Prevalence, complications, and hospital charges associated with use of bone-morphogenetic proteins in spinal fusion procedures

Perspectives on treatment decision-making across racial groups in adults with degenerative lumbar disease - A pilot study

Introduction

Degenerative lumbar spine disease significantly impairs quality of life, yet racial and socioeconomic disparities in surgical treatment persist, particularly among BIPOC (Black, Indigenous, and Persons of Color) patients, who often experience worse outcomes and are less likely to undergo surgery despite similar or higher pain levels.

Objectives

This study explored factors that influence treatment decisions among BIPOC and Non-Hispanic White (NHW) patients with degenerative lumbar spine disease, with a focus on understanding how these factors may contribute to disparities in surgical care utilization.

Methods

An explorative qualitative study was conducted using semi-structured interviews with 20 patients (10 BIPOC, 10 NHW) considering lumbar spine surgery for spinal stenosis or disc herniation at three major academic institutions in Massachusetts. Thematic analysis identified key themes related to emotional suffering, financial concerns, support systems, and familiarity with spine surgery.

Results

BIPOC patients expressed greater anxiety about surgery, often shaped by prior negative healthcare experiences and broader systemic mistrust. Financial and occupational concerns were more significant for BIPOC patients, who frequently prioritized employment over symptom relief. In contrast, NHW patients more often cited quality-of-life goals as their primary motivator. While perception of support systems were comparable between the groups, emotional suffering was universally reported emotional suffering, with participants using terms such as "miserable," "scared," "embarrassed," and "ashamed."

Conclusion

Emotional, financial, and trust-related differences shape surgical decision-making among racially and ethnically diverse patients with lumbar spine disease. Incorporating culturally responsive communication strategies and decision aids that address patients fears, values, and social contexts may enhance shared decision-making and promote more equitable access to spine surgery.

Bone morphogenetic protein 2 rescues neurogenic abnormalities and angiogenic factors in mice with bilateral cavernous nerve injury

BACKGROUND

Bone morphogenetic protein 2 (BMP2), a key isoform within the bone morphogenetic protein family, plays a critical role in promoting angiogenesis and peripheral nerve regeneration, but its specific role in neurogenic erectile dysfunction (ED) remains unclear.

AIM

This study aimed to explore the therapeutic efficacy of exogenous recombinant BMP2 protein administration in restoring erectile function in a mouse model of cavernous nerve injury (CNI)-induced ED.

METHODS

Twelve-week-old male C57BL/6 mice were used to evaluate BMP2 expression and erectile function following CNI. Western blotting and immunofluorescence staining were employed to assess BMP2 levels in corpus cavernosum tissues from both sham-operated and CNI-induced ED mice. Erectile function was measured through electrical stimulation of bilateral cavernous nerves, with subsequent intracavernous pressure parameter recordings. Mechanistic investigations included immunofluorescence staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and western blot analysis. Additionally, ex vivo neurite outgrowth assays were conducted using dorsal root ganglia (DRG) and major pelvic ganglia (MPG) tissues.

OUTCOMES

In vivo intracavernous pressure, neurovascular regeneration, proliferation, apoptosis, ex vivo neurite sprouting, and survival signaling were measured.

RESULTS

Bone morphogenetic protein 2 expression was significantly decreased in the corpus cavernosum of CNI mice. Exogenous administration of recombinant BMP2 protein effectively enhanced erectile function in CNI mice, likely through the restoration of endothelial cells, smooth muscle cells, pericytes, and neuronal cells within the corpus cavernosum. Immunofluorescence staining and western blot analysis demonstrated that BMP2 treatment promoted angiogenesis by increasing endothelial cell proliferation and reducing apoptosis in the corpus cavernosum. Furthermore, ex vivo assays revealed that BMP2 promoted neurite sprouting in DRG and MPG tissues exposed to lipopolysaccharide. Mechanistic studies further indicated that BMP2 increased the expression of neurotrophic factors and VEGF, activating the AKT/eNOS signaling pathway.

CLINICAL IMPLICATIONS

Bone morphogenetic protein 2 may be used as a strategy to treat neurogenic ED or other neurovascular diseases.

STRENGTHS AND LIMITATIONS

Bone morphogenetic protein 2 has dual roles in vascular and neuronal development. Our study focused on broadly evaluating the role of BMP2 in neurogenic ED. Future studies will evaluate the nerve regeneration effects and novel signaling pathways of BMP2 in a sciatic nerve injury mouse model. In view of its properties as an angiogenic factor, its dose concentration should be strictly controlled to avoid potential side effects.

CONCLUSIONS

The exogenous administration of recombinant BMP2 protein significantly improved erectile function in CNI mice, suggesting BMP2 as a promising therapeutic candidate for neurogenic ED.

Radiographic and Clinical Comparison of Polyetheretherketone Versus 3D-Printed Titanium Cages in Lumbar Interbody Fusion-A Single Institution's Experience

Background/Objectives: Spinal fusion surgery is an accepted form of management for select patients who suffer from degenerative lumbar disease. The need for cost-effective durable techniques is paramount as our population ages. This study compares the radiographic and clinical outcomes of PEEK and 3D-printed titanium interbody cages. Methods: This study compared two cohorts which underwent either PEEK or 3D-printed titanium (3DPT) interbody fusion at a single institution between 2013 and 2022. The PEEK cohort was a retrospective analysis of a prospectively collected registry. The 3DPT data were prospectively collected. The inclusion criteria were adults >18 years who underwent 1 or 2 level lumbar interbody fusion for degenerative spine disease with at least 6 months follow-up. Patient demographics, radiographs, and PROMs were collected. The cohorts were compared using ANOVA for continuous variables and Fisher's exact test for categorical variables, with significance set to 0.05. Results: The final study included 91 patients, 49 PEEK and 42 3DPT. The 3DPT patients were older (p = 0.047) with increased incidence of hypertension (p < 0.001). The 3DPT patients had less bone morphogenetic protein (BMP) usage (80.9% vs. 54.8%; p = 0.012), but more cellular allograft (p < 0.001). Fusion rate was high for both cohorts, with PEEK at 95.9% and 3DPT at 97.6%. There was no significant difference in reoperation rate. Both the PEEK and 3DPT cohorts demonstrated an improvement in the Oswestry Disability Index (ODI) and EuroQol 5 Dimension (EQ-5D) at 1 and 2 years compared to preoperative baseline. More patients in the 3DPT group met the MCID for EQ-5D at 1 and 2 years compared to PEEK; however, this was not significant (p = 0.350; p = 1.000). Conclusions: The 3DPT interbody provided comparable if not superior fusion properties to the PEEK interbody given the decreased use of BMP. Both cohorts demonstrated similar improvements in ODI and EQ-5D compared to preoperative baseline. These results suggest that 3DPT cages may be a cost-effective alternative in spinal fusion. Further studies utilizing a larger population with higher follow-up rates are indicated to determine the economic and clinical benefits of 3DPT compared to PEEK cages in lumbar fusion surgery.

Disparities Attributable to Sex Differences in 4680 Lumbar Fusion Outcomes

BACKGROUND

While studies have examined the relationship between sex and outcomes after lumbar fusion surgery, few have strictly controlled for other patient-level variables. In this study, we use coarsened exact matching (CEM) to determine the effect of patient-reported sex on spinal fusion outcomes.

METHODS

Outcomes across 4680 consecutive adult single-level, posterior-only lumbar fusions at a multihospital academic medical center were retrospectively assessed. First, univariate analyses were performed to broadly examine the effect of sex on surgical outcomes, uncontrolled for other patient factors. Next, the population was split by sex (male vs. female) and matched 1:1 on demographic and medical factors known to influence outcomes (including age, race, smoking status, and past surgical history) using CEM. CEM effectively controls for confounding variable bias by creating pairs of matched samples and preserving the fidelity of each covariate through binning. Primary outcomes included 30-day and 90-day readmissions, emergency department visits, reoperations, and mortality. Secondary outcomes included discharge disposition and length of hospital stay.

RESULTS

Between otherwise exactly matched male-female pairs, females were less likely to be discharged home (odds ratio 1.70, P < 0.001) and had a longer length of stay (mean: 95.7 vs. 87 hours, P < 0.001). No differences in readmissions or reoperations were observed between matched cohorts.

CONCLUSIONS

Female patients encountered longer hospital stays and higher odds of nonhome discharge after single-level lumbar fusion compared to otherwise exactly matched male patients.

Nanoclay gels attenuate BMP2-associated inflammation and promote chondrogenesis to enhance BMP2-spinal fusion

Bone morphogenetic protein 2 (BMP2) is clinically applied for treating intractable fractures and promoting spinal fusion because of its osteogenic potency. However, adverse effects following the release of supraphysiological doses of BMP2 from collagen carriers are widely reported. Nanoclay gel (NC) is attracting attention as a biomaterial, given the potential for localized efficacy of administered agents. However, the efficacy and mechanism of action of NC/BMP2 remain unclear. This study explored the efficacy of NC as a BMP2 carrier in bone regeneration and the enhancement mechanism. Subfascial implantation of NC containing BMP2 elicited superior bone formation compared with collagen sponge (CS). Cartilage was uniformly formed inside the NC, whereas CS formed cartilage only on the perimeter. Additionally, CS induced a dose-dependent inflammatory response around the implantation site, whereas NC induced a minor response, and inflammatory cells were observed inside the NC. In a rat spinal fusion model, NC promoted high-quality bony fusion compared to CS. In vitro, NC enhanced chondrogenic and osteogenic differentiation of hBMSCs and ATDC5 cells while inhibiting osteoclastogenesis. Overall, NC/BMP2 facilitates spatially controlled, high-quality endochondral bone formation without BMP2-induced inflammation and promotes high-density new bone, functioning as a next-generation BMP2 carrier.

