Efficacy and safety of recombinant human bone morphogenetic protein-2/calcium phosphate matrix for closed tibial diaphyseal fracture: a double-blind, randomized, controlled phase-II/III trial

Three-dimensional printing in orthopaedic surgery: A review of current and future applications

Three-dimensional (3D) printing is a form of technology in which 3D physical models are created. It has been used in a variety of surgical specialities ranging from cranio-maxillo-facial to orthopaedic surgery and is currently an area of much interest within the medical profession. Within the field of orthopaedic surgery, 3D printing has several clinical applications including surgical education, surgical planning, manufacture of patient-specific prostheses/patient specific instruments and bone tissue engineering. This article reviews the current practices of 3D printing in orthopaedic surgery in both clinical and pre-clinical settings along with discussing its potential future applications.

Therapeutic effect of autologous bone grafting with adjuvant bone morphogenetic protein on long bone nonunion: a systematic review and meta-analysis

BACKGROUND

The recombinant human bone morphogenetic protein (rhBMP) is a common graft substitute for treating cases of long bone nonunion. However, the feasibility of combining an autologous bone graft (ABG) with rhBMPs remains uncertain. Thus, this systematic review and meta-analysis aimed to evaluate the synergistic effect of ABG and rhBMPs on the healing of long bone nonunion.

METHODS

A systematic literature search was performed on PubMed, Web of Science, Cochrane Library, and China National Knowledge Infrastructure. Two authors independently screened the studies, extracted data, and assessed the quality of the trials. Statistical analyses were performed using Stata 12.0.

RESULTS

Of the 202 citations, five studies involving a total of 394 cases met the eligibility criteria; thus, they were included in this study. The pooled data revealed no significant differences among the groups in terms of postoperative healing rate (risk ratio [RR] = 1.01, 95% confidence interval [CI] = 0.96-1.06, P = 0.744), healing time (standardised mean difference =  - 0.20, 95% CI = - 0.95-0.56, P = 0.610), and pain (RR = 1.44, 95% CI = 0.25-8.29, P = 0.681). The combination of ABG and rhBMPs resulted in good limb function (RR = 1.31, 95% CI = 1.04-1.66, P = 0.023).

CONCLUSIONS

The combination of ABG and rhBMPs did not result in the healing of long bone nonunion and pain reduction. Nevertheless, it conferred good limb function. Thus, the findings in this study are insufficient to support the use of rhBMPs as an adjuvant to ABG.

Effect of Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) with Hydroxyapatite Carrier in Induced Membrane Technique: A Retrospective Propensity Score-Matched Study

OBJECTIVES

To determine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) with hydroxyapatite (HA) carrier augmentation in managing critical-sized bone defect (CSBD) with induced membrane technique (IMT).

DESIGN

Retrospective comparative study.

SETTING

Academic level I trauma center.

PATIENTS/PARTICIPANTS

The study included 14 patients who underwent rhBMP-2 with HA carrier (rhBMP-2/HA) augmentation in IMT for managing CSBD (BMP group). Moreover, 14 patients who underwent IMT without rhBMP-2 augmentation were matched by propensity score analysis (non-BMP group).

INTERVENTION

IMT with or without rhBMP-2/HA augmentation.

MAIN OUTCOME MEASUREMENT

Changes in quality and quantity measurements of grafted bone to regenerated bone using serial computed tomography.

RESULTS

In the BMP and non-BMP groups, the changes in densities from grafted bone to regenerated bone were +379.63 Hounsfield unit and +248.55 Hounsfield unit (P = 0.034), changes in dense bone percentage were +37.52% and +23.31% (P = 0.027), corticalization rates under the plate were 79.70% and 39.30% (P = 0.007), changes in volume were -20.77% and -23.35% (P = 0.812), union rates were 85.71% and 78.57% (P = 0.622), numbers of patients requiring additional procedures were 4 and 3 (P = 0.663), and time to union were 316.3 and 585.45 days (P = 0.040), respectively.

CONCLUSIONS

RhBMP-2/HA augmentation increases the density of regenerated bone, enhances corticalization under the plate, and shortens the time to union while managing CSBD with IMT.

LEVEL OF EVIDENCE

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

Experimental study of a 3D printed permanent implantable porous Ta-coated bone plate for fracture fixation

Metal plates have always been the gold standard in the clinic for internal fracture fixation due to their high strength advantages. However, high elastic modulus can cause stress shielding and lead to bone embrittlement. This study used an electron beam melting method to prepare personalized porous Ti6Al4V (pTi) bone plates. Then, chemical vapor deposition (CVD) technology coats tantalum (Ta) metal on the pTi bone plates. The prepared porous Ta-coated bone plate has an elastic modulus similar to cortical bone, and no stress shielding occurred. In vitro experiments showed that compared with pTi plates, Ta coating significantly enhances the attachment and proliferation of cells on the surface of the scaffold. To better evaluate the function of the Ta-coated bone plate, animal experiments were conducted using a coat tibia fracture model. Our results showed that the Ta-coated bone plate could effectively fix the fracture. Both imaging and histological analysis showed that the Ta-coated bone plate had prominent indirect binding of callus formation. Histological results showed that new bone grew at the interface and formed good osseointegration with the host bone. Therefore, this study provides an alternative to bio-functional Ta-coated bone plates with improved osseointegration and osteogenic functions for orthopaedic applications.

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Porous Ta coated bone plate has a low elastic modulus, which can avoid stress shielding.

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Porous Ta coated bone plate has excellent biocompatibility and can be permanently implanted in the body.

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Porous Ta coated bone plate has excellent osseointegration properties and can promote fracture healing.

Bone Morphogenetic Protein-2 Rapidly Heals Two Distinct Critical Sized Segmental Diaphyseal Bone Defects in a Porcine Model

INTRODUCTION

Segmental bone defects (SBDs) are devastating injuries sustained by warfighters and are difficult to heal. Preclinical models that accurately simulate human conditions are necessary to investigate therapies to treat SBDs. We have developed two novel porcine SBD models that take advantage of similarities in bone healing and immunologic response to injury between pigs and humans. The purpose of this study was to investigate the efficacy of Bone Morphogenetic Protein-2 (BMP-2) to heal a critical sized defect (CSD) in two novel porcine SBD models.

