Bone Graft Substitution and Augmentation

Kneadable dough-type hydrogel transforming from dynamic to rigid network to repair irregular bone defects

Irregular bone defects, characterized by unpredictable size, shape, and depth, pose a major challenge to clinical treatment. Although various bone grafts are available, none can fully meet the repair needs of the defective area. Here, this study fabricates a dough-type hydrogel (DR-Net), in which the first dynamic network is generated by coordination between thiol groups and silver ions, thereby possessing kneadability to adapt to various irregular bone defects. The second rigid covalent network is formed through photocrosslinking, maintaining the osteogenic space under external forces and achieving a better match with the bone regeneration process. In vitro, an irregular alveolar bone defect is established in the fresh porcine mandible, and the dough-type hydrogel exhibits outstanding shape adaptability, perfectly matching the morphology of the bone defect. After photocuring, the storage modulus of the hydrogel increases 8.6 times, from 3.7 kPa (before irradiation) to 32 kPa (after irradiation). Furthermore, this hydrogel enables effective loading of P24 peptide, which potently accelerates bone repair in Sprague-Dawley (SD) rats with critical calvarial defects. Overall, the dough-type hydrogel with kneadability, space-maintaining capability, and osteogenic activity exhibits exceptional potential for clinical translation in treating irregular bone defects.

Surgical Site-Released Tissue Is Potent to Generate Bone onto TCP and PCL-TCP Scaffolds In Vitro

There is evidence that surgical site tissue (SSRT) released during orthopedic surgery has a strong mesenchymal regenerative potential. Some data also suggest that this tissue may activate synthetic or natural bone substitute materials and can thus upgrade its osteopromoting properties. In this comparative in vitro study, we investigate the composition of SSRT during total hip replacement (n = 20) harvested using a surgical suction handle. In addition, the osteopromoting effect of the cells isolated from SSRT is elucidated when incubated with porous beta-tricalcium phosphate (β-TCP) or 80% medical-grade poly-ε-caprolactone (PCL)/20% TCP composite material. We identified multiple growth factors and cytokines with significantly higher levels of PDGF and VEGF in SSRT compared to peripheral blood. The overall number of MSC was 0.09 ± 0.12‱ per gram of SSRT. A three-lineage specific differentiation was possible in all cases. PCL-TCP cultures showed a higher cell density and cell viability compared to TCP after 6 weeks in vitro. Moreover, PCL-TCP cultures showed a higher osteocalcin expression but no significant differences in osteopontin and collagen I synthesis. We could demonstrate the high regenerative potential from SSRT harvested under vacuum in a PMMA filter device. The in vitro data suggest advantages in cytocompatibility for the PCL-TCP composite compared to TCP alone.

Controlled release of a non-steroidal anti-inflammatory drug from a photocurable polymeric calcium phosphate cement

In this research, a photocurable composite based on tetracalcuim phosphate ceramic and, hydroxyethyl methacrylate-modified poly(acrylic-maleic acid) was developed and studied as a potential drug delivery system for bone defects. Different concentrations (5, 10 and 20 wt. %) of a non-steroidal anti-inflammatory drug, Indomethacin, were loaded on to the composite and its release behavior was investigated in phosphate buffered solution during 504 h. The obtained release data were fitted by both power law (Peppas) and Weibull equations. The composites were also characterized after different soaking periods using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Fourier transforming infrared spectroscopy. The results of XRD and SEM analyses revealed the formation of nanosized needle/flake-like apatite crystals on the composites surfaces; however, better apatite formation was observed for the composites loaded with higher amounts of Indomethacin. The morphological observations and quantitative estimations revealed that the loaded composites were gradually degraded in the phosphate-buffered saline. Moreover, a controlled release of Indomethacin was found from the composites in which a higher drug concentration led to a more drug level as well as sustained release profile. In drug release modeling, better regression coefficient was obtained from the Weibull equation, compared to the power law, meaning that the Weibull equation suggests a better description of the indomethacin release from the composites during the whole period of the test. In conclusion, the photocurable composite with apatite formation ability can be successfully used for the controlled release of indomethacin as an anti-inflammatory drug in bone defects.

BMP-2 (and partially GDF-5) coating significantly accelerates and augments bone formation close to hydroxyapatite/tricalcium-phosphate/brushite implant cylinders for tibial bone defects in senile, osteopenic sheep

Bilateral defects (diameter 8 mm) in the medial tibial head of senile, osteopenic female sheep (n = 48; 9.63 ± 0.10 years; mean ± SEM) were treated with hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP)/dicalcium phosphate dihydrate (DCPD; brushite) cylinders coated with BMP-2 (25 or 250 micrograms) or growth differentiation factor (GDF)-5 (125 or 1250 micrograms; left side); cylinders without BMP served as controls (right side). Three, 6, and 9 months post-operation (n = 6 each group), bone structure and formation were analyzed in vivo by X-ray and ex vivo by osteodensitometry, histomorphometry, and micro-computed tomography (micro-CT) at 3 and 9 months. Semi-quantitative X-ray evaluation showed significantly increasing bone densities around all implant cylinders over time. High-dose BMP-2-coated cylinders (3 and 9 months) and low-dose GDF-5-coated cylinders (3 and 6 months) demonstrated significantly higher densities than controls (dose-dependent for BMP-2 at 3 months). This was confirmed by osteodensitometry at 9 months for high-dose BMP-2-coated cylinders (and selected GDF-5 groups), and was again dose-dependent for BMP-2. Osteoinduction by BMP-2 was most pronounced in the adjacent bone marrow (dynamic histomorphometry/micro-CT). BMP-2 (and partially GDF-5) significantly increased the bone formation in the vicinity of HA/TCP/DCPD cylinders used to fill tibial bone defects in senile osteopenic sheep and may be suitable for surgical therapy of critical size, non-load-bearing bone defects in cases of failed tibial head fracture or defect healing.

