The diamond concept--open questions

Transcutaneous CO2 application combined with low-intensity pulsed ultrasound accelerates bone fracture healing in rats

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapy that accelerates fracture healing. As a new treatment method for fracture, we recently reported that the transcutaneous application of CO2 accelerated fracture healing in association with promoting angiogenesis, blood flow, and endochondral ossification. We hypothesized that transcutaneous CO2 application, combined with LIPUS, would promote bone fracture healing more than the single treatment with either of them.

METHODS

Femoral shaft fractures were produced in 12-week-old rats. Animals were randomly divided into four groups: the combination of CO2 and LIPUS, CO2, LIPUS, and control groups. As the transcutaneous CO2 application, the limb was sealed in a CO2-filled bag after applying hydrogel that promotes CO2 absorption. Transcutaneous CO2 application and LIPUS irradiation were performed for 20 min/day, 5 days/week. At weeks 1, 2, 3, and 4 after the fractures, we assessed the fracture healing process using radiography, histology, immunohistochemistry, real-time PCR, and biomechanical assessment.

RESULTS

The fracture healing score using radiographs in the combination group was significantly higher than that in the control group at all time points and those in both the LIPUS and CO2 groups at weeks 1, 2, and 4. The degree of bone fracture healing in the histological assessment was significantly higher in the combination group than that in the control group at weeks 2, 3, and 4. In the immunohistochemical assessment, the vascular densities of CD31- and endomucin-positive microvessels in the combination group were significantly higher than those in the control and LIPUS groups at week 2. In the gene expression assessment, significant upregulation of runt-related transcription factor 2 (Runx2) and vascular endothelial growth factor (VEGF) was detected in the combination group compared to the LIPUS and CO2 monotherapy groups. In the biomechanical assessment, the ultimate stress was significantly higher in the combination group than in the LIPUS and CO2 groups.

CONCLUSION

The combination therapy of transcutaneous CO2 application and LIPUS had a superior effect in promoting fracture healing through the promotion of angiogenesis and osteoblast differentiation compared to monotherapy.

FixThePig: a custom 3D-printed femoral intramedullary nailing for preclinical research applications

Background

Critical-size bone defects (CSBDs) pose significant challenges in clinical orthopaedics and traumatology. Developing reliable preclinical models that accurately simulate human conditions is crucial for translational research. This study addresses the need for a reliable preclinical model by evaluating the design and efficacy of a custom-made 3D-printed intramedullary nail (IMN) specifically for CSBDs in minipigs. The study aims to answer the following questions: Can a custom-made 3D-printed IMN be designed for femoral osteosynthesis in minipigs? Does the use of the custom-made IMN result in consistent and reproducible surgical procedure, particularly in the creation and fixation of CSBDs? Can the custom-made IMN effectively treat and promote bone consolidation of CSBDs?

Hypothesis

The custom-made 3D-printed IMN can be designed to effectively create, fix and treat CSBDs in minipigs, resulting in consistent surgical outcomes.

Materials and Methods

The IMN was designed based on CT scans of minipig femurs, considering factors such as femoral curvature, length, and medullary canal diameters. It was 3D-printed in titanium and evaluated through both in vitro and in vivo testing. Female Aachen minipigs underwent bilateral femoral surgeries to create and fix CSBDs using the custom-made IMN. Post-operative follow-up included X-rays and CT scans every 2 weeks, with manual examination of explanted femurs to assess consolidation and mechanical stability after 3 months.

Results

The custom-made IMN effectively fitted the minipig femoral anatomy and facilitated reproducible surgical outcomes. Symmetric double osteotomies were successfully performed, and allografts showed minimal morphological discrepancies. However, proximal fixation faced challenges, leading to non-union in several cases, while most distal osteotomy sites achieved stable consolidation.

Discussion

The custom-made 3D-printed IMN demonstrated potential in modelling and treating CSBDs in minipigs. While the design effectively supported distal bone healing, issues with proximal fixation highlight the need for further refinements. Potential improvements include better screw placement, additional mechanical support, and adaptations such as a reduction clamp or a cephalic screw to enhance stability and distribute forces more effectively.

[Non-unions of the upper extremities]

The diagnosis and treatment of non-unions still represents an interdisciplinary challenge. Therefore, prevention, early detection and specific treatment are of great importance. Non-unions of the upper extremities, although less common than that of the lower extremities, requires special attention for successful treatment due to the central role of the shoulder girdle and arm in day to day activities. Successful treatment of non-unions requires a comprehensive evaluation of the patient's medical history, a thorough clinical examination and in particular radiological imaging. In order to effectively treat the pseudarthrosis it is crucial to distinguish between pseudarthroses that are suspected to be due to infections and those that are not. This article presents a treatment algorithm for managing both pseudarthrosis due to infection and pseudarthrosis without infection in the upper extremities.

Short-Term Celecoxib Promotes Bone Formation without Compromising Cefazolin Efficacy in an Early Orthopaedic Device-Related Infection: Evidence from a Rat Model

Non-steroidal anti-inflammatory drugs (NSAIDs) are crucial components of multimodal analgesia for musculoskeletal injuries, targeting cyclooxygenase (COX) enzymes (COX-1 and/or COX-2 isoenzymes). Concerns exist regarding their potential interference with bone healing and orthopaedic device-related infections (ODRI), where data are limited. This study aimed to investigate whether the COX-selectivity of NSAIDs interfered with antibiotic efficacy and bone changes in the setting of an ODRI. In vitro testing demonstrated that combining celecoxib (a COX-2 inhibitor) with cefazolin significantly enhanced antibacterial efficacy compared to cefazolin alone (p < 0.0001). In vivo experiments were performed using Staphylococcus epidermidis in the rat proximal tibia of an ODRI model. Long and short durations of celecoxib treatment in combination with antibiotics were compared to a control group receiving an antibiotic only. The long celecoxib treatment group showed impaired infection clearance, while the short celecoxib treatment showed increased bone formation (day 6, p < 0.0001), lower bone resorption (day 6, p < 0.0001), and lower osteolysis (day 6, BV/TV: p < 0.0001; BIC: p = 0.0005) compared to the control group, without impairing antibiotic efficacy (p > 0.9999). Given the use of NSAIDs as part of multimodal analgesia, and considering these findings, short-term use of COX-2 selective NSAIDs like celecoxib not only aids pain management but also promotes favorable bone changes during ODRI.

Polytherapy versus monotherapy in the treatment of tibial non-unions: a retrospective study

BACKGROUND

Treating tibial non-unions efficiently presents a challenge for orthopaedic trauma surgeons. The established gold standard involves implanting autologous bone graft with adequate fixation, but the addition of biologicals according to the so-called diamond concept has become increasingly popular in the treatment of non-unions. Previous studies have indicated that polytherapy, which involves implanting mesenchymal stem cells, bioactive factors and osteoconductive scaffolds, can improve bone healing. This study aims to evaluate the efficacy of polytherapy compared with monotherapy in treating tibial non-unions of varying severity.

MATERIALS AND METHODS

Data from consecutive tibial non-unions treated between November 2014 and July 2023 were retrospectively analysed. The Non Union Scoring System (NUSS) score before non-union surgery, and the Radiographic Union Score for Tibial fractures (RUST), scored at 1, 3, 6, 9, 12 and 18 months post-surgery, were recorded. Initially, a comparison was made between the polytherapy and monotherapy groups. Subsequently, patients receiving additional surgical non-union treatment were documented, and the frequency of these treatments was tallied for a subsequent per-treatment analysis.

RESULTS

A total of 34 patients were included and divided into a polytherapy group (n = 15) and a monotherapy group (n = 19). The polytherapy group demonstrated a higher NUSS score (44 (39, 52) versus 32 (29, 43), P = 0.019, z = -2.347) and a tendency towards a higher success rate (93% versus 68%, P = 0.104) compared with the monotherapy group. For the per-treatment analysis, 44 treatments were divided into the polytherapy per-treatment group (n = 20) and the monotherapy per-treatment group (n = 24). The polytherapy per-treatment group exhibited a higher NUSS score (48 (43, 60) versus 38 (30, 50), P = 0.030, z = -2.173) and a higher success rate (95% versus 58%, P = 0.006) than the monotherapy per-treatment group. Within the monotherapy per-treatment group, the NUSS score displayed excellent predictive performance (AUC = 0.9143). Setting the threshold value at 48, the sensitivity and specificity were 100.0% and 70.0%, respectively.

CONCLUSIONS

Polytherapy is more effective than monotherapy for severe tibial non-unions, offering a higher success ratio. The NUSS score supports decision-making in treating tibial non-unions.

LEVEL OF EVIDENCE

Level III.