MATERIALS AND METHODS

Two CSDs were performed in Yucatan Minipigs including a 25.0-mm SBD treated with intramedullary nailing (IMN) and a 40.0-mm SBD treated with dual plating (ORIF). In control animals, the defect was filled with a custom spacer and a bovine collagen sponge impregnated with saline (IMN25 Cont, n = 8; ORIF40 Cont, n = 4). In experimental animals, the SBD was filled with a custom spacer and a bovine collage sponge impregnated with human recombinant BMP-2 (IMN25 BMP, n = 8; ORIF40 BMP, n = 4). Healing was quantified using monthly modified Radiographic Union Score for Tibia Fractures (mRUST) scores, postmortem CT scanning, and torsion testing.

RESULTS

BMP-2 restored bone healing in all eight IMN25 BMP specimens and three of four ORIF40 BMP specimens. None of the IMN25 Cont or ORIF40 Cont specimens healed. mRUST scores at the time of sacrifice increased from 9.2 (±2.4) in IMN25 Cont to 15.1 (±1.0) in IMN25 BMP specimens (P < .0001). mRUST scores increased from 8.2 (±1.1) in ORIF40 Cont to 14.3 (±1.0) in ORIF40 BMP specimens (P < .01). CT scans confirmed all BMP-2 specimens had healed and none of the control specimens had healed in both IMN and ORIF groups. BMP-2 restored 114% and 93% of intact torsional stiffness in IMN25 BMP and ORIF40 BMP specimens.

CONCLUSIONS

We have developed two porcine CSD models, including fixation with IMN and with dual-plate fixation. Porcine models are particularly relevant for SBD research as the porcine immunologic response to injury closely mimics the human response. BMP-2 restored healing in both CSD models, and the effects were evident within the first month after injury. These findings support the use of both porcine CSD models to investigate new therapies to heal SBDs.

Molecular enhancement of fracture healing - Is there a role for Bone Morphogenetic Protein-2, parathyroid hormone, statins, or sclerostin-antibodies?

Enhancement of fracture healing has been a hot topic over the last two decades. This narrative review article is aimed to provide an update on current clinical use and evidence on four clinically available agents in the treatment of fracture healing: bone morphogenetic proteins-2 (BMP-2), parathyroid hormone, statins and sclerostin-antibodies. After first promising results from animal and clinical studies in the early 2000s, BMP-2 was studied mainly in open tibia shaft fractures treated with intramedullary nailing. There are conflicting results from different randomized clinical trials (RCTs) regarding fracture healing time and complications compared to BMP-2 free control treatment in open tibia fractures, as BMP-2 could not show significant differences in patients treated with reamed nails compared to BMP-2 free control treatment with reamed nailing only. Given that fact, its official use was limited in Europe to open tibia shaft fractures treated with unreamed tibial nailing by the European Medical Agency (EMA). Another more recent RCT failed to show equivalence of BMP- 2 together with allograft versus autograft for the treatment of tibia fractures with critical size defects. Recombinant human parathyroid hormone has proven anabolic effects on bone metabolism and is commonly used in treatment of severe osteoporosis. Different animal trials suggested an enhancement effect in fracture healing by PTH. In several clinical trials, PTH seems to have a stimulative effect for lower limb fractures. Statins, commonly used in treatment of dyslipidemia, could also enhance fracture healing in animal trials, especially when they were applied locally at the fracture site. For statins, there is only one RCT that failed to show significant effects for the oral administration of statins in undisplaced distal radius fractures. The role of sclerostin in fracture healing has more and more been understood. Application of sclerostin antibodies has been shown to be beneficial for fracture healing in animal trials. However, no RCTs on the effect of sclerostin antibodies on fracture healing have been performed yet. In conclusion, the "magic bullet" for molecular enhancement of fracture healing has not been identified yet, at least not with its optimal dosage and delivery method.

Growth Factors, Carrier Materials, and Bone Repair

This chapter provides an overview of the growth factors active in bone regeneration and healing. Both normal and impaired bone healing are discussed, with a focus on the spatiotemporal activity of the various growth factors known to be involved in the healing response. The review highlights the activities of most important growth factors impacting bone regeneration, with a particular emphasis on those being pursued for clinical translation or which have already been marketed as components of bone regenerative materials. Current approaches the use of bone grafts in clinical settings of bone repair (including bone grafts) are summarized, and carrier systems (scaffolds) for bone tissue engineering via localized growth factor delivery are reviewed. The chapter concludes with a consideration of how bone repair might be improved in the future.

Supramolecular self-assembling peptides to deliver bone morphogenetic proteins for skeletal regeneration

Recombinant human bone morphogenetic proteins (BMPs) have shown clinical success in promoting bone healing, but they are also associated with unwanted side effects. The development of improved BMP carriers that can retain BMP at the defect site and maximize its efficacy would decrease the therapeutic BMP dose and thus improve its safety profile. In this review, we discuss the advantages of using self-assembling peptides, a class of synthetic supramolecular biomaterials, to deliver recombinant BMPs. Peptide amphiphiles (PAs) are a broad class of self-assembling peptides, and the use of PAs for BMP delivery and bone regeneration has been explored extensively over the past decade. Like many self-assembling peptide systems, PAs can be designed to form nanofibrous supramolecular biomaterials in which molecules are held together by non-covalent bonds. Chemical and biological functionality can be added to PA nanofibers, through conjugation of chemical moieties or biological epitopes to PA molecules. For example, PA nanofibers have been designed to bind heparan sulfate, a natural polysaccharide that is known to bind BMPs and potentiate their signal. Alternatively, PA nanofibers have been designed to synthetically mimic the structure and function of heparan sulfate, or to directly bind BMP specifically. In small animal models, these bio-inspired PA materials have shown the capacity to promote bone regeneration using BMP at doses 10-100 times lower than established therapeutic doses. These promising results have motivated further evaluation of PAs in large animal models, where their safety and efficacy must be established before clinical translation. We conclude with a discussion on the possiblity of combining PAs with other materials used in orthopaedic surgery to maximize their utility for clinical translation.

An Assessment of Randomized Controlled Trial Quality in The Journal of Bone & Joint Surgery: Update from 2001 to 2013

BACKGROUND

The quality of reporting of randomized controlled trials (RCTs) published in The Journal of Bone & Joint Surgery (JBJS) from 1988 to 2000 was previously analyzed. The purpose of this current study was to analyze the quality of reporting of RCTs published in JBJS from 2001 to 2013 to identify trends over time and potential areas of improvement for future clinical trials.