Hydroxyapatite-chitosan composites derived from sea cucumbers and shrimp shells ameliorate femoral bone defects in an albino rat model

Background and Aim

A bone defect is defined as a critically sized autologous bone and a bone gap. Bone grafting is one of the most commonly used surgical methods to enhance bone regeneration in orthopedic procedures. A composite of collagen, hydroxyapatite (HA), and chitosan (Ch) is suitable as a bone matrix and stimulates ossification. This study aimed to evaluate the use of natural HA-Ch composites derived from sea cucumbers and shrimp shells and quantify the levels of cytokines, polymorphonuclear neutrophils (PMNs), serum liver enzymes, calcium, phosphate, and procollagen type 1 N-terminal propeptide (PINP) in albino rats with femoral bone defects.

Materials and Methods

A total of 48 albino rats with femoral bone defects were divided into 4 groups (n = 12 each): (C-) placebo, (C+) polyethylene glycol, (T1) HA, and (T2) HA-Ch groups. Each group was divided into two subgroups (n = 6 each), with euthanization on 7- and 42-day post-treatment, respectively. Procollagen Type 1 N-terminal propeptide and the cytokines interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor-alpha were quantified using enzyme-linked immunosorbent assay. Flow cytometry was performed to evaluate PMNs. A clinical chemistry analyzer was used to measure the serum levels of liver enzymes, calcium, and phosphate.

Results

There was a significant decrease in the level of IL-6 on 7 days and in the level of IL-10 on 42 days in the HA-Ch group. The level of PMNs also decreased significantly on 7 and 42 days in the HA-Ch group. Regarding serum liver enzymes, alkaline phosphatase (ALP) levels in the HA-Ch group increased significantly on 42 days. Calcium and phosphate levels increased significantly on 7 and 42 days in the HA and HA-Ch groups, and PINP levels increased significantly on 7 and 42 days in the HA-Ch group.

Conclusion

The HA-Ch composite derived from sea cucumbers and shrimp shells ameliorated femoral bone defects in albino rats. The HA-Ch composite modulated the levels of IL-6, IL-10, PMNs, ALP, calcium, phosphate, and PINP on 7- and 42-day post-treatment.

Alveolar cleft bone grafting at different age periods

Relevance. Anatomical and functional disorders in congenital clefts may be various. Their severity depends on the cleft size and on the combination of a cleft lip with an alveolar cleft. Alveolar cleft bone grafting (ACBG) is one of the most important surgeries for patients with cleft lip and palate rehabilitation. The study aimed to analyze the results of alveolar cleft bone grafting in various age groups, summarizing the available data and supplementing them with our own experience.

Materials and methods. In our clinic, 488 patients of different ages (from 4 to 18 years old), including patients with bilateral clefts, underwent ACBG.

Results. The result analysis showed the time of surgery should depend not on the child's age but on the orthodontic preparation of the child for ACBG.

Conclusion. The literature data and our experience allowed us to develop indications for ACBG at different ages

Current Trends in Orthobiologics: An 11-Year Review of the Orthopaedic Literature

BACKGROUND

The use of "orthobiologics" or regenerative therapies in orthopaedic surgery has grown in recent years. Particular interest has been raised with regard to platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cells. Although studies have analyzed outcomes after orthobiologic treatment, no study has analyzed how the literature as a whole has evolved.

PURPOSE

To evaluate trends in platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cell publications and to assess how these might inform efforts to establish minimum reporting standards and forecast future use.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A database was compiled systematically using PubMed to identify articles published between 2009 and 2019 within 9 prominent orthopaedic journals and pertaining to the use of platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cells in the treatment of musculoskeletal conditions. Included articles were classified as clinical, nonclinical (translational or basic science), or review, and a variety of study parameters were recorded for each. Additional queries were performed to identify articles that utilized minimum reporting standards.

RESULTS

A total of 474 articles (132 clinical, 271 nonclinical, 71 review) were included, consisting of 244 (51.5%) platelet-rich plasma, 146 (30.8%) bone marrow aspirate, 72 (15.2%) adipose-derived cells, and 12 (2.5%) amniotic cells. The greatest annual increase in publications for each orthobiologic topic was from 2018 to 2019. The American Journal of Sports Medicine demonstrated the highest number of overall (34.2%) and clinical (50.0%) publications, and accounted for 44.3% of all platelet-rich plasma publications. The Journal of Orthopaedic Research accounted for the second highest overall number of publications (24.9%) and highest nonclinical publications (41.0%). Platelet-rich plasma accounted for 91.5% of all level 1 clinical studies, while much greater than half of bone marrow aspirate, adipose-derived cells, and amniotic cell publications were level 3 or lower. Out of the 207 articles that used some form of reporting protocol, 59 (28.5%) used an established algorithm and 125 (60.4%) used their own.

CONCLUSION

Interest in orthobiologics continues to grow, as evidenced by an increasing trend in publications over an 11-year period. However, current reporting on orthobiologic formulations is largely heterogeneous, emphasizing the need for minimum reporting standards and higher-quality studies.

Osteoperiosteal Decortication and Autogenous Cancellous Bone Graft Combined with Bridge Plating for Non-hypertrophic Diaphyseal Nonunion

Backgroud

The aim of this study was to evaluate results of osteoperiosteal decortication and autogenous cancellous bone graft combined with a bridge plating technique in atrophic and oligotrophic femoral and tibial diaphyseal nonunion.

Methods

We retrospectively reviewed 31 patients with atrophic or oligotrophic femoral and tibial diaphyseal nonunion treated with osteoperiosteal decortication and autogenous cancellous bone graft between January 2008 and December 2018. Patients with hypertrophic nonunion, infected nonunion, and nonunion treated with autogenous cancellous bone graft alone were excluded. The nonunion site was exposed by using the Judet technique of osteoperiosteal decortication. Nonunion with a lack of stability was stabilized with a new plate using a bridge plating technique or augmented by supplemental fixation with a plate. Nonunion with malalignment was stabilized with a new plate after deformity correction. Autogenous cancellous bone graft was harvested from the posterior iliac crest and placed within the area of decortication. A basic demographic survey was conducted, and the type of existing implants, mechanical stability of the implants, the type of implants used for stabilization, the operation time, the time to bone union, and postoperative complications were investigated.