The guanine nucleotide exchange factor DOCK5 negatively regulates osteoblast differentiation and BMP2-induced bone regeneration via the MKK3/6 and p38 signaling pathways

DOCK5 (dedicator of cytokinesis 5), a guanine nucleotide exchange factor for Rac1, has been implicated in BMP2-mediated osteoblast differentiation, but its specific role in osteogenesis and bone regeneration remained unclear. This study investigated the effect of DOCK5 on bone regeneration using C21, a DOCK5 chemical inhibitor, and Dock5-deficient mice. Osteoblast differentiation and bone regeneration were analyzed using bone marrow mesenchymal stem cells (BMSCs) and various animal models. C21 significantly enhanced osteoblast differentiation and mineral deposition in mouse MC3T3-E1 cells and in human and mouse BMSCs. Dock5 knockout (KO) mice exhibited increased bone mass and mineral apposition rate, with their BMSCs showing enhanced osteoblast differentiation. Calvarial defect and ectopic bone formation models demonstrated significant induction of bone regeneration in Dock5 KO mice compared to wild-type (WT) mice. Moreover, DOCK5 inhibition by C21 in WT mice enhanced BMP2-induced subcutaneous ectopic bone formation. The mechanism responsible for enhanced bone formation induced by DOCK5 inhibition may involve the suppression of Rac1 under TAK1, accompanied by the activation of MKK3/6 and p38 induced by BMP2. These findings strongly suggest that DOCK5 negatively regulates osteoblast differentiation and bone regeneration through signaling pathways involving TAK1, MKK3/6, and p38, providing new insights into potential therapeutic strategies for bone regeneration.

Developing a risk score to inform the use of rhBMP-2 in adult spinal deformity surgery

BACKGROUND

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has not shown superior benefit overall in cost-effectiveness during adult spinal deformity (ASD) surgery.

STUDY DESIGN/SETTING

Retrospective PURPOSE: Generate a risk score for pseudarthrosis to inform the utilization of rhBMP-2, balancing costs against quality of life and complications.

METHODS

ASD patients with 3-year data were included. Quality of life gained was calculated from ODI to SF-6D and translated to quality-adjusted life years (QALYs). Cost was calculated using the PearlDiver database and CMS definitions for complications and comorbidities. Established weights were generated for predictive variables via logistic regression to yield a predictive risk score for pseudarthrosis that accounted for frailty, diabetes, depression, ASA grade, thoracolumbar kyphosis and three-column osteotomy use. Risk score categories, established via conditional inference tree (CIT)-derived thresholds were tested for cost-utility of rhBMP-2 usage, controlling for age, prior fusion, and baseline deformity and disability.

RESULTS

64% of ASD patients received rhBMP-2 (308/481). There were 17 (3.5%) patients that developed pseudarthrosis. rhBMP-2 use overall did not lower pseudarthrosis rates (OR: 0.5, [0.2-1.3]). Pseudarthrosis rates for each risk category were: No Risk (NoR) 0%; Low-Risk (LowR) 1.6%; Moderate Risk (ModR) 9.3%; High-Risk (HighR) 24.3%. Patients receiving rhBMP-2 had similar QALYs overall to those that did not (0.163 vs. 0.171, p = .65). rhBMP-2 usage had worse cost-utility in the LowR cohort (p < .001). In ModR patients, rhBMP-2 usage had equivocal cost-utility ($53,398 vs. $61,581, p = .232). In the HighR cohort, the cost-utility was reduced via rhBMP-2 usage ($98,328 vs. $211,091, p < .001).

CONCLUSION

Our study shows rhBMP-2 demonstrates effective cost-utility for individuals at high risk for developing pseudarthrosis. The generated score can aid spine surgeons in the assessment of risk and enhance justification for the strategic use of rhBMP-2 in the appropriate clinical contexts.

LEVEL OF EVIDENCE

III.

Treatment of Bone Defects and Nonunion via Novel Delivery Mechanisms, Growth Factors, and Stem Cells: A Review

Bone nonunion following a fracture represents a significant global healthcare challenge, with an overall incidence ranging between 2 and 10% of all fractures. The management of nonunion is not only financially prohibitive but often necessitates invasive surgical interventions. This comprehensive manuscript aims to provide an extensive review of the published literature involving growth factors, stem cells, and novel delivery mechanisms for the treatment of fracture nonunion. Key growth factors involved in bone healing have been extensively studied, including bone morphogenic protein (BMP), vascular endothelial growth factor (VEGF), and platelet-derived growth factor. This review includes both preclinical and clinical studies that evaluated the role of growth factors in acute and chronic nonunion. Overall, these studies revealed promising bridging and fracture union rates but also elucidated complications such as heterotopic ossification and inferior mechanical properties associated with chronic nonunion. Stem cells, particularly mesenchymal stem cells (MSCs), are an extensively studied topic in the treatment of nonunion. A literature search identified articles that demonstrated improved healing responses, osteogenic capacity, and vascularization of fractures due to the presence of MSCs. Furthermore, this review addresses novel mechanisms and materials being researched to deliver these growth factors and stem cells to nonunion sites, including natural/synthetic polymers and bioceramics. The specific mechanisms explored in this review include BMP-induced osteoblast differentiation, VEGF-mediated angiogenesis, and the role of MSCs in multilineage differentiation and paracrine signaling. While these therapeutic modalities exhibit substantial preclinical promise in treating fracture nonunion, there remains a need for further research, particularly in chronic nonunion and large animal models. This paper seeks to identify such translational hurdles which must be addressed in order to progress the aforementioned treatments from the lab to the clinical setting.

A systematic review and meta-analysis on the use of regenerative graft materials for socket preservation in randomized clinical trials

OBJECTIVE

To evaluate if regenerative materials with/without scaffold deployed in dental socket preservation led to reduced radiographic height and width bone resorption.

STUDY DESIGN

English-written human studies from January 2010 to December 2023 were selected from PubMed, EMBASE, MEDLINE, Cochrane CENTRAL, Google Scholar and manually searched journals. Six meta-analyses were conducted, addressing treatments with all blood-derived growth factor preparations as well as L-platelet-rich fibrin (L-PRF) separately, and recombinant human BMP-2 (rhBMP-2). An unpaired t-test on L-PRF and rhBMP-2 determined the clinically best preservation treatment. Cochrane risk of bias in all studies was analyzed.

RESULTS

Twenty-nine articles (1068 participants) were included. Meta-analyses on blood-derived preparations demonstrated nonsignificant alveolar width, but significant (p = .001) height preservation. L-PRF vs. natural healing demonstrated nonsignificant changes in both dimensions. RhBMP-2 caused highly significant reduced horizontal (p = .01) and vertical (p < .0008) bone resorptions. When comparing mean resorption rates, significant benefits of rhBMP-2 over L-PRF were observed for width but not height preservation (p < .0001 and p = .057, respectively). Six studies recorded low, 8 moderate, and 15 high net risks.

CONCLUSIONS

Regenerative materials appear beneficial for radiographic bone width and height preservation after tooth extraction. Although rhBMP-2 performed better in alveolar width preservation, L-PRF can be an autologous and cost-effective alternative.

Treatment of adult spine deformity: A retrospective comparison of bone morphogenic protein and bone marrow aspirate with bone allograft

BACKGROUND  : The use of bone morphogenic protein (BMP-2) in adult spine deformity (ASD) surgery remains controversial more than two decades following its approval for clinical application in spine surgery. This study was performed to assess outcomes in patients undergoing ASD surgery with BMP application compared with a combination of bone marrow aspirate, cancellous bone chips and i-Factor.

METHODS

This was a retrospective cohort study. ASD patients were stratified by use of intra-operative BMP (BMP +) or not (BMA + I) and surveyed for the development of complications and mechanical failure. Quality of life gained following the procedure was evaluated using quality-adjusted life years (QALYs). Cost was calculated using the PearlDiver database and CMS definitions. Multivariable analyses (ANCOVA) and logistic regression were used to adjust for confounding.

RESULTS

512 patients were included (60% BMP +). At baseline, BMP + patients were older (62.5 vs 60.8 years, p < 0.010). Radiographic and quality-of-life metrics did not differ at follow up timepoints (all p > 0.05). BMP use was associated with higher supplemental rod use (OR: 7.0, 1.9 - 26.2, p = 0.004), greater number of levels fused (OR: 1.1, 1.03 - 1.17, p = 0.003) and greater neurological complications (OR: 5.0, 1.3 - 18.7, p = 0.017). Controlling for rod use and levels fused, BMP use was not associated with a lower risk of mechanical complications (OR 0.3, 95% CI: 0.2 - 3.0, p = 0.353), rod breakage (OR: 3.3, 0.6 - 18.7, p = 0.182) or implant failure (OR: 0.3, 0.04 - 1.51). At 2 years, the BMP + cohort exhibited higher overall costs ($108,062 vs $95,144, p = 0.002), comparable QALYs (0.163 vs 0.171, p = 0.65) and higher cost per QALY (p = 0.001) at two years.

CONCLUSIONS

In this analysis, BMP-2 application was not associated with superior outcomes when compared to a less costly biologic alternative (bone marrow aspirate + cancellous bone chips + i-Factor) following ASD surgery. The use of BMP-2 in ASD surgery appears to have reduced cost-efficacy at two years postoperatively.

Nanofibrous 3D scaffolds capable of individually controlled BMP and FGF release for the regulation of bone regeneration

The current clinical applications of bone morphogenetic proteins (BMPs) are limited to only a few specific indications. Locally controlled delivery of combinations of growth factors can be a promising strategy to improve BMP-based bone repair. However, the success of this approach requires the development of an effective release system and the correct choice of growth factors capable of enhancing BMP activity. Basic fibroblast growth factor (bFGF, also known as FGF-2) has shown promise in promoting bone repair, although conflicting results have been reported. Considering the complex biological activities of FGF-2, we hypothesized that FGF-2 can promote BMP-induced bone regeneration only if the dosage and kinetic parameters of the two factors are individually tailored. In this study, we conducted systematic in vitro studies on cell proliferation, differentiation, and mineralization in response to factor dose, delivery mode (sequential or simultaneous), and release rate. Subsequently, we designed individually controlled BMP-7 and FGF-2 release poly(lactide-co-glycolide) (PLGA) nanospheres attached to the poly(l-lactic acid) (PLLA) nanofibrous scaffolds. The data showed that BMP-7-induced bone formation was accelerated by a relatively higher FGF-2 dose (100 ng/scaffold) delivered at a faster release rate, or by a relatively lower FGF-2 dose (10 ng/scaffold) at a slower release rate in an in vivo bone regeneration model. In contrast, a very high dose of FGF-2 (1000 ng/scaffold) inhibited bone regeneration under all conditions. In vitro and in vivo data suggest that FGF-2 improved BMP-7-induced bone regeneration by coordinating FGF-2 dosage and release kinetics to enhance stem cell migration, proliferation, and angiogenesis. STATEMENT OF SIGNIFICANCE: Bone morphogenetic proteins (BMPs) are the most potent growth/differentiation factors in bone development and regeneration. However, the clinical applications of BMPs have been limited to only a few specific indications due to the required supraphysiological dosages with the current BMP products and their side effects. Locally controlled delivery of BMPs and additional growth factors that can enhance their osteogenic potency are highly desired. However, different growth factors act with different mechanisms. Here we report a nanofibrous scaffold that mimics collagen in size and geometry and is immobilized with biodegradable nanospheres to achieve local and distinct release profiles of BMP7 and FGF2. Systematic studies demonstrated low dose BMP7 and FGF2 with different temporal release profiles can optimally enhance bone regeneration.

