Fusion Rates of Lateral Lumbar Interbody Fusion Using Recombinant Human Bone Morphogenetic Protein-2

Risk factors affecting spinal fusion: A meta-analysis of 39 cohort studies

PURPOSE

We performed a meta-analysis to identify risk factors affecting spinal fusion.

METHODS

We systematically searched PubMed, Embase, and the Cochrane Library from inception to January 6, 2023, for articles that report risk factors affecting spinal fusion. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using fixed-effects models for each factor for which the interstudy heterogeneity I2 was < 50%, while random-effects models were used when the interstudy heterogeneity I2 was ≥ 50%. Using sample size, Egger's P value, and heterogeneity across studies as criteria, we categorized the quality of evidence from observational studies as high-quality (Class I), moderate-quality (Class II or III), or low-quality (Class IV). Furthermore, the trim-and-fill procedure and leave-one-out protocol were conducted to investigate potential sources of heterogeneity and verify result stability.

RESULTS

Of the 1,257 citations screened, 39 unique cohort studies comprising 7,145 patients were included in the data synthesis. High-quality (Class I) evidence showed that patients with a smoking habit (OR, 1.57; 95% CI, 1.11 to 2.21) and without the use of bone morphogenetic protein-2 (BMP-2) (OR, 4.42; 95% CI, 3.33 to 5.86) were at higher risk for fusion failure. Moderate-quality (Class II or III) evidence showed that fusion failure was significantly associated with vitamin D deficiency (OR, 2.46; 95% CI, 1.24 to 4.90), diabetes (OR, 3.42; 95% CI, 1.59 to 7.36), allograft (OR, 1.82; 95% CI, 1.11 to 2.96), conventional pedicle screw (CPS) fixation (OR, 4.77; 95% CI, 2.23 to 10.20) and posterolateral fusion (OR, 3.63; 95% CI, 1.25 to 10.49).

CONCLUSIONS

Conspicuous risk factors affecting spinal fusion include three patient-related risk factors (smoking, vitamin D deficiency, and diabetes) and four surgery-related risk factors (without the use of BMP-2, allograft, CPS fixation, and posterolateral fusion). These findings may help clinicians strengthen awareness for early intervention in patients at high risk of developing fusion failure.

Bibliometric and trend analysis of the top 100 most-cited articles on lateral interbody fusion (LIF)

PURPOSE

Lateral interbody fusion (LIF) is an increasingly popular minimally-invasive spine procedure. This study identifies notable trends in LIF literature and provides a detailed review of the bibliometric aspects of the top 100 most-cited articles.

METHODS

Articles were queried from the Web of Science database. Inclusion criteria consisted of peer-reviewed articles, full-text availability, and LIF focus. Network analysis including co-authorship mapping and bibliographic coupling were complemented by trend analysis to determine prominent contributors and themes. Analyses were conducted using VOSviewer and Bibliometrix (RStudio).

RESULTS

There has been a rapid increase in LIF publication and citation count since 1998. Leading journals were Spine (n = 24), Journal of Neurosurgery Spine (n = 22), and European Spine Journal (n = 12). NuVasive funded the most publications (n = 17), followed by DePuy Synthes Spine (n = 4). The United States was the most represented country (n = 81); however, trend analysis suggests a steadily growing international contribution. The most prolific author was J.S. Uribe (n = 16), followed by a tie in second place by E. Dakwar and L. Pimenta (n = 8). The most frequent keywords, "complication" (n = 34), "surgery" (n = 30), and "outcomes" (n = 24), demonstrated a patient-centric theme.

CONCLUSIONS

This bibliometric analysis provides in-depth insights into the evolution and trends of LIF over the last two decades. The trends and themes identified demonstrate the innovative, collaborative, and patient-focused characteristics of this subfield. Future researchers can use this as a foundation for understanding the past and present state of LIF research while designing investigations.