Preventing Atrophic Long-Bone Nonunion: Retrospective Analysis at a Level I Trauma Center

Background: Among the risk factors for nonunion are unchangeable patient factors such as the type of injury and comorbidities, and factors that can be influenced by the surgeon such as fracture treatment and the postoperative course. While there are numerous studies analyzing unchangeable factors, there is poor evidence for factors that can be affected by the physician. This raises the need to fill the existing knowledge gaps and lay the foundations for future prevention and in-depth treatment strategies. Therefore, the goal of this study was to illuminate knowledge about nonunion in general and uncover the possible reasons for their development; Methods: This was a retrospective analysis of 327 patients from 2015 to 2020 from a level I trauma center in Germany. Information about patient characteristics, comorbidities, alcohol and nicotine abuse, fracture classification, type of osteosynthesis, etc., was collected. Matched pair analysis was performed, and statistical testing performed specifically for atrophic long-bone nonunion; Results: The type of osteosynthesis significantly affected the development of nonunion, with plate osteosynthesis being a predictor for nonunion. The use of wire cerclage did not affect the development of nonunion, nor did the use of NSAIDs, smoking, alcohol, osteoporosis and BMI; Conclusion: Knowledge about predictors for nonunion and strategies to avoid them can benefit the medical care of patients, possibly preventing the development of nonunion.

Development of a 3D multifunctional collagen scaffold impregnated with peptide LL-37 for vascularised bone tissue regeneration

Bone is a highly dynamic connective tissue that provides structural support, locomotion and acts as a shield for many vital organs from damage. Bone inherits the ability to heal after non-severe injury. In case of severe bone abnormalities due to trauma, infections, genetic disorders and tumors, there is a demand for a scaffold that can enhance bone formation and regenerate the lost bone tissue. In this study, a 3D collagen scaffold (CS) was functionalized and assessed under in vitro and in vivo conditions. For this, a collagen scaffold coated with hydroxyapatite (Ap-CS) was developed and loaded with a peptide LL-37. The physico-chemical characterisation confirmed the hydroxyapatite coating on the outer and inner surfaces of Ap-CS. In vitro studies confirmed that LL-37 loaded Ap-CS promotes osteogenic differentiation of human osteosarcoma cells without showing significant cytotoxicity. The efficacy of the LL-37 loaded Ap-CS for bone regeneration was evaluated at 4 and 12 weeks post-implantation by histopathological and micro-CT analysis in rabbit femur defect model. The implanted LL-37 loaded Ap-CS facilitated the new bone formation at 4 weeks compared with Ap-CS without LL-37. The LL-37 loaded Ap-CS incorporating apatite and peptide LL-37 would be useful as a multifunctional scaffold for bone tissue engineering.

Outcomes of Humerus Nonunion Surgery in Patients With Initial Operative Fracture Fixation

OBJECTIVES

To describe outcomes following humerus aseptic nonunion surgery in patients whose initial fracture was treated operatively and to identify risk factors for nonunion surgery failure in the same population.

METHODS

DESIGN

Retrospective case series.

SETTING

Eight, academic, level 1 trauma centers.

PATIENTS SELECTION CRITERIA

Patients with aseptic humerus nonunion (OTA/AO 11 and 12) after the initial operative management between 1998 and 2019.

OUTCOME MEASURES AND COMPARISONS

Success rate of nonunion surgery.

RESULTS

Ninety patients were included (56% female; median age 50 years; mean follow-up 21.2 months). Of 90 aseptic humerus nonunions, 71 (78.9%) united following nonunion surgery. Thirty patients (33.3%) experienced 1 or more postoperative complications, including infection, failure of fixation, and readmission. Multivariate analysis found that not performing revision internal fixation during nonunion surgery (n = 8; P = 0.002) and postoperative de novo infection (n = 9; P = 0.005) were associated with an increased risk of recalcitrant nonunion. Patient smoking status and the use of bone graft were not associated with differences in the nonunion repair success rate.

CONCLUSIONS

This series of previously operated aseptic humerus nonunions found that more than 1 in 5 patients failed nonunion repair. De novo postoperative infection and failure to perform revision internal fixation during nonunion surgery were associated with recalcitrant nonunion. Smoking and use of bone graft did not influence the success rate of nonunion surgery. These findings can be used to give patients a realistic expectation of results and complications following humerus nonunion surgery.

LEVEL OF EVIDENCE

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

Sintered fluorapatite scaffolds as an autograft-like engineered bone graft

Hydroxyapatite (HA)-based materials are widely used as bone substitutes due to their inherent biocompatibility, osteoconductivity, and bio-absorption properties. However, HA scaffolds lack compressive strength when compared to autograft bone. It has been shown that the fluoridated form of HA, fluorapatite (FA), can be sintered to obtain this desired strength as well as slower degradation properties. Also, FA surfaces have been previously shown to promote stem cell differentiation toward an osteogenic lineage. Thus, it was hypothesized that FA, with and without stromal vascular fraction (SVF), would guide bone healing to an equal or better extent than the clinical gold standard. The regenerative potentials of these scaffolds were tested in 32 Lewis rats in a femoral condylar defect model with untreated (negative), isograft (positive), and commercial HA as controls. Animals were survived for 12 weeks post-implantation. A semi-quantitative micro-CT analysis was developed to quantify the percent new bone formation within the defects. Our model showed significantly higher (p < .05) new bone depositions in all apatite groups compared to the autograft group. Overall, the FA group had the most significant new bone deposition, while the differences between HA, FA, and FA + SVF were insignificant (p > .05). Histological observations supported the micro-CT findings and highlighted the presence of healthy bone tissues without interposing capsules or intense immune responses for FA groups. Most importantly, the regenerating bone tissue within the FA + SVF scaffolds resembled the architecture of the surrounding trabecular bone, showing intertrabecular spaces, while the FA group presented a denser cortical bone-like architecture. Also, a lower density of cells was observed near FA granules compared to HA surfaces, suggesting a reduced immune response. This first in vivo rat study supported the tested hypothesis, illustrating the utility of FA as a bone scaffold material.

Physiologically engineered porous titanium/brushite scaffolds for critical-size bone defects: A design and manufacturing study

Repairing critical-size bone defects still represents a critical clinical challenge in the field of trauma surgery. This study focuses on a physiological design and manufacturing of porous composite scaffold (titanium Ti with 10 % mole iron doped brushite DCPD-Fe3+) which can mimic the biomechanical properties of natural cortical bone, specifically for the purpose of repairing critical-size defects. To achieve this, the principle of design of experiments (DOE) was applied for investigating the impact of sintering temperature, mineral ratio, and volume fraction of porosity on the mechanical properties of the fabricated scaffolds. The fabricated scaffolds had open porosity up to 60 %, with pore size approximately between 100 μm and 850 μm. The stiffness of the porous composite scaffolds varied between 3.30 GPa and 20.50 GPa, while the compressive strength ranged from approximately 130 MPa-165 MPa at sintering temperatures equal to or exceeding 1000 °C. Scaffolds with higher porosity and mineral content demonstrated lower stiffness values, resembling natural bone. Numerical simulation was employed by Ansys Workbench to investigate the stress and strain distribution of a critical size defect in mid-shaft femur which was designed to be replaced with the fabricated scaffold. The fabricated scaffolds showed flexible biomechanical behaviour at the bone/scaffold interface, generating lower stress levels and indicating a better match with the femoral shaft stiffness. The experimental and numerical findings demonstrated promising applications for manufacturing a patient-specific bone scaffold for critical and potentially large defects for reducing stress shielding and minimizing non-union risk.

Use of Autologous Bone Graft with Bioactive Glass as a Bone Substitute in the Treatment of Large-Sized Bone Defects of the Femur and Tibia

BACKGROUND

Managing bone defects in non-union surgery remains challenging, especially in cases of large defects exceeding 5 cm in size. Historically, amputation and compound osteosynthesis with a remaining PMMA spacer have been viable and commonly used options. The risk of non-union after fractures varies between 2% and 30% and is dependent on various factors. Autologous bone grafts from the iliac crest are still considered the gold standard but are limited in availability, prompting consideration of artificial grafts.

OBJECTIVES

The aims and objectives of the study are as follows: 1. To evaluate the radiological outcome of e.g., the consolidation and thus the stability of the bone (three out of four consolidated cortices/Lane-Sandhu-score of at least 3) by using S53P4-type bioactive glass (BaG) as a substitute material for large-sized bone defects in combination with autologous bone using the RIA technique. 2. To determine noticeable data-points as a base for future studies.

