Posterior lumbar interbody fusion using recombinant human bone morphogenetic protein type 2 with cylindrical interbody cages

Effect of Mixture of Recombinant Human Bone Morphogenic Protein-2 and Demineralized Bone Matrix in Lateral Lumbar Interbody Fusion

OBJECTIVE

This study aims to determine the optimal dose of recombinant-human bone morphogenic protein-2 (rhBMP-2) for successful bone fusion in minimally invasive lateral lumbar interbody fusion (MIS LLIF). Previous studies show that rhBMP is an effective alternative to autologous iliac crest bone graft, but the optimal dose remains uncertain. The study analyzes the fusion rates associated with different rhBMP doses to provide a recommendation for the optimal dose in MIS LLIF.

METHODS

Ninety-three patients underwent MIS LLIF using demineralized bone matrix (DBM) or a mixture of rhBMP-2 and DBM as fusion material. The group was divided into the following three groups according to the rhBMP-2 usage : group A, only DBM was used (n=27); group B, 1 mg of rhBMP-2 per 5 mL of DBM paste (n=41); and group C, 2 mg of rhBMP-2 per 5 mL of DBM paste (n=25). Demographic data, clinical outcomes, postoperative complication and fusion were assessed.

RESULTS

At 12 months post-surgery, the overall fusion rate was 92.3% according to Bridwell fusion grading system. Groups B and C, who received rhBMP-2, had significantly higher fusion rates than group A, who received only DBM. However, there was no significant increase in fusion rate when the rhBMP-2 dosage was increased from group B to group C. The groups B and C showed significant improvement in back pain and Oswestry disability index compared to the group A. The incidence of screw loosening was decreased in groups B and C, but there was no significant difference in the occurrence of other complications.

CONCLUSION

Usage of rhBMP-2 in LLIF surgery leads to early and increased final fusion rates, which can result in faster pain relief and return to daily activities for patients. The benefits of using rhBMP-2 were not significantly different between the groups that received 1 mg/5 mL and 2 mg/5 mL of rhBMP-2. Therefore, it is recommended to use 1 mg of rhBMP-2 with 5 mL of DBM, taking both economic and clinical aspects into consideration.

Efficacy and Outcome Measurement of iFactor/ABM/P-15 in Lumbar Spine Surgery: A Systematic Review

STUDY DESIGN

Systematic Review.

OBJECTIVES

To determine the efficacy and overall outcomes of iFactor/ABM/P-15 following lumbar spine surgery.

METHODS

We performed a search of the Cochrane Library, Medline Ovid, PubMed, and SCOPUS databases from inception until August 2023. Eligible studies included outcomes of patients receiving iFactor following lumbar spine surgery. The primary outcomes of interest were fusion rates and iFactor efficacy after lumbar surgery in patients who received iFactor. Secondary outcomes included patient-reported outcomes and complication rates.

RESULTS

A total of 766 titles were initially screened. After inclusion criteria were applied, 5 studies (388 patients) were included, which measured overall outcomes of iFactor/ABM/P-15 following lumbar spine surgery. These studies showed acceptable reliability for inclusion based on the Methodical Index for Non-Randomized studies and Critical Appraisal Skills Programme assessment tools. iFactor/ABM/P-15 facilitated significantly faster bone development in various procedures while maintaining favorable clinical outcomes compared to traditional grafts.

CONCLUSIONS

This systematic review found that iFactor/ABM/P-15 use for lumbar spine surgery maintains similar managing patient-reported outcomes relative to other grafting methods. In regard to rates of fusion, iFactor/ABM/P-15 showed a significantly faster rate of fusion when compared to traditional grafts including allograft, autograft, demineralized bone matrix (DBM), and recombinant human bone morphogenetic protein-2 (rhBMP-2). Future multicenter randomized control trials with larger sample sizes are recommended to further assess iFactor/ABM/P-15 efficacy in lumbar spine surgery.

Demineralized bone matrix for repair and regeneration of maxillofacial defects: A narrative review

OBJECTIVES

Demineralized bone matrix (DBM) is a well-established bone graft material widely accepted by dentists and the public for its favorable osteoconductivity and osteoinductive potential. This article aimed to provide a narrative review of the current therapeutic applications and limitations of DBM in maxillofacial bone defects.

STUDY SELECTION, DATA, AND SOURCES

Randomized controlled trials, prospective or retrospective clinical studies, case series and reports, and systematic reviews. MEDLINE, PubMed, and Google Scholar were searched using keywords.

CONCLUSIONS

Some evidence supported the therapeutic application of DBM in periodontal intrabony defects, maxillary sinus lifts, ridge preservation, ridge augmentation, alveolar cleft repair, orthognathic surgery, and other regional maxillofacial bone defects. However, the limitations of DBM should be considered when using it, including potential low immunogenicity, instability of osteoinductive potential, handling of the graft material, and patient acceptance.

CLINICAL SIGNIFICANCE

With the increasing demand for the treatment of maxillofacial bone defects, DBM is likely to play a greater role as a promising bone graft material. Safe and effective combination treatment strategies and how to maintain a stable osteoinductive potential will be the future challenges of DBM research.

Unique Characteristics of New Bone Formation Induced by Lateral Lumbar Interbody Fusion Procedure

Introduction

Despite the absence of bone grafting in the area outside the cage, lateral bridging callus outside cages (LBC) formation is often observed here following extreme lateral interbody fusion (XLIF) conversely to conventional methods of transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. The LBC, which may increase stabilization and decrease nonunion rate in treated segments, has rarely been described. This study aimed to identify the incidence and associated factors of LBC following XLIF.

Methods

We enrolled 136 consecutive patients [56 males, 80 females; mean age 69.6 (42-85) years] who underwent lumbar fusion surgery using XLIF, including L4/5 level with posterior fixation at a single institution between February 2013 and February 2018. One year postoperatively, the treated L4/5 segments were divided into the LBC formation and non-formation groups. Potential influential factors, such as age, sex, body mass index, bone density, height of cages, cage material (titanium or polyetheretherketone [PEEK]), presence or absence of diffuse idiopathic skeletal hyperostosis (DISH), and radiological parameters, were evaluated. Multivariate logistic regression analysis was performed for factors significantly different from the univariate analysis.

Results

The incidence of LBC formation was 58.8%. Multivariate logistic regression analysis showed that the length of osteophytes [+1 mm; odds ratio, 1.29; 95% confidence interval, 1.17-1.45; p<0.0001] was significant LBC formation predictive factors. Receiver operating characteristic curve analysis demonstrated that the cut-off value for osteophyte length was 14 mm, the sensitivity was 58.8%, the specificity was 84.4%, and the area under the ROC curve for this model was 0.79.

Conclusions

The incidence of LBC formation was 58.8% in L4/5 levels one year after the XLIF procedure. We demonstrated that the length of the osteophyte was significantly associated with LBC formation.

Strategies of immobilizing BMP-2 with 3D-printed scaffolds to improve osteogenesis

The management and definitive treatment of critical-size bone defects in severe trauma, tumor resection and congenital malformation are troublesome for orthopedic surgeons and patients worldwide without recognized good treatment strategies. Researchers and clinicians are working to develop new strategies to treat these problems. This review aims to summarize the techniques used by additive manufacturing scaffolds loaded with BMP-2 to promote osteogenesis and to analyze the current status and trends in relevant clinical translation. Optimize composite scaffold design to enhance bone regeneration through printing technology, material selection, structure design and loading methods of BMP-2 to advance the clinical therapeutic bone repair field.

Postoperative Lumbar Fusion Bone Morphogenic Protein-Related Epidural Cyst Formation

Bone morphogenetic protein is broadly used in spinal surgery to enhance fusion rates. Several complications have been associated with the use of bone morphogenetic protein, including postoperative radiculitis and pronounced bone resorption/osteolysis. Bone morphogenetic protein-related epidural cyst formation may represent another complication that has not been described aside from limited case reports. In this case series, we retrospectively reviewed imaging and clinical findings of 16 patients with epidural cysts on postoperative MR imaging following lumbar fusion. In 8 patients, mass effect on the thecal sac or lumbar nerve roots was noted. Of these, 6 patients developed new postoperative lumbosacral radiculopathy. During the study period, most patients were managed conservatively, and 1 patient required revision surgery with cyst resection. Concurrent imaging findings included reactive endplate edema and vertebral bone resorption/osteolysis. Epidural cysts had characteristic findings on MR imaging in this case series and may represent an important postoperative complication in patients following bone morphogenetic protein-augmented lumbar fusion.