Lateral Lumbar Interbody Fusion With rhBMP-2 can Achieve High Fusion Rates in Adult Spine Deformity Surgeries

STUDY DESIGN

An ambispective, observational study of the prospective, institutional adult spine deformity (ASD) database.

OBJECTIVES

The study investigates the clinical and radiographic fusion rates with lateral interbody approach and rhBMP-2 in multiple-level lumbar fusion in the ASD population. Previous studies have reported over 10% pseudoarthrosis rate with multiple segment fusions. Lateral lumbar interbody fusion (LLIF) allows multiple-level, less-invasive access to the anterior lumbar spine. We hypothesized that fusion rates with lateral approach with rhBMP-2 use are superior to the published data on lumbar fusion in ASD patients.

METHODS

The institutional ASD database was searched to identify eligible patients with two or more levels of LLIF (T12-L5), >4 levels of posterior instrumentations and >2 years of follow-up between the years 2010 and 2018. Antero-posterior and lateral 36-inch standing radiographs for each patient and computed tomography scans in select patients were studied to ascertain fusion status and patients were divided into two groups based on fusion status.

RESULTS

The study included 179 patients with a mean age of 65.3 years and 74% female patients. The median number of interbody fusions was performed at 3 (IQR 3-4) levels. The mean follow-up duration was 4.4 years (SD = 1.9). 169 patients (94.5%) had successful arthrodesis, while 10 patients (5.5%) had radiological pseudoarthrosis at one level. Of the 10 patients, 8 (4.4%) were either clinically asymptomatic or had manageable back pain. Two patients (1.1%) required revision surgery for symptomatic pseudoarthrosis.

CONCLUSION

This is the largest known series of ASD patients investigating the fusion rates with multiple-level LLIFs. LLIF along with rhBMP-2 can achieve high fusion success across interbody fusion levels in multi-segmental ASD surgeries.

Comparing Bone Fusion Rates Between Novel Unidirectional Porous Tricalcium Beta-Phosphate and Autologous Bone in Lumbar Lateral Interbody Fusion: A Two-Year Radiographic Outcome Study

This retrospective cohort study aims to examine the potential differences in bone fusion between autologous bone and artificial bone in the lumbar lateral interbody fusion at 2two years post-surgery. The bone fusions performed in 15 cases and at 34 intervertebral levels were compared to assess the differences between the artificial bone, Affinos® (Kuraray Co., Tokyo, Japan), and autogenous bone. Two years post-surgery, we evaluated computed tomography (CT) multi-planar reconstruction images in the coronal and sagittal planes. One year after surgery, out of the 24 windows, 17 (70.8%) windows transplanted with autologous bones showed bone fusion. Additionally, out of the 38 windows, 18 (47.4%) windows transplanted with Affinos® showed bone fusion. Two years post-surgery, out of the 24 windows, 19 (79.2%) windows transplanted with autologous bones showed bone fusion. Additionally, out of the 38 windows, 30 (79.0%) windows transplanted with Affinos® showed bone fusion, and no difference was observed in the fusion rate at two years post-surgery (P = 0.238). In cases using Affinos® for transplanted bone, the bone fusion rate increased between one and two years. The rate of bony fusion using Affinos® in lateral lumbar interbody fusion (LLIF) cages is at par with that of autologous bone grafts at two years post-surgery. Affinos® is a promising candidate for graft material in LLIF surgery.

Lateral lumbar interbody fusion - clinical outcomes, fusion rates and complications with recombinant human bone morphogenetic protein-2

BACKGROUND

The authors report an Australian experience of lateral lumbar interbody fusion (LLIF) with respect to clinical outcomes, fusion rates, and complications, with recombinant human bone morphogenetic protein-2 (rhBMP-2) and other graft materials.

METHODS

Retrospective cohort study of LLIF patients 2011-2021. LLIFs performed lateral decubitus by four experienced surgeons past their learning curve. Graft materials classified rhBMP-2 or non-rhBMP-2. Patient-reported outcomes assessed by VAS, ODI, and SF-12 preoperatively and postoperatively. Fusion rates assessed by CT postoperatively at 6 and 12 months. Complications classified minor or major. Clinical outcomes and complications analysed and compared between rhBMP-2 and non-rhBMP-2 groups.