METHODS

In our clinic, 13 patients received bioactive glass (BaG) as a substitute in non-union therapy to promote osteoconductive aspects. BaG is a synthetic material composed of sodium, silicate, calcium, and phosphate. The primary endpoint of our study was to evaluate the radiological consolidation of bone after one and two years. To assess bone stabilization, we used a modified Lane-Sandhu score, considering only radiological criteria. A bone was considered stabilized if it achieved a minimum score of 3. For full consolidation (all four cortices consolidated), a minimum score of 4 was required. Each bone defect exceeded 5 cm in length, with an average size of 6.69 ± 1.92 cm.

RESULTS

The mean follow-up period for patients without final bone consolidation was 34.25 months, with a standard deviation of 14.57 months, a median of 32.00 months and a range of 33 months. In contrast, patients with a fully consolidated non-union had an average follow-up of 20.11 ± 15.69 months and a range of 45 months. Overall, the mean time from non-union surgery to consolidation for patients who achieved final union was 14.91 ± 6.70 months. After one year, six patients (46.2%) achieved complete bone consolidation according to the Lane-Sandhu score. Three patients (23.1%) displayed evident callus formation with expected stability, while three patients (23.1%) did not develop any callus, and one patient only formed a minimal callus with no expected stability. After two years, 9 out of 13 patients (69.2%) had a score of 4. The remaining four patients (30.8%) without expected stability either did not heal within two years or required a revision during that time.

CONCLUSIONS

Bioactive glass (BaG) in combination with autologous bone (RIA) appears to be a suitable filler material for treating extensive non-unions of the femur and tibia. This approach seems to show non-inferiority to treatment with Tricalcium Phosphate (TCP). To ensure the success of this treatment, it is crucial to validate the procedure through a randomized controlled trial (RCT) with a control group using TCP, which would provide higher statistical power and more reliable results.

The Impact of Injury of the Tibial Nutrient Artery Canal on Type of Nonunion of Tibial Shaft Fractures: A Retrospective Computed Tomography Study

RATIONALE AND OBJECTIVES

Blood supply is vital for sound callus formation. The tibial nutrient artery (TNA) is the main diaphyseal artery nurturing the tibial shaft. The objective is to investigate the impact of TNA canal (TNAC) injury on the development of atrophic, oligotrophic, and hypertrophic nonunion in patients with tibial shaft fractures.

MATERIALS AND METHODS

Between January 2010 and December 2020, patients with a nonunion of a tibial shaft fracture were retrospectively included. Two readers independently evaluated the integrity of the TNAC and classified nonunion type. A multinomial regression model was utilized to evaluate if a TNAC injury has an impact on the type of nonunion.

RESULTS

From an initial set of 385 patients with the diagnosis of a nonunion of the lower leg, a total of 60 patients could be finally included in the study. Most patients were males (78%), diabetic (95%), smokers (73%), and had an American Society of Anesthesiologists (ASA) score of 2 (72%). TNAC injury was noted in 24 patients (40%): an iatrogenic TNAC injury was observed in 13 (22%) patients, a traumatic TNAC injury in 11 (18%) patients. Most patients had a hypertrophic nonunion (29 patients (48%)), followed by an oligotrophic nonunion (24 patients (40%)) and lastly an atrophic nonunion (seven patients (11%)). The multinomial regression model showed that there was no impact of TNAC injury on the development of a specific type of non-union (p = 0.798 for oligotrophic vs. atrophic nonunion; p = 0.943 for hypertrophic vs. atrophic nonunion). Furthermore, patients were about four times more likely to develop an oligotrophic/hypertrophic nonunion rather than atrophic one (odds ratio 3.75 and 4.25, respectively), regardless of the presence of a TNAC injury.

CONCLUSION

In the evaluated patient cohort with tibial shaft fractures, we could not find a statistically significant association between TNAC injury and type of nonunion. However, patients were almost four times more likely to develop oligotrophic or hypertrophic nonunion rather than an atrophic one although common risk factors for impaired (micro)vascular blood supply were highly prevalent in the study group. Multicenter studies with a larger number of atrophic nonunions are warranted to further evaluate this result.

Lower-limb internal loading and potential consequences for fracture healing

Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success. Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach. Results: Mean peak forces differed with femoral compression (1,330-1,936 N at mid-shaft) amounting to about half of tibial compression (2,299-5,224 N). Mean peak bending moments in the frontal plane were greater in the femur (71-130 Nm) than in the tibia (from 26 to 43 Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (-38 to 43 Nm) reaching substantially higher values in the tibia (-63 to -175 Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (-13 to -40 Nm) versus tibia (15-48 Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up (p < 0.001) compared to tibial fractures. Specifically, compression (r = 0.304), sagittal bending (r = 0.259), and frontal bending (r = -0.318) showed strong associations (p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone. Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level.

[Reconstruction of a metadiaphyseal bone defect after open comminuted fracture of the proximal femur using a modified Masquelet technique]

The reconstruction of segmental bone defects after surgical treatment of infected delayed unions as well as nonunions, places the highest demands on the surgical technical implementation. After treating the fracture-related infection, guaranteeing biomechanical stability is crucial for the success of the treatment. The presented case describes the successful treatment of an infected delayed union after an open metadiaphyseal comminuted fracture of the proximal femur using a modified Masquelet technique. A solid allogeneic bone graft in combination with autologous cancellous bone were inserted into a 7 cm subtrochanteric defect zone and stabilized with a combined plate and nail osteosynthesis.

Synthetic Calcium-Phosphate Materials for Bone Grafting

Synthetic bone grafting materials play a significant role in various medical applications involving bone regeneration and repair. Their ability to mimic the properties of natural bone and promote the healing process has contributed to their growing relevance. While calcium-phosphates and their composites with various polymers and biopolymers are widely used in clinical and experimental research, the diverse range of available polymer-based materials poses challenges in selecting the most suitable grafts for successful bone repair. This review aims to address the fundamental issues of bone biology and regeneration while providing a clear perspective on the principles guiding the development of synthetic materials. In this study, we delve into the basic principles underlying the creation of synthetic bone composites and explore the mechanisms of formation for biologically important complexes and structures associated with the various constituent parts of these materials. Additionally, we offer comprehensive information on the application of biologically active substances to enhance the properties and bioactivity of synthetic bone grafting materials. By presenting these insights, our review enables a deeper understanding of the regeneration processes facilitated by the application of synthetic bone composites.

Three-Dimensional Printed Polycaprolactone Mesh in Pediatric Cranial Vault Remodeling Surgery

BACKGROUND

The surgical management of craniosynostosis has greatly evolved with improvements in both technology and understanding of the disease process. Some drawbacks remain regarding bone regeneration within the surgical bony gaps. Generally, bony gaps improve in the 12 to 24 months after surgery, but some gaps may remain for longer and cause deformity and/or require additional bony reconstruction. These considerations make tissue-engineered bone very attractive. Novel 3-dimensional printed bioresorbable mesh implants made of Polycaprolactone (PCL) can be used to fill the surgical bony defects.

OBJECTIVES

The authors seek to investigate how the use of a 3-dimensional printed biodegradable PCL mesh applied to bony defects in cranial vault surgery affects bone healing.

METHODS

Case series analysis of 8 pediatric patients who have undergone surgical intervention using PCL mesh implants for reconstruction of bony defects during craniosynostosis correction surgery.

FINDINGS

Radiological evaluation of 3 patients at random time points between 9 and 12 months postoperative revealed persistent bony gaps in areas where PCL mesh was laid. One patient who underwent a subsequent cranial vault surgery at 9 months was found to have less bone regeneration in the defect area where PCL mesh was used when compared with an adjacent area where a particulate bone graft was used.

CONCLUSIONS

Based on our experience, the use of PCL mesh on its own did not augment bone regeneration. It is possible that a greater amount of time or increased vascularization of the scaffold is required, which supports the concept of regenerative matching axial vascularization or the further addition of osteogenic factors to increase the rate of bone formation.

Arginine Availability in Reamed Intramedullary Aspirate as Predictor of Outcome in Nonunion Healing

Fracture healing and nonunion development are influenced by a range of biological factors. Adequate amino acid concentrations, especially arginine, are known to be important during normal bone healing. We hypothesize that bone arginine availability in autologous bone marrow grafting, when using the reamer-irrigator-aspirator (RIA) procedure, is a marker of bone healing capacity in patients treated for nonunion. Seventeen patients treated for atrophic long bone nonunion by autologous bone grafting by the RIA procedure were included and divided into two groups, successful treatment of nonunion and unsuccessful, and were compared with control patients after normal fracture healing. Reamed bone marrow aspirate from a site distant to the nonunion was obtained and the amino acids and enzymes relevant to arginine metabolism were measured. Arginine and ornithine concentrations were higher in patients with successful bone healing after RIA in comparison with unsuccessful healing. Ornithine concentrations and arginase-1 expression were lower in all nonunion patients compared to control patients, while citrulline concentrations were increased. Nitric oxide synthase 2 (Nos2) expression was significantly increased in all RIA-treated patients, and higher in patients with a successful outcome when compared with an unsuccessful outcome. The results indicate an influence of the arginine-nitric oxide metabolism in collected bone marrow, on the outcome of nonunion treatment, with indications for a prolonged inflammatory response in patients with unsuccessful bone grafting therapy. The determination of arginine concentrations and Nos2 expression could be used as a predictor for the successful treatment of autologous bone grafting in nonunion treatment.