METHODS

A manual search of the JBJS database identified RCTs published between January 2001 and December 2013. Quality assessments, using the Detsky quality-of-reporting index (Detsky score), a modified Cochrane risk-of-bias tool, and abstraction of relevant data identifying predictors of quality, were conducted.

RESULTS

A total of 5,780 publications were identified in JBJS from 2001 to 2013, with 285 RCTs (4.9%), representing an increase from the prior 13-year period. The overall mean transformed Detsky score (and standard error) increased significantly (p < 0.001) from 68.1% ± 1.67% to 76.24% ± 0.72%. The percentage of multicenter RCTs decreased from 67% to 31%. The percentage of positive trials also decreased from 80% to 50.5%, as did the mean sample size (212 to 166). Regression analysis indicated that trials with an epidemiologist as the first author and nonsurgical trials were significantly associated (p = 0.001) with a higher overall trial quality score. The categories of the lowest mean methodology scores were randomization and concealment, eligibility criteria, and reasons for patient exclusion, as identified with the Detsky score, and patient and assessor blinding, as identified with the risk-of-bias assessment.

CONCLUSIONS

The quantity and quality of published RCTs in JBJS have increased in the 2001 to 2013 time period compared with the previous time period. Although these improvements are encouraging, trends to smaller, single-center trials were also observed. To efficiently determine the efficacy of orthopaedic treatments and limit bias, high-quality randomized trials of appropriate sample size and rigorous design are needed.

Romosozumab in Skeletally Mature Adults with a Fresh Unilateral Tibial Diaphyseal Fracture: A Randomized Phase-2 Study

BACKGROUND

Romosozumab is an antibody that binds and inhibits sclerostin, thereby increasing bone formation and decreasing bone resorption. A double-blinded, randomized, phase-2, dose-finding trial was performed to evaluate the effect of romosozumab on the radiographic and clinical outcomes of surgical fixation of tibial diaphyseal fractures.

METHODS

Patients (18 to 82 years old) were randomized 3:1:1:1:1:1:1:1:1:1 to a placebo or 1 of 9 romosozumab treatment groups. Patients received subcutaneous injections of romosozumab or the placebo postoperatively on day 1 and weeks 2, 6, and 12. The primary outcome was the time to radiographic evidence of healing ("radiographic healing") analyzed after the week-24 assessments had been completed for all patients.

RESULTS

A total of 402 patients were randomized: 299 to the romosozumab group and 103 to the placebo group. The median time to radiographic healing (the primary outcome) ranged from 14.4 to 18.6 weeks in the romosozumab groups and was 16.4 weeks (95% confidence interval [CI]: 14.6 to 18.0 weeks) in the placebo group, which was not a significant difference. There was also no significant difference in the median time to clinical healing, no relationship between romosozumab dose/frequency and unplanned revision surgery, and no apparent treatment benefit in terms of physical function. The safety and tolerability profile of romosozumab was comparable with that of the placebo.

CONCLUSIONS

Romosozumab did not accelerate tibial fracture-healing in this patient population. Additional studies of patients at higher risk for delayed healing are needed to explore the potential of romosozumab to accelerate tibial fracture-healing.

LEVEL OF EVIDENCE

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

Preclinical safety and efficacy of 24R,25-dihydroxyvitamin D3 or lactosylceramide treatment to enhance fracture repair

Background/Objective

Cyp24a1-null mice deficient in 24,25(OH)₂D₃ display impaired callus formation during the endochondral phase of bone fracture repair. The 24,25(OH)₂D₃ metabolite acted by binding to the TLC domain containing 3B isoform 2 (TLCD3B2, previously named FAM57B2) effector protein, which then synthesizes lactosylceramide (LacCer). Treatment with 24,25(OH)₂D₃ or LacCer restored callus size and mechanical properties in Cyp24a1-null mice.

Methods

To assess the safety of these molecules and test their efficacy for bone healing in wild-type, non-genetically modified mice, we treated 12-week-old, osteotomized C57BL/6 female mice with each compound for up to 21 days post-osteotomy. Control cohorts were injected with vehicle.

Results

Neither compound was found to exhibit any nephro- nor hepato-toxicity. Calcemia remained stable throughout the experiment and was unaffected by either treatment. Supplementation with 24,25(OH)₂D₃ increased circulating levels of this metabolite about 8-fold, decreased 1,25(OH)₂D₃ levels, and significantly increased circulating 1,24,25(OH)₃D₃ levels, suggesting 1?-hydroxylation of 24,25(OH)₂D₃. TLCD3B2 was found to be expressed in fracture callus at the surface of unmineralized or pre-mineralized cartilage on day 10 and day 12 post-osteotomy and to progressively recede to become undetectable by day 18. Treatment with 24,25(OH)₂D₃ or LacCer reduced the number of TLCD3B2-positive cells. Both treatments also significantly increased stiffness and elastic modulus of the healing bone callus.

Conclusion

Exogenous administration of 24,25(OH)₂D₃ or LacCer improved the biomechanical properties of repaired bones in wild-type animals without affecting circulating calcium levels or other blood parameters, demonstrating preclinical safety and efficacy.

Translational potential

Our data suggest the use of 24R,25-dihydroxyvitamin D₃ or lactosylceramide for ameliorating fracture healing in clinical practice.

The biology and treatment of acute long-bones diaphyseal fractures: Overview of the current options for bone healing enhancement

Diaphyseal fractures represent a complex biological entity that could often end into impaired bone-healing, with delayed union and non-union occurring up to 10% of cases. The role of the modern orthopaedic surgeon is to optimize the fracture healing environment, recognize and eliminate possible interfering factors, and choose the best suited surgical fixation technique. The impaired reparative process after surgical intervention can be modulated with different surgical techniques, such as dynamization or exchange nailing after failed intramedullary nailing. Moreover, the mechanical stability of a nail can be improved through augmentation plating, bone grafting or external fixation techniques with satisfactory results. According to the "diamond concept", local therapies, such as osteoconductive scaffolds, bone growth factors, and osteogenic cells can be successfully applied in "polytherapy" for the enhancement of delayed union and non-union of long bones diaphyseal fractures. Moreover, systemic anti-osteoporosis anabolic drugs, such as teriparatide, have been proposed as off-label treatment for bone healing enhancement both in fresh complex shaft fractures and impaired unions, especially for fragility fractures. The article aims to review the biological and mechanical principles of failed reparative osteogenesis of diaphyseal fractures after surgical treatment. Moreover, the evidence about the modern non-surgical and pharmacological options for bone healing enhancement will discussed.