Lumbar spine intervertebral disc gene delivery of BMPs induces anterior spine fusion in lewis rats

Minimally invasive techniques and biological autograft alternatives such as the bone morphogenetic proteins (BMPs) can reduce morbidity associated with spinal fusions. This study was a proof-of-concept for gene-therapy-mediated anterior spine fusion that could be adapted to percutaneous technique for clinical use. Isogeneic bone marrow stromal cells genetically programmed to express b-galactosidase (LACZ, a marker gene), BMP2, BMP7, a mixture of BMP2 and BMP7 infected cells (homodimers, HM), or BMP2/7 heterodimers (HT) were implanted into the discs between lumbar vertebrae 4 and 5 (L4/5) and L5/6 of male Lewis rats. Spine stiffening was monitored at 4, 8 and 12 weeks using noninvasive-induced angular displacement (NIAD) testing. At 12 weeks isolated spines were assessed for fusion and bone formation by palpation, biomechanical testing [four-point bending stiffness, moment to failure in extension, and in vitro angular displacement (IVAD)], faxitron x-rays, microCT, and histology. Progressive loss of NIAD occurred in only the HT group (p < 0.001), and biomechanical tests correlated with the NIAD results. Significant fusion occurred only in the HT group (94% of animals with one or both levels) as assessed by palpation (p < 0.001), which predicted HT bone production assessed by faxitron (p ≤ 0.001) or microCT (p < 0.023). Intervertebral bridging bone was consistently observed only in HT-treated specimens. Induced bone was located anterior and lateral to the disc space, with no bone formation noted within the disc. Percutaneous anterior spine fusions may be possible clinically, but induction of bone inside the disc space remains a challenge.

The efficacy of platelet-rich plasma applicated in spinal fusion surgery: A meta-analysis

Objective

The purpose of this meta-analysis is to evaluate the effect of the application of platelet-rich plasma (PRP) in spinal fusion surgery on the fusion rate of the spine.

Methods

A comprehensive search of the PubMed, Embase, Cochrane Library, and Science Direct databases was conducted to identify randomized control trials (RCTs) or observational cohort studies that evaluated the efficacy and safety of PRP in spinal fusion. Data on final fusion rate, changes in the visual analog scale (VAS), estimated blood loss (EBL), and operative time was collected from the eligible studies for meta-analysis. Patients were divided into PRP and non-PRP groups according to whether PRP was used during the spinal fusion procedure.

Results

According to the selection criteria, 4 randomized controlled trials and 8 cohort studies with 833 patients and 918 levels were included. The outcomes indicated that PRP application is associated with a lower fusion rat (OR = 0.62, 95% CI: (0.43, 0.89), P = 0.009) at final follow-up (>24 months). Subgroup analysis showed a lower rate of spinal fusion in the PRP group compared to the non-PRP group (OR = 0.35, 95% CI: (0.21, 0.58), P < 0.001) when spinal fusion was assessed using only anterior-posterior radiographs. When the bone graft material was a combination of autologous bone + artificial bone, the spinal fusion rate was lower in the PRP group than in the non-PRP group (OR = 0.34, 95% CI: (0.16, 0.71), P = 0.004). The PRP and non-PRP groups showed no significant differences in VAS changes at the 24th postoperative month (WMD = 0.36, 95% CI: (−0.37, 1.09), P = 0.33); Application of PRP does not reduce the estimated blood loss (WMD = −86.03, 95% CI: (−188.23, 16.17), P = 0.10). In terms of operation time, using PRP does not prolong operation time (WMD = −3.74, 95% CI: (−20.53, 13.04), P = 0.66).

Conclusion

Compared with bone graft fusion alone, PRP cannot increase the rate of spinal fusion. Inappropriate methods of spinal fusion assessment or mixing PRP with artificial/allograft bone may have been responsible for the lower rate of spinal fusion in the PRP group.

Systematic Review Registration

doi: 10.37766/inplasy2022.5.0055

Metal Phenolic Nanodressing of Porous Polymer Scaffolds for Enhanced Bone Regeneration via Interfacial Gating Growth Factor Release and Stem Cell Differentiation

Porous polymer scaffolds are essential materials for tissue engineering because they can be easily processed to deliver stem cells or bioactive factors. However, scaffolds made of synthetic polymers normally lack a bioactive cell-material interface and undergo a burst release of growth factors, which may hinder their further application in tissue engineering. In this paper, a metal-phenolic network (MPN) was interfacially constructed on the pore surface of a porous poly(dl-lactide) (PPLA) scaffold. Based on the molecular gating property of the MPN supramolecular structure, the PPLA@MPN scaffold achieved the sustained release of the loaded molecules. In addition, the MPN coating provided a bioactive interface, thus encouraging the migration and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The PPLA@MPN scaffolds exhibited enhanced bone regeneration in a rat femoral defect model in vivo compared to PPLA, which is ascribed to the combined effect of sustained bone morphogenetic protein-2 (BMP-2) release and the osteogenic ability of MPN. This nanodressing technique provides a viable and straightforward strategy for enhancing the performance of porous polymer scaffolds in bone tissue engineering.

Cost-effectiveness of 4 mg dibotermin alfa/absorbable collagen sponge versus iliac crest bone graft for lumbar degenerative disc disease in the United Kingdom

AIMS

To develop a model to evaluate the cost-effectiveness of 4 mg dibotermin alfa/absorbable collagen sponge (ACS) versus iliac crest bone graft (ICBG) in patients with lumbar degenerative disc disease in the United Kingdom.

MATERIALS & METHODS

A Markov decision-analytic model was constructed to calculate costs and quality-adjusted life-years over a 4-year time horizon in each treatment group, from a United Kingdom National Health Service perspective. An individual patient data meta-analysis was undertaken to synthesize data from four randomized controlled trials and two single-arm studies concerning health-related quality of life and procedural resource use. Current cost data from the United Kingdom were then applied to determine the overall mean cost per patient in each group. One-way and probabilistic sensitivity analyses were undertaken to explore the impact of parameter uncertainty.

RESULTS

The model predicted 4-year discounted cost savings of £192 per patient treated with dibotermin alfa/ACS, compared with ICBG, and a gain of 0.0114 QALYs per patient over the same time period. Sensitivity analyses indicated that the results were most sensitive to variability in the differences in health-related quality of life and secondary surgery rate, with dibotermin alfa/ACS having a 60% probability of being cost-effective at a willingness-to-pay threshold of £20,000 per QALY gained.

LIMITATIONS

There is uncertainty in the difference in cost and QALYs between the two groups. However, comprehensive sensitivity analyses were undertaken to explore this and present the results in a transparent manner.

CONCLUSIONS

Our results provide an economic case for the use of 4 mg dibotermin alfa/ACS versus iliac crest bone graft, with additional health benefits predicted at reduced overall cost.

Osteobiologics

BACKGROUND

Osteobiologics are engineered materials that facilitate bone healing and have been increasingly used in spine surgery. Autologous iliac crest bone grafts have been used historically, but morbidity associated with graft harvesting has led surgeons to seek alternative solutions. Allograft bone, biomaterial scaffolds, growth factors, and stem cells have been explored as bone graft substitutes and supplements.

OBJECTIVE

To review current and emerging osteobiologic technologies.

METHODS

A literature review of English-language studies was performed in PubMed. Search terms included combinations of "spine," "fusion," "osteobiologics," "autologous," "allogen(e)ic," "graft," "scaffold," "bone morphogenic protein," and "stem cells."

RESULTS

Evidence supports allograft bone as an autologous bone supplement or replacement in scenarios where minimal autologous bone is available. There are promising data on ceramics and P-15; however, comparative human trials remain scarce. Growth factors, including recombinant human bone morphogenic proteins (rhBMPs) 2 and 7, have been explored in humans after successful animal trials. Evidence continues to support the use of rhBMP-2 in lumbar fusion in patient populations with poor bone quality or revision surgery, while there is limited evidence for rhBMP-7. Stem cells have been incredibly promising in promoting fusion in animal models, but human trials to this point have only involved products with questionable stem cell content, thereby limiting possible conclusions.

CONCLUSION

Engineered stem cells that overexpress osteoinductive factors are likely the future of spine fusion, but issues with applying viral vector-transduced stem cells in humans have limited progress.

Commercial Bone Grafts Claimed as an Alternative to Autografts: Current Trends for Clinical Applications in Orthopaedics

In the last twenty years, due to an increasing medical and market demand for orthopaedic implants, several grafting options have been developed. However, when alternative bone augmentation materials mimicking autografts are searched on the market, commercially available products may be grouped into three main categories: cellular bone matrices, growth factor enhanced bone grafts, and peptide enhanced xeno-hybrid bone grafts. Firstly, to obtain data for this review, the search engines Google and Bing were employed to acquire information from reports or website portfolios of important competitors in the global bone graft market. Secondly, bibliographic databases such as Medline/PubMed, Web of Science, and Scopus were also employed to analyse data from preclinical/clinical studies performed to evaluate the safety and efficacy of each product released on the market. Here, we discuss several products in terms of osteogenic/osteoinductive/osteoconductive properties, safety, efficacy, and side effects, as well as regulatory issues and costs. Although both positive and negative results were reported in clinical applications for each class of products, to date, peptide enhanced xeno-hybrid bone grafts may represent the best choice in terms of risk/benefit ratio. Nevertheless, more prospective and controlled studies are needed before approval for routine clinical use.

