Evaluation of hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute for posterolateral spinal fusion

Iliac crest bone graft versus cell-based grafts to augment spinal fusion: a systematic review and meta-analysis

INTRODUCTION

Despite successful fusion rates with iliac crest bone graft (ICBG), donor-site morbidity and increased operating time remain a considerable limitation and drive the search for alternatives. In this systematic review, grafts with additional cellular supplementation were compared with ICBG for spinal arthrodesis. We compared safety, efficacy and long-term outcomes, thus providing the current and relevant evidence for orthopaedic surgeons to make informed choices regarding this rapidly developing field.

METHODS

An electronic literature search was conducted according to the PRISMA guidelines by two independent reviewers for articles published up to 1st March 2023 using PubMed, EMBASE and the Cochrane Central Register of Controlled Trial. Cellular allografts were not included. The following data were extracted: Number of patients, type of graft, fusion assessment method, follow-up duration, fusion rates, clinical outcomes and complications. The methodological quality of evidence (MQOE) was assessed using the Risk of Bias 2 (RoB-2) tool and Risk of Bias In Non-Randomised Studies (ROBINS) tool developed by Cochrane for evaluating bias in randomised and non-randomised studies.

RESULTS

Ten studies fulfiled the inclusion criteria, including 465 patients. The mean number of patients per study was 43.8 (std dev. 28.81, range 12-100). Two studies demonstrated cell-based therapy to be significantly more successful in terms of fusion rates compared to ICBG. However, the remaining eight demonstrated equivocal results. No study found that cell-based therapy was inferior. No difference was seen between the two groups in three studies who focused on degenerative cohorts. No difference in functional outcome scores was seen between the groups. A number of different preparation techniques for cell-based grafts were used throughout the studies.

CONCLUSION

Cell-based therapy offers a promising alternative to ICBG in spinal fusion surgery, which could help reduce the associated morbidity to patients. This review found that cell-based therapy is non-inferior to iliac crest bone graft and may offer patients an alternative treatment option with fewer complications and reduced post-operative pain. However, the literature to date is limited by heterogeneity of the cell preparation and grafting process. Future research with a unified approach to the cell preparation process is required to fully delineate the potential advantages of this technology.

In vivo characterization of 3D-printed polycaprolactone-hydroxyapatite scaffolds with Voronoi design to advance the concept of scaffold-guided bone regeneration

Three-dimensional (3D)-printed medical-grade polycaprolactone (mPCL) composite scaffolds have been the first to enable the concept of scaffold-guided bone regeneration (SGBR) from bench to bedside. However, advances in 3D printing technologies now promise next-generation scaffolds such as those with Voronoi tessellation. We hypothesized that the combination of a Voronoi design, applied for the first time to 3D-printed mPCL and ceramic fillers (here hydroxyapatite, HA), would allow slow degradation and high osteogenicity needed to regenerate bone tissue and enhance regenerative properties when mixed with xenograft material. We tested this hypothesis in vitro and in vivo using 3D-printed composite mPCL-HA scaffolds (wt 96%:4%) with the Voronoi design using an ISO 13485 certified additive manufacturing platform. The resulting scaffold porosity was 73% and minimal in vitro degradation (mass loss <1%) was observed over the period of 6 months. After loading the scaffolds with different types of fresh sheep xenograft and ectopic implantation in rats for 8 weeks, highly vascularized tissue without extensive fibrous encapsulation was found in all mPCL-HA Voronoi scaffolds and endochondral bone formation was observed, with no adverse host-tissue reactions. This study supports the use of mPCL-HA Voronoi scaffolds for further testing in future large preclinical animal studies prior to clinical trials to ultimately successfully advance the SGBR concept.

An in vivo study to investigate an original intramedullary bone graft harvesting technology

BACKGROUND

Harvesting bone graft (BG) from the intramedullary canal to treat bone defects is largely conducted using the Reamer-Irrigator-Aspirator (RIA) system. The RIA system uses irrigation fluid during harvesting, which may result in washout of osteoinductive factors. Here, we propose a new harvesting technology dedicated to improving BG collection without the potential washout effect of osteoinductive factors associated with irrigation fluid. This novel technology involves the conceptual approach of first aspirating the bone marrow (BM) with a novel aspirator prototype, followed by reaming with standard reamers and collecting the bone chips with the aspirator (reaming-aspiration method, R-A method). The aim of this study was to assess the harvesting efficacy and osteoinductive profile of the BG harvested with RIA 2 system (RIA 2 group) compared to the novel harvesting concept (aspirator + R-A method, ARA group).

METHODS

Pre-planning computed tomography (CT) imaging was conducted on 16 sheep to determine the femoral isthmus canal diameter. In this non-recovery study, sheep were divided into two groups: RIA 2 group (n = 8) and ARA group (n = 8). We measured BG weight collected from left femur and determined femoral cortical bone volume reduction in postoperative CT imaging. Growth factor and inflammatory cytokine amounts of the BGs were quantified using enzyme-linked immunosorbent assay (ELISA) methods.

RESULTS

The use of the stand-alone novel aspirator in BM collection, and in harvesting BG when the aspirator is used in conjunction with sequential reaming (R-A method) was proven feasible. ELISA results showed that the collected BG contained relevant amounts of growth factors and inflammatory cytokines in both the RIA 2 and the ARA group.

CONCLUSIONS

Here, we present the first results of an innovative concept for harvesting intramedullary BG. It is a prototype of a novel aspirator technology that enables the stepwise harvesting of first BM and subsequent bone chips from the intramedullary canal of long bones. Both the BG collected with the RIA 2 system and the aspirator prototype had the capacity to preserve the BG's osteoinductive microenvironment. Future in vivo studies are required to confirm the bone regenerative capacity of BG harvested with the innovative harvesting technology.

Bicalcium Phosphate as an Asset in Regenerative Therapy

After a loss of a tooth, alveolar bone resorption is immutable, leaving the area devoid of sufficient bone quality and mass for a successful and satisfactory implant or any other dental treatment. To treat this problem of irreversible bone loss, bone grafting is the primary solution and a well-accepted technique. The use of bone grafting procedures has increased in recent years. This review is about the various bone grafting techniques and best-situated material available currently along with their trump cards and limitations. In the thorough discussion regarding bone grafting materials and their substitutes, one alloplastic material has shown unbeaten and the most satisfactory properties than any other material, "bicalcium phosphate" (BCP). BCP is a mixture of hydroxyapatite (HA) and beta-tricalcium phosphate (B-TCP) usually obtained through sintering calcium-deficient apatite (CDA) at or above 700°C or by other methods such as hydrolysis or precipitation. The review also shows comparative studies done to understand the effect, most adequate balance, and impact of ratios of HA/B-TCP on the properties, structure, and success rate of this material. The objective of the review is to enlighten the principal characteristic of the most likely used bone graft material presently, i.e., BCP. The most impeccable characteristic of BCP is its capability to osteointegrate, which results in a superior interface. This interface depicts a dynamic process that includes physicochemical reactions, crystal-protein interactions, cell and tissue colonization, and bone remodeling. BCP has certain essential properties that could be put forth as its advantage over any other substitute. These properties include bioactivity, osteointegration, osteoinduction, osteogenesis, and biodegradation, which are mostly governed by modifying the HA/B-TCP ratio. Other applications of BCP are feasible, such as in drug administration and scaffolds for tissue engineering.

Hydroxyapatite Use in Spine Surgery—Molecular and Clinical Aspect

Hydroxyapatite possesses desirable properties as a scaffold in tissue engineering: it is biocompatible at a site of implantation, and it is degradable to non-toxic products. Moreover, its porosity enables infiltration of cells, nutrients and waste products. The outcome of hydroxyapatite implantation highly depends on the extent of the host immune response. Authors emphasise major roles of the chemical, morphological and physical properties of the surface of biomaterial used. A number of techniques have been applied to transform the theoretical osteoconductive features of HAp into spinal fusion systems—from integration of HAp with autograft to synthetic intervertebral implants. The most popular uses of HAp in spine surgery include implants (ACDF), bone grafts in posterolateral lumbar fusion and transpedicular screws coating. In the past, autologous bone graft has been used as an intervertebral cage in ACDF. Due to the morbidity related to autograft harvesting from the iliac bone, a synthetic cage with osteoconductive material such as hydroxyapatite seems to be a good alternative. Regarding posterolateral lumbar fusion, it requires the graft to induce new bone growth and reinforce fusion between the vertebrae. Hydroxyapatite formulations have shown good results in that field. Moreover, the HAp coating has proven to be an efficient method of increasing screw fixation strength. It can decrease the risk of complications such as screw loosening after pedicle screw fixation in osteoporotic patients. The purpose of this literature review is to describe in vivo reaction to HAp implants and to summarise its current application in spine surgery.

