthesis model was created at the L4-5 level by creating 2 injuries. First, in each cadaver, a nucleotomy from 2 channels through the anterior side was created. Second, the cartilage of the facet joint was burred down to create a gap of 4 mm. Light-emitting-diode tracking markers were placed at L-3, L-4, L-5, and S-1. Specimens were tested in the following scenarios: intact model, bilateral pedicle screws, expandable lateral 18-mm-wide cage (alone, with unilateral pedicle screws [UPSs], and with bilateral pedicle screws [BPSs]), expandable lateral 22-mm-wide cage (alone, with UPSs, and with BPSs), and TLIF (alone, with UPSs, and with BPSs). Four of the spines were tested with the expandable lateral cages (18-mm cage followed by the 22-mm cage), and 4 of the spines were tested with the TLIF construct. All these constructs were tested in flexion-extension, axial rotation, and lateral bending.

RESULTS

The TLIF-alone construct was significantly less stable than the 18- and 22-mm-wide lateral lumbar interbody fusion (LLIF) constructs and the TLIF constructs with either UPSs or BPSs. The LLIF constructs alone were significantly less stable than the TLIF construct with BPSs. However, there was no significant difference between the 18-mm LLIF construct with UPSs and the TLIF construct with BPSs in any of the loading modes.

CONCLUSIONS

Expandable lateral cages with UPSs provide stability equivalent to that of a TLIF construct with BPSs in a degenerative spondylolisthesis model.