The Treatment of Acute Diaphyseal Long-bones Fractures with Orthobiologics and Pharmacological Interventions for Bone Healing Enhancement: A Systematic Review of Clinical Evidence

BACKGROUND

The healing of long bones diaphyseal fractures can be often impaired and eventually end into delayed union and non-union. A number of therapeutic strategies have been proposed in combination with surgical treatment in order to enhance the healing process, such as scaffolds, growth factors, cell therapies and systemic pharmacological treatments. Our aim was to investigate the current evidence of bone healing enhancement of acute long bone diaphyseal fractures.

METHODS

A systematic review was conducted by using Pubmed/MEDLINE; Embase and Ovid databases. The combination of the search terms "long-bones; diaphyseal fracture; bone healing; growth factors; cell therapies; scaffolds; graft; bone substitutes; orthobiologics; teriparatide".

RESULTS

The initial search resulted in 4156 articles of which 37 papers fulfilled the inclusion criteria and were the subject of this review. The studies included 1350 patients (837 males and 513 females) with a mean age of 65.3 years old.

CONCLUSIONS

General lack of high-quality studies exists on the use of adjuvant strategies for bone healing enhancement in acute shaft fractures. Strong evidence supports the use of bone grafts, while only moderate evidence demineralized bone matrix and synthetic ceramics. Conflicting results partially supported the use of growth factors and cell therapies in acute fractures. Teriparatide showed promising results, particularly for atypical femoral fractures and periprosthetic femoral fractures.

Nonunion - consensus from the 4th annual meeting of the Danish Orthopaedic Trauma Society

Nonunions are a relevant economic burden affecting about 1.9% of all fractures. Rather than specifying a certain time frame, a nonunion is better defined as a fracture that will not heal without further intervention.

Successful fracture healing depends on local biology, biomechanics and a variety of systemic factors. All components can principally be decisive and determine the classification of atrophic, oligotrophic or hypertrophic nonunions. Treatment prioritizes mechanics before biology.

The degree of motion between fracture parts is the key for healing and is described by strain theory. If the change of length at a given load is > 10%, fibrous tissue and not bone is formed. Therefore, simple fractures require absolute and complex fractures relative stability.

The main characteristics of a nonunion are pain while weight bearing, and persistent fracture lines on X-ray.

Treatment concepts such as ‘mechanobiology’ or the ‘diamond concept’ determine the applied osteosynthesis considering soft tissue, local biology and stability. Fine wire circular external fixation is considered the only form of true biologic fixation due to its ability to eliminate parasitic motions while maintaining load-dependent axial stiffness. Nailing provides intramedullary stability and biology via reaming. Plates are successful when complex fractures turn into simple nonunions demanding absolute stability. Despite available alternatives, autograft is the gold standard for providing osteoinductive and osteoconductive stimuli.

The infected nonunion remains a challenge. Bacteria, especially staphylococcus species, have developed mechanisms to survive such as biofilm formation, inactive forms and internalization. Therefore, radical debridement and specific antibiotics are necessary prior to reconstruction.

Cite this article: EFORT Open Rev 2020;5:46-57. DOI: 10.1302/2058-5241.5.190037

Is NO the Answer? The Nitric Oxide Pathway Can Support Bone Morphogenetic Protein 2 Mediated Signaling

The growth factor bone morphogenetic protein 2 (BMP2) plays an important role in bone development and repair. Despite the positive effects of BMP2 in fracture healing, its use is associated with negative side effects and poor cost effectiveness, partly due to the large amounts of BMP2 applied. Therefore, reduction of BMP2 amounts while maintaining efficacy is of clinical importance. As nitric oxide (NO) signaling plays a role in bone fracture healing and an association with the BMP2 pathway has been indicated, this study aimed to investigate the relationship of BMP2 and NO pathways and whether NO can enhance BMP2-induced signaling and osteogenic abilities in vitro. To achieve this, the stable BMP reporter cell line C2C12BRELuc was used to quantify BMP signaling, and alkaline phosphatase (ALP) activity and gene expression were used to quantify osteogenic potency. C2C12BRELuc cells were treated with recombinant BMP2 in combination with NO donors and substrate (Deta NONOate, SNAP & L-Arginine), NOS inhibitor (LNAME), soluble guanylyl cyclase (sGC) inhibitor (LY83583) and activator (YC-1), BMP type-I receptor inhibitor (LDN-193189), or protein kinase A (PKA) inhibitor (H89). It was found that the NOS enzyme, direct NO application, and sGC enhanced BMP2 signaling and improved BMP2 induced osteogenic activity. The application of a PKA inhibitor demonstrated that BMP2 signaling is enhanced by the NO pathway via PKA, underlining the capability of BMP2 in activating the NO pathway. Collectively, this study proves the ability of the NO pathway to enhance BMP2 signaling.

Advanced biomaterials for repairing and reconstruction of mandibular defects

Mandibles are the largest and strongest bone in the human face and are often severely compromised by mandibular defects, compromising the quality of life of patients. Mandibular defects may result from trauma, inflammatory disease and benign or malignant tumours. The reconstruction of mandibular defect has been a research hotspot in oral and maxillofacial surgery. Although the principles and techniques of mandibular reconstruction have made great progress in recent years, the development of biomedical materials is still facing technical bottleneck, and new materials directly affect technological breakthroughs in this field. This paper reviews the current status of research and application of various biomaterials in mandibular defects and systematically elaborates different allogeneic biomaterial-based approaches. It is expected that various biomaterials, in combination with new technologies such as digital navigation and 3D printing, could be tuned to build new types of scaffold with more precise structure and components, addressing needs of surgery and post-reconstruction. With the illustration and systematization of different solutions, aims to inspire the development of reconstruction biomaterials.

