Biologics in Spine Arthrodesis

Advances in implants and bone graft types for lumbar spinal fusion surgery

The increasing prevalence of spinal disorders worldwide necessitates advanced treatments, particularly interbody fusion for severe cases that are unresponsive to non-surgical interventions. This procedure, especially 360° lumbar interbody fusion, employs an interbody cage, pedicle screw-and-rod instrumentation, and autologous bone graft (ABG) to enhance spinal stability and promote fusion. Despite significant advancements, a persistent 10% incidence of non-union continues to result in compromised patient outcomes and escalated healthcare costs. Innovations in lumbar stabilisation seek to mimic the properties of natural bone, with evolving implant materials like titanium (Ti) and polyetheretherketone (PEEK) and their composites offering new prospects. Additionally, biomimetic cages featuring precisely engineered porosities and interconnectivity have gained traction, as they enhance osteogenic differentiation, support osteogenesis, and alleviate stress-shielding. However, the limitations of ABG, such as harvesting morbidities and limited fusion capacity, have spurred the exploration of sophisticated solutions involving advanced bone graft substitutes. Currently, demineralised bone matrix and ceramics are in clinical use, forming the basis for future investigations into novel bone graft substitutes. Bioglass, a promising newcomer, is under investigation despite its observed rapid absorption and the potential for foreign body reactions in preclinical studies. Its clinical applicability remains under scrutiny, with ongoing research addressing challenges related to burst release and appropriate dosing. Conversely, the well-documented favourable osteogenic potential of growth factors remains encouraging, with current efforts focused on modulating their release dynamics to minimise complications. In this evidence-based narrative review, we provide a comprehensive overview of the evolving landscape of non-degradable spinal implants and bone graft substitutes, emphasising their applications in lumbar spinal fusion surgery. We highlight the necessity for continued research to improve clinical outcomes and enhance patient well-being.

Cellular Bone Matrix in Spine Surgery - Are They Worth the Risk: A Systematic Review

STUDY DESIGN

Systematic Review.

OBJECTIVE

To review the literature for complications and outcomes after the implantation of cellular bone matrix (CBM) during spine fusion.

METHODS

The PubMed database was queried from inception to January 31, 2023 for any articles that discussed the role of and identified a specific CBM in spinal fusion procedures. Adverse events, reoperations, methods, and fusion rates were collected from all studies and reported.

RESULTS

Six hundred articles were identified, of which 19 were included that reported outcomes of 7 different CBM products. Seven studies evaluated lumbar fusion, 11 evaluated cervical fusion, and 1 study reported adverse events of a single CBM product. Only 4 studies were comparative studies while others were limited to case series. Fusion rates ranged from 68% to 98.7% in the lumbar spine and 87% to 100% in the cervical spine, although criteria for radiographic fusion was variable. While 7 studies reported no adverse events, there was no strict consensus on what constituted a complication. One study reported catastrophic disseminated tuberculosis from donor contaminated CBM. The authors of 14 studies had conflicts of interest with either the manufacturer or distributor for their analyzed CBM.

CONCLUSIONS

Current evidence regarding the use of cellular bone matrix as an osteobiologic during spine surgery is weak and limited to low-grade non-comparative studies subject to industry funding. While reported fusion rates are high, the risk of severe complications should not be overlooked. Further large clinical trials are required to elucidate whether the CBMs offer any benefits that outweigh the risks.

Impact of Teriparatide on Complications and Patient-Reported Outcomes of Patients Undergoing Long Spinal Fusion According to Bone Density

BACKGROUND

Surgery for adult spinal deformity (ASD) poses substantial risks, including the development of symptomatic pseudarthrosis, which is twice as prevalent among patients with osteoporosis compared with those with normal bone mineral density (BMD). Limited data exist on the impact of teriparatide, an osteoanabolic compound, in limiting the rates of reoperation and pseudarthrosis after treatment of spinal deformity in patients with osteoporosis.

