Major bone defect treatment with an osteoconductive bone substitute

Self-assembling peptide hydrogel scaffold integrating stem cell-derived exosomes for infected bone defects

Infected bone defect (IBD) is a great challenge in orthopedics, which involves in bone loss and infection. Here, a self-assembling hydrogel scaffold (named AMP-RAD/EXO), integrating antimicrobial peptides(AMPs), RADA16 and BMSCs exosomes with an innovative strategy, is developed and applied in IBD treatment for sustained antimicrobial ability, accelerating osteoblasts proliferation and promoting bone regeneration. AMPs present an excellent ability to inhibit infection, RADA16 is a self-assembling peptide hydrogel for AMPs delivery, and BMSCs exosomes can promote the bone regeneration. The prepared AMP-RAD/EXO exhibited a polyporous 3D structure for imbibition of BMSCs exosomes and migration of osteoblasts. In vitro studies indicate AMP-RAD/EXO can inhibit the growth of Staphylococcus aureus, accelerate the proliferation and migration of BMSCs. More importantly, in vivo results also prove that AMP-RAD/EXO exhibit an excellent effect on IBD treatment. Thus, the prepared AMP-RAD/EXO provides a multifunctional scaffold concept for bone tissue engineering technology.

Combination of a Synthetic Bioceramic Associated with a Polydioxanone-Based Membrane as an Alternative to Autogenous Bone Grafting

The purpose of this study was to evaluate the repair process in rat calvaria filled with synthetic biphasic bioceramics (Plenum® Osshp-70:30, HA:βTCP) or autogenous bone, covered with a polydioxanone membrane (PDO). A total of 48 rats were divided into two groups (n = 24): particulate autogenous bone + Plenum® Guide (AUTOPT+PG) or Plenum® Osshp + Plenum® Guide (PO+PG). A defect was created in the calvaria, filled with the grafts, and covered with a PDO membrane, and euthanasia took place at 7, 30, and 60 days. Micro-CT showed no statistical difference between the groups, but there was an increase in bone volume (56.26%), the number of trabeculae (2.76 mm), and intersection surface (26.76 mm2) and a decrease in total porosity (43.79%) in the PO+PG group, as well as higher values for the daily mineral apposition rate (7.16 µm/day). Histometric analysis presented material replacement and increased bone formation at 30 days compared to 7 days in both groups. Immunostaining showed a similar pattern between the groups, with an increase in proteins related to bone remodeling and formation. In conclusion, Plenum® Osshp + Plenum® Guide showed similar and sometimes superior results when compared to autogenous bone, making it a competent option as a bone substitute.

Engineering innovations in medicine and biology: Revolutionizing patient care through mechanical solutions

The overlap between mechanical engineering and medicine is expanding more and more over the years. Engineers are now using their expertise to design and create functional biomaterials and are continually collaborating with physicians to improve patient health. In this review, we explore the state of scientific knowledge in the areas of biomaterials, biomechanics, nanomechanics, and computational fluid dynamics (CFD) in relation to the pharmaceutical and medical industry. Focusing on current research and breakthroughs, we provide an overview of how these fields are being used to create new technologies for medical treatments of human patients. Barriers and constraints in these fields, as well as ways to overcome them, are also described in this review. Finally, the potential for future advances in biomaterials to fundamentally change the current approach to medicine and biology is also discussed.

The impact of bone graft type used to fill bone defects in patients undergoing ACL reconstruction with bone-patellar tendon-bone (BPTB) autograft on kneeling, anterior knee pain and knee functional outcomes

PURPOSE

Multiple different materials are used for filling bone defects following bone-patellar tendon-bone (BPTB) graft ACL reconstruction surgery. The theoretical objective being to minimize kneeling pain, improve clinical outcomes and reduce anterior knee pain following surgery. The impact of these materials is assessed in this study.