Optimising proliferation and migration of mesenchymal stem cells using platelet products: A rational approach to bone regeneration

This study investigates how mesenchymal stem cell's (MSCs) proliferation and migration abilities are influenced by various platelet products (PP). Donor-matched, clinical-, and control laboratory-standard PPs were generated and assessed based on their platelet and leukocyte concentrations. Bone marrow derived MSCs were exposed to these PP to quantify their effect on in vitro MSC proliferation and migration. An adapted colony forming unit fibroblast (CFU-F) assay was carried out on bone marrow aspirate using clinical-standard PP-loaded electrospun poly(ϵ-caprolactone) (PCL) membrane to mimic future clinical applications to contain bone defects. Clinical-standard PP had lower platelet (2.5 fold, p < 0.0001) and higher leukocyte (14.1 fold, p < 0.0001) concentrations compared to laboratory-standard PP. It induced suboptimal MSC proliferation compared to laboratory-standard PP and fetal calf serum (FCS). All PP induced significantly more MSC migration than FCS up to 24 h. The removal of leukocytes from PP had no effect on MSC proliferation or migration. The PP-loaded membranes successfully supported MSC colony formation. This study indicates that platelet concentrations in PP impact MSC proliferation more than the presence of leukocytes, whilst MSC migration in response to PP is not influenced by platelet or leukocyte numbers. Clinical-standard PP could be applied alongside manufactured membranes in the future treatment of bone reconstruction. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1329-1338, 2019.

Measuring outcomes following tibial fracture

AIM

The aim of this study was to determine how outcome is measured following adult tibial fracture in the modern era of functional outcome measurement and patient reported outcomes.

METHODS

A systematic review of publications since 2009 was performed, looking specifically at acute, adult tibial shaft fractures. Ovid Medline, Embase, PubMed and PsycINFO databases were searched for relevant titles which were then screened by two authors with adjudication where necessary by a third. Relevant articles were reviewed in full and data was extracted concerning the study participants, study design and any measures that were used to quantify the results following fracture. The results were collated and patient reported outcome measures were assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) standards.

RESULTS

A total of 943 titles and articles were reviewed, with 117 included for full analysis. A wide range of clinical and radiological "outcomes" were described, along with named clinician- and patient-reported outcome measures. There was considerable heterogeneity and lack of detail in the description of the simplest outcomes, such as union, infection or reoperation. Reported clinician and patient reported outcome measures are variably used. None of the identified patient reported outcome measures have been validated for use following tibial fracture.

CONCLUSION

We recommend definition of a core outcome set for use following tibial fracture. This will standardise outcome reporting following these injuries. Furthermore, there is need for a validated patient reported outcome measure to better assess patient important outcomes in this patient group.

Involvement of Bone in Systemic Endocrine Regulation

The skeleton shows an unconventional role in the physiology and pathophysiology of the human organism, not only as the target tissue for a number of systemic hormones, but also as endocrine tissue modulating some skeletal and extraskeletal systems. From this point of view, the principal cells in the skeleton are osteocytes. These cells primarily work as mechano-sensors and modulate bone remodeling. Mechanically unloaded osteocytes synthetize sclerostin, the strong inhibitor of bone formation and RANKL, the strong activator of bone resorption. Osteocytes also express hormonally active vitamin D (1,25(OH)2D) and phosphatonins, such as FGF23. Both 1,25(OH)2D and FGF23 have been identified as powerful regulators of the phosphate metabolism, including in chronic kidney disease. Further endocrine cells of the skeleton involved in bone remodeling are osteoblasts. While FGF23 targets the kidney and parathyroid glands to control metabolism of vitamin D and phosphates, osteoblasts express osteocalcin, which through GPRC6A receptors modulates beta cells of the pancreatic islets, muscle, adipose tissue, brain and testes. This article reviews some knowledge concerning the interaction between the bone hormonal network and phosphate or energy homeostasis and/or male reproduction.

Clinical Applications of Bone Tissue Engineering in Orthopedic Trauma

Purpose of Review

Orthopaedic trauma is a major cause of morbidity and mortality worldwide. Although many fractures tend to heal if treated appropriately either by nonoperative or operative methods, delayed or failed healing, as well as infections, can lead to devastating complications. Tissue engineering is an exciting, emerging field with much scientific and clinical relevance in potentially overcoming the current limitations in the treatment of orthopaedic injuries.

Recent Findings

While direct translation of bone tissue engineering technologies to clinical use remains challenging, considerable research has been done in studying how cells, scaffolds, and signals may be used to enhance acute fracture healing and to address the problematic scenarios of nonunion and critical-sized bone defects. Taken together, the research findings suggest that tissue engineering may be considered to stimulate angiogenesis and osteogenesis, to modulate the immune response to fractures, to improve the biocompatibility of implants, to prevent or combat infection, and to fill large gaps created by traumatic bone loss. The abundance of preclinical data supports the high potential of bone tissue engineering for clinical application, although a number of barriers to translation must first be overcome.

Summary

This review focuses on the current and potential applications of bone tissue engineering approaches in orthopaedic trauma with specific attention paid to acute fracture healing, nonunion, and critical-sized bone defects.

Molecular pathogenesis of fracture nonunion

Fracture nonunion, a serious bone fracture complication, remains a challenge in clinical practice. Although the molecular pathogenesis of nonunion remains unclear, a better understanding may provide better approaches for its prevention, diagnosis and treatment at the molecular level. This review tries to summarise the progress made in studies of the pathogenesis of fracture nonunion. We discuss the evidence supporting the concept that the development of nonunion is related to genetic factors. The importance of several cytokines that regulate fracture healing in the pathogenesis of nonunion, such as tumour necrosis factor-α, interleukin-6, bone morphogenetic proteins, insulin-like growth factors, matrix metalloproteinases and vascular endothelial growth factor, has been proven in vitro, in animals and in humans. Nitric oxide and the Wnt signalling pathway also play important roles in the development of nonunion. We present potential strategies for the prevention, diagnosis and treatment of nonunion, and the interaction between genetic alteration and abnormal cytokine expression warrants further investigation.

The translational potential of this article

A better understanding of nonunion molecular pathogenesis may provide better approaches for its prevention, diagnosis and treatment in clinical practice.

Can Clinical and Surgical Parameters Be Combined to Predict How Long It Will Take a Tibia Fracture to Heal? A Prospective Multicentre Observational Study: The FRACTING Study

BACKGROUND

Healing of tibia fractures occurs over a wide time range of months, with a number of risk factors contributing to prolonged healing. In this prospective, multicentre, observational study, we investigated the capability of FRACTING (tibia FRACTure prediction healING days) score, calculated soon after tibia fracture treatment, to predict healing time.

METHODS

The study included 363 patients. Information on patient health, fracture morphology, and surgical treatment adopted were combined to calculate the FRACTING score. Fractures were considered healed when the patient was able to fully weight-bear without pain.