Results

The average follow-up period was 33.3 months (range, 8–108 months). The operation time was 207 minutes (range, 100–351 minutes). All but 1 nonunion (96.7%) were healed at an average of 4.2 months (range, 3–8 months). In 1 patient, bone union failed due to implant loosening with absorbed bone graft, and solid union was achieved by an additional surgery for stable fixation with a new plate, osteoperiosteal decortication, and autogenous cancellous bone graft. There were no other major complications such as neurovascular injuries, infection, loss of fixation, and malunion.

Conclusions

Osteoperiosteal decortication and autogenous cancellous bone graft combined with stable fixation by bridge plating showed reliable outcomes in atrophic and oligotrophic diaphyseal nonunion. This treatment modality can be effective for treating atrophic and oligotrophic diaphyseal nonunion because it is very helpful stimulating bone union.

Platelet-Rich Plasma Combined With Autologous Grafting in the Treatment of Long Bone Delayed Union or Non-union: A Meta-Analysis

Background: Platelet-rich plasma (PRP) has been suggested as an emerging treatment for bone defects. However, whether PRP could enhance the therapeutic efficacy of autologous bone grafting for long bone delayed union or non-union remains unknown. A meta-analysis of randomized and non-randomized controlled trials (RCT and NRCT) was performed to summarize current evidence. Methods: Relevant RCTs and NRCTs comparing the influences of autologous bone grafting on healing of long bone delayed union or non-union with and without PRP were obtained by searching PubMed, Embase, Cochrane's Library, China National Knowledge Infrastructure, and WanFang databases from inception to September 10, 2020. A random-effect model was applied to pool the results with the incorporation of the potential heterogeneity. Subgroup analysis according to study design was also performed. Results: Six RCTs and two NRCTs with 420 patients were included. Compared to patients allocated to autologous bone grafting alone, those allocated to combined treatment with PRP and autologous bone grafting were not associated with higher rates of radiographic bone healing [risk ratio (RR): 1.06, 95% confidence interval (CI): 0.99-1.13, P = 0.09; I ² = 24%] or excellent/good posttreatment limb function (RR: 1.14, 95% CI: 0.95-1.37, P = 0.37; I ² = 0%) but was associated with a shorter healing time (mean difference: -1.35 months, 95% CI: -1.86 to -0.84, P < 0.001; I ² = 58%). Subgroup analysis according to study design showed similar results for the above outcomes (P-values for subgroup difference all >0.10). Conclusions: Combined treatment with PRP and autologous bone grafting may be effective to accelerate the healing of long bone delayed union or non-union compared to autologous bone grafting alone.

Characteristics, Treatments, and Outcomes of Tibial Plateau Nonunions: A Systematic Review

BACKGROUND

Due to the rare incidence of tibial plateau nonunions, current studies are limited to small sample sizes and patient demographics. The aim of this systematic review is to quantify and report patient and fracture traits, possible risk factors, and treatment outcomes of tibial plateau nonunions.

METHODS

PubMed, Clinical Key, and MEDLINE were searched for articles published prior to August 2020 in accordance to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The authors used varying combinations of the following terms to identify relevant articles: "tibial," "plateau," "nonunion," "non-union." Studies were assessed for patient demographics, pre-revision nonunion characteristics, treatment, and post-revision outcomes.

RESULTS

Eight studies were included, yielding 31 tibial plateau nonunions (21 males, 10 females). The majority of nonunions were associated with high energy trauma (52.2%) and were Schatzker class VI (54.8%). Schatzker class I and II nonunions were not attributed to neglect, contradicting previous suggestions. Time to union was 4.0 months, the most common treatments being autologous bone grafting (76.7%) and revision plating (63.3%).

CONCLUSION

This study demonstrates the effectiveness of autologous bone grafts and revision plating for tibial plateau nonunions. Physicians may use these findings to guide decision making in the event of high energy plateau nonunions. Lastly, various limitations exist within the current literature, emphasizing the need for standardized reporting measures.

Local administration of HMGB-1 promotes bone regeneration on the critical-sized mandibular defects in rabbits

Reconstruction of a critical-sized osseous defect is challenging in maxillofacial surgery. Despite novel treatments and advances in supportive therapies, severe complications including infection, nonunion, and malunion can still occur. Here, we aimed to assess the use of a beta-tricalcium phosphate (β-TCP) scaffold loaded with high mobility group box-1 protein (HMGB-1) as a novel critical-sized bone defect treatment in rabbits. The study was performed on 15 specific pathogen-free New Zealand rabbits divided into three groups: Group A had an osseous defect filled with a β-TCP scaffold loaded with phosphate-buffered saline (PBS) (100 µL/scaffold), the defect in group B was filled with recombinant human bone morphogenetic protein 2 (rhBMP-2) (10 µg/100 µL), and the defect in group C was loaded with HMGB-1 (10 µg/100 µL). Micro-computed tomography (CT) examination demonstrated that group C (HMGB-1) showed the highest new bone volume ratio, with a mean value of 66.5%, followed by the group B (rhBMP-2) (31.0%), and group A (Control) (7.1%). Histological examination of the HMGB-1 treated group showed a vast area covered by lamellar and woven bone surrounding the β-TCP granule remnants. These results suggest that HMGB-1 could be an effective alternative molecule for bone regeneration in critical-sized mandibular bone defects.