METHODS

A prospective monocentric cohort study was conducted from January 2018 to March 2020. There were 128 skeletally mature athletic patients who underwent ACL reconstruction using the same arthroscopic-assisted BPTB technique, with a minimum follow-up of two years identified in our database. After obtaining approval from the local ethics committee, 102 patients were included in the study. Patients were divided into three groups based on type of bone substitute. The Bioactive glass 45S5 ceramic Glassbone™ (GB), collagen and hydroxyapatite bone void filler in sponge form Collapat® II (CP), and treated human bone graft Osteopure®(OP) bone substitutes were used according to availability. Clinical evaluation of patients at follow-up was performed using the WebSurvey software. A questionnaire completed in the 2nd post-operative year included three items: The ability to kneel, the presence of donor site pain, and the palpation of a defect. Another assessment tool included the IKDC subjective score and Lysholm score. These two tools were completed by patients preoperatively, and postoperatively on three occasions (6 months, 1 year, and 2 years).

RESULTS

A total of 102 patients were included in this study. In terms of Kneeling pain, the percentage of GB and CP patients' who kneel with ease were much higher than that of OP patients (77.78%, 76.5% vs 65.6%, respectively). All three groups experienced an important increase in IKDC and Lysholm scores. There was no difference in anterior knee pain between the groups.

CONCLUSION

The use of Glassbone® and Collapat II® bone substitutes reduced the incidence of kneeling pain compared to Osteopure®. There was no influence of the bone substitute type on the functional outcome of the knee or on the anterior knee pain at two years of follow.

Poly(β-amino ester) Dual-Drug-Loaded Hydrogels with Antibacterial and Osteogenic Properties for Bone Repair

In this study, we developed a poly(β-amino ester) (PBAE) hydrogel for the double release of vancomycin (VAN) and total flavonoids of Rhizoma Drynariae (TFRD). VAN was covalently bonded to PBAE polymer chains and was released to enhance the antimicrobial effect first. TFRD chitosan (CS) microspheres were physically dispersed in the scaffold, TFRD was released from the microspheres, and osteogenesis was induced subsequently. The scaffold had good porosity (90.12 ± 3.27%), and the cumulative release rate of the two drugs in PBS (pH 7.4) solution exceeded 80%. In vitro antimicrobial assays demonstrated the antibacterial properties of the scaffold against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Besides these, cell viability assays indicated that the scaffold had good biocompatibility. Moreover, alkaline phosphatase and matrix mineralization were expressed more than in the control group. Overall, cell experiments confirmed that the scaffolds have enhanced osteogenic differentiation capabilities. In conclusion, the dual-drug-loaded scaffold with antibacterial and bone regeneration effects is promising in the field of bone repair.

Nanoparticles as Next-Generation Tooth-Whitening Agents: Progress and Perspectives

Whitening agents, such as hydrogen peroxide and carbamide peroxide, are currently used in clinical applications for dental esthetic and dental care. However, the free radicals generated by whitening agents cause pathological damage; therefore, their safety issues remain controversial. Furthermore, whitening agents are known to be unstable and short-lived. Since 2001, nanoparticles (NPs) have been researched for use in tooth whitening. Importantly, nanoparticles not only function as abrasives but also release reactive oxygen species and help remineralization. This review outlines the historical development of several NPs based on their whitening effects and side effects. NPs can be categorized into metals or metal oxides, ceramic particles, graphene oxide, and piezoelectric particles. Moreover, the status quo and future prospects are discussed, and recent progress in the development of NPs and their applications in various fields requiring tooth whitening is examined. This review promotes the research and development of next-generation NPs for use in tooth whitening.

Bone Regeneration in Load-Bearing Segmental Defects, Guided by Biomorphic, Hierarchically Structured Apatitic Scaffold