Use of rhBMP-2 for adult spinal deformity surgery: patterns of usage and changes over the past decade

OBJECTIVE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to increase fusion rates; however, cost, limited FDA approval, and possible complications impact its use. Decisions regarding rhBMP-2 use and changes over time have not been well defined. In this study, the authors aimed to assess changes in rhBMP-2 use for adult spinal deformity (ASD) surgery over the past decade.

METHODS

A retrospective review of the International Spine Study Group prospective multicenter database was performed to identify ASD patients treated surgically from 2008 to 2018. For assessment of rhBMP-2 use over time, 3 periods were created: 2008-2011, 2012-2015, and 2016-2018.

RESULTS

Of the patients identified, 1180 met inclusion criteria, with a mean age 60 years and 30% of patients requiring revision surgery; rhBMP-2 was used in 73.9% of patients overall. The mean rhBMP-2 dose per patient was 23.6 mg. Patients receiving rhBMP-2 were older (61 vs 58 years, p < 0.001) and had more comorbidities (Charlson Comorbidity Index 1.9 vs 1.4, p < 0.001), a higher rate of the Scoliosis Research Society-Schwab pelvic tilt modifier (> 0; 68% vs 62%, p = 0.026), a greater deformity correction (change in pelvic incidence minus lumbar lordosis 15° vs 12°, p = 0.01), and more levels fused (8.9 vs 7.9, p = 0.003). Over the 3 time periods, the overall rate of rhBMP-2 use increased and then stabilized (62.5% vs 79% vs 77%). Stratified analysis showed that after an overall increase in rhBMP-2 use, only patients who were younger than 50 years, those who were smokers, those who received a three-column osteotomy (3CO), and patients who underwent revision sustained an increased rate of rhBMP-2 use between the later two periods. No similar increases were noted for older patients, nonsmokers, primary surgery patients, and patients without a 3CO. The total rhBMP-2 dose decreased over time (26.6 mg vs 24.8 mg vs 20.7 mg, p < 0.001). After matching patients by preoperative alignment, 215 patients were included, and a significantly lower rate of complications leading to revision surgery was observed within the 2012-2015 period compared with the 2008-2011 (21.4% vs 13.0%, p = 0.029) period, while rhBMP-2 was increasingly used (80.5% vs 66.0%, p = 0.001). There was a trend toward a lower rate of pseudarthrosis for patients in the 2012-2015 period, but this difference did not reach statistical significance (7% vs 4.2%, p = 0.283).

CONCLUSIONS

The authors found that rhBMP-2 was used in the majority of ASD patients and was more commonly used in those with greater deformity correction. Additionally, over the last 10 years, rhBMP-2 was increasingly used for ASD patients, but the dose has decreased.

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.

Invasive Treatments for Low Back Disorders

OBJECTIVE

This abbreviated version of the American College of Occupational and Environmental Medicine's Low Back Disorders guideline reviews the evidence and recommendations developed for invasive treatments used to manage low back disorders.

METHODS

Comprehensive systematic literature reviews were accomplished with article abstraction, critiquing, grading, evidence table compilation, and guideline finalization by a multidisciplinary expert panel and extensive peer-review to develop evidence-based guidance. Consensus recommendations were formulated when evidence was lacking and often relied on analogy to other disorders for which evidence exists. A total of 47 high-quality and 321 moderate-quality trials were identified for invasive management of low back disorders.

RESULTS

Guidance has been developed for the invasive management of acute, subacute, and chronic low back disorders and rehabilitation. This includes 49 specific recommendations.

CONCLUSION

Quality evidence should guide invasive treatment for all phases of managing low back disorders.

Bone morphogenetic protein-2 against iliac crest bone graft for the posterolateral fusion of the lumbar spine: A meta-analysis

BACKGROUND

The impact of bone morphogenetic protein-2 compared to autologous iliac crest bone graft to improve fusion rates for the posterolateral fusion of the lumbar spine remains inconclusive. This meta-analysis was performed to evaluate this relationship.

METHODS

A systematic literature search up to May 2020 was performed and 14 studies were detected with 1516 subjects with 789 of them were bone morphogenetic protein-2 and 727 of them were autologous iliac crest bone graft. They reported relationships between bone morphogenetic protein-2 and autologous iliac crest bone graft on fusion rates for the posterolateral fusion of the lumbar spine. Odds ratio (OR) with 95% confidence intervals (CIs) was calculated comparing the bone morphogenetic protein-2 or autologous iliac crest bone graft on the posterolateral fusion of the lumbar spine risks using the dichotomous and continuous method with a random- or fixed-effect model.

RESULTS

Bone morphogenetic protein-2 had significantly higher fusion rates (OR, 4.19; 95% CI, 2.82-6.20, P < .001); lower surgery time (OR, -26.64; 95% CI, -38.71 to -14.57, P < .001); lower blood loss (OR, -92.84; 95% CI, -131.71 to -53.97, P < .001); lower additional surgical procedures (OR, 0.46; 95% CI, 0.31-0.69, P < .001) and higher Oswestry Disability Index (OR, 1.49; 95% CI, 0.02-2.97, P = .05) compared to autologous iliac crest bone graft. However, no significant difference was found between bone morphogenetic protein-2 and autologous iliac crest bone graft in non-union rates (OR, 0.34; 95% CI, 0.08-1.53, P < .001); hospitalisation days (OR, -0.21; 95% CI, -0.48 to 0.07, P = .14) and adverse events (OR, 0.78; 95% CI, 0.52-1.16, P = .22).

CONCLUSIONS

Bone morphogenetic protein-2 significantly had a higher fusion rate, lower surgery time, lower blood loss, lower additional surgical procedures and higher Oswestry Disability Index compared to autologous iliac crest bone graft. This relationship forces us to recommend bone morphogenetic protein-2 for the posterolateral fusion of the lumbar spine to avoid any possible negative postoperative results.

Applications of Bone Morphogenetic Proteins in Dentistry: A Bibliometric Analysis

Background

Many articles on bone morphogenetic proteins (BMPs) have been published. Bibliometric analysis is helpful to determine the most influential studies in a specific field. This bibliometric analysis is aimed at identifying and analyzing the top 50 most-cited articles on the dental applications of BMPs.

Methods

An electronic search was conducted using the Web of Science (WoS) “All Databases” without any restriction of language, study design, or publication year. Of 1341 publications, the top 50 were included based on their citation count. After downloading the full texts, their bibliometric data including publication title, authorship, citation count, current citation index 2019, citation density, year of publication, country and institution of origin, journal of publication, type of BMP, study design, evidence level of publication, and keywords were extracted and analyzed.

Results

The citation counts for the top 50 publications ranged from 81 to 557 (median 113.5). The most prolific year was 1997 (n = 7). Wikesjö UM (n = 12) and Wozney JM (n = 11) were the major contributors in this study. Most of the articles were generated primarily from the USA (n = 24), with Loma Linda University Medical Center, USA being the most prolific institution (n = 5). Majority of the articles were published in the Clinical Oral Implants Research and Journal of Periodontology, with nine publications each. Most of the publications were animal studies (n = 30) and focused on BMP-2 (n = 39). Most of the articles were within evidence level V (n = 36). The most frequently used keyword in the top articles was “bone regeneration” (n = 23).

Conclusion

The present study presents insights into the past and recent trends in the applications of BMPs in dentistry. A statistically significant association was observed between citation count, citation density, and age of publication.

Characteristics of Reported Industry Payments to Neurosurgeons: A 5-Year Open Payments Database Study

OBJECTIVE

The aim of this study was to characterize the payments made by medical industry to neurosurgeons from 2014 to 2018.

METHODS

A retrospective study was performed from January 1, 2014 to December 31, 2018 of the Open Payments Database. Collected data included the total number of industry payments, the aggregate value of industry payments, and the mean value of each industry payment made to neurosurgeons per year over the 5-year period.

RESULTS

A total of 105,150 unique surgeons, with 13,668 (12.99%) unique neurosurgeons, were identified to have received an industry payment during 2014-2018. Neurosurgeons were the second highest industry-paid surgical specialty, with a total 421,151 industry payments made to neurosurgeons, totaling $477,451,070. The mean average paid amount per surgeon was $34,932 (±$936,942). The largest proportion of payments were related to food and beverage (75.5%), followed by travel and lodging (14.9%), consulting fees (3.5%), nonconsulting service fees (2.1%), and royalties or licensing (1.9%), totaling 90.4% of all industry payments to neurologic surgeons. Summed across the 5-year period, the largest paid source types were royalties and licensing (64.0%; $305,517,489), consulting fees (11.8%; $56,445,950), nonconsulting service fees (7.3%; $34,629,109), current or prospective investments (6.8%, $32,307,959), and travel and lodging (4.8%, $22,982,165).

