Calcium phosphate ceramics as bone graft substitutes in filling bone tumor defects

Design, clinical applications and post-surgical assessment of bioresorbable 3D-printed craniofacial composite implants

This study details the design, fabrication, clinical trials' evaluation, and analysis after the clinical application of 3D-printed bone reconstruction implants made of nHAp@PLDLLA [nanohydroxyapatite@poly(L-lactide-co-D,L-lactide)] biomaterial. The 3D-printed formulations have been tested as bone reconstruction Cranioimplants in 3 different medical cases, including frontal lobe, mandibular bone, and cleft palate reconstructions. Replacing one of the implants after 6 months provided a unique opportunity to evaluate the post-surgical implant obtained from a human patient. This allowed us to quantify physicochemical changes and develop a spatial map of osseointegration and material degradation kinetics as a function of specific locations. To the best of our knowledge, hydrolytic degradation and variability in the physicochemical and mechanical properties of the biomimetic, 3D-printed implants have not been quantified in the literature after permanent placement in the human body. Such analysis has revealed the constantly changing properties of the implant, which should be considered to optimize the design of patient-specific bone substitutes. Moreover, it has been proven that the obtained composition can produce biomimetic, bioresorbable and bone-forming alloplastic substitutes tailored to each patient, allowing for shorter surgery times and faster patient recovery than currently available methods.

Antimicrobial and Cell-Friendly Properties of Cobalt and Nickel-Doped Tricalcium Phosphate Ceramics

β-Tricalcium phosphate (β-TCP) is widely used as bone implant material. It has been observed that doping the β-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of β-TCP containing nickel and cobalt ions. In this work, Ca10.5-xNix(PO4)7 and Ca10.5-xCox(PO4)7 solid solutions with the β-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the β-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the β-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped β-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials.

Iron-Based Ceramic Composite Nanomaterials for Magnetic Fluid Hyperthermia and Drug Delivery

Because of the unique physicochemical properties of magnetic iron-based nanoparticles, such as superparamagnetism, high saturation magnetization, and high effective surface area, they have been applied in biomedical fields such as diagnostic imaging, disease treatment, and biochemical separation. Iron-based nanoparticles have been used in magnetic resonance imaging (MRI) to produce clearer and more detailed images, and they have therapeutic applications in magnetic fluid hyperthermia (MFH). In recent years, researchers have used clay minerals, such as ceramic materials with iron-based nanoparticles, to construct nanocomposite materials with enhanced saturation, magnetization, and thermal effects. Owing to their unique structure and large specific surface area, iron-based nanoparticles can be homogenized by adding different proportions of ceramic minerals before and after modification to enhance saturation magnetization. In this review, we assess the potential to improve the magnetic properties of iron-based nanoparticles and in the preparation of multifunctional composite materials through their combination with ceramic materials. We demonstrate the potential of ferromagnetic enhancement and multifunctional composite materials for MRI diagnosis, drug delivery, MFH therapy, and cellular imaging applications.

The Effect of Mineralized Plasmatic Matrix and Chitosan on the Healing of Critical-Sized Mandibular Bone Defects in a Rabbit Model

Background: In maxillofacial surgery, critical size mandibular defects remain a challenging issue. There have been numerous attempts to improve mandibular defect healing. Recently, bone tissue engineering has provided many benefits in improving bone healing. Herein, we tried to investigate the effect of Mineralized plasmatic matrix (MPM) and Chitosan to enhance tissue healing and regeneration in mandibular bone defect. Methods: A mandibular bone defect of critical size was created in 45 New Zealand rabbits. There were three groups of rabbits: the MPM group, the Chitosan group, and the control group. Radiographical, histological, and immune histochemical evaluations were performed at 4, 8, and 12 post-operative weeks. Results: The MPM group demonstrated the highest degree of bone formation with uniform radio-opacity nearly like that of adjacent healthy parent tissue. While in the chitosan group, most of the defect area was filled with radio-opaque bone with persistent small radiolucent areas. The control group showed less bone formation than the MPM and chitosan group, with more radiolucent areas. Sections stained with (H&E) demonstrated an increase in osseous tissue formation in both the MPM and chitosan groups. Staining with Masson’s trichrome revealed an increase in fibrous connective tissue proliferation in both the MPM and chitosan groups. In both the MPM and chitosan groups, nuclear factor kappa p65 was downregulated, and matrix metalloproteinase-9 was upregulated. Conclusion: According to the current study, MPM and Chitosan may have beneficial effects on the healing of critical-sized mandibular bone defects.

A novel pilot animal model for bone augmentation using osseous shell technique for preclinical in vivo studies

OBJECTIVES

Bone grafting is commonly used to reconstruct skeletal defects in the craniofacial region. Several bone augmentation models have been developed to evaluate bone formation using novel bone substitute materials. The aim of this study was to evaluate a surgical animal model for establishing a three-dimensional (3D) grafting environment in the animal's mandibular ramus for bone augmentation using the osseous shell technique, as in humans.

MATERIALS AND METHODS

Osteological survey of New Zealand white (NZW) rabbit skull (Oryctolagus cuniculus): Initial osteological and imaging surveys were performed on a postmortem skull for a feasibility assessment of the surgical procedure. Postmortem pilot surgery and cone beam computed tomography imaging: a 3D osseous defect was created in the mandibular ramus through a submandibular incision. The osseous shell plates were stabilized with osteosynthesis fixation screws, and defects were filled with particular bone grafting material. In vivo surgical procedure: surgeries were conducted in four 8-week-old NZW rabbits utilizing two osseous shell materials: xenogeneic human cortical plates and autogenous rabbit cortical plates. The created 3D defects were filled using xenograft and allograft bone grafting materials. The healed defects were evaluated for bone formation after 12 weeks using histological and cone beam computed tomography imaging analysis.