The regeneration of load-bearing segmental bone defects remains a significant clinical problem in orthopedics, mainly due to the lack of scaffolds with composition and 3D porous structure effective in guiding and sustaining new bone formation and vascularization in large bone defects. In the present study, biomorphic calcium phosphate bone scaffolds (GreenBone™) featuring osteon-mimicking, hierarchically organized, 3D porous structure and lamellar nano-architecture were implanted in a critical cortical defect in sheep and compared with allograft. Two different types of scaffolds were tested: one made of ion-doped hydroxyapatite/β-tricalcium-phosphate (GB-1) and other made of undoped hydroxyapatite only (GB-2). X-ray diffraction patterns of GB-1 and GB-2 confirmed that both scaffolds were made of hydroxyapatite, with a minor amount of β-TCP in GB-1. The chemical composition analysis, obtained by ICP-OES spectrometer, highlighted the carbonation extent and the presence of small amounts of Mg and Sr as doping ions in GB-1. SEM micrographs showed the channel-like wide open porosity of the biomorphic scaffolds and the typical architecture of internal channel walls, characterized by a cell structure mimicking the natural parenchyma of the rattan wood used as a template for the scaffold fabrication. Both GB-1 and GB-2 scaffolds show very similar porosity extent and 3D organization, as also revealed by mercury intrusion porosimetry. Comparing the two scaffolds, GB-1 showed slightly higher fracture strength, as well as improved stability at the stress plateau. In comparison to allograft, at the follow-up time of 6 months, both GB-1 and GB-2 scaffolds showed higher new bone formation and quality of regenerated bone (trabecular thickness, number, and separation). In addition, higher osteoid surface (OS/BS), osteoid thickness (OS.Th), osteoblast surface (Ob.S/BS), vessels/microvessels numbers, as well as substantial osteoclast-mediated implant resorption were observed. The highest values in OS.Th and Ob. S/BS parameters were found in GB-1 scaffold. Finally, Bone Mineralization Index of new bone within scaffolds, as determined by micro-indentation, showed a significantly higher microhardness for GB-1 scaffold in comparison to GB-2. These findings suggested that the biomorphic calcium phosphate scaffolds were able to promote regeneration of load-bearing segmental bone defects in a clinically relevant scenario, which still represents one of the greatest challenges in orthopedics nowadays.

Programmed BMP-2 release from biphasic calcium phosphates for optimal bone regeneration

This study aimed to fabricate a multi-layered biphasic calcium phosphate (BCP) platform for programmed bone morphogenetic protein-2 (BMP-2) release, which means to block the initial burst release and promote releasing during the differentiation phase of osteogenic cells. And it is to confirm in vivo whether this platform has osteogenic inductivity even when extremely low doses of BMP-2 are loaded compared to the conventional soaking method. Our strategy consisted of preparing a multilayer coating on BCP to minimize the contact between BMP-2 and BCP and allow the loading of BMP-2. The multilayer, which is surface-modified on BCP, is composed of an organosilicate and a natural polymer-based layer-by-layer (LbL) film. We applied (3-Aminopropyl)triethoxysilane (APTES) as an organosilicate was used for amine-functionalized BCP and (collagen/heparin)₅ film was used to delay and sustain BMP-2 release. The coated multilayer not only reduced the initial burst release by more than 50% but also loaded more BMP-2. For in vivo experiment, histomorphometric analysis, it was observed that the BCP platform loaded with extremely low concentration BMP-2 (0.01 mg/ml) induced a significantly larger amount of new bones at 8 weeks compared to the conventional soaking method in the rabbit calvarium onlay graft model.

Modified Alginate-Based Hydrogel as a Carrier of the CB2 Agonist JWH133 for Bone Engineering

Alginate hydrogels have been widely used as excellent scaffold materials for implantation in biological systems because of their good biocompatibility. However, it is difficult to repair bone defects with these materials because of their poor mechanical properties. The aim of the present study was to fabricate a novel degradable alginate/palygorskite (PAL) composite hydrogel with good mechanical properties and investigate its potential for application in bone defect repair. The modified alginate-based hydrogel with increasing PAL content exhibited better mechanical properties than the original alginate hydrogel. In addition, the resulting composite hydrogel was thoroughly characterized by scanning electron microscopy (SEM). With increasing PAL content, the swelling ratio of the hydrogel increased in PBS (pH = 7.4). In vitro cytocompatibility was evaluated using bone marrow-derived mesenchymal stem cells (BMSCs) to confirm that the developed composite hydrogel was cytocompatible after 1, 3, and 7 days. All these results suggest that the developed composite hydrogel has great potential for bone tissue engineering applications. JWH133 is a selective agonist of cannabinoid receptor type 2 (CB2), which exerts dual anti-inflammatory and anti-osteoclastogenic effects. We co-cultured BMSCs with composite hydrogels loaded with JWH133, and analysis of proliferation and osteogenic differentiation indicated that the composite hydrogel loaded with JWH133 may enhance the osteogenic differentiation of rat BMSCs. Furthermore, we found that the composite hydrogel loaded with JWH133 inhibited osteoclast formation and the mRNA expression of osteoclast-specific markers. In summary, the developed composite hydrogel has a high drug-loading capacity, good biocompatibility, and strong potential as a drug carrier for treating osteoporosis by promoting osteoblast and inhibiting osteoclast formation and function.