RESULTS

A cohort of 343 patients underwent 437 levels of LLIF. Mean age 67 ± 11 years (range 29-89) with a female preponderance (65%). Mean BMI 29kg/m2 (18-56). Most common operated levels L3/4 (36%) and L4/5 (35%). VAS, ODI and SF-12 improved significantly from baseline. Total complication rate 15% (53/343) with minor 11% (39/343) and major 4% (14/343). Ten patients returned to OR (2-wound infection, 8-further instrumentation and decompression). Most patients (264, 77%) received rhBMP-2, the remainder a non-rhBMP-2 graft material. No significant differences between groups at baseline. No increase in minor or major complications in the rhBMP-2 group compared to the non-rhBMP-2 group respectively; (10.6% vs 13.9% [p = 0.42], 2.7% vs 8.9% [p < 0.01]). Fusion rates significantly higher in the rhBMP-2 group at 6 and 12 months (63% vs 40%, [p < 0.01], 92% vs 80%, [p < 0.02]).

CONCLUSION

LLIF is a safe and efficacious procedure. rhBMP-2 in LLIF produced earlier and higher fusion rates compared to available non-rhBMP-2 graft substitutes.

Instrumentation choice and early radiographic outcome following lateral lumbar interbody fusion (LLIF): Lateral instrumentation versus posterior pedicle screw fixation

Background

Lateral lumbar interbody fusion (LLIF) is a minimally invasive fusion procedure that may be performed with or without supplemental instrumentation. However, there is a paucity of evidence on the effect of supplemental instrumentation technique on perioperative morbidity and fusion rate in LLIF.

Methods

A single-institutional retrospective review of patients who underwent LLIF for lumbar spondylosis was conducted. Patients were grouped according to supplemental instrumentation technique: stand-alone LLIF, LLIF with laterally placed instrumentation, or LLIF with posterior percutaneous pedicle screw fixation (PPSF). Outcomes included fusion rates, peri-operative complication, and reoperation; estimated blood loss (EBL); surgery duration; length of stay; and length of follow-up.

Results

82 patients underwent LLIF at 114 levels. 35 patients (42.7%) received supplemental lateral instrumentation, 30 (36.6%) received supplemental PPSF, and 17 (20.7%) underwent stand-alone LLIF. More patients in the lateral instrumentation group had prior lumbar fusion at adjacent levels (23/35, 65.71%) versus stand-alone (3/17, 17.6%) or PPSF (2/30, 6.67%) groups (p = 0.003). 4/17 patients (23.5%) with stand-alone LLIF and 4/35 patients (11.42%) with lateral instrumentation underwent reoperation, versus 0/30 with PPSF (p = 0.030). There was no difference in fusion rates between groups (p = 0.717). Operation duration was longer in patients with PPSF (p < 0.005) and length of follow-up was longer for PPSF than lateral instrumentation (p = 0.001). Choice of instrumentation group was a statistically significant predictor of reoperation.

Conclusions

While rates of complete radiographic fusion on imaging follow-up didn't differ, patients receiving PPSF were less likely than stand-alone or lateral instrumentation groups to require reoperation, though operative time was significantly longer. Further study of choice of supplemental instrumentation with LLIF is indicated.

The leptomeninges as a critical organ for normal CNS development and function: First patient and public involved systematic review of arachnoiditis (chronic meningitis)

BACKGROUND & IMPORTANCE

This patient and public-involved systematic review originally focused on arachnoiditis, a supposedly rare "iatrogenic chronic meningitis" causing permanent neurologic damage and intractable pain. We sought to prove disease existence, causation, symptoms, and inform future directions. After 63 terms for the same pathology were found, the study was renamed Diseases of the Leptomeninges (DLMs). We present results that nullify traditional clinical thinking about DLMs, answer study questions, and create a unified path forward.