Preoperative contrast-enhanced ultrasound (CEUS) of long bone nonunions reliably predicts microbiology of tissue culture samples but not of implant-sonication

INTRODUCTION

Bacterial infection in the context of fracture repair remains a severe complication in trauma surgery and may result in long bone nonunion. Since treatment options for aseptic and infected nonunions vary greatly, diagnostic methods should ideally differentiate between these two entities as accurately as possible. Recently, contrast-enhanced ultrasound (CEUS) has been introduced as a preoperative imaging technique to evaluate hypervascularity at the fracture site as sign of bacterial infection.

HYPOTHESIS

Preoperative CEUS predicts results of microbiological evaluation obtained either by culture of tissue samples or by analyzing the sonication fluid following removal and sonication of the implant.

PATIENTS AND METHODS

Over the course of 6 months, 26 patients with long bone nonunions were included in this study. Patients' clinical data were evaluated. Tissue samples were collected intraoperatively and examined by standard microbiological techniques. The sonication method was applied to removed implants. Additionally, 1-3 days before surgery, CEUS was performed to determine hypervascularity at the nonunion site as a possible parameter for infection.

RESULTS

Culture of tissue samples indicated infection in 50% of cases and implant sonication in 57.7% of cases. However, there was merely a fair agreement (κ=0.231) between these two diagnostic methods. CEUS predicted results of tissue culture reliably (sensitivity 92.3% and specificity 100%), whereas implant sonication showed no significant correlations with results from CEUS. Hypertrophic and atrophic nonunions were evaluated separately to determine possible differences in vascularity. We found that contrast peak enhancement of CEUS was similar in atrophic and hypertrophic nonunions with positive culture of tissue samples. Both differed significantly from culture negative cases (p=0.0016 and 0.0062). Results of implant-sonication positive or negative cases in atrophic and hypertrophic nonunions, however, were less clear and could be misleading.

DISCUSSION

We were able to confirm CEUS as a valuable preoperative diagnostic tool that reliably predicts microbiology of tissue culture samples, but not of implant sonication.

LEVEL OF EVIDENCE

I; diagnostic study.

Microfluidic 3D Platform to Evaluate Endothelial Progenitor Cell Recruitment by Bioactive Materials

Most of the conventional in vitro models to test biomaterial-driven vascularization are too simplistic to recapitulate the complex interactions taking place in the actual cell microenvironment, which results in a poor prediction of the in vivo performance of the material. However, during the last decade, cell culture models based on microfluidic technology have allowed attaining unprecedented levels of tissue biomimicry. In this work, we propose a microfluidic-based 3D model to evaluate the effect of bioactive biomaterials capable of releasing signalling cues (such as ions or proteins) in the recruitment of endogenous endothelial progenitor cells, a key step in the vascularization process. The usability of the platform is demonstrated using experimentally-validated finite element models and migration and proliferation studies with rat endothelial progenitor cells (rEPCs) and bone marrow-derived rat mesenchymal stromal cells (BM-rMSCs). As a proof of concept of biomaterial evaluation, the response of rEPCs to an electrospun composite made of polylactic acid with calcium phosphates nanoparticles (PLA+CaP) was compared in a co-culture microenvironment with BM-rMSC to a regular PLA control. Our results show a significantly higher rEPCs migration and the upregulation of several pro-inflammatory and proangiogenic proteins in the case of the PLA+CaP. The effects of osteopontin (OPN) on the rEPCs migratory response were also studied using this platform, suggesting its important role in mediating their recruitment to a calcium-rich microenvironment. This new tool could be applied to screen the capacity of a variety of bioactive scaffolds to induce vascularization and accelerate the preclinical testing of biomaterials. STATEMENT OF SIGNIFICANCE: : For many years researchers have used neovascularization models to evaluate bioactive biomaterials both in vitro, with low predictive results due to their poor biomimicry and minimal control over cell cues such as spatiotemporal biomolecule signaling, and in vivo models, presenting drawbacks such as being highly costly, time-consuming, poor human extrapolation, and ethically controversial. We describe a compact microphysiological platform designed for the evaluation of proangiogenesis in biomaterials through the quantification of the level of sprouting in a mimicked endothelium able to react to gradients of biomaterial-released signals in a fibrin-based extracellular matrix. This model is a useful tool to perform preclinical trustworthy studies in tissue regeneration and to better understand the different elements involved in the complex process of vascularization.

Aseptic nonunion of the tibia treated by plating and bone grafting: retrospective study about 40 cases

Objective

The objective of this study was to evaluate the clinical and radiological results of the treatment of aseptic nonunion of the tibia by plating and bone grafting.

Material and Methods

This retrospective study included 40 patients with aseptic nonunion of the tibia, treated in the Trauma-Orthopedic department B4 of CHU Hassan II in Fez-Morocco. The average age was 41 years (range 25–60 years). The initial fractures were in the middle third of the tibia for the majority of our patients. We used the ASAMI criteria to assess the results.

Results

We found 45 patients with aseptic nonunion of the tibia who were treated by the same surgical team and followed in postoperative consultation for a fixed period of 10 months. Three patients lost to follow-up and two patients refused the treatment. In 37 patients (92.5%), union was obtained after a mean delay of 4.3 months (range 3–7 months). The average time from initial treatment to treatment for nonunion was eight months (range 6–10 months). According to the ASAMI classification, bone results were excellent in 26, good in 8, fair in 3 and poor in 3; functional results were excellent in 10, good in 16, fair in 11 and poor in 3.

Conclusions

Our study suggests that the combination of screwed plate and autograft in the treatment of aseptic nonunion of the tibia has provided satisfactory results. A well-codified management of the initial fracture remains the gold key to prevent the occurrence of pseudarthrosis.

Spatial rhBMP2 delivery from hydroxyapatite scaffolds sustains bone regeneration in rabbit radius

Regenerating large bone defects requires a multi-faceted approach combining optimal scaffold designs with appropriate growth factor delivery. Supraphysiological doses of recombinant human bone morphogenetic protein 2(rhBMP2); typically used for the regeneration of large bone defects clinically in conjunction with an acellular collagen sponge (ACS), have resulted in many complications. In the current study, we develop a hydroxyapatite/collagen I (HA/Col) scaffold to improve the mechanical properties of the HA scaffolds while maintaining open connected porosity. Varying rhBMP2 dosages were then delivered from a collagenous periosteal membrane and paired with HA or HA/Col scaffolds to treat critical sized (15mm) diaphyseal radial defect in New Zealand white rabbits. The groups examined were ACS+76µg rhBMP2 (clinically used INFUSE dosage), HA+76µg rhBMP2, HA+15µg rhBMP2, HA/Col+15µg rhBMP2 and HA/Col+15µg rhBMP2+bone marrow derived stromal cells (bMSCs). After 8 weeks of implantation, all regenerated bones were evaluated using micro computed tomography, histology, histomorphometry and torsional testing. It was observed that the bone volume regenerated in the HA/Col + 15 µg rhBMP2 group was significantly higher than that in the groups with 76µg rhBMP2. The same scaffold and growth factor combination resulted in the highest bone mineral density of the regenerated bone, and the most bone apposition on the scaffold surface. Both the HA and HA/Col scaffolds paired with 15 µg rhBMP2 had sustained ingrowth of the mineralization front after 2 weeks compared to the groups with 76µg rhBMP2 which had far greater mineralization in the first 2 weeks after implantation. Complete bridging of the defect site and no significant differences in torsional strength, stiffness or angle at failure was observed across all groups. No benefit of additional bMSC seeding was observed on any of the quantified metrics, while bone-implant apposition was reduced in the cell seeded group. This study demonstrated that the controlled spatial delivery of rhBMP2 at the periosteum at significantly lower doses can be used as a strategy to improve bone regeneration around space maintaining scaffolds.

Efficacy of total flavonoids of Rhizoma drynariae on the blood vessels and the bone graft in the induced membrane

BACKGROUND

Total flavonoids of Rhizoma drynariae (TFRD), a Chinese medicine, is widely used in the treatment of orthopedic diseases. However, there are few basic and clinical studies on the effect of TFRD on induced membrane technique (Masquelet technique).