Saving the lower limb with GlassBONE™ - Successful surgical revision of pseudarthrosis after infected open proximal tibia fracture type IIIC with bioactive glass grafting - A case report

Background

The management of bone defect due to trauma or surgical debridement is a current problem in orthopedic trauma surgery, often complicated by infection and bone nonunion. The graft is one of the most challenging variables in surgical treatment. Bioactive Glass (BAG) as a biocompatible and osteogenic product is a promising bone substitute showing good results in maxillo-facial-, spine surgery and treatment of osteomyelitis. Surprisingly, there is very little data on BAG use in trauma surgery.

Case presentation

A 51-year-old male patient, involved in a motorcycle accident, suffered an open proximal tibia fracture, type IIIC, of the left leg. Patient was admitted in January of 2013 to a general orthopedic department for surgical treatment. After several surgical revisions due to infection, vascular damage, and bone nonunion, the patient was successfully treated with Masquelet therapy followed by GlassBONE™ grafting (GlassBONE™ 45S5; Norarker). The patient demonstrated excellent results over the course of a two-year follow-up.

Conclusions

In our experience, GlassBONE™ 45S5 has proven to be an effective bone substitute even in difficult grafting conditions, including multiple surgical revisions for bone nonunion and infection. In our case, at the end of 2 years and 3 months of follow-up, the patient reported no pain, and had no signs of infection. Bone union and full weight bearing was achieved.

This case report is oriented by the CARE guidelines for clinical case reports; the patient gave consent for publication.

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GlassBONE™ 45S5 has proven to be an effective bone substitute even in difficult grafting conditions.

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Bone nonunion was successfully treated with Masquelet therapy followed by GlassBONE™ grafting.

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Bone loss due to fracture or surgical debridement is a current problem in orthopedic trauma surgery.

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Bone fractures are the most widespread trauma in humans.

Combination of a Bioceramic Scaffold and Simvastatin Nanoparticles as a Synthetic Alternative to Autologous Bone Grafting

The fragile nature of porous bioceramic substitutes cannot match the toughness of bone, which limits the use of these materials in clinical load-bearing applications. Statins can enhance bone healing, but it could show rhabdomyolysis/inflammatory response after overdosing. In this study, the drug-containing bone grafts were developed from poly(lactic acid-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles encapsulating simvastatin (SIM) (SIM-PP NPs) loaded within an appropriately mechanical bioceramic scaffold (BC). The combination bone graft provides dual functions of osteoconduction and osteoinduction. The mechanical properties of the bioceramic are enhanced mainly based on the admixture of a combustible reverse-negative thermoresponsive hydrogel (poly(N-isopropylacrylamide base). We showed that SIM-PP NPs can increase the activity of alkaline phosphatase and osteogenic differentiation of bone marrow stem cells. To verify the bone-healing efficacy of this drug-containing bone grafts, a nonunion radial endochondral ossification bone defect rabbit model (N = 3/group) and a nonunion calvarial intramembranous defect Sprague Dawley (SD) rat model (N = 5/group) were used. The results indicated that SIM-PP NPs combined with BC can improve the healing of nonunion bone defects of the radial bone and calvarial bone. Therefore, the BC containing SIM-PP NPs may be appropriate for clinical use as a synthetic alternative to autologous bone grafting that can overcome the problem of determining the clinical dosage of simvastatin drugs to promote bone healing.