Methodological aspects of a randomized within-patient concurrent controlled design for clinical trials in spine surgery

INTRODUCTION

Randomized controlled trials are considered the highest level of evidence, but their feasibility in the surgical field is severely hampered by methodological and practical issues. Concurrent comparison between the experimental and control conditions within the same patient can be an effective strategy to mitigate some of these challenges and improve generalizability, mainly by the elimination of between-patient variability and reduction of the required sample size. This article aims (1) to describe the methodological aspects of a randomized within-patient controlled trial and (2) to quantify the added value of this design, based on a recently completed randomized within-patient controlled trial on bone grafts in instrumented lumbar posterolateral spinal fusion.

METHODS

Boundary conditions for the application of the randomized within-patient controlled trial design were identified. Between-patient variability was quantified by the intraclass correlation coefficient and concordance in the primary fusion outcome. Sample size, study duration and costs were compared with a classic randomized controlled trial design.

RESULTS

Boundary conditions include the concurrent application of the experimental and control conditions to identical but physically separated sites. Moreover, the outcome of interest should be local, uncorrelated and independently assessable. The spinal fusion outcomes within a patient were found to be more similar than between different patients (intraclass correlation coefficient 32% and concordance 64%), demonstrating a clear effect of patient-related factors. The randomized within-patient controlled trial design allowed a reduction of the sample size to one-third of a parallel-group randomized controlled trial, thereby halving the trial duration and costs.

CONCLUSION

When suitable, the randomized within-patient controlled trial is an efficient design that provides a solution to some of the considerable challenges of a classic randomized controlled trial in (spine) surgery. This design holds specific promise for efficacy studies of non-active bone grafts in instrumented posterolateral fusion surgery.

Bone Marrow Aspirate in Spine Surgery: Case Series and Review of the Literature

Background

With the modernization of biotechnology, there has been a concerted effort to create novel biomaterials to promote arthrodesis for spine surgery. The novel use of the stem cells from bone marrow aspirate (BMA) to augment spine surgery is a burgeoning field because these cells are considered to be both osteoinductive and osteogenic. We sought to review the evidence behind the use of BMAs in spinal fusions and report the results of our own case series.

Methods

PubMed and EMBASE databases were searched for studies that investigated the use of stem cells for spine surgery. For our own case series, the medical records of 150 consecutive patients who underwent a lumbar spinal fusion with BMA were retrospectively reviewed for adverse events (AEs) for up to two years after surgery.

Results

In our case series, there were no AEs identified in 49% of our patients. Of the identified AEs, 61% were unrelated to the use of BMA (e.g., UTI and heart failure), with the remaining 39% likely unrelated to its use (e.g., back pain and anemia). There was a 92.8% arthrodesis rate with the use of BMA.

Conclusions

We reviewed the rationale, basic science, and clinical science for BMA usage in spine surgery and concluded that BMA is safe for use in spine surgery and is associated with a high rate of arthrodesis.

Avian Egg: A Multifaceted Biomaterial for Tissue Engineering

Most components in avian eggs, offering a natural and environmentally friendly source of raw materials, hold great potential in tissue engineering. An avian egg consists of several beneficial elements: the protective eggshell, the eggshell membrane, the egg white (albumen), and the egg yolk (vitellus). The eggshell is mostly composed of calcium carbonate and has intrinsic biological properties that stimulate bone repair. It is a suitable precursor for the synthesis of hydroxyapatite and calcium phosphate, which are particularly relevant for bone tissue engineering. The eggshell membrane is a thin protein-based layer with a fibrous structure and is constituted of several valuable biopolymers, such as collagen and hyaluronic acid, that are also found in the human extracellular matrix. As a result, the eggshell membrane has found several applications in skin tissue repair and regeneration. The egg white is a protein-rich material that is under investigation for the design of functional protein-based hydrogel scaffolds. The egg yolk, mostly composed of lipids but also diverse essential nutrients (e.g., proteins, minerals, vitamins), has potential applications in wound healing and bone tissue engineering. This review summarizes the advantages and status of each egg component in tissue engineering and regenerative medicine, but also covers their current limitations and future perspectives.

Efficacy for Whitlockite for Augmenting Spinal Fusion

Whitlockite (WH) is the second most abundant inorganic component of human bone, accounting for approximately 25% of bone tissue. This study investigated the role of WH in bone remodeling and formation in a mouse spinal fusion model. Specifically, morphology and composition analysis, tests of porosity and surface area, thermogravimetric analysis, an ion-release test, and a cell viability test were conducted to analyze the properties of bone substitutes. The MagOss group received WH, Group A received 100% beta-tricalcium phosphate (β-TCP), Group B received 100% hydroxyapatite (HAp), Group C received 30% HAp/70% β-TCP, and Group D received 60% HAp/40% β-TCP (n = 10 each). All mice were sacrificed 6 weeks after implantation, and micro-CT, hematoxylin and eosin (HE) staining, and Masson trichome (MT) staining and immunohistochemistry were performed. The MagOss group showed more homogeneous and smaller grains, and nanopores (<500 nm) were found in only the MagOss group. On micro-CT, the MagOss group showed larger fusion mass and better graft incorporation into the decorticate mouse spine than other groups. In the in vivo experiment with HE staining, the MagOss group showed the highest new bone area (mean: decortication group, 9.50%; A, 15.08%; B, 15.70%; C, 14.76%; D, 14.70%; MagOss, 22.69%; p < 0.0001). In MT staining, the MagOss group demonstrated the highest new bone area (mean: decortication group, 15.62%; A, 21.41%; B, 22.86%; C, 23.07%; D, 22.47%; MagOss, 26.29%; p < 0.0001). In an immunohistochemical analysis for osteocalcin, osteopontin, and CD31, the MagOss group showed a higher positive area than other groups. WH showed comparable bone conductivity to HAp and β-TCP and increased new bone formation. WH is likely to be used as an improved bone substitute with better bone conductivity than HAp and β-TCP.

Stem Cells and Spinal Fusion

BACKGROUND

This manuscript is a review of the literature investigating the use of mesenchymal stem cells (MSCs) being applied in the setting of spinal fusion surgery. We mention the rates of pseudarthrosis, discuss current bone grafting options, and examine the preclinical and clinical outcomes of utilizing MSCs to assist in successfully fusing the spine.

METHODS

A thorough literature review was conducted to look at current and previous preclinical and clinical studies using stem cells for spinal fusion augmentation. Searches for PubMed/MEDLINE and ClinicalTrials.gov through January 2021 were conducted for literature mentioning stem cells and spinal fusion.

RESULTS

All preclinical and clinical studies investigating MSC use in spinal fusion were examined. We found 19 preclinical and 17 clinical studies. The majority of studies, both preclinical and clinical, were heterogeneous in design due to different osteoconductive scaffolds, cells, and techniques used. Preclinical studies showed promising outcomes in animal models when using appropriate osteoconductive scaffolds and factors for osteogenic differentiation. Similarly, clinical studies have promising outcomes but differ in their methodologies, surgical techniques, and materials used, making it difficult to adequately compare between the studies.

CONCLUSION

MSCs may be a promising option to use to augment grafting for spinal fusion surgery. MSCs must be used with appropriate osteoconductive scaffolds. Cell-based allografts and the optimization of their use have yet to be fully elucidated. Further studies are necessary to determine the efficacy of MSCs with different osteoconductive scaffolds and growth/osteogenic differentiation factors.

LEVEL OF EVIDENCE

3.

Synthesis and characterization of a photo-cross-linked bioactive polycaprolactone-based osteoconductive biocomposite

In this study, a light cross-linkable biocomposite scaffold based on a photo-cross-linkable poly (propylene fumarate) (PPF)-co-polycaprolactone (PCL) tri-block copolymer was synthesized and characterized. The developed biodegradable scaffold was further modified with β-tricalcium phosphate (β-TCP) bioceramic for bone tissue engineering applications. The developed biocomposite was characterized using H nuclear magnetic resonance and Fourier transform infrared spectroscopy. Moreover, the bioceramic particle size distribution and morphology were evaluated using Brunauer-Emmett-Teller method, X-ray diffraction, and scanning electron microscopy. The mechanical properties and biodegradation of the scaffolds were also evaluated. Cytotoxicity and mineralization assays were performed to analyze the biocompatibility and bioactivity capacity of the developed biocomposite. The characterization data confirmed the development of a biodegradable and photo-cross-linkable PCL-based biocomposite reinforced with β-TCP bioceramic. In vitro analyses demonstrated the biocompatibility and mineralization potential of the synthesized bioceramic. Altogether, the results of the present study suggest that the photo-cross-linkable PCL-PPF-PCL tri-block copolymer reinforced with β-TCP is a promising biocomposite for bone tissue engineering applications. According to the results, this newly synthesized material has a proper chemical composition for further clinically-relevant studies in tissue engineering.