METHODS

Osteoporotic patients on teriparatide (OP-T group) were compared with patients with osteopenia (OPE group) and those with normal BMD. OP-T patients were matched with OPE patients and patients with normal BMD at a 1:2:2 ratio. All patients had a minimum 2-year follow-up and underwent posterior spinal fusion (PSF) involving >7 instrumented levels. The primary outcome was the 2-year reoperation rate. Secondary outcomes included pseudarthrosis with or without implant failure, proximal junctional kyphosis (PJK), and changes in patient-reported outcomes (PROs). Clinical outcomes were analyzed using conditional logistic regression. Changes in PROs were analyzed using a mixed-effects model.

RESULTS

Five hundred and forty patients (52.6% normal BMD, 32.9% OPE, 14.4% OP-T) were included. In the unmatched cohort, 2-year reoperation rates (odds ratio [OR] = 0.45 [95% confidence interval (CI): 0.20 to 0.91]) and pseudarthrosis rates (OR = 0.25 [95% CI: 0.08 to 0.61]) were significantly lower in the OP-T group than the OPE group. Seventy-eight patients in the OP-T group were matched to 156 patients in the OPE group. Among these matched patients, at 2 years, 23.1% (36) in the OPE group versus 11.5% (9) in the OP-T group had a reoperation (OR = 0.45, p = 0.0188), 21.8% (34) versus 6.4% (5) had pseudarthrosis with or without implant failure (OR = 0.25, p = 0.0048), and 6.4% (10) versus 7.7% (6) had PJK (OR = 1.18, p = 0.7547), respectively. At 2 years postoperatively, PROs were better among OP-T patients than OPE patients. Subsequently, 78 patients in the OP-T group were matched to 156 patients in the normal BMD group. Among these matched patients, there was no significant difference in 2-year reoperation (OR = 0.85 [95% CI: 0.37 to 1.98]), pseudarthrosis (OR = 0.51 [95% CI: 0.181 to 1.44]), and PJK rates (OR = 0.77 [95% CI: 0.28 to 2.06).

CONCLUSIONS

Osteoporotic patients on teriparatide demonstrated lower reoperation and symptomatic pseudarthrosis rates 2 years postoperatively compared with osteopenic patients. Moreover, patient-reported and clinical outcomes for osteoporotic patients on teriparatide were not different from those for patients with normal BMD.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

The combined use of carbon nanotubes with synthetic ceramics enhances posterolateral fusion: an experimental study in a rat spinal fusion model

PURPOSE

The aim of the present study was to evaluate the effectiveness of carbon nanotubes (CNTs)/ HA-tricalcium phosphate (TCP) composite in a posterolateral spinal fusion model.

METHODS

At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Sprague Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later, all animals were killed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro-computed tomography (mCT).

RESULTS

In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3) (p < 0.001). Although in Group 2, in which only CNTs were used, the ratio was found to be statistically significantly higher than group 1(p < 0.001), the difference was not considered as significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e., no bone formation was observed.

CONCLUSIONS

The CNTs/HA-TCP composite is a promising synthetic bone graft substitute for spinal fusion. Although CNTs are inadequate in producing spinal fusion when they are used alone, due to their high biocompatibility due to their high biocompatibility, and multiple effect on bone regeneration, they seem to increase fusion rates significantly when they are used in combination with ceramic-based synthetic grafts.

Biomechanical Comparison of Different Numbers and Configurations of Cross-Links in Long-Segment Spinal Fixation-An Experimental Study in a Porcine Model

STUDY DESIGN

Biomechanical study.

OBJECTIVE

Cross-links are a type of common clinical spinal instrumentation. However, the effects of the position and number of cross-links have never been investigated in long-segment spinal fixation, and the variables have not been optimized. We conducted an in vitro biomechanical study by using a porcine long-segment spinal model with 5 different crosslink configurations to determine the optimal construct for clinical practice.