Minimally invasive injectable lumbar interbody fusion with mineralized collagen-modified PMMA bone cement: A new animal model

This study was to develop a feasible and safe animal model for minimally invasive injectable lumbar interbody fusion using a novel biomaterial, mineralized collagen-polymethylmethacrylate bone cement (MC-PMMA), with unilateral pedicle screw fixation in an in vivo goat model. Eight goats (Capra aegagrus hircus) were divided into three groups: MC-PMMA, unmodified commercial-polymethylmethacrylate bone cement (UC-PMMA), and a control group (titanium cage filled with autogenous bone, TC-AB). Each group of goats was treated with minimally invasive lumbar interbody fusion at the L3/L4 and L5/L6 disc spaces (injected for MC-PMMA and UC-PMMA, implanted for TC-AB). The pedicle screws were inserted at the L3, L4, L5, and L6 vertebrae, respectively, and fixed on the left side. The characteristics of osteogenesis and bone growth were assessed at the third and the sixth month, respectively. The methods of evaluation included the survival of each animal, X-ray imaging, and 256-layer spiral computed tomography (256-CT) scanning, imaged with three-dimensional microfocus computed tomography (micro-CT), and histological analysis. The results showed that PMMA bone cement can be extruded smoothly after doping MC, the MC-PMMA integrates better with bone than the UC-PMMA, and all goats recovered after surgery without nerve damage. After 3 and 6 months, the implants were stable. New trabecular bone was observed in the TC-AB group. In the UC-PMMA group a thick fibrous capsule had formed around the implants. The MC-PMMA was observed to have perfect osteogenesis and bone ingrowth to adjacent bone surface. Minimally invasive injectable lumbar interbody fusion using MC-PMMA bone cement was shown to have profound clinical value, and the MC-PMMA showed potential application prospects.

Evaluation of Demineralized Bone Matrix Particles Delivered by Alginate Hydrogel for a Bone Graft Substitute: An Animal Experimental Study

BACKGROUND Our objective was to explore a synthetic alginate hydrogel delivery system for the delivery of demineralized bone matrix (DBM) particles for bone graft substitutes. MATERIAL AND METHODS The physiochemical properties of surface morphology, porosity measurements, in vitro degradation, equilibrium swelling, and mechanical testing of combined DBM powder and alginate in amounts of 0 mg/1 mL, 25 mg/1 mL, 50 mg/1 mL, and 100 mg/1 mL were detected. In vitro cell culture and in vivo studies using Sprague-Dawley rats were performed to evaluate the biocompatibility and osteoinductivity of DBM-alginate (ADBM) composites. RESULTS DBM particles were uniformly scattered in all composites, and macro-scale pores were omnipresent. All composites showed a similar low degradation rate, with approximately 85% of weight remaining after 15 days. As the concentration of DBM particles in composites increased, degradation in collagenase and elastic modulus increased and the pore area and swelling ratio significantly decreased. No cytotoxicity of ADBM or alginate on mesenchymal stem cells (MSCs) was observed. Cell cultivation with ADBM showed greater osteogenic potential, evidenced by the upregulation of alkaline phosphatase and alizarin red staining activity and the mRNA expression level of marker genes RUNX2, OCN, OPN, and collagen I compared with the cells grown in alginate. Evaluation of ectopic bone formation revealed the osteoinductivity of the ADBM composites was significantly greater than that of DBM particles. Osteoinduction of the composites was demonstrated by a cranial defect model study. CONCLUSIONS The delivery of DBM particles using a synthetic alginate hydrogel carrier may be a promising approach in bone tissue engineering for bone defects.

Modifying MSC Phenotype to Facilitate Bone Healing: Biological Approaches

Healing of fractures and bone defects normally follows an orderly series of events including formation of a hematoma and an initial stage of inflammation, development of soft callus, formation of hard callus, and finally the stage of bone remodeling. In cases of severe musculoskeletal injury due to trauma, infection, irradiation and other adverse stimuli, deficient healing may lead to delayed or non-union; this results in a residual bone defect with instability, pain and loss of function. Modern methods of mechanical stabilization and autologous bone grafting are often successful in achieving fracture union and healing of bone defects; however, in some cases, this treatment is unsuccessful because of inadequate biological factors. Specifically, the systemic and local microenvironment may not be conducive to bone healing because of a loss of the progenitor cell population for bone and vascular lineage cells. Autologous bone grafting can provide the necessary scaffold, progenitor and differentiated lineage cells, and biological cues for bone reconstruction, however, autologous bone graft may be limited in quantity or quality. These unfavorable circumstances are magnified in systemic conditions with chronic inflammation, including obesity, diabetes, chronic renal disease, aging and others. Recently, strategies have been devised to both mitigate the necessity for, and complications from, open procedures for harvesting of autologous bone by using minimally invasive aspiration techniques and concentration of iliac crest bone cells, followed by local injection into the defect site. More elaborate strategies (not yet approved by the U.S. Food and Drug Administration-FDA) include isolation and expansion of subpopulations of the harvested cells, preconditioning of these cells or inserting specific genes to modulate or facilitate bone healing. We review the literature pertinent to the subject of modifying autologous harvested cells including MSCs to facilitate bone healing. Although many of these techniques and technologies are still in the preclinical stage and not yet approved for use in humans by the FDA, novel approaches to accelerate bone healing by modifying cells has great potential to mitigate the physical, economic and social burden of non-healing fractures and bone defects.

Selected Nanomaterials' Application Enhanced with the Use of Stem Cells in Acceleration of Alveolar Bone Regeneration during Augmentation Process

Regenerative properties are different in every human tissue. Nowadays, with the increasing popularity of dental implants, bone regenerative procedures called augmentations are sometimes crucial in order to perform a successful dental procedure. Tissue engineering allows for controlled growth of alveolar and periodontal tissues, with use of scaffolds, cells, and signalling molecules. By modulating the patient's tissues, it can positively influence poor integration and healing, resulting in repeated implant surgeries. Application of nanomaterials and stem cells in tissue regeneration is a newly developing field, with great potential for maxillofacial bony defects. Nanostructured scaffolds provide a closer structural support with natural bone, while stem cells allow bony tissue regeneration in places when a certain volume of bone is crucial to perform a successful implantation. Several types of selected nanomaterials and stem cells were discussed in this study. Their use has a high impact on the efficacy of the current and future procedures, which are still challenging for medicine. There are many factors that can influence the regenerative process, while its general complexity makes the whole process even harder to control. The aim of this study was to evaluate the effectiveness and advantage of both stem cells and nanomaterials in order to better understand their function in regeneration of bone tissue in oral cavity.

Epidemiology, Clinical Assessments, and Current Treatments of Nonunions

PURPOSE OF REVIEW

The failure of bony union following a fracture, termed a fracture nonunion, has severe patient morbidity and economic consequences. This review describes current consensuses and future directions of investigation for determining why, detecting when, and effective treatment if this complication occurs.