Bone marrow coagulated and low-level laser therapy accelerate bone healing by enhancing angiogenesis, cell proliferation, osteoblast differentiation, and mineralization

The present study evaluated bone marrow aspirate (BMA) and low-level laser therapy (LLLT) on bone healing. It was created critical-size defects (CSD) of 5 mm diameter in rat calvaria of 64 rats. Animals were randomly divided into four groups: Control (blood clot), BMA (coagulated BMA), LLLT (laser irradiation and blood clot), and BMA/LLLT (laser irradiation and coagulated BMA). Euthanasia was performed at 15 or 30 days postoperative. Immunohistochemical reactions were performed to identify vascular endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA), runt-related transcription factor-2 (Runx2), bone morphogenetic protein-2 (BMP-2), osteocalcin (OCN), and osteopontin (OPN). The markers were quantified, and data were statistically analyzed. Groups BMA/LLLT and LLLT presented significantly higher VEGF expression than group control. Group BMA/LLLT presented a significantly higher expression of PCNA than all experimental groups. Groups BMA and BMA/LLLT presented significantly higher expression of BMP-2 than all experimental groups. Groups LLLT and BMA/LLLT presented significantly higher expression of OPN than groups control and BMA. Groups LLLT, BMA, and BMA/LLLT presented a significantly higher expression of OCN than group control. It can be concluded that the association of BMA and LLLT enhanced bone healing by improving expression of VEGF, PCNA, Runx2, BMP-2, OPN, and OCN.

Tailored Three-Dimensionally Printed Triply Periodic Calcium Phosphate Implants: A Preclinical Study for Craniofacial Bone Repair

Finding alternative strategies for the regeneration of craniofacial bone defects (CSD), such as combining a synthetic ephemeral calcium phosphate (CaP) implant and/or active substances and cells, would contribute to solving this reconstructive roadblock. However, CaP's architectural features (i.e., architecture and composition) still need to be tailored, and the use of processed stem cells and synthetic active substances (e.g., recombinant human bone morphogenetic protein 2) drastically limits the clinical application of such approaches. Focusing on solutions that are directly transposable to the clinical setting, biphasic calcium phosphate (BCP) and carbonated hydroxyapatite (CHA) 3D-printed disks with a triply periodic minimal structure (TPMS) were implanted in calvarial critical-sized defects (rat model) with or without addition of total bone marrow (TBM). Bone regeneration within the defect was evaluated, and the outcomes were compared to a standard-care procedure based on BCP granules soaked with TBM (positive control). After 7 weeks, de novo bone formation was significantly greater in the CHA disks + TBM group than in the positive controls (3.33 mm3 and 2.15 mm3, respectively, P=0.04). These encouraging results indicate that both CHA and TPMS architectures are potentially advantageous in the repair of CSDs and that this one-step procedure warrants further clinical investigation.

Stem Cells and Spinal Fusion

There are a number of bone regeneration therapeutics available to aid spinal fusion; however, many are associated with pseudarthrosis, inflammation, and other complications. Mesenchymal stem cells for fusion has been promoted to mitigate these risks and achieve successful bony fusion. This article reviews the clinical studies available with use in spinal fusion. Preliminary results demonstrate that stem cells can provide high rates of fusion, comparable to autograft, without associated morbidity. Autologous and allogeneic stem cell sources showed similar rates of fusion in this review. Further research is required to evaluate which clinical situations are the optimum for stem cell use.

Substantial Overview on Mesenchymal Stem Cell Biological and Physical Properties as an Opportunity in Translational Medicine

Mesenchymal stem cells (MSC) have piqued worldwide interest for their extensive potential to treat a large array of clinical indications, their unique and controversial immunogenic and immune modulatory properties allowing ample discussions and debates for their possible applications. Emerging data demonstrating that the interaction of biomaterials and physical cues with MSC can guide their differentiation into specific cell lineages also provide new interesting insights for further MSC manipulation in different clinical applications. Moreover, recent discoveries of some regulatory molecules and signaling pathways in MSC niche that may regulate cell fate to distinct lineage herald breakthroughs in regenerative medicine. Although the advancement and success in the MSC field had led to an enormous increase in the amount of ongoing clinical trials, we still lack defined clinical therapeutic protocols. This review will explore the exciting opportunities offered by human and animal MSC, describing relevant biological properties of these cells in the light of the novel emerging evidence mentioned above while addressing the limitations and challenges MSC are still facing.

Graft Materials and Biologics for Spinal Interbody Fusion

Spinal fusion is the most widely performed procedure in spine surgery. It is the preferred treatment for a wide variety of pathologies including degenerative disc disease, spondylolisthesis, segmental instability, and deformity. Surgeons have the choice of fusing vertebrae by utilizing cages containing autografts, allografts, demineralized bone matrices (DBMs), or graft substitutes such as ceramic scaffolds. Autografts from the iliac spine are the most commonly used as they offer osteogenic, osteoinductive, and osteoconductive capabilities, all while avoiding immune system rejection. Allografts obtained from cadavers and living donors can also be advantageous as they lack the need for graft extraction from the patient. DBMs are acid-extracted organic allografts with osteoinductive properties. Ceramic grafts containing hydroxyapatite can be readily manufactured and are able to provide osteoinductive support while having a long shelf life. Further, bone-morphogenetic proteins (BMPs), mesenchymal stem cells (MSCs), synthetic peptides, and autologous growth factors are currently being optimized to assist in improving vertebral fusion. Genetic therapies utilizing viral transduction are also currently being devised. This review provides an overview of the advantages, disadvantages, and future directions of currently available graft materials. The current literature on growth factors, stem cells, and genetic therapy is also discussed.

BMSC affinity peptide-functionalized β-tricalcium phosphate scaffolds promoting repair of osteonecrosis of the femoral head

BACKGROUND

Osteonecrosis of the femoral head (ONFH) is a disabling disease. Early treatment is crucial to the prognosis of the disease. Core decompression (CD) is one of the most commonly used methods for the treatment of early ONFH. But it could not prevent the collapse of the necrotic femoral head. How to improve the therapeutic effect of early ONFH on the basis of CD has become an area of focused research.

METHODS

Functional β-tricalcium phosphate (β-TCP) scaffolds modified by DPIYALSWSGMA (DPI) peptide, a bone marrow-derived mesenchymal stem cell (BMSC) affinity peptide, were constructed using an adsorption/freeze-drying strategy. The affinity of DPI peptide towards rabbit BMSCs was investigated using flow cytometry and fluorescence cytochemistry. In vitro cell adhesion assay was performed to study the adherent ability of rabbit BMSCs on functional β-TCP scaffolds. After the rabbit model of early ONFH was established, DPI peptide-modified and pure β-TCP scaffolds were transplanted into the remaining cavity after CD. Meanwhile, rabbits treated with pure CD were used as blank control. Twelve weeks after surgery, histological analysis was performed to show the therapeutic effect of three methods on early ONFH.

RESULTS

The result of ImageXpress Micro Confocal indicated that fabricated DPI peptide-modified functional β-TCP scaffolds exhibited green fluorescence. In flow cytometry, the average fluorescence intensity for rabbit BMSCs incubated with FITC-DPI was significantly higher than that of FITC-LSP (P = 2.733 × 10^-8). In fluorescence cytochemistry, strong fluorescent signals were observed in rabbit BMSCs incubated with FITC-DPI and FITC-RGD, whereas no fluorescent signals in cells incubated with FITC-LSP. In cell adhesion assay, the number of adherent cells to β-TCP-DPI scaffolds was more than that of pure β-TCP scaffolds (P = 0.033). The CD + β-TCP-DPI group expressed the lowest vacant bone lacunae percentage compared to CD group (P = 2.350 × 10^-4) and CD + β-TCP group (P = 0.020). The expression content of COL1 in CD + β-TCP-DPI group was much higher than CD group (P = 1.262 × 10^-7) and CD + β-TCP group (P = 1.666 × 10^-7) according to the integrated optical density (IOD) analyses.