Enhancement of peri-implant bone osteogenic activity induced by a peptidomimetic functionalization of titanium

Osteoblast cell adhesion to the extracellular matrix is established through two main pathways: one is mediated by the binding between integrin and a minimal adhesion sequence (RGD) on the extracellular protein, the other is based on the interactions between transmembrane proteoglycans and heparin-binding sequences found in many matrix proteins. The aim of this study is the evaluation in an in vivo endosseous implant model of the early osteogenic response of the peri-implant bone to a biomimetic titanium surface functionalized with the retro-inverso 2DHVP peptide, an analogue of Vitronectin heparin binding site. The experimental plan is based on a bilateral study design of Control and 2DHVP implants inserted respectively in the right and left femur distal metaphysis of adult male Wistar rats (n=16) weighing about 300grams and evaluated after 15days. Fluorochromic bone vital markers were given in a specific time frame, in order to monitor the dynamic of new bone deposition. The effect inducted by the peptidomimetic coating on the surrounding bone were qualitatively and quantitatively evaluated by means of static and dynamic histomorphometric analyses performed within three concentric and subsequent circular Regions of Interest (ROI) of equivalent thickness (220μm), ROI1 adjacent to the interface, ROI2, the middle, and ROI3 the farthest. The data indicated that these functionalized implants stimulated a higher bone apposition rate (p<0,01) and larger and rapid osteoblast activation in terms of mineralizing surface within ROI1 compared to the control (p<0,01). These higher osteoblast recruitment and activation leads to a greater bone-to-implant contact reached for DHVP samples (p<0,5). This represents an initial stimulus of the osteogenic activity that might results in a faster and better osteointegration process.

A Study of BMP-2-Loaded Bipotential Electrolytic Complex around a Biphasic Calcium Phosphate-Derived (BCP) Scaffold for Repair of Large Segmental Bone Defect

A bipotential polyelectrolyte complex with biphasic calcium phosphate (BCP) powder dispersion provides an excellent option for protein adsorption and cell attachment and can facilitate enhanced bone regeneration. Application of the bipotential polyelectrolyte complex embedded in a spongy scaffold for faster healing of large segmental bone defects (LSBD) can be a promising endeavor in tissue engineering application. In the present study, a hollow scaffold suitable for segmental long bone replacement was fabricated by the sponge replica method applying the microwave sintering process. The fabricated scaffold was coated with calcium alginate at the shell surface, and genipin-crosslinked chitosan with biphasic calcium phosphate (BCP) dispersion was loaded at the central hollow core. The chitosan core was subsequently loaded with BMP-2. The electrolytic complex was characterized using SEM, porosity measurement, FTIR spectroscopy and BMP-2 release for 30 days. In vitro studies such as MTT, live/dead, cell proliferation and cell differentiation were performed. The scaffold was implanted into a 12 mm critical size defect of a rabbit radius. The efficacy of this complex is evaluated through an in vivo study, one and two month post implantation. BV/TV ratio for BMP-2 loaded sample was (42±1.76) higher compared with hollow BCP scaffold (32±0.225).

Extracellular calcium-binding peptide-modified ceramics stimulate regeneration of calvarial bone defects

Secreted protein, acidic, cysteine-rich (SPARC)-related modular calcium binding 1 (SMOC1) has been implicated in the regulation of osteogenic differentiation of human bone marrow mesenchymal stem cells (BMSCs). In this study, we found that a peptide (16 amino acids in length), which is located in the extracellular calcium (EC) binding domain of SMOC1, stimulated osteogenic differentiation of human BMSCs in vitro and calvarial bone regeneration in vivo. Treatment of BMSCs with SMOC1-EC peptide significantly stimulated their mineralization in a dose-dependent manner without changing their rate of proliferation. The expression of osteogenic differentiation marker genes, including type 1 collagen and osteocalcin, also increased in a dose-dependent manner. To examine the effect of the SMOC1-EC peptide on bone formation in vivo, the peptide was covalently immobilized onto hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) particles. X-ray photoelectron spectroscopy analysis showed that the peptide was successfully immobilized onto the surface of HA/β-TCP. Implantation of the SMOC1-EC peptide-immobilized HA/β-TCP particles into mouse calvarial defects and subsequent analyses using microcomputed tomography and histology showed significant bone regeneration compared with that of calvarial defects implanted with unmodified HA/β-TCP particles. Collectively, our data suggest that a peptide derived from the EC domain of SMOC1 induces osteogenic differentiation of human BMSCs in vitro and efficiently enhances bone regeneration in vivo.