Fatal Fat Embolism Syndrome After Posterior Spinal Fusion: A Case Report

Posterior spinal fusion with instrumentation is a routine elective treatment of lumbar stenosis with radiculopathy and myelopathy. Fat embolism syndrome (FES) is a rare complication of this procedure. We describe the first documented case of fatal FES after an L3-L5 posterior spinal fusion using off-label bone morphogenic protein 2 (BMP-2) and allograft instead of iliac crest bone grafting. Postoperatively, the patient developed delayed cerebral symptoms with swift respiratory failure and cardiac arrest. Based on our investigation, it is likely that pedicle screw fixation was the cause of the fat embolisms with little effect from BMP-2.

A triple growth factor strategy for optimizing bone augmentation in mice

With dental implant treatment becoming the gold standard, the need for effective bone augmentation prior to implantation has grown. This study aims to evaluate a bone augmentation strategy integrating three key growth factors: bone morphogenetic protein-2 (BMP-2), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF). Collagen scaffolds incorporating BMP-2, IGF-1, or VEGF were fabricated and categorized into five groups based on their content: scaffold alone; BMP-2 alone (BMP-2); BMP-2 and IGF-1 (BI); BMP-2, IGF-1, and VEGF (BIV); and BMP-2 and IGF-1 with an earlier release of VEGF (BI + V). The prepared scaffolds were surgically implanted into the calvarias of C57BL/6JJcl mice, and hard tissue formation was assessed after 10 and 28 days through histological, tomographic, and biochemical analyses. The combination of BMP-2 and IGF-1 induced a greater volume of hard tissue augmentation compared with that of BMP-2 alone, regardless of VEGF supplementation, and these groups had increased levels of cartilage compared with others. The volume of hard tissue formation was greatest in the BIV group. In contrast, the BI + V group exhibited a hard tissue volume similar to that of the BI group. While VEGF and CD31 levels were highest in the BIV group at 10 days, there was no correlation at the same time point between hard tissue formation and the quantity of M2 macrophages. In conclusion, the simultaneous release of BMP-2, IGF-1, and VEGF proved to be effective in promoting bone augmentation.

G. AR, Al Kawas S, Samsudin AR, A. C. SA. Impact of Bone Morphogenetic Protein 7 and Prostaglandin receptors on osteoblast healing and organization of collagen

PURPOSE

This study seeks to investigate the impact of co-administering either a Prostaglandin EP2 receptor agonist or an EP1 receptor antagonist alone with a low dose BMP7 on in vitro healing process, collagen content and maturation of human osteoblasts.

METHODOLOGY

Human osteoblast cells were used in this study. These cells were cultured and subjected to different concentrations of Prostaglandin EP2 receptor agonist, EP1 receptor antagonist, BMP7, Control (Ct) (Vehicle alone), and various combinations treatments. Cell viability at 24, 48 and 72 hours (h) was evaluated using the XTT assay. A wound healing assay was conducted to observe the migration ability of human osteoblast cells. Additionally, Sirius red staining and Fourier-Transform Infrared Spectroscopy Imaging (FT-IR) was employed to analyze various parameters, including total protein concentration, collagen production, mature collagen concentration, and mineral content.

RESULTS

The combination of low dose BMP7 and Prostaglandin EP2 receptor agonist resulted to the lowest cell viability when compared to both the Ct and individual treatments. In contrast, the Prostaglandin EP1 receptor antagonist alone showed the highest cellular viability at 72 h. In the wound healing assay, the combined treatment of low dose BMP7 with the Prostaglandin EP2 receptor agonist and EP1 receptor antagonist showed a decrease in human osteoblast healing after 24 h. Analysis of FT-IR data indicated a reduction in total protein content, collagen maturity, collagen concentration and mineral content in combination treatment compared to the single or Ct treatments.

CONCLUSION

The combination of a Prostaglandin EP2 receptor agonist or an EP1 receptor antagonist when combined with low dose BMP7 significantly hinders both human osteoblast healing and collagen maturity/concentration in comparison to low dose BMP7 treatment alone.

A synthetic retinoic acid receptor γ antagonist (7C)-loaded nanoparticle enhances bone morphogenetic protein-induced bone regeneration in a rat spinal fusion model

BACKGROUND CONTEXT

Bone morphogenetic proteins (BMPs) have potent osteoinductivity and have been applied clinically for challenging musculoskeletal conditions. However, the supraphysiological doses of BMPs used in clinical settings cause various side effects that prevent widespread use, and therefore the BMP dosage needs to be reduced.

PURPOSE

To address this problem, we synthesized 7C, a retinoic acid receptor γ antagonist-loaded nanoparticle (NP), and investigated its potential application in BMP-based bone regeneration therapy using a rat spinal fusion model.

STUDY DESIGN

An experimental animal study.

METHODS

Fifty-three male 8-week-old Sprague-Dawley rats underwent posterolateral spinal fusion and were divided into the following five treatment groups: (1) no recombinant human (rh)BMP-2 and blank-NP (Control), (2) no rhBMP-2 and 1 μg 7C-NP (7C group), (3) low-dose rhBMP-2 (0.5 μg) and 1 μg blank-NP (L-BMP group), (4) low-dose rhBMP-2 (0.5 μg) and 1 μg 7C-NP (L-BMP + 7C group), and (5) high-dose rhBMP-2 (5.0 μg) and 1 μg blank-NP (H-BMP group). Micro-computed tomography and histologic analysis were performed 2 and 6 weeks after the surgery.

RESULTS

The spinal fusion rates of the Control and 7C groups were both 0%, and those of the L-BMP, L-BMP + 7C, and H-BMP groups were 55.6%, 94.4%, and 100%, respectively. The L-BMP + 7C group markedly promoted cartilaginous tissue formation during BMP-induced endochondral bone formation that resulted in a significantly better spinal fusion rate and bone formation than in the L-BMP group. Although spinal fusion was slower in the L-BMP + 7C group, the L-BMP + 7C group formed a spinal fusion mass with better bone quality than the spinal fusion mass in the H-BMP group.

CONCLUSIONS

The combined use of 7C-NP with rhBMP-2 in a rat posterolateral lumbar fusion model increased spinal fusion rate and new bone volume without deteriorating the quality of newly formed bone.

CLINICAL SIGNIFICANCE

7C-NP potentiates BMP-2-induced bone regeneration and has the potential for efficient bone regeneration with low-dose BMP-2, which can reduce the dose-dependent side effects of BMP-2 in clinical settings.

Fracture healing on non-union fracture model promoted by non-thermal atmospheric-pressure plasma

Non-thermal atmospheric-pressure plasma (NTAPP) is attracting widespread interest for use in medical applications. The tissue repair capacity of NTAPP has been reported in various fields; however, little is known about its effect on fracture healing. Non-union or delayed union after a fracture is a clinical challenge. In this study, we aimed to investigate how NTAPP irradiation promotes fracture healing in a non-union fracture model and its underlying mechanism, in vitro and in vivo. For the in vivo study, we created normal and non-union fracture models in LEW/SsNSlc rats to investigate the effects of NTAPP. To create a fracture, a transverse osteotomy was performed in the middle of the femoral shaft. To induce the non-union fracture model, the periosteum surrounding the fracture site was cauterized after a normal fracture model was created. The normal fracture model showed no significant difference in bone healing between the control and NTAPP-treated groups. The non-union fracture model demonstrated that the NTAPP-treated group showed consistent improvement in fracture healing. Histological and biomechanical assessments confirmed the fracture healing. The in vitro study using pre-osteoblastic MC3T3-E1 cells demonstrated that NTAPP irradiation under specific conditions did not reduce cell proliferation but did enhance osteoblastic differentiation. Overall, these results suggest that NTAPP is a novel approach to the treatment of bone fractures.

What Is the Evidence Surrounding the Cost-Effectiveness of Osteobiologic Use in ACDF Surgery? A Systematic Review of the Literature

STUDY DESIGN

This study constitutes a systematic review of the literature.

OBJECTIVE

The aim of this study was to identify and present all available studies that report on the costs of osteobiologics used in anterior cervical discectomy and fusion (ACDF).

METHODS

The literature was systematically reviewed to identify studies with specific inclusion criteria: (1) randomized controlled trials and observational studies, (2) in adult patients, (3) with herniated disc(s) or degenerative cervical spine disease, (4) reporting on either direct or indirect costs of using specific osteobiologics in an ACDF operation. (5) Only studies in English were included. The quality of the included studies was assessed using the MINORS and RoB 2.0 tools.

RESULTS

Overall, 14 articles were included; one randomized controlled trial and 13 observational studies. The most commonly used osteobiologics other than autograft/iliac crest bone graft (ICBG) were allograft and bone morphogenetic protein (BMP). None of the studies was reported to be industry-supported. There was considerable heterogeneity on the reported costs. Overall, most studies reported on surgery-related costs, such as anesthesia, operating room, surgical materials and surgeon's fee. Only two studies, both using allograft, reported the exact cost of the osteobiologic used (450 GBP, $700). Some of the studies reported on the cost of care during hospitalization for the surgical operation, such as radiology studies, emergency room costs, cardiologic evaluation, laboratory studies, pharmacy costs, and room costs. Only a few studies reported on the cost of follow-up, reoperation, and physical therapy and rehabilitation.

CONCLUSION

Based on the data of this current systematic review, no recommendations can be made regarding the cost-effectiveness of using osteobiologics in ACDF. Given the high costs of osteobiologics, this remains a topic of importance. The design of future studies on the subject should include cost effectiveness.