METHODS

The prospective PRISMA protocol is published at Arcsology.org. We used four platforms, 10 sources, extraction software, and critical review with ≥2 researchers at each phase. All human sources to 12/6/2020 were eligible for qualitative synthesis utilizing R. Weekly updates since cutoff strengthen conclusions.

RESULTS

Included were 887/14286 sources containing 12721 DLMs patients. Pathology involves the subarachnoid space (SAS) and pia. DLMs occurred in all countries as a contributor to the top 10 causes of disability-adjusted life years lost, with communicable diseases (CDs) predominating. In the USA, the ratio of CDs to iatrogenic causes is 2.4:1, contradicting arachnoiditis literature. Spinal fusion surgery comprised 54.7% of the iatrogenic category, with rhBMP-2 resulting in 2.4x more DLMs than no use (p<0.0001). Spinal injections and neuraxial anesthesia procedures cause 1.1%, and 0.2% permanent DLMs, respectively. Syringomyelia, hydrocephalus, and arachnoid cysts are complications caused by blocked CSF flow. CNS neuron death occurs due to insufficient arterial supply from compromised vasculature and nerves traversing the SAS. Contrast MRI is currently the diagnostic test of choice. Lack of radiologist recognition is problematic.

DISCUSSION & CONCLUSION

DLMs are common. The LM clinically functions as an organ with critical CNS-sustaining roles involving the SAS-pia structure, enclosed cells, lymphatics, and biologic pathways. Cases involve all specialties. Causes are numerous, symptoms predictable, and outcomes dependent on time to treatment and extent of residual SAS damage. An international disease classification and possible treatment trials are proposed.

Efficacy and safety of a modified lateral lumbar interbody fusion in L4-5 lumbar degenerative diseases compared with traditional XLIF and OLIF: a retrospective cohort study of 156 cases

BACKGROUND

The authors designed a modified lateral lumbar interbody fusion (LLIF) procedure named as XOLIF and compared the efficacy and safety with traditional LLIF procedures.

METHODS

Patients were divided into XLIF, OLIF, and XOLIF group according to the surgical approach. Cases of psoas major and vascular space stenosis, psoas major muscle elevation, psoas major muscle hypertrophy, and high iliac crest were recorded. Basic information, composition ratio of specific cases, Visual analog scale (VAS), Oswestry Disability Index (ODI), interbody fusion rate and complications were compared between the 3 groups.

RESULTS

The study included 156 cases of L4-5 LLIF. There was no statistical difference in age, gender, BMI among the three groups. Cases with stenosis between psoas muscle and artery accounted for 11.8 and 18.4% of the XLIF and XOLIF group, respectively, while no case of this type had undergone OLIF surgery, the difference was statistically significant (P < 0.05). The proportions of high iliac crest cases in the OLIF and XOLIF group were 12.5 and 18.4%, respectively, while the XLIF group with vertical approach is not suitable for cases with high iliac crest. The postoperative VAS and ODI of the three groups were significantly improved compared with those before operation. There were 51 cases (32.7%) of complications including 21cases in XLIF group, 20 cases in OLIF Group and 10 cases in XOLIF group. XOLIF group has more advantages in reducing lumbar plexus injury and the risk of vascular injury.

CONCLUSIONS

XOLIF showed good clinical efficacy and technical advantages with a low incidence of intraoperative and postoperative complications, especially in the specific cases.

Is Platelet-Rich Plasma Effective in Enhancing Spinal Fusion? Systematic Overview of Overlapping Meta-Analyses

STUDY DESIGN

Systematic review.

OBJECTIVES

We performed this systematic overview on overlapping meta-analyses that analyzed the role of platelet-rich plasma(PRP) in enhancing spinal fusion and identify which study provides the current best evidence on the topic and generate recommendations for the same.