CONCLUSION

Functional β-TCP scaffolds modified by DPI peptide were successfully synthesized using an adsorption/freeze-drying strategy. DPI peptide has good affinity towards rabbit BMSCs. The adhesion of rabbit BMSCs on DPI peptide-modified β-TCP scaffolds was apparently enhanced. CD followed by implantation of DPI peptide-modified β-TCP scaffolds can apparently improve the treatment of early ONFH compared with pure CD and CD followed by implantation of unmodified β-TCP scaffolds. Our current study provides an improved method for the treatment of early ONFH.

3D bioprinted hydrogel model incorporating β-tricalcium phosphate for calcified cartilage tissue engineering

One promising strategy to reconstruct osteochondral defects relies on 3D bioprinted three-zonal structures comprised of hyaline cartilage, calcified cartilage, and subchondral bone. So far, several studies have pursued the regeneration of either hyaline cartilage or bone in vitro while-despite its key role in the osteochondral region-only few of them have targeted the calcified layer. In this work, we present a 3D biomimetic hydrogel scaffold containing β-tricalcium phosphate (TCP) for engineering calcified cartilage through a co-axial needle system implemented in extrusion-based bioprinting process. After a thorough bioink optimization, we showed that 0.5% w/v TCP is the optimal concentration forming stable scaffolds with high shape fidelity and endowed with biological properties relevant for the development of calcified cartilage. In particular, we investigate the effect induced by ceramic nano-particles over the differentiation capacity of bioprinted bone marrow-derived human mesenchymal stem cells in hydrogel scaffolds cultured up to 21 d in chondrogenic media. To confirm the potential of the presented approach to generate a functional in vitro model of calcified cartilage tissue, we evaluated quantitatively gene expression of relevant chondrogenic (COL1, COL2, COL10A1, ACAN) and osteogenic (ALPL, BGLAP) gene markers by means of RT-qPCR and qualitatively by means of fluorescence immunocytochemistry.

Effect of strontium substituted ß-TCP associated to mesenchymal stem cells from bone marrow and adipose tissue on spinal fusion in healthy and ovariectomized rat

Despite alternatives to autogenous bone graft for spinal fusion have been investigated, it has been shown that osteoconductive materials alone do not give a rate of fusion comparable with autogenous bone. This study analyzed a strontium substituted ß-tricalcium phosphate (Sr-ßTCP) associated with syngeneic, unexpanded, and undifferentiated mesenchymal stem cells from bone marrow (BMSC) or adipose tissue (ADSC) as a new tissue engineering approach for spinal fusion procedures. A posterolateral fusion was performed in 15 ovariectomized (OVX) and 15 sham-operated (SHAM) Inbred rats. Both SHAM and OVX animals were divided into three groups: Sr-ßTCP, Sr-ßTCP + BMCSs, and Sr-ßTCP + ADSCs. Animals were euthanized 8 weeks after surgery and the spines evaluated by manual palpation, micro-CT, and histology. For both SHAM and OVX animals, the fusion tissue in the Sr-ßTCP + BMSCs group was more solid. This effect was significantly higher in OVX animals by comparing the Sr-ßTCP + BMCSs group with Sr-ßTCP + ADSCs. Radiographical score, based on micro-CT 2D image, highlighted that the Sr-ßTCP + BMCSs group presented a similar fusion to Sr-ßTCP and higher than Sr-ßTCP + ADSCs in both SHAM and OVX animals. Micro-CT 3D parameters did not show significant differences among groups. Histological score showed significantly higher fusion in Sr-ßTCP + BMSCs group than Sr-ßTCP and Sr-ßTCP + ADSCs, for both SHAM and OVX animals. In conclusion, our results suggest that addition of BMSCs to a Sr-ßTCP improve bone formation and fusion, both in osteoporotic and nonosteoporotic animal, whereas spinal fusion is not enhanced in rats treated with Sr-ßTCP + ADSCs. Thus, for conducting cells therapy in spinal surgery BMSCs still seems to be a better choice compared with ADSCs.

Evidence of Negative Effects of Defect Size and Older Patient Age by Quantitative CT-Based 3D Image Analysis in Ultraporous Beta-Tricalcium Phosphate Grafted Extremity Bone Defects at One Year

Introduction

Synthetic bone graft materials are commonly used to fill defects after curettage of benign bone lesions. Ultraporous beta tricalcium phosphate (TCP) is a popular synthetic compound used in this situation. Prior clinical studies based on plain X-ray analysis suggest incorporation of TCP is incomplete, even when combined with bone marrow (BMA).

Purpose

The purpose was to analyze volumetric CT-based changes in defects grafted with TCP with/without BMA in a completed prospective RCT to objectively determine (1) relationship between size and age versus TCP incorporation and (2) whether there is an advantage to addition of BMA.

Methods

Twenty-one patients with CT scans at ≥1 year follow-up available for digital analysis (TCP=10, TCP w/BMA =11) form the study population. CT image stacks were evaluated by creating volumetric masks using MIMICS imaging software for total defect, graft remaining, and graft incorporated volumes graft incorporation endpoints.

Results

Overall, there was significant (p=0.0029) negative correlation (r² = 0.38) between defect size and ratio of incorporated bone to defect size. This relationship remained strong (r² = 0.56) particularly for defects > 20 cc but not for smaller defects. Bone width was also a significantly related factor (r² = 0.94), with less graft incorporation in larger bone sites, in part likely due to the linear relationship between defect size and bone width. Relationship with age was complex and closely tied to defect volume. For larger defect volumes, younger patients were more successful at graft incorporation. Although age itself was not an independently significant factor, as defect volume increased, advanced age more negatively impacted new bone formation.

Conclusions

Larger size defect and affected bone and advancing age appear to be important negative factors in synthetic graft incorporation. Results showed no advantage to addition of BMA to TCP.

Variability in the Preparation, Reporting, and Use of Bone Marrow Aspirate Concentrate in Musculoskeletal Disorders: A Systematic Review of the Clinical Orthopaedic Literature

BACKGROUND

Interest in the therapeutic potential of bone marrow aspirate concentrate (BMAC) has grown exponentially. However, comparisons among studies and their processing methods are challenging because of inconsistent reporting of protocols, as well as poor characterization of the composition of the initial bone marrow aspirate and of the final products delivered. The purpose of this study was to perform a systematic review of the literature to evaluate the level of reporting related to the protocols used for BMAC preparation and the composition of BMAC utilized in the treatment of musculoskeletal diseases in published clinical studies.

METHODS

A systematic review of the literature was performed by searching PubMed, MEDLINE, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials from 1980 to 2016. Inclusion criteria were human clinical trials, English language, and manuscripts that reported on the use of BMAC in musculoskeletal conditions.

RESULTS

After a comprehensive review of the 986 identified articles, 46 articles met the inclusion criteria for analysis. No study provided comprehensive reporting that included a clear description of the preparation protocol that could be used by subsequent investigators to repeat the method. Only 14 (30%) of the studies provided quantitative metrics of the composition of the BMAC final product.

CONCLUSIONS

The reporting of BMAC preparation protocols in clinical studies was highly inconsistent and studies did not provide sufficient information to allow the protocol to be reproduced. Moreover, comparison of the efficacy and yield of BMAC products is precluded by deficiencies in the reporting of preparation methods and composition. Future studies should contain standardized and stepwise descriptions of the BMAC preparation protocol, and the composition of the BMAC delivered, to permit validating and rationally optimizing the role of BMAC in musculoskeletal care.

Bone substitutes: a review of their characteristics, clinical use, and perspectives for large bone defects management

Bone replacement might have been practiced for centuries with various materials of natural origin, but had rarely met success until the late 19th century. Nowadays, many different bone substitutes can be used. They can be either derived from biological products such as demineralized bone matrix, platelet-rich plasma, hydroxyapatite, adjunction of growth factors (like bone morphogenetic protein) or synthetic such as calcium sulfate, tri-calcium phosphate ceramics, bioactive glasses, or polymer-based substitutes. All these substitutes are not suitable for every clinical use, and they have to be chosen selectively depending on their purpose. Thus, this review aims to highlight the principal characteristics of the most commonly used bone substitutes and to give some directions concerning their clinical use, as spine fusion, open-wedge tibial osteotomy, long bone fracture, oral and maxillofacial surgery, or periodontal treatments. However, the main limitations to bone substitutes use remain the management of large defects and the lack of vascularization in their central part, which is likely to appear following their utilization. In the field of bone tissue engineering, developing porous synthetic substitutes able to support a faster and a wider vascularization within their structure seems to be a promising way of research.