PURPOSE

This trial is to explore effects of TFRD on vascularization of the induced membrane, and mineralization of the bone graft in rats with femoral bone defects.

STUDY DESIGN AND METHODS

Forty-eight Sprague-Dawley rats were randomly divided into high dose group (H-TFRD), medium dose group (M-TFRD), low dose group (L-TFRD) and control group (control). The segmental bone defects were established with 12 rats in per group. The polymethyl methacrylate (PMMA) spacer was implanted into the femoral bone defect of rats in the first-stage surgery. About 4 weeks after first-stage surgery, induced membranes of 6 rats in each group were selected. The blood vessels and angiogenesis-related factors in the induced membrane were analyzed by hematoxylin-eosin (HE) and masson staining, western blot, qPCR and immunohistostaining. The remaining rats in per group underwent second-stage surgery (bone grafting). Twelve weeks after the bone grafting, the bone tissues was examined by X-ray, micro-computed tomography (Micro-CT), HE staining and enzyme-linked immunosorbent assay (ELISA) to evaluate the growth of the bone graft. Meanwhile, the TFRD-containing serum was collected from rats to culture osteoblasts in vitro. Cell Counting Kit-8 (CCK-8) method, Alizarin Red S (ARS) staining, western blot and immunofluorescence were used to detect effects of TFRD on the osteoblasts' proliferation and BMP-SMAD signaling pathway.

RESULTS

Compared with the L-TFRD and control groups, the number of blood vessels and the expression of angiogenesis-related factors (VEGF, TGF-β1, BMP-2, PDGF-BB and CD31) were higher in the H-TFRD and M-TFRD groups. The Lane-Sandhu X-ray score, bone mass and growth rate of the bone graft in the H-TFRD and M-TFRD groups were significantly better than those in the L-TFRD and control groups. In addition, medium and high doses of TFRD significantly increased the expression of BMP-SMAD pathway proteins (BMP-2, SMAD1, SMAD4, SMAD5 and RUNX2) in rat serum and bone graft. In vitro, after osteoblasts were intervened with TFRD-containing serum from the H-TFRD and M-TFRD groups, the cell viability, the number of mineralized nodules and the phosphorylation of BMP-SMAD pathway proteins were markedly increased.

CONCLUSION

TFRD could promote the formation of blood vessels and the expression of angiogenesis-related factors during the formation of the induced membrane. During the growing period of bone graft, it could facilitate the growth and mineralization of bone graft in a dose-dependent manner, which is partly related to the activation and phosphorylation of BMP-SMAD signaling pathway.

Continuous and intermittent parathyroid hormone administration promotes osteogenic differentiation and activity of programmable cells of monocytic origin

Bone healing deficiencies are challenging for orthopedic practice. The use of stem cells with scaffolds to treat bone tissue losses currently is popular for promoting regeneration of tissue. Programmable cells of monocytic origin (PCMO) may differentiate into three germ layers and may be a promising alternative treatment due to their stem cell-like properties. Parathyroid hormone (PTH) participates in bone metabolism. Intermittent administration of PTH promotes osteogenic activity of mesenchymal stem cdells (MSC). We investigated the osteogenic effects of continuous and intermittent administration of PTH on PCMO. Mononuclear cells were harvested from the peripheral blood of healthy donors. Isolated cells were cultured for six days in a de-differentiation medium. Indirect immunocytochemistry using anti-CD14, anti-CD45 and anti-CD90 primary antibodies, as well as electron microscopy were used to detect PCMO. PCMO then were cultured in an osteogenic differentiation medium supplemented with continuous or intermittent 50 ng/ml PTH. The PTH-free control group (CG), intermittent PTH treated group (IPG) and continuous PTH treated group (CPG) were cultured and assessed for their differentiation into osteogenic lineage cells by indirect immunocytochemistry using anti-collagen I, anti-osteonectin and anti-osteocalcin primary antibodies. Osteoblast-like cells obtained by continuous or intermittent PTH administration exhibited increased levels of collagen I, osteonectin and osteocalcin immunoreactivity. We found that continuous and intermittent PTH administration to PCMO enhanced their differentiation to osteogenic lineage cells and increased osteoblastic activity.

CD301b+ macrophages mediate angiogenesis of calcium phosphate bioceramics by CaN/NFATc1/VEGF axis

Calcium phosphate (CaP) bioceramics are important for tissue regeneration and immune response, yet how CaP bioceramics influence these biological processes remains unclear. Recently, the role of immune cells in biomaterial-mediated regeneration, especially macrophages, has been well concerned. CD301b⁺ macrophages were a new subset of macrophages we have discovered, which were required for bioceramics-mediated bone regeneration. Nevertheless, the impact of CD301b⁺ macrophages on angiogenesis, which is a vital prerequisite to bone formation is yet indistinct. Herein, we found that CD301b⁺ macrophages were closely correlated to angiogenesis of CaP bioceramics. Additionally, depletion of CD301b⁺ macrophages led to the failure of angiogenesis. We showed that store-operated Ca²⁺ entry and calcineurin signals regulated the VEGF expression of CD301b⁺ macrophages via the NFATc1/VEGF axis. Inhibition of calcineurin effectively impaired angiogenesis via decreasing the infiltration of CD301b⁺ macrophages. These findings provided a potential immunomodulatory strategy to optimize the integration of angiogenesis and bone tissue engineering scaffold materials.

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BCP bioceramics need the involvement of CD301b⁺ macrophages to promote angiogenesis.

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Surrounding BCP, CD301b⁺ macrophages are controlled by CaN and SOCE to express VEGF.

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BCP bioceramics direct CD301b⁺ macrophages' infiltration partly through calcineurin.

Collagen-based biocomposites inspired by bone hierarchical structures for advanced bone regeneration: ongoing research and perspectives

Bone is a hard-connective tissue composed of matrix, cells and bioactive factors with a hierarchical structure, where the matrix is mainly composed of type I collagen and hydroxyapatite. Collagen fibers assembled by collagen are the template for mineralization and make an important contribution to bone formation and the bone remodeling process. Therefore, collagen has been widely clinically used for bone/cartilage defect regeneration. However, pure collagen implants, such as collagen scaffolds or sponges, have limitations in the bone/cartilage regeneration process due to their poor mechanical properties and osteoinductivity. Different forms of collagen-based composites prepared by incorporating natural/artificial polymers or bioactive inorganic substances are characterized by their interconnected porous structure and promoting cell adhesion, while they improve the mechanical strength, structural stability and osteogenic activities of the collagen matrix. In this review, various forms of collagen-based biocomposites, such as scaffolds, sponges, microspheres/nanoparticles, films and microfibers/nanofibers prepared by natural/synthetic polymers, bioactive ceramics and carbon-based materials compounded with collagen are reviewed. In addition, the application of collagen-based biocomposites as cytokine, cell or drug (genes, proteins, peptides and chemosynthetic) delivery platforms for proangiogenesis and bone/cartilage tissue regeneration is also discussed. Finally, the potential application, research and development direction of collagen-based biocomposites in future bone/cartilage tissue regeneration are discussed.

Recycled windshield glass as new material for producing ultrasonic phantoms of cortical bone-healing stages

The quantitative ultrasound technique was used to evaluate bone-mimicking phantoms; however, these phantoms do not mimic the intermediate stages of cortical bone healing. We propose using windshield glass as an original material to produce phantoms that mimic the characteristics of three different stages of cortical bone healing. This material was processed via a route that included breaking, grinding, compacting, drying, and sintering in four temperature groups: 625 °C, 645 °C, 657 °C, and 663 °C. The parameters evaluated were the ultrasonic longitudinal phase velocity (cL), corrected (αc) ultrasonic attenuation coefficient, and bulk density (ρs). The results showed that the mean values ofcL,αc,andρsvaried from 2, 398 to 4, 406 m·s^-1, 3 to 10 dB·cm^-1, and 1, 563 to 2, 089 kg·m^-3, respectively. The phantoms exhibited properties comparable with the three stages of cortical bone healing and can be employed in diagnostic and therapeutic studies using ultrasound.