RESULTS

Clinical analysis 12 weeks after surgery revealed the stability of the 3D grafted bone augmentation defects using the osseous shell technique. Imaging and histological analyses confirmed the effectiveness of this model in assessing bone formation.

CONCLUSIONS

The proposed animal model is a promising model with the potential to study various bone grafting materials for augmentation in the mandibular ramus using the osseous shell technique without compromising the health of the animal. The filled defects could be analyzed for osteogenesis, quantification of bone formation, and healing potential using histomorphometric analysis, in addition to 3D morphologic evaluation using radiation imaging.

Clinical outcome of porous hydroxyapatite/collagen graft on bone defects following curettage of bone tumors

Hydroxyapatite/collagen (HAp/col) has been reported to be a highly useful bone-like nanocomposite. This study included 33 human patients to investigate the details of the clinical outcomes, which are (1) onset of timing of bone regeneration, (2) replacement by regenerated bone of HAp/col and (3) complications, in human cases grafting HAp/col in large bone defects, following curettage of bone tumors. Porous HAp/col initiated bone regeneration approximately 59 days following the surgery. In 15 cases (45%), complete replacement by newly formed bone was observed 12 months after surgery. On the other hand, incomplete replacement of HAp/col at the final follow-up was observed in 13 cases (39%). In these cases, HAp/col could not be detected in the transparent area of postoperative plain radiographs owing to quick absorption; moreover, it was difficult to distinguish whether the transparent area in plain radiographs was remaining HAp/col, recurrence, or remaining tumor. In addition, larger HAp/col implantation volume (≧15 cm³ ) was associated with poorer result of complete replacement (log-rank, p = .005). Further studies are warranted for the construction of a new artificial bone graft substitute that is more quickly and surely regenerated by newly formed bone in large bone defects.

Compositions and Structural Geometries of Scaffolds Used in the Regeneration of Cleft Palates: A Review of the Literature

Cleft palate (CP) is one of the most common birth defects, presenting a multitude of negative impacts on the health of the patient. It also leads to increased mortality at all stages of life, economic costs and psychosocial effects. The embryological development of CP has been outlined thanks to the advances made in recent years due to biomolecular successions. The etiology is broad and combines certain environmental and genetic factors. Currently, all surgical interventions work off the principle of restoring the area of the fissure and aesthetics of the patient, making use of bone substitutes. These can involve biological products, such as a demineralized bone matrix, as well as natural–synthetic polymers, and can be supplemented with nutrients or growth factors. For this reason, the following review analyzes different biomaterials in which nutrients or biomolecules have been added to improve the bioactive properties of the tissue construct to regenerate new bone, taking into account the greatest limitations of this approach, which are its use for bone substitutes for large areas exclusively and the lack of vascularity. Bone tissue engineering is a promising field, since it favors the development of porous synthetic substitutes with the ability to promote rapid and extensive vascularization within their structures for the regeneration of the CP area.

Regenerative Approaches for the Treatment of Large Bone Defects

A variety of engineered materials have gained acceptance in orthopedic practice as substitutes for autologous bone grafts, although the regenerative efficacy of these engineered grafts is still limited compared with that of transplanted native tissues. For bone defects greater than 4-5 cm, however, common bone grafting procedures are insufficient and more complicated surgical interventions are required to repair and regenerate the damaged or missing bone. In this review, we describe current grafting materials and surgical techniques for the reconstruction of large bone defects, followed by tissue engineering (TE) efforts to develop improved therapies. Particular emphasis is placed on graft vascularization, because for both autologous bone and engineered alternatives, achieving adequate vascular development within the regenerating bone tissues remains a significant challenge in the context of large bone defects. To this end, TE and surgical strategies to induce development of a vasculature within bone grafts are discussed. Impact statement This review aims to present an accessible and thorough overview of current orthopedic surgical techniques as well as bone tissue engineering and vascularization strategies that might one day offer improvements to clinical therapies for the repair of large bone defects. We consider the lessons that clinical orthopedic reconstructive practices can contribute to the push toward engineered bone.

Biocompatible Customized 3D Bone Scaffolds Treated with CRFP, an Osteogenic Peptide

BACKGROUND

Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the principal load or if metallic, they can support loading, but can lead to stress shielding and are unable to integrate fully. In this study, we developed biocompatible, 3D printed scaffolds derived from µCT images of the bone that can overcome these issues and support the growth of osteoblasts.

METHODS

Cylindrical scaffolds were fabricated with acrylonitrile butadiene styrene (ABS) and Stratasys^® MED 610 (MED610) materials. The 3D-printed scaffolds were seeded with Mus musculus calvaria cells (MC3T3). After the cells attained confluence, osteogenesis was induced with and without the addition of calcitonin receptor fragment peptide (CRFP) and the bone matrix production was analyzed. Mechanical compression testing was carried out to measure compressive strength, stiffness, and elastic modulus.

RESULTS

For the ABS scaffolds, there was a 9.8% increase in compressive strength (p < 0.05) in the scaffolds with no pre-coating and the treatment with CRFP, compared to non-treated scaffolds. Similarly, MED610 scaffolds treated with CRFP showed an 11.9% (polylysine pre-coating) and a 20% (no pre-coating) increase (p < 0.01) in compressive strength compared to non-treated scaffolds.