Design and characterization of calcium phosphate ceramic scaffolds for bone tissue engineering

OBJECTIVES

Our goal is to review design strategies for the fabrication of calcium phosphate ceramic scaffolds (CPS), in light of their transient role in bone tissue engineering and associated requirements for effective bone regeneration.

METHODS

We examine the various design options available to meet mechanical and biological requirements of CPS and later focus on the importance of proper characterization of CPS in terms of architecture, mechanical properties and time-sensitive properties such as biodegradability. Finally, relationships between in vitro versus in vivo testing are addressed, with an attempt to highlight reliable performance predictors.

RESULTS

A combinatory design strategy should be used with CPS, taking into consideration 3D architecture, adequate surface chemistry and topography, all of which are needed to promote bone formation. CPS represent the media of choice for delivery of osteogenic factors and anti-infectives. Non-osteoblast mediated mineral deposition can confound in vitro osteogenesis testing of CPS and therefore the expression of a variety of proteins or genes including collagen type I, bone sialoprotein and osteocalcin should be confirmed in addition to increased mineral content.

CONCLUSIONS

CPS are a superior scaffold material for bone regeneration because they actively promote osteogenesis. Biodegradability of CPS via calcium and phosphate release represents a unique asset. Structural control of CPS at the macro, micro and nanoscale and their combination with cells and polymeric materials is likely to lead to significant developments in bone tissue engineering.

Biological functionalization of dental implants with fibronectin: a scanning electron microscopic study

OBJECTIVES

Early stages of peri-implant bone formation play an essential role in the osseointegration and long-term success of dental implants. Biological implant surface coatings are an emerging technology to enhance the attachment of the implant to the surrounding bone and stimulate bone regeneration. The purpose of this study was to determine the effect of coating the implant surface with fibronectin on osseointegration.

MATERIAL AND METHODS

The experiment was conducted on a total of twelve New Zealand white mature male rabbits, weight between 2.5-4 kg. Twenty four pure titanium implants were used in this study. Each rabbits received two implants, one implant in each tibia; the implant in the right limb was coated with fibronectin (experimental group), whilst on the contralateral side the implants were placed without coating (control group). Six rabbits were sacrificed for Scanning Electron Microscopic evaluation after 4 and 8 week healing periods.

RESULTS

The results of the present study demonstrating the mean gap distance between the bone and implant was greater in the control group compared to fibronection group at both observation periods however, the difference between these two groups was not statistically significant.

CONCLUSION

Thus, it could be suggested that the biological functionalization of dental implants with fibronectin, may influence the integration or biocompatibility and bonding of the implant to the surrounding bone.

New bio-ceramization processes applied to vegetable hierarchical structures for bone regeneration: an experimental model in sheep

Bone loss is still a major problem in orthopedics. The purpose of this experimental study is to evaluate the safety and regenerative potential of a new scaffold based on a bio-ceramization process for bone regeneration in long diaphyseal defects in a sheep model. The scaffold was obtained by transformation of wood pieces into porous biomorphic silicon carbide (BioSiC®). The process enabled the maintenance of the original wood microstructure, thus exhibiting hierarchically organized porosity and high mechanical strength. To improve cell adhesion and osseointegration, the external surface of the hollow cylinder was made more bioactive by electrodeposition of a uniform layer of collagen fibers that were mineralized with biomimetic hydroxyapatite, whereas the internal part was filled with a bio-hybrid HA/collagen composite. The final scaffold was then implanted in the metatarsus of 15 crossbred (Merinos-Sarda) adult sheep, divided into 3 groups: scaffold alone, scaffold with platelet-rich plasma (PRP) augmentation, and scaffold with bone marrow stromal cells (BMSCs) added during implantation. Radiological analysis was performed at 4, 8, 12 weeks, and 4 months, when animals were sacrificed for the final radiological, histological, and histomorphometric evaluation. In all tested treatments, these analyses highlighted the presence of newly formed bone at the bone scaffolds' interface. Although a lack of substantial effect of PRP was demonstrated, the scaffold+BMSC augmentation showed the highest value of bone-to-implant contact and new bone growth inside the scaffold. The findings of this study suggest the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of wood-derived bone scaffolds, and document a suitable augmentation procedure in enhancing bone regeneration, particularly when combined with BMSCs.