CONCLUSIONS

Our study shows that over the most recent 5-year period (2014-2018) of the Centers for Medicare and Medicaid Services Open Payments Database, there was a decreasing trend of the total number of payments, but an increasing trend of the total amount paid to neurosurgeons.

Bone Morphogenetic Protein-2 in Development and Bone Homeostasis

Bone morphogenetic proteins (BMPs) are multi-functional growth factors belonging to the Transforming Growth Factor-Beta (TGF-β) superfamily. These proteins are essential to many developmental processes, including cardiogenesis, neurogenesis, and osteogenesis. Specifically, within the BMP family, Bone Morphogenetic Protein-2 (BMP-2) was the first BMP to be characterized and has been well-studied. BMP-2 has important roles during embryonic development, as well as bone remodeling and homeostasis in adulthood. Some of its specific functions include digit formation and activating osteogenic genes, such as Runt-Related Transcription Factor 2 (RUNX2). Because of its diverse functions and osteogenic potential, the Food and Drug Administration (FDA) approved usage of recombinant human BMP-2 (rhBMP-2) during spinal fusion surgery, tibial shaft repair, and maxillary sinus reconstructive surgery. However, shortly after initial injections of rhBMP-2, several adverse complications were reported, and alternative therapeutics have been developed to limit these side-effects. As the clinical application of BMP-2 is largely implicated in bone, we focus primarily on its role in bone. However, we also describe briefly the role of BMP-2 in development. We then focus on the structure of BMP-2, its activation and regulation signaling pathways, BMP-2 clinical applications, and limitations of using BMP-2 as a therapeutic. Further, this review explores other potential treatments that may be useful in treating bone disorders.

Comparative Clinical Effectiveness and Safety of Bone Morphogenetic Protein Versus Autologous Iliac Crest Bone Graft in Lumbar Fusion: A Meta-analysis and Systematic Review

STUDY DESIGN

This is a systematic literature review and meta-analysis.

OBJECTIVE

We aimed to evaluate the efficacy and safety of recombinant human bone morphogenetic protein (RhBMP) and autologous iliac crest bone graft (ICBG) in lumbar fusion.

SUMMARY OF BACKGROUND DATA

RhBMP has been emphasized in lumbar fusion due to high fusion success rate. However, ICBG remains the criterion standard graft approach for lumbar fusion. The safety and effectiveness of rhBMP are controversial.

METHODS

Prospective randomized controlled trials were searched from PubMed, EMBASE, and Cochrane Central Register of Controlled Trails by using Medical Subject Headings terms "bone morphogenetic protein,' "bone transplantation,' and "spinal fusion.' Two independent investigators screened eligible studies, assessed the bias of original articles, extracted data including fusion success, Oswestry disability index improvement, improved short form 36 questionnaire scores, adverse events and re-operation, and a subgroup analysis. The GRADE approach was used to grade quality of evidence.

RESULTS

Twenty randomized controlled trials (2185 patients) met the inclusion criteria. There were higher fusion success rate (odds ratio [OR] 3.79, 95% confidence interval [CI] 1.88-7.63, P = 0.0002), better improvement of Oswestry Disability Index (mean difference 1.54, 95% CI 0.18-2.89, P = 0.03), and lower re-operation rate (OR 0.59, 95% CI 0.43-0.80, P = 0.0007) in rhBMP group. Heterogeneity was obvious in fusion success rate (I = 58%); hence, a subgroup analysis, based on protein type (rhBMP-2 or rhBMP-7), was performed, which suggested that only rhBMP-2 was better than ICBG for lumbar fusion. There was no difference in the incidence of adverse events between rhBMP and ICBG (OR 0.91, 95% CI 0.70-1.18, P = 0.47).

CONCLUSION

In lumbar fusion, rhBMP-2 exhibited a higher fusion success rate and reduced the risk of re-operation. No difference in complication rate is between rhBMP (rhBMP-2 and rhBMP-7) and ICBG. We suggest rhBMP especially rhBMP-2 as an effective substitute for ICBG for lumbar fusion.

LEVEL OF EVIDENCE

1.

Evaluation of Heterotopic Ossification After Using Recombinant Human Bone Morphogenetic Protein-2 in Transforaminal Lumbar Interbody Fusion: A Computed Tomography Review of 996 Disc Levels

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Reported incidences and complications of heterotopic ossification (HO) after using recombinant human bone morphogenetic protein-2 (rhBMP-2) in transforaminal lumbar interbody fusion (TLIF) have been inconclusive. This study was designed to evaluate both incidences of radiologic and symptomatic HO in a large series of TLIFs using rhBMP-2.

METHODS

A total of 996 disc levels in 927 consecutive TLIF patients were retrospectively evaluated at 6-month postoperative follow-up in a single surgical practice. Subjects were separated into the BMP group and the control group. Operative reports, pre- and postoperative medical records were reviewed. Computed tomography (CT) scans were analyzed and graded independently for ossification at each disc level of TLIF.

RESULTS

A total of 933 disc levels were in the BMP group, and 63 were in the control group. Six-month fusion rate of interbody was 92.5% in the BMP group, which was significantly higher in contrast to 71.4% in the control group (P < .001). The incidence of radiologic HO in the BMP group was 13.5%, which was significantly higher than 1.6% in the control group (P = .006). After controlling for basic demographics and comorbidities, the presence of radiologic HO was significantly associated with the use of rhBMP-2 (P = .026). However, only one case in the BMP group (0.11%) developed a symptomatic HO (mild-medium left buttock pain, treated nonsurgically) involving left foramen of L5-S1.

CONCLUSIONS

rhBMP-2 can be safely used in TLIF with regard to HO. There was a low rate of radiologic HO and minimal symptomatic HO, with high fusion rates at 6 months postoperative.

Clinical experience with the use of a spherical bioactive glass putty for cervical and lumbar interbody fusion

Background

A retrospective clinical case series study was conducted to evaluate the use of a novel, spherical bioactive glass bone graft (BioSphere Putty) as a graft material for cervical and lumbar interbody fusion.

Methods

Data was collected from a single surgeon using BioSphere Putty along with standardized hardware in anterior cervical decompression and fusion (ACDF), transforaminal lumbar interbody fusion (TLIF), and anterior lumbar interbody fusion (ALIF) surgical procedures. BioSphere Putty was used in combination with cancellous allograft (ACDF and ALIF) or in combination with autograft (TLIF). Clinical outcomes were assessed at 1- and 2-year using radiographic imaging and the visual analog pain scale (VAS). VAS scores at the 1- and 2-year follow-up periods were statistically compared to pre-operative scoring. Successful clinical outcomes were determined by a combination of the presence of a complete radiographic fusion and a decrease in VAS at 1-year and 1- and 2-year follow-up periods.

Results

The retrospective review of the patient data identified 248 cases that had either 1- or 1- & 2-year follow-up. This consisted of 115 ACDF procedures and 133 lumbar fusion procedures. Lumbar fusion cases were further sub-grouped with 103 patients undergoing TLIF procedures and 30 patients undergoing ALIF procedures. The global results for the series as a whole showed clinical outcomes comparative to other advanced biologic bone grafts. Radiographically all patients demonstrated fusion (100% fusion rate) and there were no clinical adverse events, infections, or graft-related complications in any of the patients in the series. One-year VAS scores were consistent with historical norms and demonstrated significant decreases in pre-operative pain for both ACDF patients (78% decrease) and lumbar patients (66% decrease TLIF/ALIF) (t test, P<0.05). By 2 years, VAS scores continued to drop with significant decreases for the ACDF patients (96%), TLIF patients (82%), and ALIF patients (80%) (t test, P<0.05). VAS scores were also assessed for each individual patient. The data showed a VAS score decrease from pre-operative levels in 93% of the ACDF patients and 89% of the lumbar patients. Combined with the 100% radiographic fusion rate in all patients, this resulted in a in a clinical success rate of 93% for the ACDF patients and 89% for the lumbar patients.

Conclusions

The results of this clinical case series demonstrated that BioSphere Putty is a clinically effective and versatile synthetic bone graft material in the spine.