CONCLUSIONS

MED610 scaffolds are excellent BGS as they support osteoblast growth and show enhanced bone growth with enhanced compressive strength when augmented with CRFP.

FDA-approved bone grafts and bone graft substitute devices in bone regeneration

To induce bone regeneration there is a complex cascade of growth factors. Growth factors such as recombinant BMP-2, BMP-7, and PDGF are FDA-approved therapies in bone regeneration. Although, BMP shows promising results as being an alternative to autograft, it also has its own downfalls. BMP-2 has many adverse effects such as inflammatory complications such as massive soft-tissue swelling that can compromise a patient's airway, ectopic bone formation, and tumor formation. BMP-2 may also be advantageous for patients not willing to give up smoking as it shows bone regeneration success with smokers. BMP-7 is no longer an option for bone regeneration as it has withdrawn off the market. PDGF-BB grafts in studies have shown PDGF had similar fusion rates to autologous grafts and fewer adverse effects. There is also an FDA-approved bioactive molecule for bone regeneration, a peptide P-15. P-15 was found to be effective, safe, and have similar outcomes to autograft at 2 years post-op for cervical radiculopathy due to cervical degenerative disc disease. Growth factors and bioactive molecules show some promising results in bone regeneration, although more research is needed to avoid their adverse effects and learn about the long-term effects of these therapies. There is a need of a bone regeneration method of similar quality of an autograft that is osteoconductive, osteoinductive, and osteogenic. This review covers all FDA-approved bone regeneration therapies such as the "gold standard" autografts, allografts, synthetic bone grafts, and the newer growth factors/bioactive molecules. It also covers international bone grafts not yet approved in the United States and upcoming technologies in bone grafts.

Mechanistic Illustration: How Newly-Formed Blood Vessels Stopped by the Mineral Blocks of Bone Substitutes Can Be Avoided by Using Innovative Combined Therapeutics

One major limitation for the vascularization of bone substitutes used for filling is the presence of mineral blocks. The newly-formed blood vessels are stopped or have to circumvent the mineral blocks, resulting in inefficient delivery of oxygen and nutrients to the implant. This leads to necrosis within the implant and to poor engraftment of the bone substitute. The aim of the present study is to provide a bone substitute currently used in the clinic with suitably guided vascularization properties. This therapeutic hybrid bone filling, containing a mineral and a polymeric component, is fortified with pro-angiogenic smart nano-therapeutics that allow the release of angiogenic molecules. Our data showed that the improved vasculature within the implant promoted new bone formation and that the newly-formed bone swapped the mineral blocks of the bone substitutes much more efficiently than in non-functionalized bone substitutes. Therefore, we demonstrated that our therapeutic bone substitute is an advanced therapeutical medicinal product, with great potential to recuperate and guide vascularization that is stopped by mineral blocks, and can improve the regeneration of critical-sized bone defects. We have also elucidated the mechanism to understand how the newly-formed vessels can no longer encounter mineral blocks and pursue their course of vasculature, giving our advanced therapeutical bone filling great potential to be used in many applications, by combining filling and nano-regenerative medicine that currently fall short because of problems related to the lack of oxygen and nutrients.

Bone Grafts and Substitutes in Dentistry: A Review of Current Trends and Developments

After tooth loss, bone resorption is irreversible, leaving the area without adequate bone volume for successful implant treatment. Bone grafting is the only solution to reverse dental bone loss and is a well-accepted procedure required in one in every four dental implants. Research and development in materials, design and fabrication technologies have expanded over the years to achieve successful and long-lasting dental implants for tooth substitution. This review will critically present the various dental bone graft and substitute materials that have been used to achieve a successful dental implant. The article also reviews the properties of dental bone grafts and various dental bone substitutes that have been studied or are currently available commercially. The various classifications of bone grafts and substitutes, including natural and synthetic materials, are critically presented, and available commercial products in each category are discussed. Different bone substitute materials, including metals, ceramics, polymers, or their combinations, and their chemical, physical, and biocompatibility properties are explored. Limitations of the available materials are presented, and areas which require further research and development are highlighted. Tissue engineering hybrid constructions with enhanced bone regeneration ability, such as cell-based or growth factor-based bone substitutes, are discussed as an emerging area of development.

Three-Dimensionally-Printed Bioactive Ceramic Scaffolds: Construct Effects on Bone Regeneration

BACKGROUND/PURPOSE

The utilization of three-dimensionally (3D)-printed bioceramic scaffolds composed of beta-tricalcium phosphate in conjunction with dipyridamole have shown to be effective in the osteogenesis of critical bone defects in both skeletally immature and mature animals. Furthermore, previous studies have proven the dura and pericranium's osteogenic capacity in the presence of 3D-printed scaffolds; however, the effect galea aponeurotica on osteogenesis in the presence of 3D scaffolds remains unclear.

METHOD/DESCRIPTION

Critical-sized (11 mm) bilateral calvarial defects were created in 35-day old rabbits (n = 7). Two different 3D scaffolds were created, with one side of the calvaria being treated with a solid nonporous cap and the other with a fully porous cap. The solid cap feature was designed with the intention of preventing communication of the galea and the ossification site, while the porous cap permitted such communication. The rabbits were euthanized 8 weeks postoperatively. Calvaria were analyzed using microcomputed tomography, 3D reconstruction, and nondecalcified histologic sectioning in order assess differences in bone growth between the two types of scaffolding.