MATERIALS AND METHODS

We conducted independent and duplicate electronic database searches in PubMed, Web of Science, Embase, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews of Effects till October-2020 for meta-analyses that analyzed the role of PRP in spinal fusion procedures. Methodological quality assessment was made using Oxford Levels of Evidence, AMSTAR scoring, and AMSTAR 2 grades. We then utilized the Jadad decision algorithm to identify the study with highest quality to represent the current best evidence to generate recommendations.

RESULTS

3 meta-analyses fulfilling the eligibility criteria were included. The AMSTAR scores of included studies varied from 5-8(mean:6.3) and all included studies had critically low reliability in their summary of results due to their methodological flaws according to AMSTAR 2 grades. The current best evidence showed that utilization of PRP was not associated with significant improvement in patient-reported outcomes such as Visual Analog Score for pain compared to the standard fusion procedure. Moreover, PRP was found to be associated with lower fusion rates.

CONCLUSION

Based on this systematic overview, the effectiveness of PRP as a biological agent in augmenting spinal fusion is limited. Current evidence does not support the use of PRP as an adjuvant to enhance spinal fusion.

A Clinical Study on the Effect of Different Ratios of Recombinant Human Bone Morphogenetic Protein-2 Compound to Autogenous Bone on Cervical Interbody Fusion Based on Smart Healthcare

With an increasing elderly population worldwide, the incidence of spine degenerative diseases with neck and shoulder pain as the main symptom is rising obviously, which has now become one of the important and difficult problems in sociomedical science. This study was to explore the effects of different ratios of recombinant human bone morphogenetic protein-2 (rhBMP-2) compound to the autogenous bone on cervical interbody fusion. 90 cervical degeneration patients with the need of surgical treatment admitted to our hospital from January 2019 to January 2020 were selected as the research objects and equally divided into group A, group B, and group C according to the order of admission, with 30 cases in each group and the ratios of rhBMP-2 compound to autogenous bone being 2 : 1, 1 : 1, and 1 : 2 respectively, and standard anterior cervical diskectomy and fusion (ACDF) treatment was performed to all patients to compare their surgery-related indexes, the Japanese Orthopaedic Association (JOA) score, the visual analog scale (VAS) score, the effect of cervical interbody fusion, and the postoperative complication rate (CR). Compared with group A and group C, group B achieved the significantly better surgery-related indexes (P < 0.05), significantly higher postoperative JOA scores (P < 0.05), significantly lower postoperative neck and upper limb VAS scores (P < 0.05), significantly better effect of cervical interbody fusion (P < 0.05), and significantly lower postoperative CR (P < 0.05). 1 : 1 is the best ratio of rhBMP-2 compound to the autogenous bone, for it can optimize patients' perioperative indexes, reduce the postoperative pain, lower the possibility of complications, and improve the effect of cervical interbody fusion, which should be promoted and applied in practice.

Comparative Study of Radiological and Clinical Outcomes in Patients Undergoing Minimally Invasive Lateral Lumbar Interbody Fusion Using Demineralized Bone Matrix Alone or with Low-Dose Escherichia coli-Derived rhBMP-2

OBJECTIVE

To compare the results of interbody fusion in patients undergoing minimally invasive lateral lumbar interbody fusion (LLIF) using demineralized bone matrix (DBM) alone versus DBM+recombinant human bone morphogenetic protein-2 (rhBMP2).

METHODS

This retrospective case-controlled study was conducted in patients undergoing minimally invasive LLIF (n = 54) for lumbar interbody fusion; they were divided into 2 groups: DBM-only group and DMB+rhBMP2 group. The improvements of segmental and lumbar lordosis and restoration of disc height were measured, and the interbody fusion rates were determined using a modified Bridwell grading system. Clinical outcomes after surgery, such as visual analog scale scores of back pain and leg pain, and Oswestry disability index were compared.