Fusion rate and influence of surgery-related factors in lumbar interbody arthrodesis for degenerative spine diseases: a meta-analysis and systematic review

The aim of this meta-analysis and systematic review is to summarize and critically analyze the influence of surgery-related factors in lumbar interbody fusion for degenerative spine diseases. A systematic review of the literature was carried out with a primary search being performed on Medline through PubMed. The 2009 PRISMA flowchart and checklist were taken into account. Sixty-seven articles were included in the analysis: 48 studies were level IV of evidence, whereas 19 were level III. All interbody fusion techniques analyzed have proved to reach a good fusion rate. An overall mean fusion rate of 93% (95% CI 92-95%, p < 0.001) was estimated pooling the selected studies. The influence of sagittal parameters and cages features in fusion rate was not clear. Autograft is considered the gold standard material. The use of synthetic bone substitutes and biological factors alone or combined with bone graft have shown conflicting results. Low level of evidence studies and high heterogeneity (χ² = 271.4, df = 72, p < 0.001; I² = 73.5%, τ² = 0.05) in data analysis could result in the risk of bias. Further high-quality studies would better clarify these results in the future.

Efficacy and safety of bone substitutes in lumbar spinal fusion: a systematic review and network meta-analysis of randomized controlled trials

PURPOSE

A variety of alternative grafts to autologous iliac crest bone (ICBG) have been developed for lumbar spondylodesis, due to frequent complications following ICBG harvest. The optimal alternative graft to ICBG, however, remains elusive till now. The purpose of this study was to compare the efficacy and safety of fusion materials in lumbar degeneration diseases and to provide a ranking spectrum of the grafts.

METHODS

Randomized controlled trials (RCTs) comparing different bone grafts in lumbar arthrodesis were eligible for inclusion. A network meta-analysis was performed for endpoints including fusion rate and incidence of adverse events.

RESULTS

Twenty-seven RCTs involving 2488 patients and 13 available interventions were included. rhBMP-2 provided the highest fusion rate, being significantly superior to that of ICBG (OR = 0.21, p < 0.001), autograft local bone (ALB) (OR = 0.18, p = 0.022), rhBMP-7 (OR = 0.15, p < 0.001), allograft (OR = 0.13, p = 0.009), and DBM + ALB (OR = 0.07, p = 0.048). The treatment efficacy of allograft could be significantly enhanced by bone marrow concentrate (BMC) supplying (OR = 0.16, p = 0.010). ICBG ranks second on the frequency of complications, which is significantly higher than that of allograft (OR = 0.14, p = 0.041) and ALB (OR = 0.14, p = 0.030). All of the other comparisons showed similar efficacy and safety profiles between groups.

CONCLUSION

Ranking spectrums of the efficacy and safety for various bone grafts were provided graphically. Though rhBMP-2 was of the highest success rate, the application should be taken with proper caution because of the widely proposed life-threatening adverse events. ALB, ALB plus synthetic ceramic materials and allograft mixed with BMC were also proved to be potentially effective alternative graft to ICBG. These slides can be retrieved under Electronic Supplementary Material.

rhBMP-2 (Recombinant Human Bone Morphogenetic Protein-2) in real world spine surgery. A phase IV, National, multicentre, retrospective study collecting data from patient medical files in French spinal centres

BACKGROUND

This is a Phase IV, national, multicentre, retrospective study to observe the real-world use of rhBMP-2 in France.

HYPOTHESIS

There was no statistical hypothesis, the statistical analyses were descriptive in nature.

PATIENTS AND METHODS

Data was collected from patient medical files in 10 French spinal centres. Primary objectives were to understand which patients were treated with rhBMP-2, commercialised in Europe as InductOs™ and how rhBMP-2 was used during spinal fusion surgery in France between 2011 and 2012.

RESULTS

Four hundred patients (634 levels) treated with rhBMP-2 were included in the analysis. The most frequent primary diagnostic indication for rhBMP-2 use was degenerative disc disease (DDD; 129/400; 32.3% of patients) followed by spondylolisthesis (119/400; 29.8%), deformity (59/400; 14.8%) and pseudoarthrosis (29/400; 7.3%). The most frequently treated level was L4-L5 (33.8% of levels in 53.5% of patients); followed by L5-S1 (29.8%, 47.3%), L3-L4 (16.7%, 26.5%), and L2-L3 (7.3%, 11.5%), all other levels (less than 5% of patients). No interbody fusion device was used in 42.7% of levels. Wetted matrix of rhBMP-2 was placed in the interbody space in 58.4% of levels (370/634). The most common procedure for rhBMP-2 treatment was posterior lumbar fusion (PLF) (221/634; 34.9% of levels), followed by anterior lumbar interbody fusion (ALIF) (188/634; 29.7%), posterior lumbar interbody fusion (PLIF) (111/634; 17.5%), lateral lumbar interbody fusion (LLIF) (106/634; 16.7%), transforaminal lumbar interbody fusion (TLIF) (4/634; 0.6%) and 'other' (4/634; 0.6%). Thirty-one adverse events of Interest (AEI) were recorded in 27 patients. One AEI was considered related to rhBMP-2. Unplanned secondary spine interventions at index level treated with rhBMP-2 were required in 4 patients.

DISCUSSION

In years 2011 and 2012 when the surgeries captured in this retrospective study were done, rhBMP-2 was indicated for single level (L4-S1) anterior lumbar spine fusion as a substitute for autogenous bone graft in adults with DDD. The most common procedure for the treatment with rhBMP-2 was PLF (off-label use), followed by ALIF (on-label use). The safety findings confirm a predictable and manageable safety profile.

LEVEL OF EVIDENCE

IV.

Collagen Type I: A Versatile Biomaterial

Collagen type I is the most abundant matrix protein in the human body and is highly demanded in tissue engineering, regenerative medicine, and pharmaceutical applications. To meet the uprising demand in biomedical applications, collagen type I has been isolated from mammalians (bovine, porcine, goat and rat) and non-mammalians (fish, amphibian, and sea plant) source using various extraction techniques. Recent advancement enables fabrication of collagen scaffolds in multiple forms such as film, sponge, and hydrogel, with or without other biomaterials. The scaffolds are extensively used to develop tissue substitutes in regenerating or repairing diseased or damaged tissues. The 3D scaffolds are also used to develop in vitro model and as a vehicle for delivering drugs or active compounds.

Minimally Effective Dose of Bone Morphogenetic Protein in Minimally Invasive Lumbar Interbody Fusions: Six Hundred Ninety Patients in a Dose-Finding Longitudinal Cohort Study

STUDY DESIGN

Retrospective longitudinal cohort.

OBJECTIVE

We sought to demonstrate the minimally effective bone morphogenetic protein (BMP) dose to achieve fusion in minimally invasive transforaminal lumbar interbody fusions.

SUMMARY OF BACKGROUND DATA

Multiple studies have been conducted, which used a wide range of BMP doses for lumbar fusions highlighting associated risks and benefits. There is, however, a paucity in the literature in determining the minimally effective dose.

METHODS

Consecutive patients who underwent transforaminal lumbar interbody fusion from 2009 to 2014 were reviewed. Fusion was determined by a combination of computed tomography and dynamic x-ray by independent radiologists. We used backward stepwise multiple logistic regression with fusion as the dependent variable to determine whether BMP dose/level was a significant predictor for fusion. To determine the minimally effective dose of BMP/level, separate logistic regressions for different BMP dose ranges and sensitivity analyses were used. A P value ≤0.025 was considered significant.

RESULTS

There were 1102 interspaces among 690 patients. Average BMP dose was 1.28 mg/level. Overall fusion was 95.2% with a mean follow-up of 19 months. BMP dose/level was a significant predictor for fusion. Odds of fusion increased by 2.02 when BMP dose range was increased from (0.16-1 mg/level) to (1.0-2 mg/level), but fusion odds did not increase when BMP dose increased to more than 2 mg/level.

CONCLUSION

BMP dose/level was a significant predictor for fusion. There was a significant increase in odds of fusion when BMP dose increased from 0.16 to 1 mg/level to 1.0 to 2 mg/level. No benefit from increasing the dose more than 2 mg/level was found, suggesting 1.0 mg/level to be the minimally effective BMP dose.

LEVEL OF EVIDENCE

3.

Impact of Iliac Crest Bone Grafting on Postoperative Outcomes and Complication Rates Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

OBJECTIVE

The relationship between bone graft technique and postoperative outcomes for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has not been well-defined. This study aims to determine the effect of iliac crest bone grafting (ICBG) on patient-reported outcomes (PROs) and complication rates following MIS TLIF.

METHODS

Primary, single-level MIS TLIF patients were consecutively analyzed. Patients that prospectively received a percutaneous technique of ICBG were compared to patients that retrospectively received bone morphogenetic protein-2 (BMP-2). Complication rates were assessed perioperatively and up to 1 year postoperatively. Changes in Oswestry Disability Index (ODI), visual analogue scale (VAS) back, and VAS leg pain were compared. Rates of minimum clinically important difference (MCID) achievement at final follow-up for ODI, VAS back, and VAS leg scores were compared.