RECENT FINDINGS

Current nonunion investigation is emphasizing an expanded understanding of the biology of healing. This has led to assessments of the immune environment, multiple cytokines and morphogenetic factors, and the role of skeletogenic stem cells in the development of nonunion. Detecting biological markers and other objective diagnostic criteria is also a current objective of nonunion research. Treatment approaches in the near future will likely be dominated by the development of specific adjunct therapies to the nonunion surgical management, which will be informed by an expanded mechanistic understanding of nonunion biology. Current consensus among orthopedists is that improved diagnosis and treatment of nonunion hinges first on discoveries at the bench side with later translation to the clinic.

Injectable porcine bone demineralized and digested extracellular matrix-PEGDA hydrogel blend for bone regeneration

Extracellular matrix (ECM) has a major role in the structural support and cellular processes of organs and tissues. Proteins extracted from the ECM have been used to fabricate different scaffolds for tissue engineering applications. The aims of the present study were to extract, characterize and fabricate a new class of hydrogel with proteins isolated from pig bone ECM and combine them with a synthetic polymer so it could be used to promote bone regeneration. Porcine bone demineralized and digested extracellular matrix (pddECM) containing collagen type I was produced, optimized and sterilized with high pressurized CO₂ method. The pddECM was further blended with 20% w/v polyethylene glycol diacrylate (PEGDA) to create an injectable semi interpenetrating polymer network (SIPN) scaffold with enhanced physicochemical properties. The blend tackled the shortfall of natural polymers, such as lack of structural stability and fast degradation, preserving its structure in more than 90% after 30 days of incubation; thus, increasing the material endurance in a simulated physiological environment. The manufactured injectable hydrogel showed high cytocompatibility with hOb and SaOs-2 cells, promoting osteogenic proliferation within 21 days of culture. The hydrogel had a high compression modulus of 520 kPa, low swelling (5.3 mg/mg) and millimetric volume expansion (19.5%), all of which are favorable characteristics for bone regeneration applications.

Nonunions of Bisphosphonate Fractures of the Femur: Presentation, Etiopathogenesis, Diagnosis, and Operative Treatment

Patients presenting with femoral fractures and long-term use of bisphosphonate treatment are at risk of developing a delayed union and/or nonunion as a result of the atypical metabolic activity prevailing at the fracture edges of the affected extremity. The treatment of these nonunions poses a serious challenge to orthopaedic surgeons worldwide and necessitates specialized techniques and materials to design a construct that will last a long period (greater than 6 months), while still allowing weight-bearing in this elderly population. Treatment options, timing of intervention, selection of implant, and the option of bone grafting are discussed to assist the clinician to make the right decisions in these complex clinical cases.

Multidirectional percutaneous drilling and autologous bone marrow injection for the treatment of femoral diaphyseal nonunions: a prospective interventional study

Background

To examine the outcomes of multidirectional percutaneous drilling and autologous concentrated bone marrow (BM) transplantation for atrophic femoral diaphyseal nonunion characterized by intact hardware and mechanical stability at the nonunion site.

Methods

Fourteen patients (22–63 years of age) were admitted to our hospital with atrophic femoral diaphyseal nonunion. All patients were treated with a combination of multidirectional percutaneous drilling and autologous concentrated BM transplantation. Radiographic evaluation was conducted every month after transplantation until bone healing was achieved.

Results

Bony union was achieved in 13 of the 14 patients (92.9%) after an average of 3.9 months (range: 2.5–6 months). The average radiographic union scale in tibial (RUST) scale score improved significantly from the preoperative period (6.15±1.21) to follow-up (11.23±0.73; P<0.05). The mean follow-up after transplantation was 31.4±9.5 months (range: 18–50 months). At the final follow-up, the quality of function had improved significantly, allowing a return to normal activities.

Conclusion

Combined multidirectional percutaneous drilling and autologous concentrated BM transplantation is an easy, safe, inexpensive, and efficacious method to treat atrophic femoral diaphyseal nonunion characterized by intact hardware and mechanical stability at the nonunion site.

Trial registration number: ISRCTN29808592

Induced membrane technique using enriched bone grafts for treatment of posttraumatic segmental long bone defects

BACKGROUND

Reconstruction of posttraumatic bone defects represents a difficult challenge. The induced membrane technique is an effective two-stage procedure for bone defect reconstruction. To overcome the problems of autologous bone grafting, different graft substitutes have been investigated. The aim of the present study is to evaluate our clinical experience in reconstruction of critical posttraumatic bone defects using an induced membrane technique based on a combination of autologous graft and allograft (cancellous bone) enriched with platelet-rich plasma (PRP) and bone marrow concentrate aspirate (BMCA).

MATERIALS AND METHODS

Between 2009 and 2014, we reconstructed 18 posttraumatic bone defects in 16 patients. Their average length was 6.4 cm (range 1.6-13.2 cm). The defect location was the femur in nine cases (50%), the tibia in eight (44%) cases, and the humerus in one (6%) case. In all cases, we used a combination of autologous and cancellous allograft graft enriched with PRP and BMCA. Bone fixation was achieved using intramedullary nailing in 2 cases (11%), plating in 15 cases (66%), and external fixation in 1 case (6%).

RESULTS

Both clinical and radiographic union were achieved in 13 (72%) cases (13 patients). Five (28%) cases (four patients) developed nonunion. Nonunion was observed in two of eight (25%) tibial defects and in three (33%) of nine femoral defects (ns). Three of 4 (75%) double defects had delayed union, whereas 2 of 14 (14%) single defects did not heal (p = 0.016). The average length of the 13 defects that united was 6 cm (range 1.6-11.8 cm), while the length of the 5 defects that did not unite was 10.3 cm (range 6-13.2 cm) (p = 0.009).

CONCLUSIONS

In this series using an induced membrane technique based on a combination of autograft and allograft enriched with BMCA and PRP, the healing rate was lower than in other series where autologous bone graft alone was employed. Nonunion was more frequent in longer and double defects. Further research aimed at developing effective alternative options to autogenous cancellous bone graft is desirable.