A Comprehensive Review of the Historical Description of Spine Surgery and Its Evolution

Major strides in the advancement of spine surgery came about in the 21st century. However, the extensive history of spine surgery can be traced back to long before this time. A clear description of the journey from a primitive yet accurate understanding of the human musculoskeletal system to today's modern aspects of spinal techniques is lacking. A narrative literature review was conducted to elucidate where spine surgery began and the techniques used that evolved over time. This review was conducted using PubMed and Google Scholar. Search terms used included "history of spine surgery," "evolution of spine surgery," "origins of spine surgery," "history of laminectomy," "history of spinal fusion," "history of lumbar interbody fusion," "minimally invasive spine surgery," and "navigation in spine surgery." We highlight the evolution of the basic understanding of anatomy and non-surgical and surgical techniques, including bracing, laminectomy, discectomy, and spinal fusion. The current evolution and integration of minimally invasive techniques, lumbar interbody fusion techniques, robotics, navigation, and motion preservation are discussed, as these are the major areas of focus for technological advancement. This review presents an overarching synopsis of the events that chronicle the progress made in spine surgery since its conception. The review uniquely contributes to the growing body of literature on the expansion of spine surgery and highlights major events in its history.

Day one versus day zero postoperative physical therapy among patients with lumbar spinal fusion: a length of stay comparison

BACKGROUND CONTEXT

Postoperative physical therapy (PT) following lumbar spinal fusion is an effective form of postoperative rehabilitation. However, it is unknown when a postoperative PT protocol should be optimally initiated.

PURPOSE

This study sought to compare lengths of stay between patients on a day zero PT protocol and those on a day one PT protocol.

STUDY DESIGN/SETTING

Retrospective chart review.

PATIENT SAMPLE

Patients who underwent lumbar spinal surgery at a large midwestern tertiary medical care center from January 1, 2018 through April 30, 2019 were eligible for their medical record's inclusion.

PRIMARY OUTCOME MEASURE

Length of hospital stay following surgery.

METHODS

Patients were stratified by having started postoperative PT on the same day as surgery (day zero) or having started postoperative PT on the day following surgery (day one).

RESULTS

A total of 164 patients were included in the study, 69 in the day zero group and 95 patients in the day one group. Most patients were female (59%, n = 98), and patients' average age was 62 years (SD = 13). Average length of stay was 61 hours (SD = 20) for those on the day zero protocol and 75 hours (SD = 32) for those on the day one protocol.

CONCLUSIONS

This study suggests that a postoperative physical therapy protocol initiated on day zero is associated with patients experiencing a shorter length of hospital stay compared to a similar PT protocol initiated on postoperative day one.

Safety and Reoperation Rates in Non-instrumented Lumbar Fusion Surgery: Secondary Report From a Randomized Controlled Trial of ABM/P-15 vs Allograft With Minimum 5 years Follow-Up

STUDY DESIGN

Randomized controlled trial with minimum of 5-years follow-up.

OBJECTIVE

The purpose of this study is to evaluate the peri- and postoperative complications rates, ectopic bone migration, and reoperation rates, and secondly evaluate the 5-year patient reported outcomes (PROs), in patients treated with decompression and non-instrumented posterolateral fusion with ABM/P-15 or allograft.

METHODS

Patients with degenerative spondylolisthesis were enrolled in a Randomized Clinical Trial and randomized 1:1 to either ABM/P-15 or allograft bone. Patient Reported Outcomes were collected at 5-year follow-up, and patients were invited to a clinical follow-up including a computed tomography scan (CT) to evaluate signs of osteolysis, ectopic bone formation, and bone migration.

RESULTS

Of 101 subjects enrolled in the primary study, 83 patients were available for the 5-year follow-up. We found a statistically significant difference in back pain and Oswestry Disability Index between groups. Fifty-eight patients agreed to participate in the CT study. Sixty percentage in the ABM/P-15 group vs 30% in the allograft group was classified as fused (P = .037). There were no differences in complications, reoperation-, or infection rates between the 2 groups. We found 2 patients with migration of graft material. Both patients were asymptomatic at minimum 5-year follow-up.

CONCLUSION

Our study indicated that complication rates are no higher in patients treated with ABM/P-15 than allograft. We found significantly higher fusion rates in the AMB/P-15 group than in the allograft group, and patients in the ABM/P-15 group reported less back pain and lower disability score at 5-year follow-up.

Delivery of Growth Factors to Enhance Bone Repair

The management of critical-sized bone defects caused by nonunion, trauma, infection, malignancy, pseudoarthrosis, and osteolysis poses complex reconstruction challenges for orthopedic surgeons. Current treatment modalities, including autograft, allograft, and distraction osteogenesis, are insufficient for the diverse range of pathology encountered in clinical practice, with significant complications associated with each. Therefore, there is significant interest in the development of delivery vehicles for growth factors to aid in bone repair in these settings. This article reviews innovative strategies for the management of critical-sized bone loss, including novel scaffolds designed for controlled release of rhBMP, bioengineered extracellular vesicles for delivery of intracellular signaling molecules, and advances in regional gene therapy for sustained signaling strategies. Improvement in the delivery of growth factors to areas of significant bone loss has the potential to revolutionize current treatment for this complex clinical challenge.

Cytomodulin-10 modified GelMA hydrogel with kartogenin for in-situ osteochondral regeneration

The incidence of osteochondral defect is increasing year by year, but there is still no widely accepted method for repairing the defect. Hydrogels loaded with bioactive molecules have provided promising alternatives for in-situ osteochondral regeneration. Kartogenin (KGN) is an effective and steady small molecule with the function of cartilage regeneration and protection which can be further boosted by TGF-β. However, the high cost, instability, and immunogenicity of TGF-β would limit its combined effect with KGN in clinical application. In this study, a composite hydrogel CM-KGN@GelMA, which contained TGF-β1 analog short peptide cytomodulin-10 (CM-10) and KGN, was fabricated. The results indicated that CM-10 modified on GelMA hydrogels exerted an equivalent role in enhancing chondrogenesis as TGF-β1, and this effect was also boosted when combined with KGN. Moreover, it was revealed that CM-10 and KGN had a synergistic effect on promoting the chondrogenesis of BMSCs by up-regulating the expression of RUNX1 and SOX9 at both mRNA and protein levels in vitro. Finally, the composite hydrogel exhibited a satisfactory osteochondral defect repair effect in vivo, showing similar structures close to the native tissue. Taken together, this study has revealed that CM-10 may serve as an alternative for TGF-β1 and can collaborate with KGN to accelerate chondrogenesis, which suggests that the fabricated CM-KGN@GelMA composite hydrogel can be acted as a potential scaffold for osteochondral defect regeneration. STATEMENT OF SIGNIFICANCE: Kartogenin and TGF-β have shown great value in promoting osteochondral defect regeneration, and their combined application can enhance the effect and show great potential for clinical application. Herein, a functional CM-KGN@GelMA hydrogel was fabricated, which was composed of TGF-β1 mimicking peptide CM-10 and KGN. CM-10 in hydrogel retained an activity like TGF-β1 to facilitate BMSC chondrogenesis and exhibited boosting chondrogenesis by up-regulating RUNX1 and SOX9 when being co-applied with KGN. In vivo, the hydrogel promoted cartilage regeneration and subchondral bone reconstruction, showing similar structures as the native tissue, which might be vital in recovering the bio-function of cartilage. Thus, this study developed an effective scaffold and provided a promising way for osteochondral defect repair.

Systemic Diclofenac Sodium Reduces Postoperative rhBMP-2 Induced Neuroinflammation: A Rodent Model Study

STUDY DESIGN

This is a basic science, animal research study.

OBJECTIVE

This study aims to explore, in rodent models, the effectiveness of systemic nonsteroidal anti-inflammatory drugs in reducing recombinant human bone morphogenetic protein-2 (rhBMP-2) induced neuroinflammation.

SUMMARY OF BACKGROUND DATA

rhBMP-2 is increasingly used to augment fusion in lumbar interbody fusion surgeries, although it can cause complications including postoperative radiculitis.

MATERIALS AND METHODS

Eighteen 8-week-old Sprague-Dawley rats underwent Hargreaves testing to measure the baseline thermal withdrawal threshold before undergoing surgical intervention. The L5 nerve root was exposed and wrapped with an Absorbable Collagen Sponge containing rhBMP-2. Rats were randomized into 3 groups: (1) Low dose (LD), (2) high dose (HD) diclofenac sodium, and (3) saline, receiving daily injection treatment. Hargreaves testing was performed postoperatively on days 5 and 7. Seroma volumes were measured by aspiration and the nerve root was then harvested for hematoxylin and eosin, immunohistochemistry, Luxol Fast Blue staining, and real-time quantitative polymerase chain reaction. The Student t test was used to evaluate the statistical significance among groups.

RESULTS

The intervention groups showed reduced seroma volume, and a general reduction of inflammatory markers (MMP12, MAPK6, GFAP, CD68, and IL18) compared with controls, with the reduction in MMP12 being statistically significant ( P = 0.02). Hematoxylin and eosin and immunohistochemistry of the nerve roots showed the highest macrophage density in the saline controls and the lowest in the HD group. Luxol Fast Blue staining showed the greatest extent of demyelination in the LD and saline groups. Lastly, Hargreaves testing, a functional measure of neuroinflammation, of the HD group demonstrated a minimal change in thermal withdrawal latency. In contrast, the thermal withdrawal latency of the LD and saline groups showed a statistically significant decrease of 35.2% and 28.0%, respectively ( P < 0.05).

CONCLUSION

This is the first proof-of-concept study indicating that diclofenac sodium is effective in alleviating rhBMP-2-induced neuroinflammation. This can potentially impact the clinical management of rhBMP-2-induced radiculitis. It also presents a viable rodent model for evaluating the effectiveness of analgesics in reducing rhBMP-2-induced inflammation.