RESULTS

There were no significant differences in disc height, lumbar and segmental lordosis, or interbody fusion rate between the 2 groups. However, the proportion of Bridwell grade 1 as complete interbody bridging was higher in the DBM+rhBMP2 group than in the DBM-only group at both 6 and 12 months (P < 0.001). Clinical parameters showed equally significant improvement during follow-up in both groups, with no significant differences between the groups.

CONCLUSION

In minimally invasive LLIF, adding Escherichia coli-derived rhBMP2 to DBM did not affect clinical outcomes or radiation parameters, but increased the speed of fusion and interbody bony bridging rate.

Early Fusion Rates After Direct Lateral Lumbar Interbody Fusion With Bone-Morphogenetic Protein

BACKGROUND

Direct lateral (transpsoas) lumbar interbody fusion (LLIF) reportedly achieves union by 1 year postoperatively, but how soon fusion occurs after these minimally invasive procedures is unclear. This study investigated LLIF fusion progression at 6 months and 1 year in a large-scale cohort using bone morphogenetic protein (BMP) graft and examined risk factors associated with failed fusion.

METHODS

Patients undergoing primary LLIF with a single surgical team from 2015 through 2016 with polyetheretherketone (PEEK) iimplants and BMP graft were identified. Retrospective chart review included demographics and medical history, construct length and location, and concurrent L5-S1 fusion. Inclusion criteria included minimum 1-year follow-up and postoperative lumbar computed tomography at 6 months and 1 year, which was independently assessed for bony union at each level.

RESULTS

166 patients underwent LLIF at a total of 312 levels. Seventy-nine patients (48%) underwent 1-level fusion; 45 (27%), 2 levels; and 42 (25%), 3 or more levels. At 6 months, 160 (51%) levels showed fusion. At 1 year, 70% of the remainder were fused, and total fusion rate was 85%. Fusion rates from L1 through L4 were similar (84%-87%). Nonunion was not significantly associated with construct length (P = .19), concurrent anterior L5-S1 interbody fusion (P = .50), age (P = .70), BMI (P = .15), or comorbidities such as diabetes (P = .86) or thyroid disease (P = .46).

CONCLUSIONS

This large retrospective cohort study corroborates prior 1-year LLIF fusion rate reports (85%) independent of construct length or location or medical comorbidities. Significantly, half showed fusion by 6 months, earlier than previously described and validating the efficacy of LLIF.

LEVEL OF EVIDENCE

5.

CLINICAL RELEVANCE

This study presents a large cohort of patients to support effective lumbar fusion after LLIF with BMP-2.

Safety Profile, Surgical Technique, and Early Clinical Results for Simultaneous Lateral Lumbar Interbody Fusion and Anterior Lumbar Interbody Fusion in a Lateral Position

STUDY DESIGN

Description of surgical technique and retrospective review.

OBJECTIVE

To describe a novel surgical technique for multilevel lumbar fusion and describe early clinical results.

SUMMARY OF BACKGROUND DATA

Patients with multilevel lumbar spinal stenosis and adult degenerative scoliosis often require multilevel interbody placement to achieve indirect decompression and lordosis. We describe a case series of patients treated with simultaneous lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF) at L5-S1.

METHODS

We retrospectively reviewed a consecutive series of patients treated for multilevel lumbar spinal stenosis with simultaneous ALIF and LLIF with at least 3-month follow-up. All patients received supplemental percutaneous bilateral pedicle screw placement as well. We measured on preoperative radiographs their lumbar lordosis, pelvic incidence, and L5-S1 lordosis. Intraoperative factors such as operative time, estimated blood loss, fluids provided, number of levels fused, and whether a trainee was present during the procedure were all recorded.