LEVEL OF EVIDENCE

III.

Establishment and effects of allograft and synthetic bone graft substitute treatment of a critical size metaphyseal bone defect model in the sheep femur

Assessment of bone graft material efficacy is difficult in humans, since invasive methods like staged CT scans or biopsies are ethically unjustifiable. Therefore, we developed a novel large animal model for the verification of a potential transformation of synthetic bone graft substitutes into vital bone. The model combines multiple imaging methods with corresponding histology in standardized critical sized cancellous bone defect. Cylindrical bone voids (10 ml) were created in the medial femoral condyles of both hind legs (first surgery at right hind leg, second surgery 3 months later at left hind leg) in three merino‐wool sheep and either (i) left empty, filled with (ii) cancellous allograft bone or (iii) a synthetic, gentamicin eluting bone graft substitute. All samples were analysed with radiographs, MRI, μCT, DEXA and histology after sacrifice at 6 months. Unfilled defects only showed ingrowth of fibrous tissue, whereas good integration of the cancellous graft was seen in the allograft group. The bone graft substitute showed centripetal biodegradation and new trabecular bone formation in the periphery of the void as early as 3 months. μCT gave excellent insight into the structural changes within the defects, particularly progressive allograft incorporation and the bone graft substitute biodegradation process. MRI completed the picture by clearly visualizing soft tissue ingrowth into unfilled bone voids and presence of fluid collections. Histology was essential for verification of trabecular bone and osteoid formation. Conventional radiographs and DEXA could not differentiate details of the ongoing transformation process. This model appears well suited for detailed in vivo and ex vivo evaluation of bone graft substitute behaviour within large bone defects.

Comparison of Bone Grafts From Various Donor Sites in Human Bone Specimens

The objective of the current study was to compare the three-dimensional (3D) morphometric microstructure in human cadaveric bone specimens taken from various commonly utilized donor sites for autogenous bone grafting. Autogenous bone grafts can be harvested from various anatomic sites and express heterogeneous bone quality with a specific 3D microstructure for each site. The long-term structural integrity and susceptibility to resorption of the graft depend on the selected donor bone. Micro-computed tomography generates high-resolution datasets of bone structures and calcifications making this modality versatile for microarchitecture analysis and quantification of the bone. Six bone specimens, 10 mm in length, where anatomically possible, were obtained from various anatomical sites from 10 human dentate cadavers (4 men, 6 women, mean age 69.5 years). Specimens were scanned using a micro-computed tomography device and volumetrically reconstructed. A virtual cylindrical inclusion was reconstructed to analyze the bone mineral density and structural morphometric analysis using bone indices: relative bone volume, surface density, trabecular thicknesses, and trabecular separation. Calvarial bone specimens showed the highest mineral density, followed by the chin, then mandibular ramus then the tibia, whereas iliac crest and maxillary tuberosity had lower bone mineral densities. The pairwise comparison revealed statistically significant differences in the bone mineral density and relative bone volume index in the calvaria, mandibular ramus, mandibular symphysis groups when compared with those in the iliac crest and maxillary tuberosity, suggesting higher bone quality in the former groups than in the latter; tibial specimens expressed variable results.

Orthobiologics for Bone Healing

Orthobiologics are a group of biological materials and substrates that promote bone, ligament, muscle, and tendon healing. These substances include bone autograft, bone allograft, demineralized bone matrix, bone graft substitutes, bone marrow aspirate concentrate, platelet-rich plasma, bone morphogenetic proteins, platelet-derived growth factor, parathyroid hormone, and vitamin D and calcium. Properties of orthobiologics in bone healing include osteoconduction, osteoinduction, and osteogenesis. This article discusses the important properties of orthobiologics in bone healing, many of the orthobiologics currently available for bone healing, the related literature, their current clinical uses in sports medicine, and systemic factors that inhibit bone healing.

An in vivo comparative study of the gelatin microtissue-based bottom-up strategy and top-down strategy in bone tissue engineering application

Tissue-engineered bone grafts (TEBGs) represent a promising treatment for bone defects. Nevertheless, drawbacks of the current construction strategy (top-down [TD] strategy) such as limited transmission of nutrients and nonuniform distribution of seeded cells, result in an unsatisfied therapeutic effect on large segmental bone defects. Theoretically, tissue-engineered microtissue (TEMT)-based bottom-up (BU) strategy is effective in preserving seed cells and vascularization, thus being regarded as a better alternative for TEBGs. Yet, there are few studies focusing on the comparison of the in vivo performance of TEBGs fabricated by TD or BU strategy. Here, we developed an ectopic bone formation rat model to compare the performance of these two construction strategies in vivo. TEBGs made from gelatin TEMT (BU strategy) and bulk tissue (BT; TD strategy) were seeded with equal number of rat bone marrow-derived mesenchymal stem cells and fabricated in 5 mm polydimethylsiloxane chambers. The grafts were implanted into subcutaneous pockets in the same rat. Four weeks after implantation, microcomputed tomography and hematoxylin and eosin staining results demonstrated that more bony tissue was formed in the microtissue (MT) group than in the BT group. CD31 staining further confirmed that there were more blood vessels in the MT group, indicating that the BU strategy was superior in inducing angiogenesis. This comparative study provides evidence that the BU construction strategy is more effective for in vivo application and bone defect treatment by bone tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 678-688, 2019.

Bioactive hydrogels for bone regeneration

Bone self-healing is limited and generally requires external intervention to augment bone repair and regeneration. While traditional methods for repairing bone defects such as autografts, allografts, and xenografts have been widely used, they all have corresponding disadvantages, thus limiting their clinical use. Despite the development of a variety of biomaterials, including metal implants, calcium phosphate cements (CPC), hydroxyapatite, etc., the desired therapeutic effect is not fully achieved. Currently, polymeric scaffolds, particularly hydrogels, are of interest and their unique configurations and tunable physicochemical properties have been extensively studied. This review will focus on the applications of various cutting-edge bioactive hydrogels systems in bone regeneration, as well as their advantages and limitations. We will examine the composition and defects of the bone, discuss the current biomaterials for bone regeneration, and classify recently developed polymeric materials for hydrogel synthesis. We will also elaborate on the properties of desirable hydrogels as well as the fabrication techniques and different delivery strategies. Finally, the existing challenges, considerations, and the future prospective of hydrogels in bone regeneration will be outlined.