Stem Cells in Spinal Fusion

STUDY DESIGN

Review of literature.

OBJECTIVES

This review of literature investigates the application of mesenchymal stem cells (MSCs) in spinal fusion, highlights potential uses in the development of bone grafts, and discusses limitations based on both preclinical and clinical models.

METHODS

A review of literature was conducted looking at current studies using stem cells for augmentation of spinal fusion in both animal and human models.

RESULTS

Eleven preclinical studies were found that used various animal models. Average fusion rates across studies were 59.8% for autograft and 73.7% for stem cell-based grafts. Outcomes included manual palpation and stressing of the fusion, radiography, micro-computed tomography (μCT), and histological analysis. Fifteen clinical studies, 7 prospective and 8 retrospective, were found. Fusion rates ranged from 60% to 100%, averaging 87.1% in experimental groups and 87.2% in autograft control groups.

CONCLUSIONS

It appears that there is minimal clinical difference between commercially available stem cells and bone marrow aspirates indicating that MSCs may be a good choice in a patient with poor marrow quality. Overcoming morbidity and limitations of autograft for spinal fusion, remains a significant problem for spinal surgeons and further studies are needed to determine the efficacy of stem cells in augmenting spinal fusion.

Use of Nanocrystalline Hydroxyapatite With Autologous BMA and Local Bone in the Lumbar Spine: A Retrospective CT Analysis of Posterolateral Fusion Results

STUDY DESIGN

A retrospective, multicenter, medical record review and independent analysis of computed tomographic scans was performed in 46 patients to determine radiographic arthrodesis rates after 1-segment, 2-segment, or 3-segment instrumented posterolateral fusions (PLF) using autograft, bone marrow aspirate (BMA), and a nanocrystalline hydroxyapatite bone void filler (nHA).

OBJECTIVE

To determine the radiographic arthrodesis rates after instrumented lumbar PLF using local autograft, BMA, and nHA.

SUMMARY OF BACKGROUND DATA

The use of iliac crest autograft in posterolateral spine fusion carries real and significant risks. Many forms of nanocrystalline hydroxyapatite have been studied in various preclinical models, but no human studies have reviewed its efficacy as a bone graft supplement in PLF.

METHODS

Posterolateral arthrodesis progression was documented approximately 12 months postoperatively using a computed tomographic scan and evaluated by an independent radiologist for the presence of bridging bone. One-year postoperative clinical outcomes were assessed using the PROLO score.

RESULTS

Radiographically, 91% patients treated exhibited bilateral or unilateral posterolateral bridging bone. Ninety-four percent of the segments treated exhibited bilateral or unilateral posterolateral bridging bone, whereas 6% segments exhibited no posterolateral bridging bone on either side. A total of 93% individual sites treated exhibited posterolateral bridging bone. In 1-segment, 2-segment, and 3-segment arthrodesis, 88%, 93%, and 100%, respectively, of individual sites exhibited radiographic bridging bone. One-year postoperative PROLO scores for 77% patients were excellent or good. There were no complications related to the posterolateral graft mass and no symptomatic nonunions.

CONCLUSIONS

The arthrodesis rates after instrumented lumbar fusion using local autograft mixed with BMA and the nHA is equivalent to the rates reported for iliac crest autograft in these indications, including stringent indications, such as 3-segment procedures. By approximately 12 months postoperatively, there was no significant difference in the rates of bridging bone between the 1-segment, 2-segment, and 3-segment procedures.

Autogenous Bone Marrow Aspirate Coated Synthetic Hydroxyapatite for Reconstruction of Maxillo-Mandibular Osseous Defects: A Prospective Study

PURPOSE

This prospective study was conducted to evaluate the bone regeneration capacity of synthetic hydroxyapatite mixed with autogenous bone marrow aspirate when used as a bone graft substitute in maxillo-mandibular osseous defects.

METHODS

This study included nine patients with histopathalogically proven benign osteolytic lesions in maxilla and mandible that were treated with enucleation or marginal resection followed by bone marrow aspirate coated synthetic biphasic hydroxyapatite (hydroxyapatite and beta tricalcium phosphate) graft placement. Incorporation of graft was assessed based on Irwin's radiologic staging. The efficacy of graft to form new bone was radiologically evaluated by observing the sequential changes of density at grafted site using gray scale level histogram which was processed in adobe photoshop 7.0 elements. Clinical assessment of recipient and donor sites was done.

RESULTS

Based on Irwin's radiologic staging, at 6 month follow up period, obvious incorporation of graft with new bone was observed. Sequential changes in bone density measured by gray scale histogram revealed initial resorption followed by replacement of BMA coated hydroxyapatite with new bone formation. None of the patients eventually had complications like infection, wound dehiscence, graft loss at recipient sites at 6 months follow up period.

CONCLUSION

Autogenous bone marrow aspirate in combination with synthetic hydroxyapatite is an effective option for accelerating bone regeneration in small to moderate sized jaw bone defects. This mixture provides all the three critical elements needed for bone regeneration (osteogenesis, osteoinduction and osteoconduction) with an added advantage of obviating donor site morbidity.

Histological Evaluation of Hydroxyapatite Granules with and without Platelet-Rich Plasma versus an Autologous Bone Graft: Comparative study of biomaterials used for spinal fusion in a New Zealand white rabbit model

OBJECTIVES

Hydroxyapatite (HA) has osteoconductive properties and is widely used as a bone graft substitute. Platelet-rich plasma (PRP) is an autologous product with osteoinductive effects. Hypothetically, a combination of both would augment the bone formation effect of HA and widen its application in spinal fusion surgeries. This study aimed to compare new bone formation with HA granules alone and in combination with PRP versus an autologous bone graft during a lumbar intertransverse process spinal fusion.

METHODS

A total of 16 adult New Zealand white rabbits underwent single-level bilateral intertransverse process fusion at the L5-L6 vertebrae. One side of the spine received either HA granules alone or a combination of HA granules and PRP, while the contralateral side received an autologous bone graft. Four animals each from the HA group and the HA plus PRP group versus the autograft group were assessed either at six or 16 weeks by undecalcified histology and histomorphometry. The mean percentage of new bone areas over the corresponding fusion masses were compared between groups.

RESULTS

No significant difference in new bone formation was observed between the HA and HA plus PRP groups at six or 16 weeks. The autograft group had significantly more new bone formation at six and 16 weeks (P = 0.004 and <0.001, respectively).

CONCLUSION

An autologous bone graft remains superior to HA granules, with or without PRP. HA granules demonstrated an excellent osteoconductive scaffold but had poor biodegradability. While PRP enhances the properties of HA granules, these biomaterials do not have a synergistic effect.

Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model

BACKGROUND

Advances in immunomagnetic cell sorting have enabled isolation and purification of pleuripotent stem cells from marrow aspirates and have expanded stem cell therapies to include allogeneic sources.

PURPOSE

This study aimed to determine the safety and efficacy of allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold in lumbar interbody spinal fusion using an ovine model.

STUDY DESIGN

Thirty-two skeletally mature ewes underwent a single-level interbody fusion procedure using a Polyetheretherketone fusion cage supplemented with either iliac crest autograft (AG) or an osteconductive scaffold (Mastergraft Matrix, Medtronic, Memphis, TN, USA) with 2.5×10(6) MPCs, 6.25×10(6) MPCs, or 12.5×10(6) MPCs.

METHODS

Plain radiographs and computed tomography scans were scored for bridging bone at multiple points during healing and at necropsy. The biomechanical competency of fusion was scored by manual palpation and quantified using functional radiographs at necropsy. Postnecropsy histopathology and histomorphometric analysis assessed the local response to MPC treatment and quantified the volume and connectivity of newly formed bridging bone. Safety was assessed by serum biochemistry, hematology, and organ histopathology.

RESULTS

Mesenchymal precursor cell treatment caused no adverse systemic or local tissue responses. All analyses indicated MPCs combined with an osteoconductive scaffold achieved similar or better fusion success as AG treatment after 16 weeks, and increasing the MPC dose did not enhance fusion. Manual palpation of the fusion site indicated more than 75% of MPC-treated and 65% of AG-treated animals achieved rigid fusion, which was corroborated with functional radiography. Computed tomography fusion scores indicated all animals in the MPC- and AG-treatment groups were fused at 16 weeks, yet X-ray scores indicated only 67% of the AG-treated animals were fused. Histomorphometry analyses showed equivalent outcomes for fusion connectivity and bony fusion area for MPC- and AG-treated groups. Approximately 6% residual graft material remained in the MPC-treated fusion sites at 16 weeks.