METHODS

Five modalities with paired segmental screws from T15-L5 were tested in 20 porcine spines. The spines without cross-links composed the control group, Group A; those with a single cross-link from L2-3 composed Group B; those with 2 cross-links from L1-2 and L3-4 composed Group C; those with 2 cross-links from T15-L1 and L4-5 composed Group D; and those with 3 cross-links from T15-L1, L2-3 and L4-5 composed Group E. Spinal stiffnesses in flexion, extension, lateral bending, and axial rotation were compared among 5 different cross-link configurations in 5-level porcine spinal units.

RESULTS

Flexional, extensional and lateral bending stiffnesses did not significantly change with an increasing number of cross-links or positions in the construct. Axial stiffness was significantly increased with 2 cross-links compared to one (P < 0.05) and with placement more distant from the center of the long spinal fixation construct (P < 0.05).

CONCLUSIONS

Two cross-links individually placed proximal and distal from the center of a construct is an optimal and efficient configuration to achieve biomechanical stability in non-rigid lumbar spines undergoing long-level fixation.

Lumbar Interbody Fusion and Osteobiologics for Lumbar Fusion

Lumbar interbody fusion (LIF) is an excellent treatment option for a number of lumbar diseases. LIF can be performed through posterior, transforaminal, anterior, and lateral or oblique approaches. Each technique has its own pearls and pitfalls. Through LIF, segmental stabilization, neural decompression, and deformity correction can be achieved. Minimally invasive surgery has recently gained popularity and each LIF procedure can be performed using minimally invasive techniques to reduce surgery-related complications and improve early postoperative recovery. Despite advances in surgical technology, surgery-related complications after LIF, such as pseudoarthrosis, have not yet been overcome. Although autogenous iliac crest bone graft is the gold standard for spinal fusion, other bone substitutes are available to enhance fusion rate and reduce complications associated with bone harvest. This article reviews the surgical procedures and characteristics of each LIF and the osteobiologics utilized in LIF based on the available evidence.

Ceramic bone graft substitute (Mg-HA) in spinal fusion: A prospective pilot study

Background: Iliac crest bone graft (ICBG) is considered the gold standard for spine surgical procedures to achieve a successful fusion due to its known osteoinductive and osteoconductive properties. However, complications related to harvesting procedure and donor site morbidity have been largely reported in the literature, favoring the development of a wide range of alternative products to be used as bone graft extenders or substitutes for spine fusion. Among all, ceramic-based biomaterials have been widely studied and employed in the last years as bone graft substitutes. Methods: We report here the results of a prospective pilot study aimed to evaluating the grade of ossification obtained by the use of an Mg-doped hydroxyapatite (HA) product to achieve postero-lateral fusion in degenerative spine diseases. Results: Results show a successful degree of fusion of about 62% at the 12-month follow-up and an improvement of quality of life and health status following surgery, as evaluated by clinical scores (ODI, VAS, and EQ-5L). No adverse events related to the material were reported. Conclusion: The present pilot study shows the effectiveness and the safety profile of an Mg-doped HA bone graft substitute used to achieve postero-lateral fusion in the treatment of degenerative spine diseases, laying down the basis for further larger clinical investigations.

Trailblazing: the historical development of the posterior lumbar interbody fusion (PLIF)

Today, the posterior lumbar interbody fusion (PLIF), and related methods of fusion, represent the gold standard in spinal arthrodesis. However, despite the PLIF being first performed in the 1940s, its reputation was marked by animosity for the next fifty years. Only due to the extraordinary talent and perseverance from a small group of pioneers, was the operation eventually appreciated to be an ideal fusion technique. This process of popularization has assisted the surgical community to better recognize the complexities of spinal biomechanics and has encouraged the momentum of success in modern spinal surgery. Neither the complete origins of the technique, nor the remarkable story of its propagation, have previously been reported.