Current Status of Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) in Maxillofacial Surgery: Should It Be Continued?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has shown potential in maxillofacial surgery owing to its osteoinductive properties. However, concerns about its safety and high cost have limited its widespread use. This review presents the status of rhBMP-2 use in maxillofacial surgery, focusing on its clinical application, efficacy, safety, and limitations. Studies have demonstrated rhBMP-2's potential to reduce donor site morbidity and increase bone height in sinus and ridge augmentation; however, it may not outperform autogenous bone grafts. In medication-related osteonecrosis of the jaw treatment, rhBMP-2 has been applied adjunctively with promising results, although its long-term safety requires further investigation. However, in maxillofacial trauma, its application is limited to the restoration of large defects. Safety concerns include postoperative edema and the theoretical risk of carcinogenesis. Although postoperative edema is manageable, the link between rhBMP-2 and cancer remains unclear. The limitations include the lack of an ideal carrier, the high cost of rhBMP-2, and the absence of an optimal dosing regimen. In conclusion, rhBMP-2 is a promising graft material for maxillofacial surgery. However, it has not yet become the gold standard owing to safety and cost concerns. Further research is required to establish long-term safety, optimize dosing, and develop better carriers.

Engineered biomaterials in stem cell-based regenerative medicine

Stem cell-based regenerative therapies, which harness the self-renewal and differentiation properties of stem cells, have been in the spotlight due to their widespread applications in treating degenerative, aging, and other, generally intractable diseases. Therapeutically effective hematopoietic stem cells, mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells have been used in numerous basic and translational studies with exciting results. However, pre-/post-transplantation issues of poor cell survival and retention, uncontrolled differentiation, and insufficient numbers of cells engrafted into host tissues are the major challenges in stem cell-based regenerative therapies. Engineered biomaterials have adjustable biochemical and biophysical properties that significantly affect cell behaviors, such as cell engraftment, survival, migration, and differentiation outcomes, thereby enhancing the engraftment of implanted stem cells and guiding tissue regeneration. Therefore, the combination of stem cell biology with bioengineered materials is a promising strategy to improve the therapeutic outcomes of stem cell-based regenerative therapy. In this review, we summarize the advances in the modulation of behaviors of stem cells via engineered biomaterials. We then present different approaches to harnessing bioengineered materials to enhance the transplantation of stem cells. Finally, we will provide future directions in regenerative therapy using stem cells.

Engineered dual affinity protein fragments to bind collagen and capture growth factors

Collagen type I lacks affinity for growth factors (GFs) and yet it is clinically used to deliver bone morphogenic protein 2 (BMP-2), a potent osteogenic growth factor. To mitigate this lack of affinity, supra-physiological concentrations of BMP-2 are loaded in collagen sponges leading to uncontrolled BMP-2 leakage out of the material. This has led to important adverse side effects such as carcinogenesis. Here, we design recombinant dual affinity protein fragments, produced in E. Coli, which contain two regions, one that spontaneously binds to collagen and a second one that binds BMP-2. By adding the fragment to collagen sponges, BMP-2 is sequestered enabling solid phase presentation of BMP-2. We demonstrate osteogenesis in vivo with ultra-low doses of BMP-2. Our protein technology enhances the biological activity of collagen without using complex chemistries or changing the manufacturing of the base material and so opens a pathway to clinical translation.

Assessment of Escherichia coli-derived Recombinant Human Bone Morphogenic Protein-2 on Fertilization and Early Embryonic Development in Rats

OBJECTIVE

Bone morphogenetic protein-2 (BMP-2) impacts fertility in women by affecting the menstrual cycle and embryonic development. We aimed to determine the reproductive toxicity of Escherichia coli (E. coli)-derived recombinant human BMP-2 (rhBMP-2) by measuring changes in the reproductive performance and organs in rhBMP-2-treated rats.

METHODS

Overall, 88 male and female rats each were categorized into one control and three experimental groups. rhBMP-2 was intravenously administered to the experimental groups at 0.05, 0.15, and 0.50 mg/kg/day, respectively. The male rats were administered rhBMP-2 daily, starting from 28 days before mating until the day of necropsy (48 days), after which they were euthanized and necropsied. The female rats were administered rhBMP-2 daily, starting from 14 days before mating until 7 days after fertilization (22-36 days), after which they were necropsied 13 days after fertilization.

RESULTS

No rhBMP-2-related death occurred throughout the study period. All rhBMP-2-treated groups showed swelling in the tail at the site of rhBMP-2 administration. In the high-dose rhBMP-2 group, the male rats showed a slight reduction in body weight and food consumption, whereas the female rats showed a reduction in the weights of the ovary and oviduct. Examining the fertilization status and necropsy showed no effect of rhBMP-2 on fertility and early embryonic development. The no-observed-adverse-effect level of rhBMP-2 was 0.50 mg/kg/day in all rats.

CONCLUSION

rhBMP-2 had no reproductive toxicity on the reproductive performance and organs in female and male rats. Therefore, these results provide new toxicology information on E. coli-derived rhBMP-2 as a therapeutic protein.

Current Trends in Recombinant Human Bone Morphogenetic Protein 2 (rhBMP2) Usage for Spinal Fusion Surgery

(1) Background: Since first approved by the FDA, on-label and off-label usage of recombinant human bone morphogenetic protein 2 (rhBMP2) for spinal fusion surgeries has become widespread. While many studies have investigated the safety and efficacy of its use, as well as its economic impact, few have looked at the current trends in its on- and off-label use. The goal of this study is to evaluate the current trends of on- and off-label rhBMP2 use for spinal fusion surgery. (2) Methods: A deidentified survey was created and electronically distributed to members of two international spine societies. Surgeons were asked to report their demographic information, surgical experience, and current usage of rhBMP2. They were then presented with five spinal fusion procedures and asked to report if they use rhBMP2 for these indications in their current practice. Responses were stratified between rhBMP2 users vs. non-users and on-label vs. off-label use. Data were analyzed using chi-square with Fisher's exact test for categorical data. (3) Results: A total of 146 respondents completed the survey with a response rate of 20.5%. There was no difference in overall rhBMP2 usage based on specialty, experience, or number of cases per year. Fellowship-trained surgeons and those who practice in the United States were more likely to use rhBMP2. Surgeons who were trained in the Southeast and Midwest regions reported the highest usage rates. rhBMP2 use was more common among fellowship-trained and US surgeons for ALIFs; non-US surgeons for multilevel anterior cervical discectomy and fusions; and fellowship-trained and orthopedic spine surgeons for lateral lumbar interbody fusions. Non-US surgeons were more likely to use rhBMP2 for off-label indications compared to surgeons from the US. (4) Conclusions: While various demographics of surgeons report different rates of rhBMP2 use, off-label use remains relatively commonplace amongst practicing spine surgeons.

Spatiotemporal Characterization of Human Early Intervertebral Disc Formation at Single-Cell Resolution

The intervertebral disc (IVD) acts as a fibrocartilaginous joint to anchor adjacent vertebrae. Although several studies have demonstrated the cellular heterogeneity of adult mature IVDs, a single-cell transcriptomic atlas mapping early IVD formation is still lacking. Here, the authors generate a spatiotemporal and single cell-based transcriptomic atlas of human IVD formation at the embryonic stage and a comparative mouse transcript landscape. They identify two novel human notochord (NC)/nucleus pulposus (NP) clusters, SRY-box transcription factor 10 (SOX10)⁺ and cathepsin K (CTSK)⁺ , that are distributed in the early and late stages of IVD formation and they are validated by lineage tracing experiments in mice. Matrisome NC/NP clusters, T-box transcription factor T (TBXT)⁺ and CTSK⁺ , are responsible for the extracellular matrix homeostasis. The IVD atlas suggests that a subcluster of the vertebral chondrocyte subcluster might give rise to an inner annulus fibrosus of chondrogenic origin, while the fibroblastic outer annulus fibrosus preferentially expresseds transgelin and fibromodulin . Through analyzing intercellular crosstalk, the authors further find that notochordal secreted phosphoprotein 1 (SPP1) is a novel cue in the IVD microenvironment, and it is associated with IVD development and degeneration. In conclusion, the single-cell transcriptomic atlas will be leveraged to develop preventative and regenerative strategies for IVD degeneration.

Evaluation of Topology Optimization Using 3D Printing for Bioresorbable Fusion Cages: A Biomechanical Study in a Porcine Model

STUDY DESIGN

Preclinical biomechanical study of topology optimization versus standard ring design for bioresorbable poly-ε-caprolactone (PCL) cervical spine fusion cages delivering bone morphogenetic protein-2 (BMP-2) using a porcine model.

OBJECTIVE

The aim was to evaluate range of motion (ROM) and bone fusion, as a function of topology optimization and BMP-2 delivery method.

SUMMARY OF BACKGROUND DATA

3D printing technology enables fabrication of topology-optimized cages using bioresorbable materials, offering several advantages including customization, and lower stiffness. Delivery of BMP-2 using topology optimization may enhance the quality of fusion.

METHODS

Twenty-two 6-month-old pigs underwent anterior cervical discectomy fusion at one level using 3D printed PCL cages. Experimental groups (N=6 each) included: Group 1: ring design with surface adsorbed BMP-2, Group 2: topology-optimized rectangular design with surface adsorbed BMP-2, and Group 3: ring design with BMP-2 delivery via collagen sponge. Additional specimens, two of each design, were implanted without BMP-2, as controls. Complete cervical segments were harvested six months postoperatively. Nanocomputed tomography was performed to assess complete bony bridging. Pure moment biomechanical testing was conducted in all three planes, separately. Continuous 3D motions were recorded and analyzed.

RESULTS

Three subjects suffered early surgical complications and were not evaluated. Overall, ROM for experimental specimens, regardless of design or BMP-2 delivery method, was comparable, with no clinically significant differences among groups. Among experimental specimens at the level of the fusion, ROM was <1.0° in flexion and extension, indicative of fusion, based on clinically applied criteria for fusion of <2 to 4°. Despite the measured biomechanical stability, using computed tomography evaluation, complete bony bridging was observed in 40% of the specimens in Group 1, 50% of Group 2, 100% of Group 3, and none of the control specimens.

CONCLUSION

A topology-optimized PCL cage with BMP-2 is capable of resulting in an intervertebral fusion, similar to a conventional ring-based design of the same bioresorbable material.