RESULTS

One hundred forty-nine patients were included: 101 in the BMP-2 cohort and 48 in the ICBG cohort. The ICBG cohort demonstrated increases in intraoperative blood loss and shorter lengths of stay. ICBG patients also experienced longer operative times, though this did not reach statistical significance. No significant differences in complication or reoperation rates were identified. The ICBG cohort demonstrated greater improvements in VAS leg pain at 6-week and 12-week follow-up. No other significant differences in PROs or MCID achievement rates were identified.

CONCLUSION

Patients undergoing MIS TLIF with ICBG experienced clinically insignificant increases in intraoperative blood loss and did not experience increases in postoperative pain or disability. Complication and reoperation rates were similar between groups. These results suggest that ICBG is a safe option for MIS TLIF.

The Use of Bone Morphogenetic Protein in the Intervertebral Disk Space in Minimally Invasive Transforaminal Lumbar Interbody Fusion: 10-year Experience in 688 Patients

STUDY DESIGN

Retrospective Cohort.

OBJECTIVE

The objective of this study was to characterize one surgeon's experience over a 10-year period using rhBMP-2 in the disk space for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

MIS TLIF has been utilized as a technique for decreasing patients' immediate postoperative pain, decreasing blood loss, and shortened hospital stays. Effectiveness and complications of rhBMP-2's use in the disk space is limited because of its off-label status.

METHODS

Retrospective analysis of consecutive MIS TLIFs performed by senior author between 2004 and 2014. rhBMP-2 was used in the disk space in all cases. Patients were stratified based on the dose of rhBMP-2 utilized. Patients had 9 to 12 month computerized tomography scan to evaluate for bony fusion and continued follow-up for 18 months.

RESULTS

A total of 688 patients underwent a MIS TLIF. A medium kit of rhBMP-2 was utilized in 97 patients, and small kit was used in 591 patients. Fusion rate was 97.9% and this was not different between the 2 groups with 96/97 patients fusing in the medium kit group and 577/591 patients fusing in the small kit group. Five patients taken back to the operating room for symptomatic pseudoarthrosis, 4 reoperated for bony hyperostosis, and 10 radiographic pseudoarthroses that did not require reoperation. A statistically significant difference in the rate of foraminal hyperostosis was found when using a medium sized kit of rhBMP-2 was 4.12% (4/97 patients), compared with a small kit (0/591 patients, P=0.0004).

CONCLUSIONS

Utilization of rhBMP-2 in an MIS TLIF leads to high fusion rate (97.9%), with an acceptable complication profile. The development of foraminal hyperostosis is a rare complication that only affected 0.6% of patients, and seems to be a dose related complication, as this complication was eliminated when a lower dose of rhBMP-2 was utilized.

LEVEL OF EVIDENCE

Level IV.

Prospective Evaluation of Radiculitis following Bone Morphogenetic Protein-2 Use for Transforaminal Interbody Arthrodesis in Spine Surgery

Study Design

Prospective observational cohort study.

Purpose

This study aims to evaluate the safety and efficacy of bone morphogenetic protein-2 (BMP-2) in transforaminal lumbar interbody fusion (TLIF) with regard to postoperative radiculitis.

Overview of Literature

Bone morphogenetic protein (BMP) is being used increasingly as an alternative to iliac crest autograft in spinal arthrodesis. Recently, the use of BMP in TLIF has been examined, but concerns exist that the placement of BMP close to the nerve roots may cause postoperative radiculitis. Furthermore, prospective studies regarding the use of BMP in TLIF are lacking.

Methods

This prospective study included 77 patients. The use of BMP-2 was determined individually, and demographic and operative characteristics were recorded. Leg pain was assessed using the Visual Analog Scale (VAS) for pain and the Sciatica Bothersome Index (SBI) with several secondary outcome measures. The outcome data were collected at each follow-up visit.

Results

Among the 77 patients, 29 were administered with BMP. Postoperative leg pain significantly improved according to VAS leg and SBI scores for the entire cohort, and no clinically significant differences were observed between the BMP and control groups. The VAS back, Oswestry Disability Index, and Short-Form 36 scores also significantly improved. A significantly increased 6-month fusion rate was noted in the BMP group (82.8% vs. 55.3%), but no significant differences in fusion rate were observed at the 12- and 24-month follow-up. Heterotopic ossification was observed in seven patients: six patients and one patient in the BMP and control groups, respectively (20.7% vs. 2.1%). However, no clinical effect was observed.

Conclusions

In this prospective observational trial, the use of BMP in TLIF did not lead to significant postoperative radiculitis, as measured by VAS leg and SBI scores. Back pain and other functional outcome scores also improved, and no differences existed between the BMP and control groups. The careful use of BMP in TLIF appears to be both safe and effective.

Postoperative Seroma Formation After Posterior Cervical Fusion with Use of RhBMP-2: A Report of Two Cases

CASE

We present 2 cases of postoperative seroma formation following posterior cervical fusion with the use of recombinant human bone morphogenetic protein-2 (rhBMP-2).

CONCLUSION

Although some who advocate for the off-label use of rhBMP-2 in patients undergoing posterior cervical spine fusion believe it to be safe, relatively little has been published regarding complication rates. We believe that rhBMP-2 carries a risk of seroma formation in patients who undergo posterior cervical fusion, which necessitates the use of a postoperative drain. Surgeons should have a low threshold for obtaining postoperative magnetic resonance imaging in a symptomatic patient.

Does Recombinant Human Bone Morphogenic Protein 2 Affect Perioperative Blood Loss after Lumbar and Thoracic Spinal Fusion?

STUDY DESIGN

Retrospective cohort design.

PURPOSE

This study aimed to determine whether recombinant human bone morphogenic protein 2 (rhBMP-2) reduces total perioperative blood loss during lumbar and thoracic fusion.

OVERVIEW OF LITERATURE

Previous studies on rhBMP-2 versus iliac crest bone grafting in thoracic and lumbar fusions have yielded mixed results regarding reductions in blood loss and have largely neglected the postoperative period when analyzing total blood loss. Additionally, these studies have been limited by heterogeneity and sample size.

METHODS

We analyzed the blood loss patterns of 617 consecutive adult patients undergoing lumbar and/or thoracic fusions requiring subfascial drain placement at a single institution from January 2009 to December 2016. Patients were divided into BMP and non-BMP cohorts, and a propensity score analysis was conducted to account for the differences between cohorts.

RESULTS

At a per-level fused basis, the BMP group exhibited a significant reduction in the intraoperative (66.1 mL per-level fused basis; 95% confidence interval [CI], 127.9 to 4.25 mL; p =0.036) and total perioperative blood loss (100.7 mL per-level fused basis; 95% CI, 200.9 to 0.5 mL; p =0.049). However, no significant differences were observed in an analysis when not controlling for the number of levels or when examining the postoperative drain output.

CONCLUSIONS

RhBMP-2 appears to reduce both intraoperative and total blood loss during lumbar and thoracic fusions on a per-level fused basis. This total reduction in blood loss was achieved via intraoperative effects because RhBMP-2 had no significant effect on the postoperative drain output.

Alternatives to Autologous Bone Graft in Alveolar Cleft Reconstruction: The State of Alveolar Tissue Engineering

Alveolar cleft reconstruction has historically relied on autologous iliac crest bone grafting (ICBG), but donor site morbidity, pain, and prolonged hospitalization have prompted the search for bone graft substitutes. The authors evaluated bone graft substitutes with the highest levels of evidence, and highlight the products that show promise in alveolar cleft repair and in maxillary augmentation. This comprehensive review guides the craniofacial surgeon toward safe and informed utilization of biomaterials in the alveolar cleft.A literature search was performed to identify in vitro human studies that fulfilled the following criteria: Level I or Level II of evidence, ≥30 subjects, and a direct comparison between a autologous bone graft and a bone graft substitute. A second literature search was performed that captured all studies, regardless of level of evidence, which evaluated bone graft substitutes for alveolar cleft repair or alveolar augmentation for dental implants. Adverse events for each of these products were tabulated as well.Sixteen studies featuring 6 bone graft substitutes: hydroxyapatite, demineralized bone matrix (DBM), β-tricalcium phosphate (TCP), calcium phosphate, recombinant human bone morphogenic protein-2 (rhBMP-2), and rhBMP7 fit the inclusion criteria for the first search. Through our second search, the authors found that DBM, TCP, rhBMP-2, and rhBMP7 have been studied most extensively in the alveolar cleft literature, though frequently in studies using less rigorous methodology (Level III evidence or below). rhBMP-2 was the best studied and showed comparable efficacy to ICBG in terms of volume of bone regeneration, bone density, and capacity to accommodate tooth eruption within the graft site. Pricing for products ranged from $290 to $3110 per 5 mL.The balance between innovation and safety is a complex process requiring constant vigilance and evaluation. Here, the authors profile several bone graft substitutes that demonstrate the most promise in alveolar cleft reconstruction.