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

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

Recent Research Advances in Biologic Bone Graft Materials for Spine Surgery

PURPOSE OF REVIEW

Biologic bone graft materials continue to be an important component of various spinal fusion procedures. Given the known risks and morbidity of harvesting iliac crest bone graft, the historical gold standard for spinal fusion, these biologic materials serve the purpose of improving both the efficacy and safety of spinal fusion procedures. Recent advances in biomedical and materials sciences have enabled the design of many novel materials that have shown promise as effective bone graft materials. This review will discuss current research pertaining to several of these materials, including functionalized peptide amphiphiles and other nanocomposites, novel demineralized bone matrix applications, 3D-printed materials, and Hyperelastic Bone®, among others.

RECENT FINDINGS

Recent investigation has demonstrated that novel technologies, including nanotechnology and 3D printing, can be used to produce biomaterials with significant osteogenic potential. Notably, peptide amphiphile nanomaterials functionalized to bind BMP-2 have demonstrated significant bone regenerative capacity in a pre-clinical rodent posterolateral lumbar fusion (PLF) model. Additionally, 3D-printed Hyperelastic Bone® has demonstrated promising bone regenerative capacity in several in vivo animal models. Composite materials such as TrioMatrix® (demineralized bone matrix, hydroxyapatite, and nanofiber-based collagen scaffold) have also demonstrated significant osteogenic potential in both in vitro and in vivo settings. Advances in materials science and engineering have allowed for the design and implementation of several novel biologic materials, including nanocomposites, 3D-printed materials, and various biologic composites. These materials provide significant bone regenerative capacity and have the potential to be alternatives to other bone graft materials, such as autograft and BMP-2, which have known complications.

Scientific, Clinical, Regulatory, and Economic Aspects of Choosing Bone Graft/Biological Options in Spine Surgery

Spinal arthrodesis is a major element of the spinal surgeon's practice. To attain successful fusion rates, attention must be paid to spinal segment immobilization and proper selection of bone graft. Autogenous bone graft (ie, ICBG), the "gold standard," with or without graft extenders and enhancers provides the foundation for most spinal fusions. ABG is the only graft option containing all 3 factors of new bone growth: osteoconductivity, osteoinductivity, and osteogenicity. While many bone graft alternatives function well as bone graft extenders, only growth factors proteins (ie, rhBMP-2 or OP-2) function as bone graft enhancers and substitutes. The search for optimal hybrid interbody cages, bone graft substitutes, autogenous or allogenic stem cells, and nanostructure scaffolds for release of growth factors continues.

An evaluation of biomaterials and osteobiologics for arthrodesis achievement in spine surgery

An increasing variety of orthobiologic materials, including autologous and allogeneic bone graft, bone marrow aspirate, demineralized bone matrix, ceramics, and growth factors are available to the spine surgeon. Although autologous bone graft remains the gold standard material, concerns for failure in achieving fusion have prompted evaluation of current and new biologic materials. As such, this review attempts to summarize the available biologic materials with their pertinent characteristics, advantages, disadvantages, and primary uses.

Orthobiologics in minimally invasive lumbar fusion

Minimally invasive (MI) spine surgery continues to gain popularity with patients and surgeons for its potential to decrease operative time and avoid complications commonly associated with open surgery. In the face of a changing surgical landscape, selecting the appropriate implant material to be used in MI lumbar fusion procedures will remain critically important. Various orthobiologic materials are available for use, including autologous and allogeneic bone graft, bone marrow aspirate (BMA), demineralized bone matrix (DBM), ceramics, and growth factors. The purpose of this review is to summarize the use and efficacy of currently available products, as well as highlight the development of novel therapeutic options.