Osteoprotegerin-eluting nanoparticulate mineralized collagen scaffolds improve skull regeneration

Custom synthesis of extracellular matrix (ECM)-inspired materials for condition-specific reconstruction has emerged as a potentially translatable regenerative strategy. In skull defect reconstruction, nanoparticulate mineralized collagen glycosaminoglycan scaffolds (MC-GAG) have demonstrated osteogenic and anti-osteoclastogenic properties, culminating in the ability to partially heal in vivo skull defects without the addition of exogenous growth factors or progenitor cell loading. In an effort to reduce catabolism during early skull regeneration, we fabricated a composite material (MCGO) of MC-GAG and recombinant osteoprotegerin (OPG), an endogenous anti-osteoclastogenic decoy receptor. In the presence of differentiating osteoprogenitors, MCGO demonstrated an additive effect with endogenous OPG limited to the first 14 days of culture with total eluted and scaffold-bound OPG exceeding that of MC-GAG. Functionally, MCGO exhibited similar osteogenic properties as MC-GAG, however, MCGO significantly reduced maturation and resorptive activities of primary human osteoclasts. In a rabbit skull defect model, MCGO scaffold-reconstructed defects displayed higher mineralization as well as increased hardness and microfracture resistance compared to non-OPG functionalized MC-GAG scaffolds. The current work suggests that MCGO is a development in the goal of reaching a materials-based strategy for skull regeneration.

Trends, payments, and costs associated with BMP use in Medicare beneficiaries undergoing spinal fusion

BACKGROUND CONTEXT

Bone morphogenic protein (BMP) promotes bony fusion but increases costs. Recent trends in BMP use among Medicare patients have not been well-characterized.

PURPOSE

To assess utilization trends, complication, payments, and costs associated with BMP use in spinal fusion in a Medicare-insured population.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Total of 316,070 patients who underwent spinal fusion in a 20% sample of Medicare-insured patients, 2006 to 2015.

OUTCOME MEASURES

Utilization trends across time and geography, complications, payments, and costs.

METHODS

Patients were stratified by fusion type and diagnosis. Multivariable logistic and linear regression were used to adjust for the effect of baseline characteristics on complications and total payments or cost, respectively.

RESULTS

BMP was used in 60,249 cases (19.1%). BMP utilization rates decreased from 23.1% in 2006 to 12.0% in 2015, most significantly in anterior cervical (7.5%-3.1%), posterior cervical (17.0%-8.3%), and posterior lumbar fusions (31.5%-15.8%). There are significant state- and region-level geographic differences in BMP utilization. Across all years, states with the highest BMP use were Indiana (28.5%), Colorado (26.6%), and Nevada (25.7%). States with the lowest BMP use were Maine (2.3%), Vermont (8.2%), and Mississippi (10.4%). After multivariate risk adjustment, BMP use was associated with decreased overall complications in thoracic (odds ratios [OR] [95% confidence intervals [CI]): 0.89 [0.81-0.99]) and anterior lumbar fusions (OR [95% CI]: 0.89 [0.84-0.95]), as well as increased reoperation rates in anterior cervical (OR [95% CI]: 1.11 [1.04-1.19]), posterior cervical (OR (95% CI): 1.14 (1.04-1.25)), thoracic (OR (95% CI): 1.32 (1.23-1.41)), and posterior lumbar fusions (OR (95% CI): 1.11 (1.06-1.16)). BMP use was also associated with greater total costs, independent of fusion type, after multivariate risk adjustment (p<.0001). Payments, however, were comparable between groups in anterior and posterior cervical fusion with or without BMP. BMP use was associated with greater total payments in thoracic, anterior lumbar, and posterior lumbar fusions. Notably, the difference in payments was smaller than the associated cost increase in all fusion types.

CONCLUSIONS

BMP use has declined across all fusion types over the last decade, after a peak in 2007. While BMP is associated with greater costs, reimbursement does not increase proportionally with BMP cost.

Amniotic membrane attenuates heterotopic ossification following high-dose bone morphogenetic protein-2 treatment of segmental bone defects

Treatment of large bone defects with supraphysiological doses of bone morphogenetic protein-2 (BMP-2) has been associated with complications including heterotopic ossification (HO), inflammation, and pain, presumably due to poor spatiotemporal control of BMP-2. We have previously recapitulated extensive HO in our rat femoral segmental defect model by treatment with high-dose BMP-2 (30 μg). Using this model and BMP-2 dose, our objective was to evaluate the utility of a clinically available human amniotic membrane (AM) around the defect space for guided bone regeneration and reduction of HO. We hypothesized that AM surrounding collagen sponge would attenuate heterotopic ossification compared with collagen sponge alone. In vitro, AM retained more BMP-2 than a synthetic poly(ε-caprolactone) membrane through 21 days. In vivo, as hypothesized, the collagen + AM resulted in significantly less heterotopic ossification and correspondingly, lower total bone volume (BV), compared with collagen sponge alone. Although bone formation within the defect was delayed with AM around the defect, by 12 weeks, defect BVs were equivalent. Torsional stiffness was significantly reduced with AM but was equivalent to that of intact bone. Collagen + AM resulted in the formation of dense fibrous tissue and mineralized tissue, while the collagen group contained primarily mineralized tissue surrounded by marrow-like structures. Especially in conjunction with high doses of growth factor delivered via collagen sponge, these findings suggest AM may be effective as an overlay adjacent to bone healing sites to spatially direct bone regeneration and minimize heterotopic ossification.

Do racial disparities exist in a spine surgery practice that serves a predominately minority population? Outcomes of transforaminal lumbar interbody fusion: A retrospective review

Background

Racial minority status is associated with inferior peri-operative outcomes following spinal fusion. Findings have largely been reported within institutions serving few minority patients. This study aimed to identify if racial disparities exist for transforaminal lumbar interbody fusion (TLIF) procedures within an urban academic medical center which serves a majority non-White population.

Methods

This is a retrospective review of patients who underwent a TLIF procedure at our institution between 06/2016-10/2019. Primary outcome measures included length of stay (LOS), discharge disposition, 30-day return to the emergency department (ED), 30-day readmission rate, and 30-day complication rates. One-hundred-fifty-six patients (female: male, 99: 57) met inclusion criteria. Demographic and clinical data (body mass index (BMI), comorbidities, preoperative lab values) were compared.

Results

The mean LOS was 6.2, 5.9, and 6 days in the White, Hispanic, and Black cohorts, respectively (p = 0.92). There were no differences in discharge disposition between groups (p = 0.52). Thirty-day post-operative complication rates did not differ between groups (p > 0.07). Readmission rates did not differ between groups (p > 0.05). ED visits were more prevalent in the Hispanic group with 16 visits as compared to 8 and 4 in the White and Black groups respectively (p = 0.01).

Conclusions

We found no racial disparities in terms of LOS, discharge disposition, or 30-day readmission rates. Hispanic patients demonstrated an increased utilization of the ED in the early post-operative period. Efforts to overcome language barriers, communicate instructions clearly, and outline post-operative expectations and plans may prevent the need for post-operative ED visits.

Utilization Trends, Cost, and Payments for Adult Spinal Deformity Surgery in Commercial and Medicare-Insured Populations

BACKGROUND

Previous studies have characterized utilization rates and cost of adult spinal deformity (ASD) surgery, but the differences between these factors in commercially insured and Medicare populations are not well studied.

OBJECTIVE

To identify predictors of increased payments for ASD surgery in commercially insured and Medicare populations.

METHODS

We identified adult patients who underwent fusion for ASD, 2007 to 2015, in 20% Medicare inpatient file (n = 21 614) and MarketScan commercial insurance database (n = 38 789). Patient age, sex, race, insurance type, geographical region, Charlson Comorbidity Index, and length of stay were collected. Outcomes included predictors of increased payments, surgical utilization rates, total cost (calculated using Medicare charges and hospital-specific charge-to-cost ratios), and total Medicare and commercial payments for ASD.

RESULTS

Rates of fusion increased from 9.0 to 8.4 per 10 000 in 2007 to 20.7 and 18.2 per 10 000 in 2015 in commercial and Medicare populations, respectively. The Medicare median total charges increased from $88 106 to $144 367 (compound annual growth rate, CAGR: 5.6%), and the median total cost increased from $31 846 to $39 852 (CAGR: 2.5%). Commercial median total payments increased from $58 164 in 2007 to $64 634 in 2015 (CAGR: 1.2%) while Medicare median total payments decreased from $31 415 in 2007 to $25 959 in 2015 (CAGR: -2.1%). The Northeast and Western regions were associated with higher payments in both populations, but there is substantial state-level variation.

CONCLUSION

Rate of ASD surgery increased from 2007 to 2015 among commercial and Medicare beneficiaries. Despite increasing costs, Medicare payments decreased. Age, length of stay, and BMP usage were associated with increased payments for ASD surgery in both populations.

Use of graft materials and biologics in spine deformity surgery: a state-of-the-art review

PURPOSE

The aim of the current review is to summarize the current evidence on graft materials used in fusion procedures for spinal deformity corrections.

METHODS

PubMed, Embase, and Cochrane Library were searched for relevant published observational studies and clinical trials using osteobiologics and biomaterials in spinal deformity surgery.

RESULTS

The use of autograft in deformity correction surgeries has been reported in a limited number of studies, with the harvest sites including iliac crest, ribs, and local bone. Various allografts and biologics have been used in the treatment of spinal deformities including idiopathic and degenerative scoliosis, either as stand alone or in combination with autograft. Limited number of studies reported no differences in fusion rates or outcomes. Use of rh-BMP2 in anterior, posterior or front/back approaches showed higher fusion rates than other graft materials in patients with spinal deformities. Due to the limited number of quality studies included in the review, as well as alternative factors, such as costs, availability, and surgeon expertise/preference, no definitive conclusion or recommendations can be made as to the ideal graft choice in spinal deformity surgery.

CONCLUSIONS

Most commonly used grafts included autograft, allograft and rh-BMP2, with new biologics and biomaterials constantly emerging in the market. Limited number of high-quality comparative studies and heterogeneity in study design prevented direct comparisons that can lead to meaningful recommendations. Further studies are needed to prove superiority of any single graft material and/or biologic that is also cost-effective and safe.