The Effect of Bolus Vitamin D3 Supplementation on Distal Radius Fracture Healing: A Randomized Controlled Trial Using HR-pQCT

Vitamin D is an important factor in bone metabolism. Animal studies have shown a positive effect of vitamin D₃ supplementation on fracture healing, but evidence from clinical trials is inconclusive. A randomized controlled trial was performed to assess the effects of vitamin D₃ supplementation on fracture healing using HR-pQCT-based outcome parameters. Thirty-two postmenopausal women with a conservatively treated distal radius fracture were included within 2 weeks postfracture and randomized to a low-dose (N = 10) and a high-dose (N = 11) vitamin D intervention group receiving a 6-week bolus dose, equivalent to 700 and 1800 IU vitamin D₃ supplementation per day, respectively, in addition to a control group (N = 11) receiving no supplementation. After the baseline visit 1-2 weeks postfracture, follow-up visits were scheduled at 3-4, 6-8, and 12 weeks postfracture. At each visit, HR-pQCT scans of the fractured radius were performed. Cortical and trabecular bone density and microarchitectural parameters and microfinite element analysis-derived torsion, compression, and bending stiffness were assessed. Additionally, serum markers of bone resorption (CTX) and bone formation (PINP) were measured. Baseline serum levels of 25OHD₃ were <50 nmol/L in 33% of all participants and <75 nmol/L in 70%. Compared with the control group, high-dose vitamin D₃ supplementation resulted in a decreased trabecular number (regression coefficient β: -0.22; p < 0.01) and lower compression stiffness (B: -3.63; p < 0.05, together with an increase in the bone resorption marker CTX (B: 0.062; p < 0.05). No statistically significant differences were observed between the control and low-dose intervention group. In conclusion, the bolus equivalent of 700 U/day vitamin D₃ supplementation in a Western postmenopausal population does not improve distal radius fracture healing and an equivalent dose of 1800 IU/day may be detrimental in restoring bone stiffness during the first 12 weeks of fracture healing. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Minimally invasive treatment of long bone non-unions with bone marrow concentrate, demineralized bone matrix and platelet-rich fibrin in 38 patients

To determine the efficacy of percutaneous injection of autologous bone marrow concentrated (BMC), demineralized bone matrix (DBM), and platelet rich fibrin (PRF) in the treatment of long bone non-unions. From January 2011 to January 2018 patients with non-union of the lower limbs who were on the waiting list for open grafting with established tibial or femoral non-union and minimal deformity were eligible to participate in this study. Patients were treated with a single percutaneous injection of DBM, BMC and PRF. Our study group comprised 38 patients (26 males and 12 females; mean age 39, range 18 to 65). Non-unions were located in the femur (18 cases) and in the tibia (20 cases). Clinical and imaging follow-up ranged from 4 to 60 months (mean 20 months). Bone union occurred in 30 out of 38 patients (79%) in an average of 7 months (range 3 to 12) and all healed patients had full weight bearing after 9 months on average (range 6 to 12) from injection. In 19 cases the osteosynthesis was removed 12 months on average (range 3 to 36) from surgery. One patient developed infection at the non-union site after treatment. Percutaneous injection of DBM, BMC, and PRF is an effective treatment for long-bone non-unions. This technique allows the bone to heal with a minimally invasive approach and with a hospitalization of 2 days. Key elements of bone regeneration consist of a combination of biological and biomechanical therapeutic approach.

Bone marrow aspirate concentrate/platelet-rich fibrin augmentation accelerates healing of aseptic upper limb nonunions

Introduction

Nonunions remain a significant burden in orthopedics, often afflicting young males of working age. Positive findings have been published using bone marrow aspirate concentrate (BMAC) and platelet-rich fibrin (PRF) for the treatment augmentation of lower limb nonunions. The aim of this study was to investigate if the treatment augmentation with BMAC and PRF can also accelerate the healing of nonunions of the upper limb.

Materials and methods

Sixty-eight patients (45 men, 23 women) affected by 75 nonunions of long bones of the upper limb were treated and divided into two groups. The first series was treated with standard surgery alone (group A); afterwards, the second series benefited from standard surgery with the addition of BMAC and PRF applied on lyophilized bone chips. Nonunions were classified radiographically according to the Weber–Cech method and prognostically using the Calori and Moghaddam scores. All patients were radiographically assessed at 1.5, 3, 6, 12, and 24 months of follow-up.

Results

Baseline demographic characteristics did not present differences between groups. No differences were documented in terms of complications (two in group A and three in group B). Significant differences were instead documented in terms of healing time. The first healing signs were observed 1.5 months after surgery in 90.7% of patients in group B and 34.4% of group A (p < 0.0005). At 1.5, 3, 6, and 12 months, a higher radiographic score was found for group B (all p < 0.0005), while no difference was found at final follow-up of 24 months (90.6% of group A and 97.7% of group B achieved radiological healing). Faster healing with BMAC/PRF augmentation was confirmed for all bones, as well as for the subgroup of patients affected by atrophic nonunions (p = 0.001).

Conclusion

This study showed the benefits of restoring both mechanical and biological aspects when addressing nonunions of the long bones of the upper limb. In particular, the association of BMAC and PRF to lyophilized bone chips was safe and able to accelerate healing time. These good results were confirmed for humerus, radius, and ulna sites, as well as for challenging atrophic nonunions of the upper limb.

In vivo effectiveness of hybrid membranes with osteogenic growth peptide for bone regeneration

Guided bone regeneration (GBR) technique helps to restore bone tissue through cellular selectivity principle. Currently no osteoinductive membrane exists on the market. Osteogenic growth peptide (OGP) acts as a hematopoietic stimulator. This association could improve the quality of bone formation, benefiting more than 2.2 million patients annually. The objective of this work was to develop membranes from ureasil-polyether materials containing OGP. The membranes were characterized by differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). OGP was synthesized by the solid phase method. Sterilization results using gamma radiation at 24 kGy did not change the structure of the material, as confirmed by DSC. The SAXS technique revealed the structural homogeneity of the matrix. OGP was incorporated in 66.25 × 10^-10  mol and release results showed that the ureasil-PPO400/PEO500 and ureasil-PPO400/PEO1900 membranes released 7% and 21%, respectively, after 48 h. In vivo results demonstrated that the amount and quality of bone tissue formed in the bone defects in the presence of ureasil-polyether membranes with OGP were similar to commercial collagen material with BMP. The results allow us to conclude that membranes with OGP have characteristics that make them potential candidates for the GBR.

The rationale behind implant coatings to promote osteointegration, bone healing or regeneration

Implant loosening, bone healing failure, implant-associated infections, and large bony defects remain challenges in orthopedic surgery. Implant surface modifications and coatings are being developed to promote osteointegration, prevent colonization by bacteria, and release bioactive factors. The following mini-review briefly discusses the clinical problem, explains the four "osteos", presents examples of coatings used for different orthopedic indications, and finally raises awareness of the coating and translational requirements.

Total Flavonoids of Rhizoma Drynariae Promotes Differentiation of Osteoblasts and Growth of Bone Graft in Induced Membrane Partly by Activating Wnt/β-Catenin Signaling Pathway

Total flavonoids of Rhizoma drynariae (TFRD), a Chinese medicine, is widely used in the treatment of fracture, bone defect, osteoporosis and other orthopedic diseases, and has achieved good effects. Purpose of this trial was to explore efficacy of TFRD on bone graft’s mineralization and osteoblasts’ differentiation in Masquelet induced membrane technique in rats. Forty male Sprague-Dawley rats were randomly divided into high dose group (H-TFRD), middle dose group (M-TFRD), low dose group (L-TFRD) and control group (control). The critical size bone defect model of rats was established with 10 rats in each group. Polymethyl methacrylate (PMMA) spacer was implanted into the defect of right femur in rats. After the formation of the induced membrane, autogenous bone was implanted into the induced membrane. After 12 weeks of bone graft, bone tissues in the area of bone graft were examined by X-ray, Micro-CT, hematoxylin-eosin (HE) and Masson trichrome staining to evaluate the growth of the bone graft. The β-catenin, c-myc, COL1A1, BMP-2 and OPN in bone graft were quantitatively analyzed by Western blot and Immunohistostaining. Osteoblasts were cultured in the medium containing TFRD. Cell Counting Kit-8 (CCK-8) method, Alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining, Western blot, RT-PCR and other methods were used to detect the effects of TFRD on the proliferation of osteoblasts and the regulation of Wnt/β-catenin signaling pathway. In vivo experiments showed that the growth and mineralization of bone graft in TFRD group was better. Moreover, the expression of Wnt/β-catenin and osteogenesis-related proteins in bone tissue of TFRD group was more than that in other groups. In vitro experiments indicated that osteoblasts proliferated faster, activity of ALP was higher, number of mineralized nodules and proteins related to osteogenesis were more in TFRD group. But blocking Wnt/β-catenin signaling pathway could limit these effects. Therefore, TFRD could promote mineralization of bone graft and differentiation of osteoblasts in a dose-dependent manner during growing period of the bone graft of induced membrane technique, which is partly related to the activation of Wnt/β-catenin signaling pathway.