One-step arthroscopic technique for the treatment of osteochondral lesions of the knee with bone-marrow-derived cells: three years results

Osteochondral lesions of the knee (OLK) are a common cause of knee pain and associated diseases. A new bone-marrow-derived mesenchymal stem cells technique has been developed for the treatment of OLK. 30 patients with OLK underwent arthroscopic one-step procedure. The bone marrow was harvested from the patients' posterior iliac crest and arthroscopically implanted with a scaffold into the lesion site. Clinical inspection and MRI were performed. Mean International Knee Documentation Committee (IKDC) score before surgery was 29.9 ± 13.2 and 85.4 ± 4.2 at 29 ± 4.1 months (p < 0.0005), while Knee injury and Osteoarthritis Outcome Score (KOOS) before surgery was 35.1 ± 11.9 and 87.3 ± 7.3 at 29 ± 4.1 months (p < 0.0005). Control MRI and bioptic samples showed an osteochondral regeneration of the lesion site. The one-step technique appears to be a good and reliable option for treatment of OLK at three years of follow-up. Level of evidence Case series, Level IV.

Can platelet-rich plasma (PRP) improve bone healing? A comparison between the theory and experimental outcomes

The increased concentration of platelets within platelet-rich plasma (PRP) provides a vehicle to deliver supra-physiologic concentrations of growth factors to an injury site, possibly accelerating or otherwise improving connective tissue regeneration. This potential benefit has led to the application of PRP in several applications; however, inconsistent results have limited widespread adoption in bone healing. This review provides a core understanding of the bone healing mechanisms, and corresponds this to the factors present in PRP. In addition, the current state of the art of PRP preparation, the key aspects that may influence its effectiveness, and treatment outcomes as they relate specifically to bone defect healing are presented. Although PRP does have a sound scientific basis, its use for bone healing appears only beneficial when used in combination with osteoconductive scaffolds; however, neither allograft nor autograft appear to be appropriate carriers. Aggressive processing techniques and very high concentrations of PRP may not improve healing outcomes. Moreover, many other variables exist in PRP preparation and use that influence its efficacy; the effect of these variables should be understood when considering PRP use. This review includes the essentials of what has been established, what is currently missing in the literature, and recommendations for future directions.

Physicochemical properties and cellular responses of strontium-doped gypsum biomaterials

This paper describes some physical, structural, and biological properties of gypsum bioceramics doped with various amounts of strontium ions (0.19-2.23 wt%) and compares these properties with those of a pure gypsum as control. Strontium-doped gypsum (gypsum:Sr) was obtained by mixing calcium sulfate hemihydrate powder and solutions of strontium nitrate followed by washing the specimens with distilled water to remove residual salts. Gypsum was the only phase found in the composition of both pure and gypsum:Sr, meanwhile a shift into lower diffraction angles was observed in the X-ray diffraction patterns of doped specimens. Microstructure of all gypsum specimens consisted of many rod-like small crystals entangled to each other with more elongation and higher thickness in the case of gypsum:Sr. The Sr-doped sample exhibited higher compressive strength and lower solubility than pure gypsum. A continuous release of strontium ions was observed from the gypsum:Sr during soaking it in simulated body fluid for 14 days. Compared to pure gypsum, the osteoblasts cultured on strontium-doped samples showed better proliferation rate and higher alkaline phosphatase activity, depending on Sr concentration. These observations can predict better in vivo behavior of strontium-doped gypsum compared to pure one.

What bone graft substitutes should we use in post-traumatic spinal fusion?