RESULTS

There were 15 patients included within our case series (69.5, 4 F). There were no reported intraoperative vascular or neurological complications in 15 cases. The operative time for the cases ranged from 2.7 to 8.4 hours (average=5.2±1.9 h). The average lordosis gained at L5-S1 was 8.6±3.0 degrees and the average lumbar lordosis gained was 14.7±6.4 degrees. The average PI-LL mismatch went from 22.4±13.3 degrees preoperative to 7.8±10.2 degrees postoperative. One patient had a postoperative complication of a sacral fracture requiring placement of a pelvic screw for a L2-pelvis fusion. There were 8 patients with 4+ levels of fusion. For this cohort of patients, the average lumbar lordosis gained was 16.0±7.5 degrees and the average PI-LL mismatch went from 24.7±16.3 degrees preoperative to 8.8±12.9 degrees postoperative. For the patients with 4+ levels of fusion, the average operative time was 5.9±1.8 hours.

CONCLUSIONS

We have described our early positive results with simultaneous LLIF/ALIF surgery for treatment of lumbar degenerative conditions.

Fusion rate for stand-alone lateral lumbar interbody fusion: a systematic review

BACKGROUND

Lateral lumbar interbody fusion (LLIF) is used to treat multiple conditions, including spondylolisthesis, degenerative disc disorders, adjacent segment disease, and degenerative scoliosis. Although many advocate for posterior fixation with LLIF, stand-alone LLIF is increasingly being performed. Yet the fusion rate for stand-alone LLIF is unknown.

PURPOSE

Determine the fusion rate for stand-alone LLIF.

STUDY DESIGN

Systematic review.

METHODS

We queried Cochrane, EMBASE, and MEDLINE for literature on stand-alone LLIF fusion rate with a publication cutoff of April 2020. LLIF surgery was considered stand-alone when not paired with supplemental posterior fixation. Cohort fusion rate differences were calculated and tested for significance (p<0.05). All reported means were pooled.

RESULTS

A total of 2,735 publications were assessed. Twenty-two studies met inclusion criteria, including 736 patients and 1,103 vertebral levels. Mean age was 61.7 years with BMI 26.5 kg/m². Mean fusion rate was 85.6% (range, 53.0%-100.0%), which did not differ significantly by number of levels fused (1-level, 2-level, and ≥3-level). Use of rhBMP-2 was reported in 39.3% of subjects, with no difference in fusion rates between studies using rhBMP-2 (87.7%) and those in which rhBMP-2 was not used (83.9%, odds ratio=1.37, p=0.448). Fusion rate did not differ with the addition of a lateral plate, or by underlying diagnosis. All-complication rate was 42.2% and mean reoperation rate was 11.1%, with 2.3% reoperation due to pseudarthrosis. Of the studies comparing stand-alone to circumferential fusion, pooled fusion rate was found to be 80.4% versus 91.0% (p=0.637).

CONCLUSIONS

Stand-alone LLIF yields high fusion rates overall. The wide range of reported fusion rates and lower fusion rates in studies involving subsequent surgical reoperation highlights the importance of proper training in this technique and employing a rigorous algorithm when indicating patients for stand-alone LLIF. Future research should focus on examining risk factors and patient-reported outcomes in stand-alone LLIF.

Minimally Invasive Lumbar Decompression and Removal of Symptomatic Heterotopic Bone Formation After Spinal Fusion with Recombinant Human Bone Morphogenetic Protein-2

We present a case of symptomatic heterotopic bone formation following revision of posterolateral lumbar fusion/instrumentation and "off-label" use of recombinant human bone morphogenetic protein-2, treated successfully with the use of a minimally invasive tubular approach.

Overview of Minimally Invasive Spine Surgery

Minimally invasive spine surgery (MISS) has continued to evolve over the past few decades, with significant advancements in technology and technical skills. From endonasal cervical approaches to extreme lateral lumbar interbody fusions, MISS has showcased its usefulness across all practice areas of the spine, with unique points of access to avoid pertinent neurovascular structures. Adult spine deformity has also recognized the importance of minimally invasive techniques in its ability to limit complications and to provide adequate sagittal alignment correction and improvements in patients' functional status. Although MISS has continued to make significant progress clinically, consideration must also be given to its economic impact and the learning curve surgeons experience in adding these procedures to their armamentarium. This review examines current innovations in MISS, as well as the economic impact and future directions of the field.