Heterotopic ossification following use of i-Factor for spinal fusion in Mucopolysaccharidosis 1: a case report

Mucopolysaccharidosis is a rare group of genetic disorder which results in a complex of anomalies involving various systems. In Mucopolysaccharidosis 1 progressive thoracolumbar kyphosis is a common presentation which can result in instability and neurological deficit. Posterior spinal surgery is performed to correct deformity and obtain spinal fusion. Peptide enhanced bone graft substitute (i-Factor^TM) is relatively a new component with proven efficacy to obtain early spinal fusion. An 8-year-old child with progressive high lumbar kyphosis due to Mucopolysaccharidosis 1 was admitted for Posterior spinal fusion with i-Factor bone graft substitute. Postoperatively patient had serous discharge from the wound which settled without intervention. A month after the surgery spinal radiographs revealed heterotopic ossification at the distal end of spinal construct in the paraspinal region. Patient remained asymptomatic and clinically well.

Abundant heterotopic bone formation following use of rhBMP-2 in the treatment of acetabular bone defects during revision hip arthroplasty

Revision hip arthroplasty in the setting of periacetabular bone loss presents a significant challenge, as options for restoring bone loss are limited. Recombinant human bone morphogenetic protein-2 may offer a solution by promoting bone growth to restore bone stock before implant reimplantation. Here we present a case of a patient with a periprosthetic acetabulum fracture, resulting in pelvic discontinuity as the result of significant periacetabular bone loss. Using a staged approach, periacetabular bone stock was nearly entirely reconstituted using recombinant BMPs and allograft, which resulted in stable fixation, but with abundant heterotopic bone formation. Recombinant BMP-2 offers a useful tool for restoring bone stock in complex hip arthroplasty revision cases with periacetabular bone loss; however, caution must be used as overabundant bone growth as heterotopic ossification may result.

Long-term Radiological and Clinical Outcomes After Using Bone Marrow Mesenchymal Stem Cells Concentrate Obtained With Selective Retention Cell Technology in Posterolateral Spinal Fusion

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to evaluate the long-term clinical and radiological outcomes of the use of bone marrow mesenchymal stem cell concentrate obtained with selective cell retention technology using Cellect with a particular collagen scaffold, Healos for posterolateral spinal fusion.

SUMMARY OF BACKGROUND DATA

With the increasing rate of spinal fusion, the problem of pseudarthrosis, which contributes to recurrent pain with patient disability, is considered to be the most common cause of revision lumbar spine surgery. Intensive research is being carried out to develop an alternative source of bone grafting and improve the spinal fusion rate.

METHODS

A retrospective review of hospital records was performed. Identified patients were contacted to have a clinical and radiological evaluation follow-up. Clinical outcome was evaluated using visual analog scales for the back pain (VAS), Oswestry Disability Index (ODI) scores, and quality of life (EQ-5D) questionnaire. Radiological outcome was evaluated by performing dynamic flexion/extension lateral views and calculation of segmental Cobb angle. Any implant-associated complication was reported. Computed tomography (CT) scans were also performed.

RESULTS

Twenty-one patients were included and all patients achieved successful fusion. The mean difference of the segmental Cobb angle was 0.48° (range 0.3°-0.7°). Computed tomography scans showed solid bilateral fusion with bridging bone (Grade I) in all patients, but solid unilateral fusion with bridging bone (Grade II) was detected for one patient at one level. Patients started to resume working activities within a mean period of 3.5 months. The VAS score for the residual back pain was 4.1 ± 2.1, whereas the ODI was 10.5 ± 5.6 points, and the mean disability index was 21.1%.

CONCLUSION

The use of bone marrow mesenchymal stem cell concentrate obtained with selective cell retention technology could be considered as an effective means for augmenting spinal fusion.

LEVEL OF EVIDENCE

3.

Bone Morphogenetic Protein Usage in Anterior Lumbar Interbody Fusion: What Else Can Go Wrong?

BACKGROUND

Bone morphogenetic protein (BMP) graft showed promising outcome during early phases of its use. However, unreported adverse events and off-label use shattered its safe profile and raised concerns regarding its indication. In 2008 the U.S. Food and Drug Administration prohibited its use in anterior cervical spine procedures due to the possibility of edema, hematoma, and need to intubate. At the molecular level, BMPs act as multifactorial growth factors playing a role in cartilage, heart, and bone formation. However, its unfavorable effect on bone overgrowth or heterotopic ossification post spine surgeries has been described. Reported cases in the literature were limited to epidural bone formation.

CASE DESCRIPTION

We present a rare and interesting case of a 59-year-old female, in whom BMP caused intradural bone growth several years after an anterior lumbar interbody fusion surgery.

CONCLUSION

Caution must be exercised while using BMPs because of inadvertent complications.

An effective delivery vehicle of demineralized bone matrix incorporated with engineered collagen-binding human bone morphogenetic protein-2 to accelerate spinal fusion at low dose

The aim of this study was to investigate the feasibility and efficacy of a new delivery matrix using demineralized bone matrix (DBM) incorporated with collagen-binding bone morphogenetic protein-2 (CBD-BMP-2) in the rat inter-transverse spinal fusion model. Sixty rats undergoing posterolateral (inter-transverse) spinal fusion were divided into 3 groups according to the fusion materials containing different components (n = 20 per group). Group A were implanted with DBM, Group B with combination of DBM and BMP-2 and Group C with combination of DBM and CBD-BMP-2. After surgery, the spinal fusion of all the rats was assessed by plain radiography, CT + 3D reconstruction, manual palpation and histological evaluation. Significant difference was found in terms of solid fusion rate among the three groups, with 95% in Group C, 65% in Group B and 0% in Group A (P < 0.001). Compared with Groups B and A, new bone formation was observed earlier and was obvious larger, trabecular bone microarchitecture assessment was better and bone mineral density was statistically larger in Group C. In addition, more newly woven bone and osteocytes were shown by histological evaluation in Group C at 4 weeks post-operation. The present study showed CBD domain could help BMP-2 to improve the efficiency of posterolateral spinal fusion. DBM scaffold activated by collagen-binding BMP-2 was a feasible and promising bone repair vehicle. The present study showed better results in terms of plain radiography, CT + 3D reconstruction, manual palpation and histological evaluation in the rat inter-transverse spinal fusion model using DBM+CBD-BMP-2, compared with DBM+BMP-2 and DBM alone, indicating DBM scaffold activated by collagen-binding BMP-2 was a feasible and promising bone repair vehicle.

Osteogenic Potential of Tauroursodeoxycholic Acid as an Alternative to rhBMP-2 in a Mouse Spinal Fusion Model

The non-union rate after lumbar spinal fusion is potentially as high as 48%. To support efficient bone regeneration, recombinant human bone morphogenetic protein-2 (rhBMP-2) is commonly used as it is regarded as the most potent bone-inducing molecule. However, recently, there have been increasing concerns on the use of rhBMP-2 such as serious complications, including seroma and heterotopic ossification, and the low quality of bone at the center of fusion mass. Thus, many studies were conducted to find and to develop a potential alternative to rhBMP-2. In this study, we investigated the osteogenic potential of tauroursodeoxycholic acid (TUDCA) in the mouse fusion model and compared its effects with rhBMP-2. Twenty-four mice underwent bilateral posterolateral lumbar spinal fusion bone formation at L4-L5. Collagen sponge infused with saline, TUDCA, or rhBMP-2 was implanted at the fusion area. Two and 4 weeks postimplantation, bone formation and tissue regeneration were evaluated via micro-computed tomography and histological analysis. Compared with the TUDCA-treated group, the rhBMP-2 treatment produced a higher amount of bone fusion formation after 2 weeks but also showed higher resorption of the centralized bone after 4 weeks. Interestingly, the TUDCA-treated group developed higher trabecular thickness compared with rhBMP-2 after 4 weeks. Moreover, TUDCA treatment showed distinct angiogenic activity in human umbilical vein endothelial cells as confirmed by an in vitro tube formation assay. Our findings suggest that TUDCA is comparable to rhBMP-2 in supporting bone regeneration and spinal bone formation fusion by increasing trabecular thickness and promoting angiogenesis. Finally, our results indicate that TUDCA can be utilized as a potential alternative to rhBMP-2.