An inception cohort study of patients in a military clinic treated for lower back pain with lumbar fusion and SIGNAFUSE® with a systematic review of the literature

Background: Use of synthetic bone graft substitutes for spinal fusion has increased sharply over the past 20 years. SIGNAFUSE® is one such synthetic graft material that provides an osteostimulatory effect for spinal fusion. Because clinical trials are not required for commercialization of synthetic bone graft substitutes in the United States, fusion rates attained using SIGNAFUSE for lumbar fusion are not well documented. The goal of the current study is to determine the rate of spinal fusion in a military clinic following lumbar fusion surgery augmented with SIGNAFUSE. Methods: We report a retrospective chart review of 8 patients who received lumbar spinal fusion surgery augmented with SIGNAFUSE. All patients were assessed by computed tomographic (CT) imaging at least 1-year post-surgery to determine whether bony fusion had occurred. We also systematically reviewed literature sources that report fusion rate following spinal fusion surgery, for broader context. Results: An average of 1.6 spinal levels were treated with SIGNAFUSE-loaded interbody cages. All patients had stabilization hardware via pedicle screws or integrated cage fixation. Seven of 8 patients successfully fused, for an overall fusion rate of 87.5% (95% confidence interval: 47.4% to 99.7%). Systematic review of 26 recent publications that included 1,126 patients treated with synthetic bone graft showed that the overall fusion rate in the literature is 84.4%. Conclusions: Fusion was achieved in 87.5% of patients treated with SIGNAFUSE. This is comparable to the fusion rate in a systematic review of 1,126 patients treated with synthetic bone graft materials.

Biological Rationale for the Use of Vertebral Whole Bone Marrow in Spinal Surgery

STUDY DESIGN

Laboratory study.

OBJECTIVE

Mesenchymal stem cells (MSCs) derived from whole bone marrow aspirate (BMA) and MSCs derived from density-gradient centrifugation were isolated from vertebral bodies and cultured under either hypoxic or normoxic conditions to evaluate their biological characteristics and HOX and TALE signature able to improve spinal surgery procedures.

SUMMARY OF BACKGROUND DATA

The use of spinal fusion procedures has increased over the last decades; however, failed fusion still remains an important problem. Clinician and researchers focused their attention on the therapeutic potential of bone marrow MSCs and several methods for their isolation and cultivation have been developed. However, the best source and techniques are still debated.

METHODS

MSCs morphology, surface markers, colony-forming-units, and three lineage differentiation through quantitative real-time PCR (qPCR) were evaluated. Additionally, gene expression analysis of HOX and TALE signatures during osteogenic differentiation were analyzed.

RESULTS

Our study showed that MSCs derived from whole BMA were successfully isolated and when cultured under hypoxic condition presented greater proliferation, larger colonies, and differentiated onto osteogenic and chondrogenic lineage with greater ability, while adipogenic differentiation was less efficient. Results also revealed that MSCs, differently isolated and cultured, expressed different level of HOX and TALE signatures and that HOXB8 were up-regulated with greater efficiency in MSCs derived from whole BMA under hypoxia.

CONCLUSION

Our data indicated that hypoxic preconditioning of MSCs derived from whole BMA exhibited more suitable biological characteristics and different level of HOX and TALE gene activation. We, therefore, concluded that vertebral body MSCs derived from whole BMA may provide alternative sources of MSCs for tissue engineering applications for spine surgery.

LEVEL OF EVIDENCE

N/A.

Leaping the hurdles in developing regenerative treatments for the intervertebral disc from preclinical to clinical

Chronic back and neck pain is a prevalent disability, often caused by degeneration of the intervertebral disc. Because current treatments for this condition are less than satisfactory, a great deal of effort is being applied to develop new solutions, including regenerative strategies. However, the path from initial promising idea to clinical use is fraught with many hurdles to overcome. Many of the keys to success are not necessarily linked to science or innovation. Successful translation to clinic will also rely on planning and awareness of the hurdles. It will be essential to plan your entire path to clinic from the outset and to do this with a multidisciplinary team. Take advice early on regulatory aspects and focus on generating the proof required to satisfy regulatory approval. Scientific demonstration and societal benefits are important, but translation cannot occur without involving commercial parties, which are instrumental to support expensive clinical trials. This will only be possible when intellectual property can be protected sufficiently to support a business model. In this manner, commercial, societal, medical, and scientific partners can work together to ultimately improve patient health. Based on literature surveys and experiences of the co-authors, this opinion paper presents this pathway, highlights the most prominent issues and hopefully will aid in your own translational endeavors.