Management of septic non-union of the tibia by the induced membrane technique. What factors could improve results?

INTRODUCTION

Management of septic non-union of the tibia requires debridement and excision of all infected bone and soft tissues. Various surgical techniques have been described to fill the bone defect. The "Induced Membrane" technique, described by A. C. Masquelet in 1986, is a two-step procedure using a PMMA cement spacer around which an induced membrane develops, to be used in the second step as a bone graft holder for the bone graft. The purpose of this study was to assess our clinical and radiological results with this technique in a series managed in our department.

MATERIAL AND METHOD

Nineteen traumatic septic non-unions of the tibia were included in a retrospective single-center study between November 2007 and November 2014. All patients were followed up clinically and radiologically to assess bone union time. Multivariate analysis was used to identify factors influencing union.

RESULTS

The series comprised 4 women and 14 men (19 legs); mean age was 53.9 years. Vascularized flap transfer was required in 26% of cases before the first stage of treatment. All patients underwent a two-step procedure, with a mean interval of 7.9 weeks. Mean bone defect after the first step was 52.4mm. The bone graft was harvested from the iliac crest in the majority of cases (18/19). The bone was stabilized with an external fixator, locking plate or plaster cast after the second step. Mean follow-up was 34 months. Bony union rate was 89% (17/19), at a mean 16 months after step 2. Eleven patients underwent one or more (mean 2.1) complementary procedures. Severity of index fracture skin opening was significantly correlated with union time (Gustilo III vs. Gustilo I or II, p=0.028). A trend was found for negative impact of smoking on union (p=0.06). Bone defect size did not correlate with union rate or time.

DISCUSSION

The union rate was acceptable, at 89%, but with longer union time than reported in the literature. Many factors could explain this: lack of rigid fixation after step 2 (in case of plaster cast or external fixator), or failure to cease smoking. The results showed that the induced membrane technique is effective in treating tibial septic non-union, but could be improved by stable fixation after the second step and by cessation of smoking.

LEVEL OF EVIDENCE

IV, Retrospective study.

Autologous Bone Graft Harvest Using the Reamer-Irrigator-Aspirator

Initially developed to reduce intramedullary pressures during long bone intramedullary nail placement, the reamer-irrigator-aspirator (RIA) can be used to harvest large volume autologous bone graft from the intramedullary canal of a long bone. This case-based surgical technique video demonstrates the appropriate techniques that should be applied while using the RIA to obtain autologous bone graft from the femur. A large volume of bone graft, generally between 30 and 90 cm, can be obtained using a single RIA procedure. The bone graft harvested from the intramedullary canal is excellent regarding its biochemical properties, with several studies reporting higher levels of growth factors and stem cells when compared with iliac crest bone graft. Surgical technique is key to maximize bone graft harvest, as well as to avoid complications including iatrogenic fracture, intraarticular penetration, and fragmentation of either the reamer head from the drive shaft or the guide wire. Pearls and pitfalls regarding sizing of the reamer head, determination of starting point, guide wire placement, reamer advancement, and diligent use of fluoroscopic imaging are highlighted during this video. Finally, outcomes regarding healing of long bone defects when using RIA-derived autologous bone graft and reduction in postoperative pain at the graft donor site are briefly reviewed.

Basic Science and Clinical Application of Reamed Sources for Autogenous Bone Graft Harvest

Autologous bone graft remains the only clinically available source of graft material with osteogenic, osteoinductive, and osteoconductive properties. Although iliac crest autologous bone graft has long served as the benchmark, reamed autogenous bone graft offers several advantages. Reamed autograft has a biochemical and cellular profile that is at least equivalent, and perhaps superior, to that of iliac crest autograft. In addition, larger volumes of reamed autograft can be obtained via less-invasive techniques, giving surgeons an accessible source of mesenchymal stem cells that can be reliably and repeatedly harvested. Early clinical experience involving reamed autogenous bone graft in the management of nonunion, bone defects, and arthrodesis has been encouraging and has demonstrated the necessary properties to warrant regular consideration of reamed graft for these applications.

Application of a Beta-Tricalcium Phosphate Graft to Minimize Bony Defect in Bone-Patella Tendon-Bone Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone autograft yields good clinical outcomes. Despite appropriate clinical outcomes, the most common complaint after reconstruction with a bone-patellar tendon-bone autograft is anterior knee pain at the donor graft sites. Synthetic bone grafts, such as beta-tricalcium phosphate (β-TCP), have been previously used to fill the bony defect in fractures as well as removal of bony tumors, and have shown positive utility in improving anterior knee pain after ACL reconstruction. In this Technical Note, we describe the technique of placing a β-TCP graft in the donor graft site after bone-patellar tendon-bone ACL reconstruction. After standard arthroscopic ACL reconstruction, the β-TCP is appropriately sized with an osteotome and sagital saw before being placed into the patellar and tibial donor sites. A 0-Vicryl suture is used to suture the periosteum to secure the β-TCP graft at the donor sites. This described technique allows for appropriate sizing and secure placement of the graft to maximize bone regeneration at the donor site.

Intrafibrillar silicified collagen scaffold promotes in-situ bone regeneration by activating the monocyte p38 signaling pathway

Intrafibrillar silicified collagen scaffold (SCS) is a promising biomaterial for bone regeneration because it promotes cell homing and angiogenesis in bone defects via monocyte modulation. In the present study, a rat femoral defect model was used to examine the contribution of monocyte signaling pathways to SCS modulation. Activation of the monocyte p38 signaling pathway by SCS resulted in monocyte differentiation into TRAP-positive mononuclear cells. These cells demonstrated increased secretion of SDF-1α, VEGFa and PDGF-BB, which, in turn, promoted homing of bone marrow stromal cells (BMSCs) and endothelial progenitor cells (EPCs), as well as local vascularization. Monocyte differentiation and secretion were blocked after inhibition of the p38 pathway, which resulted in reduction in cell homing and angiogenesis. Taken together, these novel findings indicate that the p38 signaling pathway is crucial in SCS-modulated monocyte differentiation and secretion, which has a direct impact on SCS-induced bone regeneration.