Sex and gender determinants following spinal fusion surgery: A systematic review of clinical data

In the last decade, numerous studies analyzed and described the surgical outcomes in male and female patients submitted to orthopedic surgery. Although this, the impact of sex/gender on spinal fusion surgery clinical outcomes is still poorly defined. This review systematically maps and synthesizes the scientific literature on sex/gender differences in postoperative outcomes for patients undergoing spinal fusion surgery. The search was performed in PubMed, Scopus, and Web of Science in the last 22 years. Clinical studies evaluating potential sex/gender differences in postoperative outcomes and/or complications, as primary or secondary aim, were included and analyzed. Out of the 1,885 records screened, 47 studies were included. These studies comprised a total of 1,158,555 patients (51.31% female; 48.69% male). About 77% of the analyzed studies reported sex/gender-related differences in postoperative outcomes. Most studies treated patients for lumbar degenerative diseases and more than 55% of them reported a worse postoperative outcome in female patients in terms of pain, disability, health-related quality of life questionnaires, and complications. Differently, a significant heterogeneity across studies on patients treated for cervical and sacral degenerative diseases as well as for spinal deformity and traumatic spinal fracture prevented the understanding of specific sex/gender differences after spinal fusion surgery. Despite this, the present review highlighted those female patients treated for lumbar degenerative spine diseases could require more clinical awareness during postoperative care. The understanding of how sex/gender differences can really affect clinical outcomes after spinal fusion surgeries is mandatory for all spinal pathological conditions to drive clinical research toward oriented and personalized protocols.

Factors Which Predict Adverse Outcomes in Anterior Cervical Discectomy and Fusion Procedures in the Nonelderly Adult Population

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

The largest published cohort of anterior cervical discectomy and fusion (ACDF) patients was queried to better characterize demographic and operative factors that predict 90-day complication and 2-year reoperation risk.

SUMMARY OF BACKGROUND DATA

The MarketScan Database was queried from 2007 to 2016 to identify adult patients until 65 years, who underwent an ACDF procedure using International Classification of Diseases 9th Version (ICD-9) and Current Procedural Terminology (CPT) codes. MarketScan is a national insurance claims database that contains millions of patient records across all 50 states.

METHODS

Multivariate logistic regression was used to identify factors associated with complications until 90 days and reoperations until 2 years.

RESULTS

Of 138,839 ACDF procedures, 8500 patients (6.1%) experienced a complication within 90 days of the ACDF, and 7433 (5.4%) underwent surgical revision by 2 years. While the use of anterior cervical plating did not predict 2-year reoperation, it was associated with dramatically reduced 90-day complication risk (adjusted odds ratio [aOR]: 0.32; 95% confidence interval [CI]: 0.30-0.34; P <0.001). Upon multivariate analysis, female sex (aOR: 0.83; 95% CI: 0.79-0.87; P <0.001) was associated with decreased risk of 2-year reoperation, while depression predicted a 50% increase in reoperation risk (aOR: 1.51; 95% CI: 1.43-1.59; P <0.001). The single largest factor associated with reoperation risk, however, was the presence of a 90-day postoperative complication (aOR: 1.79; 95% CI: 1.66-1.94; P <0.001).

CONCLUSION

Increased patient comorbidities and the use of bone morphogenic protein were found to increase the risk for postoperative complications, while cervical plating was associated with a strong decline in this risk. In addition, poor patient mental health outweighed the adverse of impact of other comorbidities on 2-year revision risk. The presence of a postoperative complication was the key modifiable risk factor associated with reoperation risk. Conclusions from this study may help surgeons better identify high-risk ACDF patients for more careful patient selection, counseling, informed consent, and management.

Demographic Predictors of Treatment and Complications for Adult Spinal Deformity: An Analysis of the National Inpatient Sample

PURPOSE

To examine the role of demographics on surgical management and inpatient complications in patients with spinal deformity between 2010 and 2014 via retrospective analysis.

METHODS

Data were obtained from the National Inpatient Sample (NIS). International Classification of Diseases 9th revision codes were used to identify patients with a primary diagnosis of adult spinal deformity (ASD). Multivariable Poisson regression analyses were used to determine whether any individual demographic variables were predictive of surgical management, surgical complexity, postoperative complications and revision operations.

RESULTS

17,433 patients were identified for analysis. Surgical intervention was performed for 94.5% of patients with a primary diagnosis of ASD. Patients at urban teaching hospitals were the most likely to receive surgery (OR= 2.13; 95% CI 1.51-2.95; p < 0.001) relative to rural patients. Female patients were the majority undergoing surgery and were more likely to receive a complication or require a revision when controlling for surgical complexity. Medicare patients were the least likely to undergo surgery and the most likely to receive complex fusion when undergoing an operation. Medicare patients were the least likely to experience complications (OR=0.89; 95% CI 0.80-0.98; p = 0.022) after adjusting for surgical complexity. With regards to race and ethnicity, Hispanics had a decreased likelihood of receiving a revision surgery.

CONCLUSION

There were substantial differences in rates of surgical management, postoperative complications, and revisions among individuals of different demographics including sex, insurance status, ethnicity and hospital teaching status. Further research evaluating the effect of demographics in spine surgery is warranted to fully understand their influence on patient outcomes.

The Rise and Fall of Bone Morphogenetic Protein 2 Throughout the United States

STUDY DESIGN

Retrospective Database Study.

OBJECTIVE

Investigate utilization of bone morphogenetic protein (BMP-2) between 2004 and 2014.

SUMMARY OF BACKGROUND DATA

The utilization, particularly off-label utilization, of BMP-2 has been controversial and debated in the literature. Given the concerns regarding cancer and potential complications, the risk benefit profile of BMP must be weighed with each surgical case. The debate regarding the costs and potential side effects of BMP-2 compared with autologous iliac crest bone harvest has continued.

METHODS

The National Inpatient Sample (NIS) database was queried for the use of BMP-2 (ICD-9-CM 84.52) between 2004 and 2014 across 44 states. The NIS database represents a 20% sample of discharges, weighted to provide national estimates. BMP-2 utilization rates in spine surgery fusion procedures were calculated as a fraction of the total number of thoracic, lumbar, and sacral spinal fusion surgeries performed each year.

RESULTS

Between 2004 and 2014, BMP-2 was utilized in 927,275 spinal fusion surgeries. In 2004, BMP-2 was utilized in 28.3% of all cases (N=48,613). The relative use of BMP-2 in spine fusion surgeries peaked in 2008 at 47.0% (N=112,180). Since then, it has continued to steadily decline with an endpoint of 23.6% of cases in 2014 (N=60,863).

CONCLUSIONS

Throughout the United States, the utilization of BMP-2 in thoracolumbar fusion surgeries increased from 28.3% to 47.0% between 2004 and 2008. However, from 2008 to 2014, the utilization of BMP-2 in thoracolumbar spine fusion surgeries decreased significantly from 47.0% to 23.4%. While this study provides information on the utilization of BMP-2 for the entire United States over an 11-year period, further research is needed to the determine the factors affecting these trends.

Off-label usage of RhBMP-2 in posterior cervical fusion is not associated with early increased complication rate and has similar clinical outcomes

BACKGROUND CONTEXT

Arthrodesis is important for the success of posterior cervical fusion (PCF), however, there exists limited data regarding the safety and efficacy of bone morphogenic protein (BMP) in PCF.

PURPOSE

The primary objective was to evaluate early postoperative complications associated with BMP in PCF and determine whether BMP leads to adverse early clinical outcomes. A secondary objective was to determine the optimal location for BMP sponge placement, within the facet joint (IF) or elsewhere, and the optimal dosage/level.

DESIGN

Retrospective, consecutive case-control study.

PATIENT SAMPLE

Seven hundred sixty-five patients who underwent PCF OUTCOME MEASURES: Patient-reported outcomes (PROs), complications, arthrodesis, optimum dose/level of BMP METHODS: Surgical data, including preoperative diagnosis, levels fused, type of bone graft, BMP dose (when used), and fusion technique were recorded. Complications were assessed by reviewing the medical record encompassing the first 6-weeks postoperative. These included medical, neurological, and wound-related complications and reoperation. Neurological complications were defined as any new weakness, radicular pain, or numbness. PROs were collected, including SF36, VAS, EQ-5D, and NDI scores. To determine the optimal dosage and location for BMP placement, a sub-analysis was performed.

RESULTS

There were no significant differences between the BMP and no BMP group with regards to wound complications, neurological complications, or reoperation. There were no differences in PROs between BMP and no BMP. Placement of BMP for IF and at a dose of 0.87 mg/level minimized wound-related complications. The BMP group had a higher fusion rate compared to the no BMP group (96% vs. 91%, p=.02) when assessed 1 year post-operatively.

CONCLUSION

BMP was not associated with a higher rate of early complications after PCF when the dose was minimized. Complications thought to be associated with BMP, such as compressive seroma, radiculitis, and wound-related complications were not seen at a higher rate. PROs at early follow-up were similar. Placement of BMP for IF and at lower doses than previously reported may minimize complications.

Effects of rhBMP-2-loaded hydroxyapatite granules/beta-tricalcium phosphate hydrogel (HA/β-TCP/hydrogel) composite on a rat model of caudal intervertebral fusion

The effects and inflammation-related side effects of bone morphogenetic protein (BMP)-2 on posterior lumbar interbody fusion are controversial. One of the potential causes for the inconsistent results is the uncontrolled release of BMP-2 from the collagen carrier. Therefore, BMP delivery systems that support effective bone regeneration while attenuating the side effects are strongly sought for. We developed NOVOSIS putty (NP), a novel composite material of hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP)/hydrogel, and BMP-2, which can sustainably release BMP-2 over 2 weeks. This study was aimed at comparing the effects and side effects of NP and collagen sponge (CS) containing BMP-2 using a rat caudal intervertebral fusion model. The fusion rates of NP with low and high doses of BMP-2 were significantly higher than those of an iliac bone (IB) graft, but those of CS with low and high doses of BMP-2 were not different from those of the IB graft. Furthermore, the incidences of ectopic bone formation and soft tissue swelling were significantly lower in the NP group than in the CS group. The HA/β-TCP/hydrogel carrier enabled superior bone induction with low-dose BMP-2 and decreased the incidence of side effects caused by high-dose BMP-2 vis-à-vis the collagen carrier.