RESULTS

Scaffolds with the solid (nonporous) cap yielded greater percent bone volume (P = 0.012) as well as a greater percent potential bone (P = 0.001) compared with the scaffolds with a porous cap. The scaffolds with porous caps also exhibited a greater percent volume of soft tissue (P < 0.001) presence. There were no statistically significant differences detected in scaffold volume.

CONCLUSION

A physical barrier preventing the interaction of the galea aponeurotica with the scaffold leads to significantly increased calvarial bone regeneration in comparison with the scaffolds allowing for this interaction. The galea's interaction also leads to more soft tissue growth hindering the in growth of bone in the porous-cap scaffolds.

Talar neck non-union in an athlete successfully treated with a synthetic bone graft: A case report

Talar neck non-union is a rare complication of talar neck fractures. No guidelines are currently available for the proper management of this complication; thus, it can be hard for orthopaedic surgeons to successfully treat. Here we are reporting a case of talar neck non-union occurring in a 22-year-old male patient after a road traffic accident and presented to our institution 10 months after the initial injury. The non-union was managed surgically with an open reduction and internal fixation with the use of a synthetic bone graft to fill the defects. The patient regained full function and remained without complications after 7 years of follow up.

Early postoperative compilations of bone filling in curettage defects

Background

Curettage is widely used in orthopedic oncology; the defect created frequently requires filling for mechanical and functional stability for the bones and adjacent joint. Allograft, bone graft substitute, and polymethyl methacrylate (PMMA) are the most common substances used each with their benefits and drawbacks. The aim of the study is to show that good functional result can be achieved with curettage and bone filler, regardless of type.

Methods

A series of 267 cases were reviewed between 1994 and 2015 who received curettage treatment and placement of a bone filler. Endpoints included fracture, infection, cellulitis, pulmonary embolism, and paresthesia. Complication rates at our single institution were compared against literature values for three study cohorts: allograft, bone graft substitute, and PMMA bone fillers. Friedman test, Wilcoxon test, and Z-score for two populations were used to compare our subset against literature values and between different bone filling types.

Results

Our cases included 18 autografts, 74 allografts, 121 bone graft substitute, and 54 PMMA of which the bulk of complications occurred. Our overall complication rate was 3.37%. Allograft has a complication rate of 1.35%, bone graft substitute of 4.13%, and PMMA of 5.56%. Other techniques did not yield any complications. Combination filling techniques PMMA + allograft and PMMA + bone graft substitute had sample sizes too small for statistical comparison. Statistical comparison yielded no significant difference between complications in any of the filling groups (P = 0.411).

Conclusions

Some has even argued that bone defects following curettage do not require bone filling for good outcome. However, many structural or biologic benefits that aid in earlier return to functionality can be conferred by filling large bone defects. There was no significant difference in postoperative complication rates between allograft, bone graft substitute, and PMMA when compared at our institution and with literature values. Nevertheless, one complication with a large defect filled with allograft, requiring a subsequent reconstruction using vascularized fibular graft. Taking everything into account, we see bone graft substitute as a suitable alternative to other bone filling modalities.

Mechanical and biological evaluation of a hydroxyapatite-reinforced scaffold for bone regeneration

With over 500,000 bone grafting procedures performed annually in the United States, the advancement of bone regeneration technology is at the forefront of medical research. Many tissue-engineered approaches have been explored to develop a viable synthetic bone graft substitute, but a major challenge is achieving a load-bearing graft that appropriately mimics the mechanical properties of native bone. In this study, sintered hydroxyapatite (HAp) was used to structurally reinforce a scaffold and yield mechanical properties comparable to native bone. HAp was packed into a cylindrical framework and processed under varying conditions to maximize its mechanical properties. The resulting HAp columns were further tested in a 6-week degradation study to determine their physical and mechanical response. The cellular response of sintered HAp was determined using a murine preosteoblast cell line, MC3T3-E1. Cell viability and morphology were studied over a one-week period and MC3T3-E1 differentiation was determined by measuring the alkaline phosphatase levels. Finite element analysis was used to determine the columns' geometric configuration and arrangement within our previously developed composite bone scaffold. It was determined that incorporating four cylindrical HAp columns, fabricated under 44 MPa of pressure and sintered at 1200°C for 5 hr, led to load-bearing properties that match the yield strength of native whole bone. These preliminary results indicate that the incorporation of a mechanically enhanced HAp structural support system is a promising step toward developing one of the first load-bearing bone scaffolds that can also support cell proliferation and osteogenic differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 732-741, 2019.

Role of Beta Tri-calcium Phosphate-based Composite Ceramic as Bone-Graft Expander in Masquelet's-Induced Membrane Technique

BACKGROUND

Filling bone defect after debridement of infected nonunion is an orthopedic challenge. Since the volume of autologous bone graft available is limited, allograft, demineralized bone matrix, and calcium phosphate ceramic-based bone graft substitutes have come up as potential autograft expanders. This study was conducted to analyze the use of beta tri-calcium phosphate (B-TCP)-based composite ceramic as autologous bone-graft expander in the management of postinfective segmental gap nonunion of long bones managed with two-stage Masquelet's technique.

MATERIALS AND METHODS

42 consecutive patients with postinfective segmental long bone defects of 4-12 cm managed with Masquelet's-induced membrane technique, operated between February 2012 and June 2015, were included in this prospective case series. During the second stage bone-grafting procedure, iliac crest autograft alone or mixed with B-TCP granules (ratio not exceeding >1:1) was used along with appropriate internal-fixation. Bony union (defined clinicoradiologically as ability to painlessly bear weight on affected limb without support along with bridging of 3 cortices on X-rays) was evaluated.