Low-dose IL-34 has no effect on osteoclastogenesis but promotes osteogenesis of hBMSCs partly via activation of the PI3K/AKT and ERK signaling pathways

Background

Inflammatory microenvironment is significant to the differentiation and function of mesenchymal stem cells (MSCs). It evidentially influences the osteoblastogenesis of MSCs. IL-34, a newly discovered cytokine, playing a key role in metabolism. However, the research on its functional role in the osteogenesis of MSCs was rarely reported. Here, we described the regulatory effects of low-dose IL-34 on both osteoblastogenesis and osteoclastogenesis.

Methods

We performed the osteogenic effects of hBMSCs by exogenous and overexpressed IL-34 in vitro, so were the osteoclastogenesis effects of mBMMs by extracellular IL-34. CCK-8 was used to assess the effect of IL-34 on the viability of hBMSCs and mBMMs. ALP, ARS, and TRAP staining was used to evaluate ALP activity, mineral deposition, and osteoclastogenesis, respectively. qRT-PCR and Western blotting analysis were performed to detect the expression of target genes and proteins. ELISA was used to evaluate the concentrations of IL-34. In vivo, a rat tibial osteotomy model and an OVX model were established. Radiographic analysis and histological evaluation were performed to confirm the therapeutic effects of IL-34 in fracture healing and osteoporosis. Statistical differences were evaluated by two-tailed Student’s t test, one-way ANOVA with Bonferroni’s post hoc test, and two-way ANOVA with Bonferroni multiple comparisons post hoc test in the comparison of 2 groups, more than 2 groups, and different time points of treated groups, respectively.

Results

Promoted osteoblastogenesis of hBMSCs was observed after treated by exogenous or overexpressed IL-34 in vitro, confirmed by increased mineral deposits and ALP activity. Furthermore, exogenous or overexpressed IL-34 enhanced the expression of p-AKT and p-ERK. The specific AKT and ERK signaling pathway inhibitors suppressed the enhancement of osteoblastogenesis induced by IL-34. In a rat tibial osteotomy model, imaging and histological analyses testified the local injection of exogenous IL-34 improved bone healing. However, the additional IL-34 has no influence on both osteoclastogenesis of mBMMs in vitro and osteoporosis of OVX model of rat in vivo.

Conclusions

Collectively, our study demonstrate that low-dose IL-34 regulates osteogenesis of hBMSCs partly via the PIK/AKT and ERK signaling pathway and enhances fracture healing, with neither promoting nor preventing osteoclastogenesis in vitro and osteoporosis in vivo.

The Influence of an Occult Infection on the Outcome of Autologous Bone Grafting During Surgical Bone Reconstruction: A Large Single-Center Case-Control Study

Background

Occult infections (OI) lack typical inflammatory signs, making them challenging to diagnose. Uncertainty remains regarding OI’s influence on the outcome of autologous bone grafting (ABG), and evidence-based recommendations regarding an appropriate course of action are missing. Thus, we sought to determine the incidence of an OI in patients receiving ABG, evaluate whether it influences the outcome of ABG and whether associated risk factors have a further negative influence.

Methods

This study was designed as a large size single-center case-control study investigating patients treated between 01/01/2010 and 31/12/2016 with a minimum follow-up of 12 months. Patients ≥18 years presenting with a recalcitrant non-union of the lower limb receiving surgical bone reconstruction, including bone grafting, were included. A total of 625 patients were recruited, and 509 patients included in the current study. All patients received surgical non-union therapy based on the “diamond concept” including bone reconstruction using ABG. Additionally, multiple tissue samples were harvested and microbiologically analyzed. Tissue samples were microbiologically evaluated regarding an OI. Bone healing was analyzed using clinical and radiological parameters, patient characteristics and comorbidities investigated and ultimately results correlated.

Results

Forty-six out of 509 cases with OI resulted in an incidence of 9.04%. Overall consolidation time was increased by 15.08 weeks and radiological outcome slightly impaired (79.38% vs 71.42%), differences were at a non-significant extent. Diabetes mellitus had a significant negative influence on consolidation time (p=0.0313), while age (p=0.0339), smoking status (p=0.0337), diabetes mellitus (p=0.0400) and increased BMI (p=0.0315) showed a significant negative influence on the outcome of bone grafting.

Conclusion

Surgeons treating recalcitrant non-unions should be aware that an OI is common. If an OI is diagnosed subsequent to ABG the majority of patients does not need immediate revision surgery. However, special attention needs to be paid to high-risk patients.

The AMANDUS Project PART II-Advanced Microperfusion Assessed Non-Union Diagnostics with Contrast-Enhanced Ultrasound (CEUS): A Reliable Diagnostic Tool for the Management and Pre-operative Detection of Infected Upper-Limb Non-unions

The management of upper-limb non-unions can be challenging, especially when infection is existent. Thus, pre-operative detection of infection plays a relevant role in non-union treatment. This study investigated in a large cohort the diagnostic potential of contrast-enhanced ultrasound (CEUS) as stand-alone method for differentiating between aseptic and infected upper-limb non-unions. Osseous perfusion of 50 upper-extremity non-unions (radius/ulna, n = 20; humerus, n = 22; clavicle, n = 8) was prospectively assessed with CEUS before revision surgery. The perfusion was quantified via time-intensity curves and peak enhancement (in arbitrary units). Significant perfusion differences between aseptic and infected non-unions could be detected (peak enhancement, p < 0.001). The sensitivity and specificity for the detection of infected upper-limb non-unions were 80% and 94.3% (cutoff peak enhancement: 130.8 arbitrary units). CEUS reliably differentiates between aseptic and infected upper-limb non-unions. Consequently, CEUS should be integrated into the daily diagnostic routine algorithm to plan non-union revision surgery more precisely as a single- or multi-step procedure.

Expression of VEGF in Peripheral Serum Is a Possible Prognostic Factor in Bone-Regeneration via Masquelet-Technique-A Pilot Study

Two-step Masquelet-technique established a new procedure in the treatment of osseous defects, addressing prerequisites postulated by the “diamond concept”. Increase in blood perfusion and growth factors are enhanced by the “Masquelet-membrane”. To describe this, we measured serum levels of Vascular Endothelial Growth Factor (VEGF) of patients with atrophic non-unions of long bones undergoing Masquelet-technique. From over 500 non-union patients undergoing Masquelet-technique with prospective follow-up we randomly selected 30 patients. 23 were included, 7 lost to follow-up or excluded because of incomplete data. Serum was drawn at specified intervals before and after surgery. Patients were followed for at least 6 months after step 2. Classification into both groups was performed according to radiological results and clinical outcome 6 months after step 2. Concentration of VEGF in patients’ serum was performed via ELISA. 14 achieved osseous consolidation (responder group), 9 cases did not (non-responder). Responders showed a significant increase of serum-VEGF in the first and second week when compared to the preoperative values of step 1. Non-responders showed a significant increase of VEGF in the second week after Steps 1 and 2. Comparison of groups showed significantly higher increase of serum-VEGF week2 after step 1 and preoperative to step 2 for responders. Results show one possibility of illustrating therapeutic progress by monitoring growth factors and possibly allowing prognostic conclusions thereof. This might lead to a more targeted treatment protocol.

Silica-Based Bioactive Glasses and Their Applications in Hard Tissue Regeneration: A Review

Regenerative medicine is a field that aims to influence and improvise the processes of tissue repair and restoration and to assist the body to heal and recover. In the field of hard tissue regeneration, bio-inert materials are being predominantly used, and there is a necessity to use bioactive materials that can help in better tissue-implant interactions and facilitate the healing and regeneration process. One such bioactive material that is being focused upon and studied extensively in the past few decades is bioactive glass (BG). The original bioactive glass (45S5) is composed of silicon dioxide, sodium dioxide, calcium oxide, and phosphorus pentoxide and is mainly referred to by its commercial name Bioglass. BG is mainly used for bone tissue regeneration due to its osteoconductivity and osteostimulation properties. The bioactivity of BG, however, is highly dependent on the compositional ratio of certain glass-forming system content. The manipulation of content ratio and the element compositional flexibility of BG-forming network developed other types of bioactive glasses with controllable chemical durability and chemical affinity with bone and bioactivity. This review article mainly discusses the basic information about silica-based bioactive glasses, including their composition, processing, and properties, as well as their medical applications such as in bone regeneration, as bone grafts, and as dental implant coatings.