STATEMENT OF SIGNIFICANCE

Intrafibrillar silicified collagen scaffold (SCS) is a promising biomaterial for bone regeneration. The present work demonstrates that SCS possesses favorable bone regeneration potential in a rat femoral defect model. The degrading scaffold modulates monocyte differentiation and release of certain cytokines to recruit MSCs and EPCs, as well as enhances local vascularization by activating the p38 MAPK signaling pathway. These findings indicate that SCS contributes to bone defect regeneration by stimulating host cell homing and promoting local angiogenesis and osteogenesis without the need for loading cytokines or xenogenous stem cells.

Biological Facet of Segmental Bone Loss Reconstruction

The management of long bone defects continues to be associated with significant challenges for optimum and timely bone repair. When bone grafting is needed, essential parameters to be addressed include adequate volume, optimum density, and structural capacity as well as potent biological properties. Although the autologous iliac crest bone graft remains the gold standard, its reduced availability and donor site morbidity have made the clinicians to seek for other alternative options. Reamer irrigator aspirator graft with materials used as graft expanders along with inductive molecules and cellular augmentation constitute the current trend for optimum bone regeneration. This article presents the contemporary thinking of the biological facet of segmental bone loss reconstruction.

Management of Distal Tibial Metaphyseal Bone Defects With an Intramedullary Nitinol Scaffold: A Novel Technique

Difficult problems that are faced when reconstructing severe pilon fractures include filling metaphyseal defects and supporting an impacted, multifragmented articular surface. Supplements to plate fixation currently available in a surgeon's armamentarium include cancellous bone autograft, structural bone allograft, demineralized bone matrix, and calcium-based cements. Cancellous autograft possesses limited inherent mechanical stability and is associated with graft site morbidity. Structural allografts incorporate inconsistently and are plagued by late resorption. Demineralized bone matrix also lacks inherent structural stability. Calcium phosphate cements are not rigidly fixed to bone unless fixation is applied from cortical bone or through a plate, which must be taken into consideration when planning fixation. The Conventus DRS (Conventus Orthopaedics, Maple Grove, MN) implant is an expandable nitinol scaffold that takes advantage of the elasticity and shape memory of nitinol alloy. Once deployed and locked, it serves as a stable intramedullary base for fragment-specific periarticular fracture fixation, even in the face of metaphyseal bone loss. Two cases of successful implant use are presented. In both cases, the implant is used to fill a metaphyseal void and provide stable articular support to the distal tibial plafond.

LEVELS OF EVIDENCE

Therapeutic Level V: Case Report, Expert Opinion.

Articular impaction injuries in the lower limb

The effective management of articular impacted fractures requires the successful elevation of the osteochondral fragment to eliminate joint incongruency and the stable fixation of the fragments providing structural support to the articular surface.The anatomical restoration of the joint can be performed either with elevation through a cortical window, through balloon-guided osteoplasty or direct visualisation of the articular surface.Structural support of the void created in the subchondral area can be achieved through the use of bone graft materials (autologous tricortical bone), or synthetic bone graft substitutes.In the present study, we describe the available techniques and materials that can be used in treating impacted osteochondral fragments with special consideration of their epidemiology and treatment options. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160072. Originally published online at www.efortopenreviews.org.

Delayed Endothelial Progenitor Cell Therapy Promotes Bone Defect Repair in a Clinically Relevant Rat Model

The repair of segmental bone defects remains a significant challenge for orthopaedic surgeons. Endothelial progenitor cells (EPCs) have successfully promoted the repair of acute defects in animal models; however, the ability of EPCs to induce the repair of chronic nonhealing defects, such as those often encountered clinically, has not been investigated. Therefore, the purpose of this study was to investigate the ability of EPCs delivered in delayed fashion to induce the repair of nonhealing defects in a clinically relevant model. In order to simulate delayed treatment, 5 mm segmental defects in Fischer 344 rat femora were treated with bone marrow-derived EPCs on a Gelfoam scaffold at 3 weeks post creation of the defect. At ten weeks posttreatment, 100% of EPC-treated defects achieved union, whereas complete union was only achieved in 37.5% of defects treated with Gelfoam alone. Furthermore, significant increases in ultimate torque (p = 0.022) and torsional stiffness (p = 0.003) were found in EPC-treated defects compared to controls. Critically, no differences in outcomes were observed between acute and delayed EPC treatments. These results suggest that EPCs can enhance bone healing when applied in an acute or delayed fashion and that their use may represent a clinically translatable therapy for bone healing in humans.

Limitation of the antibiotic-eluting bone graft substitute: An example of gentamycin-impregnated calcium sulfate

Patients with inadequate volume of alveolar processes or bone defects commonly require graft substitutes in oral, maxillofacial or orthopedic surgery. Ridge augmentation and reconstruction of facial bony defects with bone graft materials achieve better outcomes in functional and aesthetic rehabilitation. The injectable calcium sulfate filler is used widely in intra-operative applications. Calcium sulfate bone filler has been shown to upregulate bone formation-related mRNA genes in vitro and improve osseointegration in vivo. In addition, the bone graft substitute can be used as a drug delivery system for antibiotics to treat or prevent infections based on the clinical experiences. However, the influences of antibiotics addition on the calcium sulfate are not fully understood. In this study, calcium sulfate impregnated with gentamycin in different weight ratios was characterized. The results showed that gentamycin prolonged the hydration process and extended initial/final setting times of calcium sulfate. The addition of gentamycin slowed the conversion from calcium sulfate hemihydrate to dihydrate and changed the crystalline phase and microstructure. Higher amounts of gentamycin added resulted in faster degradation and lower mechanical strength of calcium sulfate. This study reveals that the extended setting time, decreased compressive strength, and the accelerated degradation of the gentamycin-impregnated calcium sulfate bone graft substitutes should be considered during intra-operative applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 80-87, 2018.