Spinal Biologics in Minimally Invasive Lumbar Surgery

As the use of minimally invasive spine (MIS) fusion approaches continues to grow, increased scrutiny is being placed on its outcomes and efficacies against traditional open fusion surgeries. While there are many factors that contribute to the success of achieving spinal arthrodesis, selecting the optimal fusion biologic remains a top priority. With an ever-expanding market of bone graft substitutes, it is important to evaluate each of their use as it pertains to MIS techniques. This review will summarize the important characteristics and properties of various spinal biologics used in minimally invasive lumbar surgeries and compare their fusion rates via a systematic review of published literature.

Nanotechnology in orthopedics: a clinically oriented review

The utility of nanotechnology in medicine, specifically within the field of orthopedics, is a topic of extensive research. Our review provides a unique comprehensive overview of the current and potential future uses of nanotechnology with respect to orthopedic sub-specialties. Nanotechnology offers an immense assortment of novel applications, most notably the use of nanomaterials as scaffolds to induce a more favorable interaction between orthopedic implants and native bone. Nanotechnology has the capability to revolutionize the diagnostics and treatment of orthopedic surgery, however the long-term health effects of nanomaterials are poorly understood and extensive research is needed regarding clinical safety.

Novel Osteobiologics and Biomaterials in the Treatment of Spinal Disorders

Spinal osteobiologics have evolved substantially in this century after the development of many product categories such as growth factors, allograft, and stem cells. The indications for the use of novel biologics within spine surgery are rapidly expanding as the mechanism of each is elucidated. While the knowledge base of bone morphogenetic protein increases with each subsequent year, the application of new nanotechnology and cell-based strategies are being reported. This review will discuss the most recent data in novel osteobiologics, and where we could use future study.

Bone morphogenetic protein use in spine surgery in the United States: how have we responded to the warnings?

BACKGROUND CONTEXT

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been widely adopted as a fusion adjunct in spine surgery since its approval in 2002. A number of concerns regarding adverse effects and potentially devastating complications of rhBMP-2 use led to a Food and Drug Administration (FDA) advisory issued in 2008 cautioning its use, and a separate warning about its potential complications was published by The Spine Journal in 2011.

PURPOSE

To compare trends of rhBMP-2 use in spine surgery after the FDA advisory in 2008 and The Spine Journal warning in 2011.

STUDY DESIGN

Retrospective cross-sectional study using a national database.

PATIENT SAMPLE

All patients from 2002 to 2013 who underwent spinal fusion surgery at an institution participating in the Nationwide Inpatient Sample (NIS).

OUTCOME MEASURES

Proportion of spinal fusion surgeries using rhBMP-2.

METHODS

We queried the NIS from 2002 to 2013 and used International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes to identify spinal fusion procedures and those that used rhBMP-2. Procedures were subdivided into primary and revision fusions, and by region of the spine. Cervical and lumbosacral fusions were further stratified into anterior and posterior approaches. The percentage of cases using BMP was plotted across time. A linear regression was fit to the data from quarter 3 of 2008 (FDA advisory) through quarter 1 of 2011, and a separate regression was fit to the data from quarter 2 of 2011 (The Spine Journal warning) onward. The slopes of these regression lines were statistically compared to determine differences in trends. No funding was received to conduct this study, and no authors had any relevant conflicts of interest.