RESULTS

Union was achieved in 80.9% patients (34/42) with index bone grafting. 100% union rate was achieved in patients where only autograft was used (15/15) and in nonsmoker femoral nonunion patients with the use of B-TCP (13/13). The use of B-TCP was associated with higher rate of nonunion in smokers (6/8, 75%) and in tibial nonunions (4/9, 55.5%). All, but one, of 8 patients with nonunion, united after the second-bone grafting procedure.

CONCLUSION

B-TCP is an efficacious and safe autologous bone graft expander in Masquelet's two-stage management of post infective segmental gap nonunion of long bones. Patients should be counseled regarding increased risk of nonunion and need for repeat grafting with its use, especially if they are smokers or site of involvement is tibia.

Combined delivery of bone morphogenetic protein-2 and insulin-like growth factor-1 from nano-poly (γ-glutamic acid)/β-tricalcium phosphate-based calcium phosphate cement and its effect on bone regeneration in vitro

In this study, nano-doped calcium phosphate cement delivery systems (poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramics and nano (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic) were fabricated, and low doses (10 µg/g) of two growth factors, insulin-like growth factor-1 and bone morphogenetic protein-2, were encapsulated then sequentially released. We characterized the delivery systems using Fourier transform infrared spectroscopy and X-ray diffraction and measured washout resistance and compressive strength, and thus optimized the most appropriate proportioning of delivery systems for the two growth factors. One of the growth factors was absorbed by the nano-poly (γ-glutamic acid)/β-tricalcium phosphate, which was then mixed into the calcium phosphate ceramic solid phase to create a new solid phase calcium phosphate ceramic. Nano-poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic carriers were then prepared by blending the new calcium phosphate ceramic solid phase powder with a solution of the remaining growth factor. The effects of different release patterns (studying sequential behavior) of insulin-like growth factor-1 and bone morphogenetic protein-2 on osteogenic proliferation and differentiation of the MC3t3-E1 mouse osteoblast cell were investigated. This combinational delivery system provided a controlled release of the two growth factors, in which nano-doping significantly affected their release kinetics. The incorporation of dual growth factors could potentially stimulate bone healing and promoting bone ingrowth processes at a low dose.

Functionalization of phosphocalcic bioceramics for bone repair applications

This work is devoted to the processing of bone morphogenetic protein (BMP-2) functionalized silicate substituted hydroxyapatite (SiHA) ceramic spheres. The motivation behind it is to develop injectable hydrogel/bioceramic composites for bone reconstruction applications. SiHA microspheres were shaped by spray drying and thoroughly characterized. The silicate substitution was used to provide preferred chemical sites at the ceramic surface for the covalent immobilization of BMP-2. In order to control the density and the release of the immobilized BMP-2, its grafting was performed via ethoxysilanes and polyethylene glycols. A method based on Kaiser's test was used to quantify the free amino groups of grafted organosilanes available at the ceramic surface for BMP-2 immobilization. The SiHA surface modification was investigated by means of X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy and thermogravimetry coupled with mass spectrometry. The BMP-2 bioactivity was assessed, in vitro, by measuring the luciferase expression of a stably transfected C3H10 cell line (C3H10-BRE/Luc cells). The results provided evidence that the BMP-2 grafted onto SiHA spheres remained bioactive.

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.

Bone regeneration using composite non-demineralized xenogenic dentin with beta-tricalcium phosphate in experimental alveolar cleft repair in a rabbit model

Background

Alveolar cleft repair is performed via bone grafting procedure to restore the dental arch continuity. A suitable bone substitute materials should possess osteoinductive and osteoconductive properties, to promote new bone formation, along with a slowly resorbable scaffold that is subsequently replaced with functionally viable bone. Calcium phosphate biomaterials have long proved their efficacy as bone replacement materials. Dentin in several forms has also demonstrated its possibility to be used as bone graft replacement material in several studies. The purpose of this study was to evaluate bone regeneration pattern and quantify bone formation after grafting pre-established experimental alveolar clefts defects model in rabbits using composite xenogenic dentin and β-TCP in comparison to β-TCP alone.

Methods

Unilateral alveolar cleft defects were created in 16 New Zealand rabbits according to previously described methodology. Alveolar clefts were allowed 8 weeks healing period. 8 defects were filled with β-TCP, whereas 8 defects filled with composite xenogenic dentin with β-TCP. Bone regeneration of the healed defects was compared at the 8 weeks after intervention. Quantification of bone formation was analyzed using micro-computed tomography (µCT) and histomorphometric analysis.

Results

µCT and histomorphometric analysis revealed that defects filled with composite dentin/β-TCP showed statistically higher bone volume fraction, bone mineral density and percentage residual graft volume when compared to β-TCP alone. An improved surgical handling of the composite dentin/β-TCP graft was also noted.

Conclusions

Composite xenogenic dentin/β-TCP putty expresses enhanced bone regeneration compared to β-TCP alone in the reconstruction of rabbit alveolar clefts defects.