RESULTS

319 fractures (88%) healed within 12 months from treatment. Forty-four fractures healed after 12 months or underwent a second surgery. FRACTING score positively correlated with days to healing: r = 0.63 (p < 0.0001). Average score value was 7.3 ± 2.5; ROC analysis showed strong reliability of the score in separating patients healing before versus after 6 months: AUC = 0.823.

CONCLUSIONS

This study shows that the FRACTING score can be employed both to predict months needed for fracture healing and to identify immediately after treatment patients at risk of prolonged healing. In patients with high score values, new pharmacological and nonpharmacological treatments to enhance osteogenesis could be tested selectively, which may finally result in reduced disability time and health cost savings.

ICS classification system of infected osteosynthesis: Long-term results

The best treatment strategy for infected osteosyntheses is still debated. While hardware removal or eventually early device exchange may be necessary in most of the cases, temporary hardware retention until fracture healing can be a valid alternative option in others. Aim of the present study is to report the long-term results of 215 patients with infected osteosyntheses, treated according to the ICS (Infection, Callus, Stability) classification in two Italian hospitals. Patients classified as ICS Type 1 (N = 83) feature callus progression and hardware stability, in spite of the presence of infection; these patients were treated with suppressive antibiotic therapy coupled with local debridement in 18.1% of the cases, and no hardware removal until bone healing. Type 2 patients (N = 75) are characterized by the presence of infection and hardware stability, but no callus progression; these patients were treated as Type 1 patients, but with additional callus stimulation therapies. Type 3 patients (N = 57), showing infection, no callus progression and loss of hardware stability, underwent removal and exchange of the fixation device. Considering only the initial treatment, performed according to the ICS classification, at a minimum 5 years follow up, 89.3% achieved bone healing and 93.5% did not show infection recurrence. The ICS classification appears as a useful and reliable tool to help standardizing the decision-making process in treating infected osteosynthesis with the most conservative approach.

Abundant heterotopic bone formation following use of rhBMP-2 in the treatment of acetabular bone defects during revision hip arthroplasty

Revision hip arthroplasty in the setting of periacetabular bone loss presents a significant challenge, as options for restoring bone loss are limited. Recombinant human bone morphogenetic protein-2 may offer a solution by promoting bone growth to restore bone stock before implant reimplantation. Here we present a case of a patient with a periprosthetic acetabulum fracture, resulting in pelvic discontinuity as the result of significant periacetabular bone loss. Using a staged approach, periacetabular bone stock was nearly entirely reconstituted using recombinant BMPs and allograft, which resulted in stable fixation, but with abundant heterotopic bone formation. Recombinant BMP-2 offers a useful tool for restoring bone stock in complex hip arthroplasty revision cases with periacetabular bone loss; however, caution must be used as overabundant bone growth as heterotopic ossification may result.

Oleanolic Acid Enhances Mesenchymal Stromal Cell Osteogenic Potential by Inhibition of Notch Signaling

Oleanolic acid (OA), a pentacyclic triterpenoid, has been shown to modulate multiple signaling pathways in a variety of cell linages. But the mechanisms underlying OA-mediated mesenchymal stromal cell (MSC) osteogenic differentiation are not known. In this study, we examined effects of OA on cell viability, osteogenic differentiation in MSCs, and the involvement of Notch and BMP signaling. OA induced bone marrow derived MSC differentiation towards osteoprogenitor cells and inhibited Notch signaling in a dose dependent manner. Constitutive activation of Notch signaling fully blocked OA induced MSC osteogenic differentiation. The expression level of early osteogenic marker genes, ALP, Runx2, and type I collagen, which play a critical role in MSC to osteoblast transition and servers as a downstream target of BMP signaling, was significantly induced by OA. Furthermore, BMP2 mediated MSC osteogenic differentiation was significantly enhance by OA treatment, indicating a synergistic effect between BMP2 and OA. Our results suggest that OA is a promising bioactive agent for bone tissue regeneration, and inhibition of Notch signaling is required for its osteogenic effects on MSCs.

Bone Morphogenetic Protein: Is There Still a Role in Orthopedic Trauma in 2017?

Approximately 10 years ago bone morphogenic protein (BMP) was seen as a miraculous adjuvant to assist with bone growth. However, in the face of an increasing number of complications and a lack of understanding its long-term effects, it is unclear what role BMP has in the current treatment of orthopedic trauma patients. This article reviews the current recommendations, trends, and associated complications of BMP use in fracture care.

Clinical application of bone morphogenetic proteins for bone healing: a systematic review

PURPOSE

This paper documents the existing evidence on bone morphogenetic proteins (BMPs) use for the treatment of bone fractures, non-union, and osteonecrosis, through a review of the clinical literature, underlying potential and limitations in terms of cost effectiveness and risk of complications.

METHODS

A systematic review was performed on the PubMed database using the following string: (bone morphogenetic proteins OR BMPs) and (bone repair OR bone regeneration) including papers from 2000 to 2016. The search focused on clinical trials dealing with BMPs application to favor bone regeneration in bone fractures, non-union, and osteonecrosis, in English language, with level of evidence I, II, III, and IV. Relevant data (type of study, number of patients, BMPs delivery material, dose, site, follow-up, outcome, and adverse events) were extracted and analyzed.

RESULTS

Forty-four articles met the inclusion criteria: 10 randomized controlled trials (RCTs), 7 comparative studies, 18 case series, and 9 case reports. rhBMP-2 was documented mainly for the treatment of fractures, and rhBMP-7 mainly for non-unions and osteonecrosis. Mixed results were found among RCTs and comparative papers: 11 reported positive results for BMPs augmentation, 3 obtained no significant effects, and 2 showed negative results. The only study comparing the two BMPs showed a better outcome with rhBMP-2 for non-union treatment.

CONCLUSION

Clinical evidence on BMPs use for the treatment of fractures, non-union, and osteonecrosis is still controversial, with the few available reports being mainly of low quality. While positive findings have been described in many studies, mixed results are still present in the literature in terms of efficacy and adverse events. The difficulties in drawing clear conclusions are also due to the studies heterogeneity, mainly in terms of different BMPs applied, with different concomitant treatments for each bone pathology. Therefore, further research with well-designed studies is needed in order to understand the real potential of this biological approach to favour bone healing.