RESULTS

A total of 4,167,079 patients in the NIS underwent spinal fusion between 2002 and 2013. We found a greater decrease in rhBMP-2 use after The Spine Journal warning compared with the FDA advisory for all fusion procedures (p=.006), primary fusions (p=.006), and revision fusions (p=.004). Lumbosacral procedures also experienced a larger decline in rhBMP-2 use after The Spine Journal article as compared with the FDA warning (p=.0008). This pattern was observed for both anterior and posterior lumbosacral fusions (p≤.0001 for both). Anterior cervical fusion was the only procedure that demonstrated a decline in rhBMP-2 use after the FDA advisory that was statistically greater than after The Spine Journal article (p=.02).

CONCLUSIONS

Warnings sanctioned through the spine literature may have a greater influence on practice of the spine surgery community as compared with advisories issued by the FDA.Comprehensive guidelines regarding safe and effective use of rhBMP-2 must be established.

A new bioinspired collagen-hydroxyapatite bone graft substitute in adult scoliosis surgery: results at 3-year follow-up

Background

Spinal fusion is a common procedure used for surgical treatment of spinal deformity. In recent years, many bone graft substitutes (BGS) have been developed to provide good arthrodesis when the available autologous bone harvested from the patient is not enough. The aim of this study was to analyze the use of a new-generation composite material (RegenOss) made of Mg-hydroxyapatite nanoparticles nucleated on type I collagen to obtain long posterolateral fusion in adult scoliosis surgery.

Methods

A total of 41 patients who underwent spinal fusion for the treatment of adult scoliosis were retrospectively analyzed. According to Lenke classification, visual analog scale (VAS) score and Oswestry Disability Index (ODI) score, radiographic rates of bone union were evaluated before surgery and at 6, 12 and 36 months of follow-up. Fusion was considered to be successful when criteria for Lenke grade A or B were satisfied. Patient-related risk factors were considered for the evaluation of the final outcome.

Results

At 36-month follow-up, radiographic evidence of spinal fusion was present in the majority of patients (95.1%). A time-dependent statistically significant improvement was evidenced after surgery for all clinical outcomes evaluated. Based on the demographic data collected, there were no statistically significant factors determining fusion. The correction of deformity was maintained at different time points. No intraoperative or postoperative complications were recorded.

Conclusions

The present study demonstrated that RegenOss can safely be used to achieve good arthrodesis when associated with autologous bone graft to obtain long spinal fusion in the treatment of adult scoliosis.

Orthobiologics in Pediatric Orthopedics

Orthobiologics are biologic devices or products used in orthopedic surgery to augment or enhance bone formation. The use of orthobiologics in pediatric orthopedics is less frequent than in other orthopedic subspecialties, mainly due to the naturally abundant healing potential and bone formation in children compared with adults. However, orthobiologics are used in certain situations in pediatric orthopedics, particularly in spine and foot surgery. Other uses have been reported in conjunction with specific procedures involving the tibia and pelvis. The use of bioabsorable implants to stabilize children's fractures is an emerging concept but has limited supporting data.

Bone grafts, bone graft extenders, substitutes and enhancers for acetabular reconstruction in revision total hip arthroplasty

Acetabular bone loss is a relevant concern for surgeons dealing with a failed total hip arthroplasty.

Since the femoral head is no longer available, allografts represent the first choice for most reconstructive solutions, either as a structural buttress or impacted bone chips.

Even though fresh-frozen bone is firmly recommended for structural grafts, freeze-dried and/or irradiated bone may be used alternatively for impaction grafting. Indeed, there are some papers on freeze-dried or irradiated bone impaction grafting, but their number is limited, as is the number of cases.

Xenografts do not represent a viable option based on the poor available evidence but bioactive bioceramics such as hydroxyapatite and biphasic calcium phosphates are suitable bone graft extenders or even substitutes for acetabular impaction grafting.

Bone-marrow-derived mesenchymal stem cells and demineralised bone matrix seem to act as reliable bone graft enhancers, i.e. adjuvant therapies able to improve the biological performance of standard bone grafts or substitutes. Among these therapies, platelet-rich plasma and bone morphogenetic proteins need to be investigated further before any recommendations can be made.