Cranial reconstruction using allogeneic mesenchymal stromal cells: A phase 1 first-in-human trial

Cranioplasty is necessary for patients that have undergone craniectomy following trauma, stroke or other causes of elevated intracranial pressure. This study assessed the effectiveness of treating cranial defects with allogeneic mesenchymal stromal cells (MSC) on a ceramic carrier and polymer scaffold, to produce viable bone and healing of a cranial void. Patients underwent a baseline computed tomography (CT) scan for construct design. Two sets of interlocking moulds were three-dimensional printed to enable shaping of two polymer meshes, which formed the boundaries of the construct corresponding to restoration of the skull interna and externa. In vitro expanded donor MSC were seeded onto ceramic granules in a good manufacturing practices facility. The inner mesh was placed in theatre, followed by the cell-loaded granules, and the outer mesh. Patients were followed-up at 3, 6 and 12 months and cosmesis assessed visually, while bone formation was assessed by CT scans at 1 day, 3 months and 12 months. Manufacture of the construct and surgery was uneventful for all three patients. Initial cosmesis was excellent with no complications. New bone formation was demonstrated by analysis of CT data; however, bone resorption was noted in all 3 cases on the 12-month CT scan. The lack of rigidity of the construct in an environment with continuous pulsatile movement may be preventing the formation of solid bone. It is possible to produce a customized allogeneic MSC construct for cranial reconstruction to replace cranial bone with good cosmesis, using a combination of medical computer modelling, rapid-prototyping and tissue engineering.

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.

Bioceramic-Based Root Canal Sealers: A Review

Bioceramic-based root canal sealers are considered to be an advantageous technology in endodontics. The aim of this review was to consider laboratory experiments and clinical studies of these sealers. An extensive search of the endodontic literature was made to identify publications related to bioceramic-based root canal sealers. The outcome of laboratory and clinical studies on the biological and physical properties of bioceramic-based sealers along with comparative studies with other sealers was assessed. Several studies were evaluated covering different properties of bioceramic-based sealers including physical properties, biocompatibility, sealing ability, adhesion, solubility, and antibacterial efficacy. Bioceramic-based sealers were found to be biocompatible and comparable to other commercial sealers. The clinical outcomes associated with the use of bioceramic-based root canal sealers are not established in the literature.

Mineral particles modulate osteo-chondrogenic differentiation of embryonic stem cell aggregates

Pluripotent stem cell aggregates offer an attractive approach to emulate embryonic morphogenesis and skeletal development. Calcium phosphate (CaP) based biomaterials have been shown to promote bone healing due to their osteoconductive and potential osteoinductive properties. In this study, we hypothesized that incorporation of CaP-coated hydroxyapatite mineral particles (MPs) within murine embryonic stem cell (ESC) aggregates could promote osteo-chondrogenic differentiation. Our results demonstrated that MP alone dose-dependently promoted the gene expression of chondrogenic and early osteogenic markers. In combination with soluble osteoinductive cues, MPs enhanced the hypertrophic and osteogenic phenotype, and mineralization of ESC aggregates. Additionally, MPs dose-dependently reduced ESC pluripotency and thereby decreased the size of teratomas derived from MP-incorporated ESC aggregates in vivo. Our data suggested a novel yet simple means of using mineral particles to control stem cell fate and create an osteochondral niche for skeletal tissue engineering applications.

STATEMENT OF SIGNIFICANCE

Directing stem cell differentiation and morphogenesis via biomaterials represents a novel strategy to promote cell fates and tissue formation. Our study demonstrates the ability of calcium phosphate-based mineral particles to promote osteochondrogenic differentiation of embryonic stem cell aggregates as well as modulate teratoma formation in vivo. This hybrid biomaterial-ESC aggregate approach serves as an enabling platform to evaluate the ability of biomaterials to regulate stem cell fate and regenerate functional skeletal tissues for clinical applications.

Role of autologous platelet-rich plasma in treatment of long-bone nonunions: a prospective study

PURPOSE

Fracture union is a complex biological process, which depends upon several systemic and local factors. Disturbance of any of these factors may lead to nonunion of the fracture. These nonunions have a huge impact on quality of life as well as socioeconomical aspects. The platelets on activation release a number of growth factors and differentiation factors, which play important role in fracture healing. This study aimed to look for efficacy of platelet-rich plasma in the treatment of established fracture nonunions of long bones.

METHODS

A total of 94 patients with established nonunion of long bone (35 tibia, 30 femur, 11 humerus, 4 radius, 12 ulna, 2 with both radius and ulna) were included in this study. We injected 15-20 ml of autologous platelet-rich plasma (>2,000,000 platelets/μl) under image intensifier at each nonunion site. The fracture union was evaluated clinically and radiologically regularly at monthly interval till 4 months.

RESULTS

Eighty-two patients had their fracture united at the end of 4 months. Thirty-four patients showed bridging trabeculae on X-rays at the end of 2 months, while 41 patients showed bridging trabeculae at the end of third month. Twelve patients did not show any attempt of union at 4 months and were labeled as failure of treatment. There were no complications.

CONCLUSION

Platelet-rich plasma is a safe and effective treatment for the treatment of nonunions. More studies are needed to look into molecular mechanism of this fracture healing acceleration by platelet-rich plasma.

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.