Fracture healing physiology and the quest for therapies for delayed healing and nonunion

Delayed healing and nonunion of fractures represent enormous burdens to patients and healthcare systems. There are currently no approved pharmacological agents for the treatment of established nonunions, or for the acceleration of fracture healing, and no pharmacological agents are approved for promoting the healing of closed fractures. Yet several pharmacologic agents have the potential to enhance some aspects of fracture healing. In preclinical studies, various agents working across a broad spectrum of molecular pathways can produce larger, denser and stronger fracture calluses. However, untreated control animals in most of these studies also demonstrate robust structural and biomechanical healing, leaving unclear how these interventions might alter the healing of recalcitrant fractures in humans. This review describes the physiology of fracture healing, with a focus on aspects of natural repair that may be pharmacologically augmented to prevent or treat delayed or nonunion fractures (collectively referred to as DNFs). The agents covered in this review include recombinant BMPs, PTH/PTHrP receptor agonists, activators of Wnt/β-catenin signaling, and recombinant FGF-2. Agents from these therapeutic classes have undergone extensive preclinical testing and progressed to clinical fracture healing trials. Each can promote bone formation, which is important for the stability of bridged calluses, and some but not all can also promote cartilage formation, which may be critical for the initial bridging and subsequent stabilization of fractures. Appropriately timed stimulation of chondrogenesis and osteogenesis in the fracture callus may be a more effective approach for preventing or treating DNFs compared with stimulation of osteogenesis alone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:213-223, 2017.

Bone healing in 2016

Delayed fracture healing and nonunion occurs in up to 5-10% of all fractures, and can present a challenging clinical scenario for the treating physician. Methods for the enhancement of skeletal repair may benefit patients that are at risk of, or have experienced, delayed healing or nonunion. These methods can be categorized into either physical stimulation therapies or biological therapies. Physical stimulation therapies include electrical stimulation, low-intensity pulsed ultrasonography, or extracorporeal shock wave therapy. Biological therapies can be further classified into local or systemic therapy based on the method of delivery. Local methods include autologous bone marrow, autologous bone graft, fibroblast growth factor-2, platelet-rich plasma, platelet-derived growth factor, and bone morphogenetic proteins. Systemic therapies include parathyroid hormone and bisphosphonates. This article reviews the current applications and supporting evidence for the use of these therapies in the enhancement of fracture healing.

Osteogenic gene array of osteoblasts cultured on a novel osteoinductive biphasic calcium phosphate bone grafting material

OBJECTIVES

Recently, novel biphasic calcium phosphate (BCP) scaffolds have emerged as a new class of bone grafts with osteoinductive potential demonstrating the ability to form ectopic bone in extra-skeletal sites. The aim of the present study was to perform an osteogenic gene array to target possible genes responsible for eliciting the changes in cell expression responsible for inducing osteoblast differentiation.

MATERIALS AND METHODS

Human MG63 osteoblast-like cells were seeded for 24 h on tissue culture plastic or osteoinductive BCP particles and analyzed for upregulated genes using an osteogenesis super-array. Osteoblast-related genes including those transcribed during bone mineralization, bone metabolism, cell growth and differentiation, as well as gene products representing extracellular matrix molecules, transcription factors, and cell adhesion molecules were investigated.

RESULTS

An upregulation of genes transcribing biglycan (1.7-fold), bone morphogenetic proteins 1, 2, 4, 6, and 7 (1.5-2.1-fold), various collagen isoforms including 1a1, 1a2, 2a1, and 5a1 (1.73-2.72-fold), colony stimulating factor 2 (2.59-fold), fibroblast growth factor receptor 2 (1.79-fold), fibronectin (2.56-fold), integrin alpha 1, 2, and 3 (1.82-2.24-fold), SOX9 (2.75-fold), transforming growth factor beta receptor 2 (1.72-fold), vitamin D (1.89-fold), and vascular endothelial growth factor A and B (2.00, 1.75-fold) were all significantly (p < 0.05) increased on BCP particles when compared to control tissue culture plastic.

CONCLUSION

In summary, a number of activated genes were involved in bone formation following osteoblast attachment to BCP particles. The involvement of key chondrogenic genes hints that bone grafts capable of spontaneously inducing ectopic bone formation may implicate endochondral ossification. Further investigations in the triggered pathways involved in the process of ectopic bone formation are necessary to understand the key inductive properties of these novel osteoinductive BCP particles.

CLINICAL RELEVANCE

Novel osteoinductive BCP particles demonstrate a wide range of significant increases over several key molecules implicated in osteogenesis that may be implicated in their ability to form ectopic bone formation.

Extracellular signaling molecules to promote fracture healing and bone regeneration

To date, the delivery of signaling molecules for bone regeneration has focused primarily on factors that directly affect the bone formation pathways (osteoinduction) or that serve to increase the number of bone forming progenitor cells. The first commercialized growth factors approved for bone regeneration, Bone Morphogenetic Protein 2 and 7 (BMP2 and BMP7), are direct inducers of osteoblast differentiation. As well, newer generations of potential therapeutics that target the Wnt signaling pathway are also direct osteoinducers. On the other hand, some signaling molecules may play a role as mitogens and serve to increase the number of bone producing cells or may increase vascularization. This is true for factors such as Platelet Derived Growth Factor (PDGF) or Fibroblast Growth Factor (FGF). Vascular Endothelial Growth Factor (VEGF) likely has a special role. Not only does it induce new blood vessel formation, it also has direct effects on osteoblasts through endothelial cell-based BMP production. In addition to these pathways that classically have targeted bone production, there are also opportunities to target other aspects of the bone healing process such as inflammation, vascularization, and cell ingress to the fracture site. Bone regeneration is highly complex with defined, yet overlapping stages of healing. We will review established and novel extracellular signaling factors associated with various stages of fracture healing that could be targeted to promote enhanced bone regeneration. Importantly, multiple potential cell and tissues could be targeted to enhance healing in addition to focusing solely on osteoinductive therapeutics.

Fracture non-union epidemiology and treatment

Fracture non-union remains a clinical problem despite advances in the understanding of basic science and technology. Each fracture has a unique personality as does the patient suffering the injury. Thus, each case must be treated on an individual basis. This article defines the problem of fracture non-union and reports recent epidemiological studies. We discuss relevant risk factors and methods for assessing patients who have a tendency toward fracture non-union. There are many treatment options for patients with non-union, where a number of these modalities are still under review. We discuss current evidence with the use of bone morphogenic protein, platelet-rich plasma and low-intensity pulsed ultrasound to augment the treatment of fracture non-union.