Cite this article: EFORT Open Rev 2016;1:431-439. DOI:10.1302/2058-5241.160025

Lumbar pseudarthrosis: a review of current diagnosis and treatment

OBJECT Failed solid bony fusion, or pseudarthrosis, is a well-known complication of lumbar arthrodesis. Recent advances in radiographic technology, biologics, instrumentation, surgical technique, and understanding of the local biology have all aided in the prevention and treatment of pseudarthrosis. Here, the current literature on the diagnosis and management of lumbar pseudarthroses is reviewed. METHODS A systematic literature review was conducted using the MEDLINE and Embase databases in order to search for the current radiographie diagnosis and surgical treatment methods published in the literature (1985 to present). Inclusion criteria included: 1) published in English; 2) level of evidence I-III; 3) diagnosis of degenerative lumbar spine conditions and/or history of lumbar spine fusion surgery; and 4) comparative studies of 2 different surgical techniques or comparative studies of imaging modality versus surgical exploration. RESULTS Seven studies met the inclusion criteria for current radiographie imaging used to diagnose lumbar pseudarthrosis. Plain radiographs and thin-cut CT scans were the most common method for radiographie diagnosis. PET has been shown to be a valid imaging modality for monitoring in vivo active bone formation. Eight studies compared the surgical techniques for managing and preventing failed lumbar fusion. The success rates for the treatment of pseudarthrosis are enhanced with the use of rigid instrumentation. CONCLUSIONS Spinal fusion rates have improved secondary to advances in biologies, instrumentation, surgical techniques, and understanding of local biology. Treatment of lumbar pseudarthrosis includes a variety of surgical options such as replacing loose instrumentation, use of more potent biologies, and interbody fusion techniques. Prevention and recognition are important tenets in the algorithm for the management of spinal pseudarthrosis.

Characterization of a shorter recombinant polypeptide chain of bone morphogenetic protein 2 on osteoblast behaviour

BACKGROUND

Recombinant bone morphogenetic protein two (rhBMP2) has been utilised for a variety of clinical applications in orthopaedic surgery and dental procedures. Despite its widespread use, concerns have been raised regarding its short half-life and transient bioactivity in vivo. Recent investigation aimed at developing rhBMP2 synthesized from a shorter polypeptide chain (108 amino acids) has been undertaken.

METHODS

The osteopromotive properties of BMP2 were investigated on cell behaviour. Five concentrations of rhBMP2_108 including 10, 50, 100, 200 and 500 ng/ml were compared to a commercially available rhBMP2 (100 ng/ml). Each of the working concentrations of rhBMP2_108 were investigated on MC3T3-E1 osteoblasts for their ability to induce osteoblast recruitment, proliferation and differentiation as assessed by alkaline phosphatase (ALP) staining, alizarin red staining, and real-time PCR for genes encoding ALP, osteocalcin (OCN), collagen-1 (COL-1) and Runx2.

RESULTS

The results demonstrate that all concentrations of rhBMP2_108 significantly improved cell recruitment and proliferation of osteoblasts at 5 days post seeding. Furthermore, rhBMP2_108 had the most pronounced effects on osteoblast differentiation. It was found that rhBMP2_108 had over a four fold significant increase in ALP activity at seven and 14 days post-seeding and the concentrations ranging from 50 to 200 ng/ml demonstrated the most pronounced effects. Analysis of real-time PCR for genes encoding ALP, OCN, COL-1 and Runx2 further confirmed dose-dependant increases at 14 days post-seeding. Furthermore, alizarin red staining demonstrated a concentration dependant increase in staining at 14 days.

CONCLUSION

The results from the present study demonstrate that this shorter polypeptide chain of rhBMP2_108 is equally as bioactive as commercially available rhBMP2 for the recruitment of progenitor cells by facilitating their differentiation towards the osteoblast lineage. Future in vivo study are necessary to investigate its bioactivity.