Ceramic and non-ceramic hydroxyapatite as a bone graft material: a brief review

Treatment of dental, craniofacial and orthopedic defects with bone graft substitutes has shown promising result achieving almost complete bone regeneration depending on product resorption similar to human bone's physicochemical and crystallographic characteristics. Among these, non-ceramic and ceramic hydroxyapatite being the main inorganic salt of bone is the most studied calcium phosphate material in clinical practices ever since 1970s and non-ceramic since 1985. Its "chemical similarity" with the mineralized phase of biologic bone makes it unique. Hydroxyapatite as an excellent carrier of osteoinductive growth factors and osteogenic cell populations is also useful as drug delivery vehicle regardless of its density. Porous ceramic and non-ceramic hydroxyapatite is osteoconductive, biocompatible and very inert. The need for bone graft material keeps on increasing with increased age of the population and the increased conditions of trauma. Recent advances in genetic engineering and doping techniques have made it possible to use non-ceramic hydroxyapatite in larger non-ceramic crystals and cluster forms as a successful bone graft substitute to treat various types of bone defects. In this paper we have mentioned some recently studied properties of hydroxyapatite and its various uses through a brief review of the literatures available to date.

Synthesis and characterization of biocompatible-nanohydroxyapatite crystals obtained by a modified sol-gel processing

A modified sol-gel process for synthesizing nanocrystalline hydroxyapatite powders (nHA) for biomedical applications, using tetrahydrated calcium nitrate [Ca(NO₃)₂∙4H₂O] and phosphorous pentoxide [P₂O₅] as precursor, is presented and discussed. The powders were washed and heat-treated at different temperatures and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The total process time reached with this modified process was less than 16 h. The results showed that there was an increment in size of the HA nanocrystals (nHA) when treated at different temperatures, ranging from 30 nm for the sample treated at 600°C to 500 nm for the sample heat-treated at 1200°C.

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.

Effects of SiO2, SrO, MgO, and ZnO dopants in tricalcium phosphates on osteoblastic Runx2 expression

Calcium phosphate materials share a compositional similarity to natural bone, which makes them excellent for use in orthopedic applications. Although these materials are osteoconductive, they lack strong osteoinductive capabilities and recent research has focused on the addition of biologics and pharmacologics with varying successes. In this study, trace elements that have been proven to play important roles in bone health and bone formation were incorporated into β-tricalcium phosphate compacts in their oxide forms (SiO2, ZnO, SrO, and MgO). Cell material interactions were characterized using human fetal preosteoblastic cells. An MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was used to evaluate cellular proliferation. Cellular differentiation was evaluated using an enzymatic colorimetric alkaline phosphatase assay as well as immunohistochemistry for Runt-related transcription factor 2 (Runx2) expression. Results prove ZnO and MgO to be effective mitogenic factors and SiO2, ZnO, and SrO to be capable of inducing rapid cellular differentiation. MgO was found to have little effect on the modulation of osteoblastic differentiation, likely due to more aggressive inherent cellular regulation of Mg(2+). In addition to the results from the study, a signaling mechanism is proposed as to the action of the dopants for further consideration.

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.

Use of a calcium sulfate-calcium phosphate synthetic bone graft composite in the surgical management of primary bone tumors

Benign primary bone tumors are commonly treated with intralesional curettage with or without the use of surgical adjuvants. The reconstructive approach to the resulting contained bone defects is controversial, and clinical practice is varied. Synthetic bone substitutes may provide early mechanical support while minimizing the risks of disease transmission, nonunion, infection, and donor-site morbidity. Limited data exists regarding the use of calcium sulfate-calcium phosphate composite bone substitute for this purpose. The authors retrospectively reviewed the clinical outcomes of 24 patients with benign primary bone tumors who underwent intralesional curettage followed by reconstruction with a calcium sulfate-calcium phosphate composite bone substitute. Mean follow-up was 23 months. The most common diagnosis was giant cell tumor of bone. Six patients had upper-extremity tumors and 18 had lower-extremity tumors. Mean preoperative radiographic tumor volume was 41.0 cm(3). Mean volume of PRO-DENSE (Wright Medical Technology, Arlington, Tennessee) used in each patient was 15.6 cm(3). Mean time to full weight bearing for all patients was 7.3 weeks. Two patients sustained local tumor recurrences. No postoperative fractures occurred, and no complications occurred related to the use of the calcium sulfate-calcium phosphate composite. One case of deep infection occurred secondary to wound breakdown. The use of a calcium sulfate-calcium phosphate composite was associated with rapid biological integration and an early return to activities of daily living, with no composite-related complications. This technique is a viable option in the reconstruction of cavitary bone defects following intralesional curettage of primary benign bone tumors.

Role of platelet-rich plasma in combination with alloplastic bone substitute in regeneration of osseous defects

INTRODUCTION

Bone grafts are frequently used for the treatment of bone defects, but can cause postoperative complications, and sometimes a sufficient quantity of bone is not available. Hence, synthetic biomaterials have been used as an alternative to autogenous bone grafts. Recent clinical reports suggest that application of autologous blood plasma enriched with platelets can enhance the formation of new bone. There are very few in vitro or in vivo studies published on the efficiency of platelet-rich plasma (PRP). The objective of this study was to evaluate the alloplastic bone substitute for its osteogenic potential with or without PRP.

MATERIALS AND METHODS

Twenty-three patients with periapical bony defects were selected for this study. Clinical parameters such as pain visual analog scale (VAS), swelling, infection, graft migration, rejection, radiographical interpretations at regular interval and scintigraphic evaluation were done to evaluate osteogenic potential of alloplastic bone substitute with or without PRP.

RESULTS

The highest acceleration in bone formation was observed in groups where alloplastic bone substitute was used with PRP. There were no statistically significant differences between the two groups regarding other outcome variables throughout the postoperative period.

CONCLUSION

Addition of PRP significantly accelerates vascularization of the graft, improves soft tissue healing, reduces postoperative morbidity and enhances bone regeneration.