Fracture healing: mechanisms and interventions

Fractures are the most common large-organ, traumatic injuries to humans. The repair of bone fractures is a postnatal regenerative process that recapitulates many of the ontological events of embryonic skeletal development. Although fracture repair usually restores the damaged skeletal organ to its pre-injury cellular composition, structure and biomechanical function, about 10% of fractures will not heal normally. This article reviews the developmental progression of fracture healing at the tissue, cellular and molecular levels. Innate and adaptive immune processes are discussed as a component of the injury response, as are environmental factors, such as the extent of injury to the bone and surrounding tissue, fixation and the contribution of vascular tissues. We also present strategies for fracture treatment that have been tested in animal models and in clinical trials or case series. The biophysical and biological basis of the molecular actions of various therapeutic approaches, including recombinant human bone morphogenetic proteins and parathyroid hormone therapy, are also discussed.

Local drug delivery for enhancing fracture healing in osteoporotic bone

Fragility fractures can cause significant morbidity and mortality in patients with osteoporosis and inflict a considerable medical and socioeconomic burden. Moreover, treatment of an osteoporotic fracture is challenging due to the decreased strength of the surrounding bone and suboptimal healing capacity, predisposing both to fixation failure and non-union. Whereas a systemic osteoporosis treatment acts slowly, local release of osteogenic agents in osteoporotic fracture would act rapidly to increase bone strength and quality, as well as to reduce the bone healing period and prevent development of a problematic non-union. The identification of agents with potential to stimulate bone formation and improve implant fixation strength in osteoporotic bone has raised hope for the fast augmentation of osteoporotic fractures. Stimulation of bone formation by local delivery of growth factors is an approach already in clinical use for the treatment of non-unions, and could be utilized for osteoporotic fractures as well. Small molecules have also gained ground as stable and inexpensive compounds to enhance bone formation and tackle osteoporosis. The aim of this paper is to present the state of the art on local drug delivery in osteoporotic fractures. Advantages, disadvantages and underlying molecular mechanisms of different active species for local bone healing in osteoporotic bone are discussed. This review also identifies promising new candidate molecules and innovative approaches for the local drug delivery in osteoporotic bone.

Constructing the toolbox: Patient-specific genetic factors of altered fracture healing

The multifaceted sequence of events that follow fracture repair can be further complicated when considering risk factors for impaired union, present in a large and growing percentage of the population. Risk factors such as diabetes, substance abuse, and poor nutrition affect both the young and old alike, and have been shown to dramatically impair the body's natural healing processes. To this end, biotherapeudic interventions such as ultrasound, electrical simulation, growth factor treatment (BMP-2, BMP-7, PDGF-BB, FGF-2) have been evaluated in preclinical models and in some cases are used widely for patients with established non-union or risk/indication or impaired healing (ie. ultrasound, BMP-2, etc.). Despite the promise of these interventions, they have been shown to be reliant on patient compliance and can produce adverse side-effects such as heterotopic ossification. Gene and cell therapy approaches have attempted to apply controlled regimens of these factors and have produced promising results. However, there are safety and efficacy concerns that may limit the translation of these approaches. In addition, none of the above mentioned approaches consider genetic variation between individual patients. Several clinical and preclinical studies have demonstrated a genetic component to fracture repair and that SNPs and genetic background variation play major roles in the determination of healing outcomes. Despite this, there is a need for preclinical data to dissect the mechanism underlying the influence of specific gene loci on the processes of fracture healing, which will be paramount in the future of patient-centered interventions for fracture repair.

BMP-7 versus BMP-2 for the treatment of long bone nonunion

The authors compared the results of treating nonunion with either bone morphogenetic protein (BMP)-7 or BMP-2. Between 2001 and 2009, 214 limb segments were treated for nonunion with either BMP-7 or BMP-2 at the authors' institution. Sixty-three subjects received 76 units of BMP-7. Radiographic healing occurred in 70% of limb segments at an average of 30 weeks after surgery, and 75% of limb segments were weight bearing at an average of 23 weeks after surgery. In 15.8%, persistent nonunion necessitated additional surgery. Average follow-up was 32 months. One hundred twelve subjects received 138 units of BMP-2. Radiographic healing occurred in 93% of limb segments at an average of 19 weeks after surgery, and 88% were weight bearing at an average of 15 weeks after surgery. In 6.25%, persistent nonunion necessitated additional surgery. Average follow-up was 17 months. Several significant differences were observed. Patients in both BMP-7 and BMP-2 groups were able to fully weight bear at an average of 23 and 15 weeks, respectively (P<.001). Further, both BMP-7 and BMP-2 groups healed at an average of 30 and 19 weeks, respectively (P<.001). Additionally, healing occurred in more limb segments in the BMP-2 group (93%) than in the BMP-7 group (70%) (P<.001). No difference in the complication rate was seen between groups. Patients who received BMP-2 for the treatment of nonunion had a higher rate of radiographic healing, achieved radiographic healing more quickly, and were able to bear weight sooner than those who underwent treatment with BMP-7.

Bone morphogenetic proteins: a powerful osteoinductive compound with non-negligible side effects and limitations

Healing and regeneration of large bone defects leading to non-unions is a great concern in orthopedic surgery. Since auto- and allografts have limitations, bone tissue engineering and regenerative medicine (TERM) has attempted to solve this issue. In TERM, healing promotive factors are necessary to regulate the several important events during healing. An ideal treatment strategy should provide osteoconduction, osteoinduction, osteogenesis, and osteointegration of the graft or biomaterials within the healing bone. Since many materials have osteoconductive properties, only a few biomaterials have osteoinductive properties which are important for osteogenesis and osteointegration. Bone morphogenetic proteins (BMPs) are potent inductors of the osteogenic and angiogenic activities during bone repair. The BMPs can regulate the production and activity of some growth factors which are necessary for the osteogenesis. Since the introduction of BMP, it has added a valuable tool to the surgeon's possibilities and is most commonly used in bone defects. Despite significant evidences suggesting their potential benefit on bone healing, there are some evidences showing their side effects such as ectopic bone formation, osteolysis and problems related to cost effectiveness. Bone tissue engineering may create a local environment, using the delivery systems, which enables BMPs to carry out their activities and to lower cost and complication rate associated with BMPs. This review represented the most important concepts and evidences regarding the role of BMPs on bone healing and regeneration from basic to clinical application. The major advantages and disadvantages of such biologic compounds together with the BMPs substitutes are also discussed.