CONCLUSIONS

Adult allogeneic MPCs delivered using an osteoconductive scaffold were both safe and efficacious in this ovine spine interbody fusion model. These results support the use ofallogeneic MPCs as an alternative to AG for lumbar interbody spinal fusion procedures.

Radiopacity of alloplastic bone grafts measured with cone beam computed tomography: An analysis in rabbit calvaria

Availability of adequate bone structure for dental implants is still a problem in dentistry. Alloplastic grafts, which promote bone regeneration, are used as bone substitutes in orthopedic and oral surgical procedures. The aim of this study was to evaluate the radiopacity of three different synthetic bone grafts in rabbit calvaria, over 3 months, using cone beam computed tomography (CBCT). Four critical-size defects were made on the calvaria of 11 rabbits. The lesions were classified into three groups according to the alloplastic grafts they received: Osteon® 70/30, Osteon collagen®, and Osteon II® groups. The fourth group received blood clot, and served as a control. The bone samples were collected and analyzed with CBCT after the 1st, 2nd, and 3rd month. One month after surgery, the lesions that received Osteon® 70/30 and Osteon collagen® grafts showed the highest radiopacity compared to the lesions with Osteon II® and blood clot. After the 2nd month, the radiopacity values between the three groups that received the grafts were more similar compared to the group with blood clot. After the 3rd month, the lesions with Osteon® 70/30 graft showed the highest radiopacity values, followed by Osteon collagen® and Osteon II® groups. The group that received blood clot showed the lowest radiopacity values. In conclusion, the grafts used in this study had higher radiopacity values compared to blood clot. Among the grafts used, the Osteon® 70/30 graft showed the highest radiopacity values in the 3-month period.

Direct comparison of current cell-based and cell-free approaches towards the repair of craniofacial bone defects - A preclinical study

For craniofacial bone defect repair, several alternatives to bone graft (BG) exist, including the combination of biphasic calcium phosphate (BCP) biomaterials with total bone marrow (TBM) and bone marrow-derived mesenchymal stromal cells (MSCs), or the use of growth factors like recombinant human bone morphogenic protein-2 (RhBMP-2) and various scaffolds. Therefore, clinicians might be unsure as to which approach will offer their patients the most benefit. Here, we aimed to compare different clinically relevant bone tissue engineering methods in an "all-in-one" study in rat calvarial defects. TBM, and MSCs committed or not, and cultured in two- or three-dimensions were mixed with BCP and implanted in bilateral parietal bone defects in rats. RhBMP-2 and BG were used as positive controls. After 7 weeks, significant de novo bone formation was observed in rhBMP-2 and BG groups, and in a lesser amount, when BCP biomaterials were mixed with TBM or committed MSCs cultured in three-dimensions. Due to the efficacy and safety of the TBM/BCP combination approach, we recommend this one-step procedure for further clinical investigation.

STATEMENT OF SIGNIFICANCE

For craniofacial repair, total bone marrow (BM) and BM mesenchymal stem cell (MSC)-based regenerative medicine have shown to be promising in alternative to bone grafting (BG). Therefore, clinicians might be unsure as to which approach will offer the most benefit. Here, BM and MSCs committed or not were mixed with calcium phosphate ceramics (CaP) and implanted in bone defects in rats. RhBMP-2 and BG were used as positive controls. After 7 weeks, significant bone formation was observed in rhBMP-2 and BG groups, and when CaP were mixed with BM or committed MSCs. Since the BM-based procedure does not require bone harvest or cell culture, but provides de novo bone formation, we recommend consideration of this strategy for craniofacial applications.

The effect of an alginate carrier on bone formation in a hydroxyapatite scaffold

This study investigated the osteoconductive properties of a porous hydroxyapatite (HA) scaffold manufactured using a novel technique similar to the bread-making process, alone and in combination with an alginate polysaccharide fiber gel (HA/APFG putty) and autologous bone marrow aspirate (BMA). The hypothesis was that the HA/APFG putty would be as osteoconductive as granular HA and that the presence of BMA would further enhance bone formation in an ovine femoral condyle critical defect model. Thirty-six defects were created and either (1) porous HA granules, (2) HA/APFG putty, or (3) HA/APFG putty + BMA were implanted. After retrieval at 6 and 12 weeks, image analysis techniques were used to quantify bone apposition rates, new bone area, bone-HA scaffold contact, and implant resorption. At 6 weeks postsurgery, significantly lower bone apposition rates were observed in the HA/APFG putty group when compared to the HA (p = 0.014) and HA/APFG putty + BMA (p = 0.014) groups. At 12 weeks, significantly increased amounts of new bone formation were measured within the HA scaffold (33.56 ± 3.53%) when compared to both the HA/APFG putty (16.69 ± 2.7%; p = 0.043) and the defects containing HA/APFG putty + BMA (19.31 ± 3.8%; p = 0.043). The use of an APFG gel as a carrier for injectable CaP bone substitute materials delayed bone formation in this model compared to HA granules alone which enhanced bone formation especially within the interconnected smaller pores. Our results also showed that the addition of autologous BMA did not further enhance its osteoconductive properties. Further study is required to optimize the degradation rate of this APFG binding agent before using as a directly injectable material for repair of bone defect. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1328-1335, 2016.

Hydroxyapatite crystals as a bone graft substitute in benign lytic lesions of bone

BACKGROUND

Bone grafts are required to fill a cavity created after curettage of benign lytic lesions of the bone. To avoid the problems associated at donor site with autologous bone graft, we require allograft or bone graft substitutes. We evaluated the healing of lytic lesions after hydroxyapatite (HA) grafting by serial radiographs.

MATERIALS AND METHODS

Forty cases of benign lytic lesions of bone were managed by simple curettage and grafting using HA blocks. Commercially available HA of bovine origin (Surgiwear Ltd., Shahjahanpur, India) was used for this purpose. Mean duration of followup was 34.8 months (range 12-84 months). Mean patient age was 19.05 years (range 3-55 years). Radiological staging of graft incorporation was done as per criteria of Irwin et al. 2001.

RESULTS

In our series, two cases were in stage I. A total of 11 cases were in stage II and 27 were in stage III. Graft incorporation was radiologically complete by 15 months. Clinical recovery was observed before radiological healing. The average time taken to return to preoperative function was 3 months. Recurrence was observed in giant cell tumor (n = 3) and chondromyxoid fibroma (n = 1). There was no incidence of graft rejection, collapse, growth plate disturbances or antigenic response.

CONCLUSIONS

We conclude that calcium HA is biologically acceptable bone graft substitute in the management of benign lytic lesions of bone.

A sequential approach in treatment of endo-perio lesion a case report

Endo-perio lesions primarily occur by way of the intimate anatomic and vascular connections between the pulp and the periodontium. Endodontic-periodontal combined lesion is a clinical dilemma because making a differential diagnosis and deciding a prognosis are difficult. An untreated primary endodontic lesion may become secondarily involved with periodontal breakdown, which clinically present unusual signs and symptoms. This may delay the diagnosis and hence the correct treatment. This case report describes diagnosis and treatment protocol for an endo-perio lesion of primary endodontic with secondary periodontal involvement.

Allograft alone versus allograft with bone marrow concentrate for the healing of the instrumented posterolateral lumbar fusion

BACKGROUND CONTEXT

Spondylodesis in the operative management of lumbar spine diseases has been the subject of numerous studies over several decades. The posterolateral fusion (PLF) with pedicle screw fixation is a commonly used procedure.

PURPOSE

To determine whether the addition of bone marrow concentrate (BMC) to allograft bone increases fusion rate after instrumented posterior lumbar fusion.

STUDY DESIGN

The study was prospective, randomized, controlled, and blinded.

METHODS

Eighty patients with degenerative disease of the lumbar spine underwent instrumented lumbar or lumbosacral PLF (22 men, 58 women; body mass index less than 35 for a good visualization of the PLF in the X-rays). In 40 cases, the PLF was done with spongious allograft chips alone (Group I, age 62.7 years in average, range 47-77 years, level of fusion 1-2). In another 40 cases, spongious allograft chips were mixed with BMC (Group II, age 58.5 years in average, range 42-80, level of fusion 1-3), including the mesenchymal stem cells (MSCs). Patients were scheduled for anteroposterior and lateral radiographs 12 and 24 months after the surgery and for computed tomography scanning 24 months after the surgery. Fusion status and the degree of mineralization of the fusion mass were evaluated separately by two radiologists blinded to patient group affiliation. The bony mass was judged as fused if there was uninterrupted bridging of well-mineralized bone between the transverse processes or sacrum, with trabeculation indicating bone maturation on least at one side of the spines.