Characteristics and Efficacy of a New 3-Dimensional Printed Mesh Structure Titanium Alloy Spacer for Posterior Lumbar Interbody Fusion

This study evaluated the characteristics of a newly developed 3-dimensional printed mesh structure titanium spacer and its efficacy for posterior lumbar interbody fusion. Posterior lumbar interbody fusion with this spacer was performed at 53 segments (40 patients; mean age, 64 years; range, 51-73 years). Data were collected prospectively. Radiographic characteristics were analyzed with changes in interbody height, instability of the segments, formation of bone bridges around the implants, and pseudarthrosis, as determined by dynamic radiographs and postoperative computed tomography scans. Clinical outcomes were evaluated with the visual analog scale for the low back and extremities, the Oswestry Disability Index, and the 36-Item Short Form Survey. Radiographically, preoperative anterior and posterior interbody height was significantly increased immediately postoperatively (P<.05), and this increase was maintained until the last follow-up. No segmental motion of 3° or greater was noted at the last follow-up. Sagittal computed tomography images showed complete anterior bone bridges for 94.3% of cases and complete posterior bone bridges for 86.7% of cases. Coronal computed tomography images showed bilateral complete bone bridges for 94.3% of cases and unilateral bone bridges for 5.7% of cases without incomplete bilateral bone bridges. No pseudarthrosis or revision, particularly including posterior lumbar interbody fusion at L5-S1, was noted. Compared with preoperative values, the visual analog scale score for the low back and extremities, the Oswestry Disability Index, and the 36-Item Short Form Survey score showed significant improvement at the last follow-up (P<.05). Posterior lumbar interbody fusion with a newly developed 3-dimensional printed mesh structure titanium spacer showed satisfactory radiographic and clinical results, with no cases of pseudarthrosis or revision, including posterior lumbar interbody fusion at L5-S1. [Orthopedics. 2017; 40(5):e880-e885.].

Neuroforaminal Bone Growth Following Minimally Invasive Transforaminal Lumbar Interbody Fusion With BMP: A Computed Tomographic Analysis

STUDY DESIGN

Computed tomographic analysis.

OBJECTIVE

To identify radiographic patterns of symptomatic neuroforaminal bone growth (NFB) in patients who have undergone a single-level minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) augmented with bone morphogenetic proteins (BMP) utilizing computed tomography (CT).

SUMMARY OF BACKGROUND DATA

BMP induces osteoblast differentiation leading to new bone formation. The association of BMP utilization and heterotopic bone formation after an MIS-TLIF has been described. However, studies have been limited in their patient population and details regarding diagnosis and treatment of NFB.

MATERIALS AND METHODS

Postoperative CT scans of the symptomatic and asymptomatic patients were analyzed to identify patterns of heterotopic bone growth on axial and sagittal views. The area of bone growth at the disk level, lateral recess, adjacent foramen, and retrovertebral area were measured. Mann-Whitney U test was used to compare the areas of bone growth between cohorts.

RESULTS

Postoperative CT images between 18 symptomatic and 13 asymptomatic patients were compared. On axial views, the symptomatic patients demonstrated greater areas of bone growth at the disk level (164.0±92.4 vs. 77.0±104.9 mm), and lateral recess (69.6±70.5 and 5.9±12.5 mm) as well as in the total cross-sectional area (290.3±162.1 vs. 119.4±115.6 mm). On sagittal imaging, the mean bone growth at the subarticular level (148.7±185.1 vs. 35.8±37.4 mm) and the total cross-sectional area (298.4±324.4 vs. 85.8±76.3 mm) were greater in symptomatic patients (P<0.01). Amount of BMP utilized and operative levels were no different between cohorts.

CONCLUSIONS

The findings of the present study suggest that an anatomic association exists between recalcitrant postoperative radiculopathy and NFB following an MIS-TLIF with BMP. Increased total bone growth as measured on serial axial and sagittal sections was associated with postoperative radiculopathy. The association between radiculopathy and the extension of BMP-induced bone growth toward the traversing nerve root appeared the most significant.

Bone Morphogenic Protein Use in Spinal Surgery

Bone morphogenic protein (BMP) provides excellent enhancement of fusion in many spinal surgeries. BMP should be a cautionary tale about the use of industry-sponsored research, perceived conflicts of interest, and holding the field of spinal surgery to the highest academic scrutiny and ethical standards. In the case of BMP, not having a transparent base of literature as it was approved led to delays in allowing this superior technology to help patients.

Formulation, Delivery and Stability of Bone Morphogenetic Proteins for Effective Bone Regeneration

Bone morphogenetic proteins (BMPs) are responsible for bone formation during embryogenesis and bone regeneration and remodeling. The osteoinductive action of BMPs, especially BMP-2 and BMP-7, has led to their use in a range of insurmountable treatments where intervention is required for effective bone regeneration. Introduction of BMP products to the market, however, was not without reports of multiple complications and side effects. Aiming for optimization of the therapeutic efficacy and safety, efforts have been focused on improving the delivery of BMPs to lower the administered dose, localize the protein, and prolong its retention time at the site of action. A major challenge with these efforts is that the protein stability should be maintained. With this review we attempt to shed light on how the stability of BMPs can be affected in the formulation and delivery processes. We first provide a short overview of the current standing of the complications experienced with BMP products. We then discuss the different delivery parameters studied in association with BMPs, and their influence on the efficacy and safety of BMP treatments. In particular, the literature addressing the stability of BMPs and their possible interactions with components of the delivery system as well as their sensitivity to conditions of the formulation process is reviewed. In summary, recent developments in the fields of bioengineering and biopharmaceuticals suggest that a good understanding of the relationship between the formulation/delivery conditions and the stability of growth factors such as BMPs is a prerequisite for a safe and effective treatment.

BMP-2-induced bone formation and neural inflammation

Bone morphogenetic protein-2 (BMP-2), a potent osteoinductive cytokine from the transforming growth factor beta (TGF-β) family, is currently the most commonly used protein-based bone graft substitute. Although clinical use of BMP-2 has significantly increased in recent years, its prominence has also highlighted various adverse events, including induction of inflammation. This review will elucidate the relationship between BMP-2 and inflammation, with an emphasis on peripheral nerve inflammation and its sequelae. As well, we review the potential additive roles of nerve released factors with BMP2 in the context of bone formation.

Feasibility of Percutaneous Posterolateral Spinal Fusion With Recombinant Bone Morphogenetic Protein-2 (rhBMP-2): A Comparison With Standard Methods Using an Animal Model Study

BACKGROUND CONTEXT

The clinical application of recombinant bone morphogenetic protein in spinal surgery has been shown to be safe and effective. However, its use in minimally invasive spine surgery has been limited to anterior interbody fusion procedures. To date, no study has evaluated the feasibility of percutaneous posterolateral fusion in the spine utilizing recombinant bone morphogenetic protein-2 (rhBMP-2).

PURPOSE

To evaluate the feasibility of percutaneous posterolateral fusion in the spine utilizing rhBMP-2.

STUDY DESIGN

Animal study.

METHODS

This is an animal research model involving 32 New Zealand white rabbits stratified into 4 study groups: control, autogenous iliac crest bone graft (ICBG), demineralized bone matrix (DBM), and rhBMP-2 groups, with 8 study subjects per group. The rhBMP-2 group was subdivided into the open technique (right side) and the percutaneous technique groups (left side). Fusion was graded at 6 weeks and 3 months after plain radiography, computed tomography, and clinical assessment with the following grading system: grade A, no bone formation; grade B, non-bridging bone formation; grade C, fusion; and grade D, fusion with ectopic bone formation.

RESULTS

No fusion was noted in the placebo and the DBM groups. However, in the DBM group, bone formation occurred in 37.5% of the subjects. The rhBMP-2 group had a higher fusion rate compared with the ICBG group at 6 weeks and 3 months. The fusion rate for the ICBG, the rhBMP-2 (open), and the rhBMP-2 (percutaneous) groups were 37.5%, 87.5%, and 50.0% at 6 weeks and 50.0%, 100.0%, and 62.5% at 3 months, respectively. Ectopic bone formation occurred in 12.5% of the cases in the rhBMP-2 (percutaneous) group and in 25.0% of the cases in the rhBMP-2 (open) group.

CONCLUSIONS

Usage of rhBMP-2 is feasible for percutaneous posterolateral fusion of the lumbar spine in this animal model. However, a more precise delivery system might improve the fusion rate when the percutaneous technique is used. A significant rate of ectopic bone formation occurred when rhBMP-2 was used.

Complications Associated With Bone Morphogenetic Protein in the Lumbar Spine

Complications associated with the use of recombinant human bone morphogenetic protein in the lumbar spine include retrograde ejaculation, ectopic bone formation, vertebral osteolysis and subsidence, postoperative radiculitis, and hematoma and seroma. These complications are controversial and remain widely debated. This article discusses the reported complications and possible implications for the practicing spine surgeon. Understanding the complications associated with the use of recombinant human bone morphogenetic protein and the associated controversies allows for informed decision making by both the patient and the surgeon. [Orthopedics. 2017; 40(2):e229-e237.].