Surgical treatment of spinal fractures consists of postural reduction and segmental arthrodesis, together with an eventual performance of spinal canal decompression. Spinal arthrodesis consists of the combination of a hardware system for mechanical stabilisation together with a biological substance for enhancement of bone formation. To date, autologous graft is the only biological substance demonstrated to possess osteogenic properties. Cancellous bone graft has greater cellular activity than cortical graft, whereas cortical graft is stronger. Consequently, according to biological and biomechanical properties of autograft, spinal posterior arthrodesis is better enhanced by cancellous autograft, whereas anterior interbody tricortical bone is more suitable for anterior fusion. Allograft does not cause harvesting complications as autograft does, and also its amount is theoretically unlimited; nevertheless the rate of bone fusion facilitated by allograft is far from that enhanced by autograft given that allograft has no osteoprogenitor cells. There is little evidence on the efficacy of demineralised bone matrix for spinal fusion. Bone morphogenetic proteins (BMPs) are in use in spinal surgery, but their exact role with respect to type, dose, and carrier, together with their cost-effectiveness, need further clinical delineation. Calcium phosphate compounds appear to be good as carriers; however, they have no osteoinductive or osteogenic properties. Current clinical literature seem to indicate their usefulness for bony fusion in spinal surgery, when combined with bone marrow aspirate or used as an extender for autologous bone graft. Age, length of fusion, location, and concurrent diseases should be definitive for fusion outcome; papers on spinal arthrodesis should neatly stratify these variables. Unfortunately, since that is not the rule, conclusions drawn from current literature are very unreliable. Autograft remains the gold standard, and cancellous bone is advisable in posterolateral approaches, whereas tricortical iliac crest autograft appears appropriate for interbody support. In longer segments, its expansion with BMPs looks safe at least. Basic knowledge has been achieved from animal experiments, and clinical application of the findings to humans should be done very cautiously; in any case, both anterior and posterior arthrodesis must be protected with instrumentation used according to appropriate biomechanical principles. A combination of failure of the correct graft together with proper instrumentation will result in poorer outcome, even if the right graft is used.

Biphasic calcium phosphate bioceramics for orthopaedic reconstructions: clinical outcomes

BCP are considered the most promising biomaterials for bone reconstruction. This study aims at analyzing the outcomes of patients who received BCP as bone substitutes in orthopaedic surgeries. Sixty-six patients were categorized according to the etiology and morphology of the bone defects and received scores after clinical and radiographic evaluations. The final results corresponded to the combination of both parameters and varied from 5 (excellent result) to 2 or lower (poor result). Most of the patients who presented cavitary defects or bone losses due to prosthesis placement or revision, osteotomies, or arthrodesis showed good results, and some of them excellent results. However, patients with segmental defects equal or larger than 3 cm in length were classified as moderate results. This study established clinical parameters where the BCP alone can successfully support the osteogenic process and where the association with other tissue engineering strategies may be considered.

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.

Extracellular matrix-mimetic adhesive biomaterials for bone repair

Limited osseointegration of current orthopedic biomaterials contributes to the failure of implants such as arthroplasties, bone screws, and bone grafts, which present a large socioeconomic cost within the United States. These implant failures underscore the need for biomimetic approaches that modulate host cell-implant material responses to enhance implant osseointegration and bone formation. Bioinspired strategies have included functionalizing implants with extracellular matrix (ECM) proteins or ECM-derived peptides or protein fragments, which engage integrins and direct osteoblast adhesion and differentiation. This review discusses (1) bone ECM composition and key integrins implicated in osteogenic differentiation, (2) the use of implants functionalized with ECM-mimetic peptides/protein fragments, and (3) growth factor-derived peptides to promote the mechanical fixation of implants to bone and to enhance bone healing within large defects.

Repair of a segmental long bone defect in human by implantation of a novel multiple disc graft

Large segmental defects of the weight bearing long bones are very difficult to reconstruct. Current treatment options are afflicted with several limitations and disadvantages. We describe a novel approach to regenerate a segmental long bone defect in a patient using a multiple disc graft. Decellularized bovine trabecular bone discs were seeded with autologous bone marrow cells and cultured in a perfusion chamber for three weeks. Multiple cell-seeded discs were implanted to close a 72 mm defect of the distal tibia in a 58-year-old woman, and fixed by an intramedullary nail. Bone formation was assessed non-invasively by plain radiographs and 18F-labeled sodium fluoride-based co-registration of positron emission- and computed tomography (PET/CT). Bone was actively formed around the grafted defect as early as six weeks after surgery. Because the tibia was sufficiently stabilized, the patient was able to freely walk with full weight bearing 6 weeks after surgery. The uneventful two-year follow-up and the satisfaction of the patient demonstrated the success of the procedure. Therefore the use of multiple cell-seeded disc grafts can be considered as a treatment alternative for patients with segmental long bone defects.