Chronology of the radiographic appearances of the calcium sulphate-calcium phosphate synthetic bone graft composite following resection of bone tumours--a preliminary study of the normal post-operative appearances

OBJECTIVE

To describe the normal chronological radiographic appearances of the calcium sulphate-calcium phosphate (CaSO(4)/CaPO(4)) synthetic graft material following bone tumour resection during the processes of graft resorption and new bone incorporation into the post-resection defect.

MATERIALS AND METHODS

Retrospective review of our oncology database identified patients who had undergone serial radiographic assessment after treatment with the CaSO(4)/CaPO(4) synthetic graft following bone tumour resection. Post-operative radiographs were assessed for (1) partial resorption of graft material with partial ingrowth of new bone at the graft site and (2) complete resorption of graft material with complete incorporation of new bone into the graft site. The pattern of resorption of graft material was also documented. Any radiographic evidence of complication was recorded. Radiographs were also divided into groups according to their interval from surgery to establish a pattern of time-related changes.

RESULTS

A total of 11 patients were identified from our database. Partial resorption of graft material/partial ingrowth of new bone was seen in nine patients, initially observed at a mean of 1.4 months from surgery. Resorption commenced peripherally with gradual inward progression in 100% (9 of 9) of cases. Complete resorption of graft/complete new bone incorporation at the graft site was seen in 89% (8 of 9) of cases followed up for more than 5 months after surgery. The other patient developed recurrence of tumour at 14 months, before complete incorporation was demonstrated. The mean time to complete incorporation of new bone was 5 months. Two patients have, to date, been followed up at 2 and 3 months respectively with a pattern of peripheral graft resorption observed so far in both cases. Ten of 13 (77%) radiographs performed 1-3 months after surgery demonstrated peripheral resorption of graft material with partial osseous ingrowth into the defect. Seven of eight (88%) radiographs performed 6-12 months after surgery demonstrated complete new bone incorporation at the graft site with graft material completely resorbed. Ten of 11 (91%) radiographs performed 1 year after surgery demonstrated complete new bone incorporation, the other examination demonstrating recurrence.

CONCLUSION

Our preliminary observations suggest a characteristic, time-related radiographic pattern during the processes of CaSO(4)/CaPO(4) bone graft resorption and complete new bone incorporation. This pattern can be directly related to processes that occur at the molecular level. Radiographic findings that are not in keeping with this may merit closer follow-up.

USE OF BIOCERAMICS IN FILLING BONE DEFECTS

Objective: To present the results from using biological ceramics for filling bone defects resulting from post-traumatic or orthopedic injuries. Methods: Thirty-six patients with bone defects caused by trauma or orthopedic injury were evaluated. Nineteen patients were male (52.8%) and 17 were female (47.2%). Their ages ranged from 19 to 84 years, with a mean of 45.7 years and median of 37 years. Only patients with defects that required at least five grams of biological ceramic were included. Eighteen cases were classified as orthopedic: bone defects were observed in 11 cases of total hip arthroplasty; one case of primary total hip arthroplasty, due to coxarthrosis; five cases of femoral or tibial open wedge osteotomy; and one case of tarsal arthrodesis. There were 18 cases of trauma-related defects; uninfected pseudarthrosis, eight cases; recent fractures of the tibial plateau with compression of the spongy bone, three cases; and exposed fractures treated with external fixators, seven cases. The surgical technique consisted of curetting and debriding the injury until bone suitable for grafting was found. Biological ceramic was then used to fill the defect and some kind of fixation was applied. Results: Among the 36 patients evaluated, it was seen that 35 (97.2%) presented integration of the biological ceramic, while one case of open fracture treated with external fixation had poor integration of the biological ceramic. Conclusion: Treatment of bone defects of orthopedic or post-traumatic etiology using a phosphocalcium ceramic composed of hydroxyapatite was shown to be a practical, effective and safe method.

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

BACKGROUND

Autologous cancellous bone is the most effective biological graft material. However, harvest of autologous bone is associated with significant morbidity. Since porous hydroxyapatite and beta-tricalcium phosphate are biodegradable materials and can be replaced by bone tissue, but it lacks osteogenic property. We conducted a study to assess their use as a scaffold and combine them with bone marrow aspirate for bone regeneration using its osteogenic property for posterolateral spinal fusion on one side and autologous bone graft on the other side and compare them radiologically in terms of graft incorporation and fusion.

MATERIALS AND METHODS

Thirty patients with unstable dorsal and lumbar spinal injuries who needed posterior stabilization and fusion were evaluated in this prospective study from October 2005 to March 2008. The posterior stabilization was done using pedicle screw and rod assembly, and fusion was done using hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute over one side of spine and autologous bone graft obtained from iliac crest over other side of spine. The patients were followed up to a minimum of 12 months. Serial radiographs were done at an interval of 3, 6, and 12 months and CT scan was done at one year follow-up. Graft incorporation and fusion were assessed at each follow-up. The study was subjected to statistical analysis using chi-square and kappa test to assess graft incorporation and fusion.

RESULTS

At the end of the study, radiological graft incorporation and fusion was evident in all the patients on the bone graft substitute side and in 29 patients on the autologous bone graft side of the spine (P > 0.05). One patient showed lucency and breakage of distal pedicle screw in autologous bone graft side. The interobserver agreement (kappa) had an average of 0.72 for graft incorporation, 0.75 for fusion on radiographs, and 0.88 for the CT scan findings.

CONCLUSION

Hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate seems to be a promising alternative to conventional autologous iliac bone graft for posterolateral spinal fusion.