RESULTS

In Group I at 12 months, the bone graft mass was assessed in X-rays as fused in no cases (0%) and at 24 months in four cases (10%). In Group II, 6 cases (15%) achieved fusion at 12 months and 14 cases (35%) at 24 months. The statistically significant difference between both groups was proven for complete fusion at both 12 (p=.041) and 24 months (p=.011). Computed tomography scans showed that 16 cases (40%) in Group I and 32 cases (80%) in Group II had evidence of at least unilateral continuous bridging bone between neighboring vertebrae at 24 months (p<.05).

CONCLUSIONS

We have confirmed the hypothesis that the autologous BMC together with the allograft is a better alternative for PLF than the allograft alone. The use of autologous MSCs in form of BMC in combination with allograft is an effective option to enhance the PLF healing.

Triphasic ceramic scaffold in paediatric and adolescent bone defects

We evaluated novel triphasic hydroxyapatite tricalcium phosphate calcium silicate scaffold (HASi) in the management of paediatric bone defects. Their main advantage is considered to be adequate strength and stimulation of bone formation without resorting to autograft. A total of 42 children younger than 16 years of age were recruited over a period of 1 year and were treated with this synthetic bone substitute as a stand-alone graft for pelvic, femur, calcaneal and ulnar osteotomies, cystic bone lesions, subtalar arthrodesis and segmental bone defects. Forty children, 22 boys and 18 girls, mean age 8.3 years and a mean follow-up of 18.51 months, were available for evaluation. Analysis showed that younger age, cancellous defects and no internal fixation were associated with significantly faster healing. Partial incorporation was observed in 22.5% and complete incorporation in 77.5% of cases at 18 months of follow-up. Sex, type of defect, BMI and the shape of the ceramic graft did not significantly affect the rate of healing. Complications attributable to HASi included four nonunions, three of which were diaphyseal. HASi was found to be safe in children with cancellous or benign cavitatory defects. It is not suitable for diaphyseal and segmental bone defects as a stand-alone graft.

Determining a clinically relevant strategy for bone tissue engineering: an "all-in-one" study in nude mice

Purpose

Autologous bone grafting (BG) remains the standard reconstruction strategy for large craniofacial defects. Calcium phosphate (CaP) biomaterials, such as biphasic calcium phosphate (BCP), do not yield consistent results when used alone and must then be combined with cells through bone tissue engineering (BTE). In this context, total bone marrow (TBM) and bone marrow-derived mesenchymal stem cells (MSC) are the primary sources of cellular material used with biomaterials. However, several other BTE strategies exist, including the use of growth factors, various scaffolds, and MSC isolated from different tissues. Thus, clinicians might be unsure as to which method offers patients the most benefit. For this reason, the aim of this study was to compare eight clinically relevant BTE methods in an “all-in-one” study.

Methods

We used a transgenic rat strain expressing green fluorescent protein (GFP), from which BG, TBM, and MSC were harvested. Progenitor cells were then mixed with CaP materials and implanted subcutaneously into nude mice. After eight weeks, bone formation was evaluated by histology and scanning electron microscopy, and GFP-expressing cells were tracked with photon fluorescence microscopy.

Results/Conclusions

Bone formation was observed in only four groups. These included CaP materials mixed with BG or TBM, in which abundant de novo bone was formed, and BCP mixed with committed cells grown in two- and three-dimensions, which yielded limited bone formation. Fluorescence microscopy revealed that only the TBM and BG groups were positive for GFP expressing-cells, suggesting that these donor cells were still present in the host and contributed to the formation of bone. Since the TBM-based procedure does not require bone harvest or cell culture techniques, but provides abundant de novo bone formation, we recommend consideration of this strategy for clinical applications.

Cell based therapies as compared to autologous bone grafts for spinal arthrodesis

STUDY DESIGN

Systematic review.

OBJECTIVE

To compare the clinical outcome of cell based grafts combined with bone extenders to autologous bone grafts.

SUMMARY OF BACKGROUND DATA

Alternative graft options that combine mesenchymal stem cells (MSCs) and bone marrow aspirate (BMA) with synthetic or allograft scaffolds have been recently used in several animal and clinical studies.

METHODS

This systematic review of the literature addresses the following key questions (KQs): (1) Does the use of MSCs or BMA combined with synthetic or allograft extenders contribute to thoracolumbar fusion rates that are comparable with the rates achieved by the use of iliac crest graft? (2) Are these fusion rates comparable with those of local bone graft (LBG)? (3) Does the addition of MSCs or BMA to iliac crest bone graft or LBG contribute to better throracolumbar fusion rates? (4) Are the cervical spine fusion outcomes achieved by the use of SCM or BMA with synthetic or allograft scaffolds comparable with the iliac crest bone graft or LBG outcomes? (5) Was there any difference in terms of fusion rates, when MSCs were compared with BMA?

RESULTS

For KQ1, 4 level II, III studies used iliac crest bone graft as control. The results of these studies were inconsistent, and the overall body of evidence was found insufficient. Three, level II, III studies were identified for KQ2. Comparable fusion rates were demonstrated between LBG and BMA combined with calcium phosphate or collagen carrier. The overall body of evidence was found weak. For KQ3, one level III study was found. No significant difference was found in the fusion rates. No studies met the criteria for KQ4, 5.

CONCLUSION

The currently available evidence is insufficient to support the use of MSCs or BMA combined with synthetic or allograft materials as a substitute or supplementary graft to autologous bone graft.

LEVEL OF EVIDENCE

2.

Calcium phosphate ceramics in bone tissue engineering: a review of properties and their influence on cell behavior

Calcium phosphate ceramics (CPCs) have been widely used as biomaterials for the regeneration of bone tissue because of their ability to induce osteoblastic differentiation in progenitor cells. Despite the progress made towards fabricating CPCs possessing a range of surface features and chemistries, the influence of material properties in orchestrating cellular events such as adhesion and differentiation is still poorly understood. Specifically, questions such as why certain CPCs may be more osteoinductive than others, and how material properties contribute to osteoinductivity/osteoconductivity remain unanswered. Therefore, this review article systematically discusses the effects of the physical (e.g. surface roughness) and chemical properties (e.g. solubility) of CPCs on protein adsorption, cell adhesion and osteoblastic differentiation in vitro. The review also provides a summary of possible signaling pathways involved in osteoblastic differentiation in the presence of CPCs. In summary, these insights on the contribution of material properties towards osteoinductivity and the role of signaling molecules involved in osteoblastic differentiation can potentially aid the design of CPC-based biomaterials that support bone regeneration without the need for additional biochemical supplements.

Bone grafts in dentistry

Bone grafts are used as a filler and scaffold to facilitate bone formation and promote wound healing. These grafts are bioresorbable and have no antigen-antibody reaction. These bone grafts act as a mineral reservoir which induces new bone formation.

Does bone marrow affect the radiological outcome when added to biphasic ceramic graft in treatment of benign bone lesions?

PURPOSE

The aim of this study is to describe the role of bone marrow aspirate in treatment of the benign bone lesions by comparing two groups of patients (16 patients in each group) with benign bone lesions treated with surgical curettage and filling the defect with either composite ceramic graft hydrated with bone marrow aspirate "group 1" or composite ceramic graft alone without a bone marrow aspirate "group 2".

MATERIALS AND METHODS

The mean age was 19.7 years (group 1) and 18.5 years (group 2). The mean size of the cavitary bone lesions was 29.2 cm(2) (group 1) and 25.9 cm(2) (group 2). The mean follow-up period was 47 months.

RESULTS

The percentage of ceraform resorption had increased from 31.3% at 6 months to 75.4% at 36 months for group 1 patients and from 20.9% at 6 months to 60.3% at 36 months for group 2 patients. The percentage of bone trabeculation through the cavitary defects had increased from 30.3% at 6 months to 85.5% at 36 months for group 1 patients and from 18.9% at 6 months to 72.0% at 36 months for group 2 patients. The mean of the percentage of ceraform persistence at 36 months after its implantation was 24.6% for group 1 patients and 39.7% for group 2 patients.

CONCLUSION

Adding bone marrow aspirate to ceraform biphasic ceramic had hastened the rate of its resorption and had decreased the rate of its persistence.