Demographic predictors of treatments and surgical complications of lumbar degenerative diseases: An analysis of over 250,000 patients from the National Inpatient Sample

ABSTRACT

This was a national database study.To examine the role of comorbidities and demographics on inpatient complications in patients with lumbar degenerative conditions.Degenerative conditions of the lumbar spine account for the most common indication for spine surgery in the elderly population in the United States. Significant studies investigating demographic as predictors of surgical rates and health outcomes for degenerative lumbar conditions are lacking.Data were obtained from the National Inpatient Sample from 2010 to 2014 and International Classification of Diseases, 9th revision, Clinical Modification codes were used to identify patients with a primary diagnosis of degenerative lumbar condition. Patients were stratified based on demographic variables and comorbidity status. Multivariate regression analyses were used to determine whether any individual demographic variables, such as race, sex, insurance, and hospital status predicted postoperative complications.A total of 256,859 patients were identified for analysis. The rate of overall complications was found to be 16.1% with a mortality rate of 0.10%. Female, Black, Hispanic, and Asian/Pacific Islander patients had lower odds of receiving surgical treatment compared to White patients (P<.001). Medicare and Medicaid patients were less likely to be surgically managed than patients with private insurance (OR = 0.75, 0.37; P<.001, respectively). Urban hospitals were more likely to provide surgery when compared to rural hospitals (P < .001). Patients undergoing fusion had more complications than decompression alone (P < .001). Females, Medicare insurance status, Medicaid insurance status, urban hospital locations, and certain geographical locations were found to predict postoperative complications (P < .001).There were substantial differences in surgical management and postoperative complications among individuals of different sex, races, and insurance status. Further investigation evaluating the effect of demographics in spine surgery is warranted to fully understand their influence on patient complications.

Selective Retinoic Acid Receptor γ Antagonist 7C is a Potent Enhancer of BMP-Induced Ectopic Endochondral Bone Formation

Bone morphogenetic proteins (BMPs) have been clinically applied for induction of bone formation in musculoskeletal disorders such as critical-sized bone defects, nonunions, and spinal fusion surgeries. However, the use of supraphysiological doses of BMP caused adverse events, which were sometimes life-threatening. Therefore, safer treatment strategies for bone regeneration have been sought for decades. Systemic administration of a potent selective antagonist of retinoic acid nuclear receptor gamma (RARγ) (7C) stimulated BMP-induced ectopic bone formation. In this study, we developed 7C-loaded poly lactic nanoparticles (7C-NPs) and examined whether local application of 7C enhances BMP-induced bone regeneration. The collagen sponge discs that absorbed recombinant human (rh) BMP-2 were implanted into the dorsal fascia of young adult mice to induce ectopic bone. The combination of rhBMP-2 and 7C-NP markedly increased the total bone volume and thickness of the bone shell of the ectopic bone in a dose-dependent manner compared to those with rhBMP-2 only. 7C stimulated sulfated proteoglycan production, expression of chondrogenic marker genes, and Sox9 reporter activity in both chondrogenic cells and MSCs. The findings suggest that selective RARγ antagonist 7C or the related compounds potentiate the bone inductive ability of rhBMP-2, as well as support any future research to improve the BMP-2 based bone regeneration procedures in a safe and efficient manner.

Use of Recombinant Human Bone Morphogenetic Protein-2 With Iliac Crest Bone Graft Instead of Iliac Crest Bone Graft Alone in Lumbar Spondylolysis

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to evaluate the clinical and radiographic effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) in pars repair of lumbar spondylolysis.

SUMMARY OF BACKGROUND DATA

BMP-2 is a growth factor that plays a role in the formation of bone and promotes bone healing. However, few studies of using rhBMP-2 in pars repair have been reported.

METHODS

Direct pars repair and pedicle screw fixation was performed, which were added with 1 mg of rhBMP-2 and iliac crest bone graft in the study group (rhBMP-2 group, n=32) and iliac crest bone graft alone in the autograft group (n=36). Patients completed the visual analog scale and the Oswestry Disability Index preoperation, 3, 6, and 12 months after the operation. Computed tomography scans with axial and sagittal reconstructions were performed at 6, 9, 12, 18, and 24 months postoperatively.

RESULTS

Baseline demographic data showed no significant difference between 2 groups. There were significant differences for the Oswestry Disability Index score at 3 and 6 months postoperatively, which were higher in the autograft group. There was no significant difference between the groups with respect to the overall union status. As for union speed, the trabecular bone appeared earlier and union rates were higher in rhBMP-2 group than in the autograft group at 9, and 12 months postoperatively. No complications were identified in either group. One case in the rhBMP-2 group and 2 cases in the autograft group underwent revision surgery.

CONCLUSION

Compared with iliac crest bone graft alone, the use of rhBMP-2 can accelerate fusion in pars repair for young patients with spondylolysis. The union rates were significantly different at 9 and 12 months after surgery. This study showed no clinical difference when adding rhBMP-2 compared with iliac crest bone graft alone.

Recombinant Human Bone Morphogenetic Protein-2 Use in Adult Spinal Deformity Surgery: Comparative Analysis and Healthcare Utilization at 24 Months' Follow-up

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used to achieve fusion in adult spinal deformity (ASD) surgery. Our aim was to investigate the long-term impact of rhBMP-2 use for clinical outcomes and health care utilization in this patient population.

METHODS

We conducted an analysis using MarketScan to identify health resource utilization of rhBMP-2 use for ASD after surgical intervention compared to fusion without rhBMP-2 at 24 months' follow-up. Outcomes assessed included length of stay, complications, pseudoarthrosis, reoperation, outpatient services, and health care payments.

RESULTS

Of 7115 patients who underwent surgery for ASD, 854 received rhBMP-2 and 6261 were operated upon without use of rhBMP-2. One month after discharge, the rhBMP-2 cohort had a nonsignificant trend in fewer complications (15.38%) than those who did not receive rhBMP-2 (18.07%), P = .0558. At 12 months, pseudoarthrosis was reported in 2.8% of cases with no BMP and 01.14% of cases with BMP, P = .0048. Average payments at 12 months were $120 138 for the rhBMP-2 group and $118 373 for the no rhBMP-2 group, P = .8228. At 24 months, payments were $141 664 for the rhBMP-2 group and $144 179 for the group that did not receive rhBMP-2, P = .5946.

CONCLUSIONS

In ASD surgery, use of rhBMP-2 was not associated with increased complications or reoperations at index hospitalization and 1-month follow-up. Overall payments, including index hospitalization, readmissions, reoperations, and outpatient services were not different compared to those without the use of rhBMP-2 at 12 months and 24 months after discharge.

To B (Bone Morphogenic Protein-2) or Not to B (Bone Morphogenic Protein-2): Mesenchymal Stem Cells May Explain the Protein's Role in Osteosarcomagenesis

Osteosarcoma (OS), a primary malignant bone tumor, stems from bone marrow-derived mesenchymal stem cells (BMSCs) and/or committed osteoblast precursors. Distant metastases, in particular pulmonary and skeletal metastases, are common in patients with OS. Moreover, extensive resection of the primary tumor and bone metastases usually leads to bone defects in these patients. Bone morphogenic protein-2 (BMP-2) has been widely applied in bone regeneration with the rationale that BMP-2 promotes osteoblastic differentiation of BMSCs. Thus, BMP-2 might be useful after OS resection to repair bone defects. However, the potential tumorigenicity of BMP-2 remains a concern that has impeded the administration of BMP-2 in patients with OS and in populations susceptible to OS with severe bone deficiency (e.g., in patients with genetic mutation diseases and aberrant activities of bone metabolism). In fact, some studies have drawn the opposite conclusion about the effect of BMP-2 on OS progression. Given the roles of BMSCs in the origination of OS and osteogenesis, we hypothesized that the responses of BMSCs to BMP-2 in the tumor milieu may be responsible for OS development. This review focuses on the relationship among BMSCs, BMP-2, and OS cells; a better understanding of this relationship may elucidate the accurate mechanisms of actions of BMP-2 in osteosarcomagenesis and thereby pave the way for clinically safer and broader administration of BMP-2 in the future. For example, a low dosage of and a slow-release delivery strategy for BMP-2 are potential topics for exploration to treat OS.

Image Guidance-Assisted Decompression and Removal of Heterotopic Ossification Following the Use of Recombinant Human Bone Morphogenetic Protein-2 in Transforaminal Lumbar Interbody Fusion

Heterotopic ossification (HO) following the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in the setting of transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) is a troublesome and well-described postoperative complication. There is currently no consensus regarding the treatment of this offending pathology. In this report, we present a retrospective single-surgeon review of 14 patients who underwent image-guided decompression of HO. We describe a new technique where navigation demonstrates a safe and thorough decompression compared to that with fluoroscopy or anatomical landmarks alone. To evaluate successful decompression, we reviewed patient self-reported clinical outcomes. Seven patients demonstrated positive results, while three had mixed outcomes and four showed poor outcomes. While more studies are needed to determine the overall efficacy of intraoperative navigation-assisted decompression, findings from this small cohort of patients suggest that it is a useful technique in the setting of the removal of heterotopic bone.

Paracrine Effects of Recombinant Human Adiponectin Promote Bone Regeneration

Bone regeneration is a delicate physiological process. Non-union and delayed fracture healing remains a great challenge in clinical practice nowadays. Bone and fat hold a close relationship to remain balanced through hormones and cytokines. Adiponectin is a well-known protein to maintain the hemostasis, which may be an interesting target for fracture healing. Herein, we provided a facile and efficient method to obtain high-purity and high-yield recombinant human adiponectin (ADPN). The biocompatibility and the pharmaceutical behaviors were evaluated in Sprague–Dawley rats. The paracrine effects of adiponectin on bone fracture healing were investigated with a rat tibia fracture model via intrabone injection. Significantly accelerated bone healing was observed in the medulla injection group, indicating the paracrine effects of adiponectin could be potentially utilized for clinical treatments. The underlying mechanism was primarily assessed, and the expression of osteogenic markers, including bone morphogenic protein 2, alkaline phosphatase, and osteocalcin, along with adiponectin receptor 1 (AdipoR1), was markedly increased at the fracture site. The increased bone healing of ADPN treatment may result from both enhanced osteogenic proliferation as well as differentiation. Cell experiments confirmed that the expression of osteogenesis markers increased significantly in ADPN treatment groups, while it decreased when the expression of AdipoR1 was knocked down by siRNA. Our study provided a feasible and efficacious way for bone fracture treatment with local administration of ADPN, which could be rapidly translated into the clinics.