Current application of β-tricalcium phosphate composites in orthopaedics

Presently, bioceramic materials have been extensively used in spinal surgery as bone grafts; however, there are some limitations for bioceramic materials. Calcium sulfate is rapidly absorbed in vivo, the degradation of which often occurs prior to the formation of new bones. Hydroxyapatite (HA) is hardly absorbed, which blocks the formation of new bones and remodeling, and results in poor local stability or permanent stress concentration. Only β-tricalcium phosphate (β-TCP) is relatively balanced between scaffold absorption and bone formation. And it is a good biodegradable ceramic material that could supply a large quantity of calcium ion and sulfate ion as well as scaffold structure for bone regeneration. However, the problem of single β-TCP is lack of osteoinductivity and osteogenicity, which restricts its application. Therefore β-TCP composite materials have been used in the field of orthopaedics in recent decades, which fully use excellent properties of other bone repairing materials, such as biodegradability, osteoinductivity, osteogenicity and osteoconductivity. These materials make up for the deficiencies of single β-TCP and endow β-TCP with more biological and physical properties.

Clinical and radiographic outcomes of extreme lateral approach to interbody fusion with β-tricalcium phosphate and hydroxyapatite composite for lumbar degenerative conditions

Background

Historically, iliac crest bone graft has been used as the graft of choice for lumbar spine fusion procedures. Because fusion techniques have become less invasive, the demand for minimally disruptive grafting options has increased. This prospective study was performed to assess clinical and radiographic outcomes of patients treated with an iliac crest bone graft alternative and lateral lumbar interbody fusion.

Methods

Fifty degenerative lumbar patients were treated with the extreme lateral approach to interbody fusion and a β-tricalcium phosphate–hydroxyapatite graft with bone marrow aspirate (BMA) at 1 or 2 adjacent levels. BMA was collected from the iliac crest with a bone aspiration needle and applied to the FormaGraft (NuVasive, Inc., San Diego, California) in a 1:1 ratio. Radiolucent cages were filled with FormaGraft strips, granules, or blocks and implanted in a standard fashion. Clinical data were collected at baseline, 6 weeks, and 3, 6, and 12 months and included visual analog scale, Oswestry Disability Index, and Short Form 36 patient-reported assessments. Fusion assessments were made from neutral anteroposterior/lateral radiographs, lateral flexion/extension radiographs, and computed tomography images taken at least 12 months after surgery.

Results

Forty-four patients treated at 49 levels completed follow-up. The mean patient age was 54.7 ± 10.8 years, and mean body mass index was 30.8 ± 7.7 kg/m². Radiographic fusion was observed in 41 of 44 assessed levels (93.2%). Blood loss was less than 100 mL in 95.5% of patients. Of the patients, 93.2% spent 1 night or less in the hospital. By the 6-week follow-up, all clinical outcomes were significantly improved (P < .05). Improvements were maintained or increased throughout the course of follow-up.

Conclusions

This report shows that the technique of extreme lateral approach to interbody fusion in combination with FormaGraft and BMA in the interbody space is a safe and effective treatment option for interbody fusion of the lumbar spine when compared with other approaches and biologic options.

Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO₃-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO₃-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO₃-HA. For silicate-substituted hydroxyapatite (SiO₄-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO₄-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy.

The Effect of Zirconia in Hydroxyapatite on Staphylococcus epidermidis Growth

Synthetic hydroxyapatite (HA) has been widely used and developed as the material for bone substitute in medical applications. The addition of zirconia is needed to improve the strength of hydroxyapatite as the bone substitute. One of the drawbacks in the use of biomedical materials is the occurrence of biomaterial-centred infections. The recent method of limiting the presence of microorganism on biomaterials is by providing biomaterial-bound metal-containing compositions. In this case, S. epidermidis is the most common infectious organism in biomedical-centred infection. Objective. This study was designed to evaluate the effect of zirconia concentrations in hydroxyapatite on the growth of S. epidermidis. Methods and Materials. The subjects of this study were twenty hydroxyapatite discs, divided into four groups in which one was the control and the other three were the treatment groups. Zirconia powder with the concentrations of 20%, 30%, and 40% was added into the three different treatment groups. Scanning electron microscope analysis was performed according to the hydroxyapatite and hydroxyapatite-zirconia specimens. All discs were immersed into S. epidermidis culture for 24 hours and later on they were soaked into a medium of PBS. The cultured medium was spread on mannitol salt agar. After incubation for 24 hours at 37°C , the number of colonies was measured with colony counter. Data obtained were analyzed using the ANOVA followed by the pairwise comparison. Result. The statistical analysis showed that different concentrations of zirconia powder significantly influenced the number of S. epidermidis colony (P < 0.05) . Conclusion. The addition of zirconia into hydroxyapatite affected the growth of S. epidermidis. Hydroxyapatite with 20% zirconia proved to be an effective concentration to inhibit the growth of S. epidermidis colony.

Osteoconductive bone graft extenders in posterolateral thoracolumbar spinal fusion: a systematic review

STUDY DESIGN

A systematic review.

OBJECTIVE

To evaluate the efficacy, safety, and outcomes of osteoconductive bone graft extenders (BGEs) compared with iliac crest bone graft (ICBG) in posterolateral thoracolumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

ICBG is the current "gold standard" for achieving spinal arthrodesis. However, morbidity associated with its harvesting has led to the increased use of BGEs.

METHODS

An electronic literature search was conducted through April 2011 using MEDLINE, EMBASE, CENTRAL, and Cochrane Library. Risk of bias and methodological assessment was performed using the Cochrane Risk of Bias Tool. Higgins I(2) test was used to assess for heterogeneity. Pooled weighted relative risk (RR) ratios were calculated to compare fusion and adverse event rates. Weighted standardized mean differences were calculated to compare functional outcome and pain scores.

RESULTS

Thirteen studies were included representing a total of 768 patients. Overall study quality was low (mean Cochrane Risk of Bias score, 4.8 out of 12; range, 3-6). Fusion rates were comparable between the BGE and ICBG groups (RR, 0.96; 95% confidence interval [CI], 0.89-1.03; P = 0.28). Higgins I(2) test (58%) suggested substantial heterogeneity in the pooling of studies. The pooled rate of donor site pain in the ICBG group was 11.2% (95% CI, 7.4%-15.1%). Reported adverse events, excluding donor site pain, were significantly lower in the BGE group (RR, 0.42; 95% CI, 0.28-0.64; P < 0.0001). Functional outcomes were not significantly different between the 2 groups.

CONCLUSION

Osteoconductive BGEs combined with local spine autograft and/or bone marrow aspirate have comparable fusion rates, similar functional outcomes, lower complication rates, and a lower risk of donor site pain than ICBG. Caution should be taken in interpreting these findings, given the low quality of the studies and the heterogeneity in the results. Randomized controlled studies using blinded assessments are required to help elucidate more conclusive evidence.

Preparation of combined β-TCP/α-CSH artificial bone graft and its performance in a spinal fusion model

To evaluate α-calcium sulfate hemihydrate (α-CSH)/β-tricalcium phosphate (β-TCP) combined artificial bone graft (COB) in an animal model of posterolateral spinal fusion, α-CSH and β-TCP were combined in a 3 : 7 weight ratio. A rabbit model of posterolateral spinal fusion was produced ( N = 36); one side was implanted with the COB, and the other with local autogenous bone. Rabbits were killed on the 4th, 8th, or 12th week after surgery and fusion, COB degradation, mineralization, and new bone formation were evaluated. Scanning electron microscopy revealed that the COB retained the porous spatial structure of β-TCP and α-CSH crystals were adhered to the surface and pores of β-TCP. At the 12th week after surgery, the fusion rate was 75.0% on the 12th week after the operation, which was higher than the fusion rate of 54.4% the autogenous bone side ( p = 0.073). Bone volume fraction of the COB was 0.49 ± 0.08 for the 4th week and 0.16 ± 0.05 for the 12th week after surgery. The mineralization rate of the new bone was greater on the side implanted with autogenous bone than on the side implanted with COB at all the three time points after surgery. At each time point after surgery, the difference in mineralization rate between the autogenous bone side and the COB side was statistically significant ( p < 0.001); α-CSH/β-TCP in a 3 : 7 weight ratio was as effective as local autogenous bone in producing spinal fusion in a rabbit model. Used in this ratio, the speed of material degradation and new bone formation are relatively equivalent, and the rate of new bone mineralization is similar to that of autogenous bone graft.