Calcium phosphate cements: Optimization toward biodegradability

Synthetic calcium phosphate (CaP) ceramics represent the most widely used biomaterials for bone regenerative treatments due to their biological performance that is characterized by bioactivity and osteoconductive properties. From a clinical perspective, injectable CaP cements (CPCs) are highly appealing, as CPCs can be applied using minimally invasive surgery and can be molded to optimally fill irregular bone defects. Such CPCs are prepared from a powder and a liquid component, which upon mixing form a paste that can be injected into a bone defect and hardens in situ within an appropriate clinical time window. However, a major drawback of CPCs is their poor degradability. Ideally, CPCs should degrade at a suitable pace to allow for concomitant new bone to form. To overcome this shortcoming, control over CPC degradation has been explored using multiple approaches that introduce macroporosity within CPCs. This strategy enables faster degradation of CPC by increasing the surface area available to interact with the biological surroundings, leading to accelerated new bone formation. For a comprehensive overview of the path to degradable CPCs, this review presents the experimental procedures followed for their development with specific emphasis on (bio)material properties and biological performance in pre-clinical bone defect models.

Effectiveness of granulocyte colony stimulating factor to enhance healing on delayed union fracture model Sprague-Dawley rat

INTRODUCTION

Delayed union is a problem that can occur after fracture healing. Many studies were conducted based on the diamond concept approach to solve the problem of delayed union. Granulocyte-colony stimulating factor (G-CSF) is one of the various substances known to have a positive role in healing skeletal tissue or adjuvant regeneration. This study was conducted to see the effect of G-CSF in affecting delayed union fracture healing.

MATERIALS AND METHOD

The experimental study was conducted by randomized posttest only control group design on 24 experimental animals Sprague-Dawley white rats that had experienced delayed union models. The study compared the treatment group injected with subcutaneous G-CSF with a control group and was divided into four groups (n = 6). Harvest and follow-up histomorphometry and immunohistochemistry were performed in the second week and in the fourth week the histomorphometry analysis consisted of the percentage of immature bone area, cartilage, and fibrous area. The semiquantitative evaluation of immunohistochemistry with the expression of BMP-2 through the immunoreactive score (IRS).

RESULT

In the evaluation of histomorphometry and immunohistochemical parameters, there were significantly more woven bone area (p = 0,015), less fibrosis area (p = 0,002) and higher BMP 2 expression (p = 0,004) in treatment group week four compared to control. .

CONCLUSION

G-CSF was shown to increase the speed of healing in Sprague-Dawley rats on delayed union models evaluated from histomorphometry and immunohistochemical aspects.

The influence of biomechanical stability on bone healing and fracture-related infection: the legacy of Stephan Perren

Bone healing is a complicated process of tissue regeneration that is influenced by multiple biological and biomechanical processes. In a minority of cases, these physiological processes are complicated by issues such as nonunion and/or fracture-related infection (FRI). Based on a select few in vivo experimental animal studies, construct stability is considered an important factor influencing both prevention and treatment of FRI. Stephan Perren played a pivotal role in the evolution of our current understanding of the critical relationship between biomechanics, fracture healing and infection. Furthermore, his concept of strain theory and the process of fracture healing is familiar to several generations of surgeons and has influenced implant development and design for the past 50 years. In this review we describe the role of biomechanical stability on fracture healing, and provide a detailed analysis of the preclinical studies addressing this in the context of FRI. Furthermore, we demonstrate how Perren's concepts of stability are still applied to current surgical techniques to aid in the prevention and treatment of FRI. Finally, we highlight the key knowledge gaps in the underlying basic research literature that need to be addressed as we continue to optimize patient care.

Expression of Vascular Endothelial Growth Factor Using Platelet Rich Fibrin (PRF) and Nanohydroxyapatite (nano-HA) in Treatment of Periodontal Intra-Bony Defects - A Randomized Controlled Trial

The study aims to assess the concentration of vascular endothelial growth factors (VEGF) with platelet rich fibrin (PRF) biomaterial, while using it separately or in combination with nanohydroxyapatite (nano-HA) for treating intra-bony defects (IBDs) using radiographic evaluation (DBS-Win software). Sixty patients with IBD (one site/patient) and chronic periodontitis were recruited randomly to test either autologous PRF platelet concentrate, nano-HA bone graft, a combination of PRF platelet concentrate and nano-HA, or alone conventional open flap debridement (OFD). Recordings of clinical parameters including probing depth (PD), gingival index (GI), and clinical attachment level (CAL) were obtained at baseline and 6 months, post-operatively. One-way analysis of variance (ANOVA) was used to compare four groups; whereas, multiple comparisons were done through Tukey’s post hoc test. The results showed that CAL at baseline changed from 6.67 ± 1.23 to 4.5 ± 1.42 in group I, 6.6 ± 2.51 to 4.9 ± 1.48 in group II, 5.2 ± 2.17 to 3.1 ± 1.27 in group III, and 4.7 ± 2.22 to 3.7 ± 2.35 in group IV after 6 months. The most significant increase in bone density and fill was observed for IBD depth in group III that was recorded as 62.82 ± 24.6 and 2.31 ± 0.75 mm, respectively. VEGF concentrations were significantly increased at 3, 7, and 14 days in all groups. The use of PRF with nano-HA was successful regenerative periodontal therapy to manage periodontal IBDs, unlike using PRF alone. Increase in VEGF concentrations in all group confirmed its role in angiogenesis and osteogenesis in the early stages of bone defect healing.

Synergistic use of biomaterials and licensed therapeutics to manipulate bone remodelling and promote non-union fracture repair

Disrupted bone metabolism can lead to delayed fracture healing or non-union, often requiring intervention to correct. Although the current clinical gold standard bone graft implants and commercial bone graft substitutes are effective, they possess inherent drawbacks and are limited in their therapeutic capacity for delayed union and non-union repair. Research into advanced biomaterials and therapeutic biomolecules has shown great potential for driving bone regeneration, although few have achieved commercial success or clinical translation. There are a number of therapeutics, which influence bone remodelling, currently licensed for clinical use. Providing an alternative local delivery context for these therapies, can enhance their efficacy and is an emerging trend in bone regenerative therapeutic strategies. This review aims to provide an overview of how biomaterial design has advanced from currently available commercial bone graft substitutes to accommodate previously licensed therapeutics that target local bone restoration and healing in a synergistic manner, and the challenges faced in progressing this research towards clinical reality.

Humeral head necrosis associated to shaft non-union with massive bone loss: a case report

Humeral non-union is a rare complication in shaft fractures, as well as humeral head necrosis is a possible complication in fracture involving the proximal third especially in four-part fractures. The presence of head osteonecrosis and diaphyseal non-union in the same arm represents a formidable challenge for an orthopaedic surgeon. We could not find any similar report in the literature dealing with this issue thus far. We present a case of a 65 years old woman referred to our hospital being affected by an atrophic humeral diaphyseal non-union with a massive bone loss (>10cm) associated to a humeral head osteonecrosis following a previous surgical procedures with a clear loosening of the hardware. At our institution,she was treated with hardware removal and insertion of a diaphyseal antibiotic spacer with Gentamycin for 2 months suspecting an active septic process at the union site despite negative cultural exams. Finally, she was treated with a cemented modular humeral megaprosthesis. At 20 months follow up, the patient, despite a reduced shoulder range of motion, referred to a pain-free recovery to an almost normal lifestyle, including car driving with no major disturbances. This case suggests that, in extreme selected cases following several failed treatments, megaprosthesis can represent a viable solution, especially in huge bone loss associated to joint degeneration, to ensure an acceptable return to a normal lifestyle.

Comparing the outcomes of the induced membrane technique between the tibia and femur: Retrospective single-center study of 33 patients

INTRODUCTION

Bone defects are challenging to treat surgically. The primary objective of our study was to compare the union rate and time to union between the tibia and femur when using the induced membrane technique. The secondary objective was to document how failures were managed.

MATERIAL AND METHODS

This retrospective, single-center study involved 33 patients (23 men, 10 women) who were older than 18 years of age. They were treated surgically for a leg fracture or long bone nonunion (22 tibia, 11 femur) using the induced membrane technique between January 2011 and December 2016 and had a complete follow-up. The minimum follow-up was 1 year for fractures and 2 years for non-union cases. Bone union was defined as the presence of at least two cortices with bridging on two radiographic views and return to full weight bearing.

RESULTS

The mean patient age was 38.3±15.5 years (18-72). The mean bone defect size was 7.9±5.0cm (2.3-18.0). The mean follow-up was 3.3±1.8 years (1-7.2). The union rate was 61% (20 patients). The mean time to union was 10±6.4 months (3-23). The time to union was significantly longer in the tibia (11.6±6.9 months [3-23]) than in the femur (6.3±2.9 months [3.4-10.3]) (p=0.025). The failure rate did not differ between the tibia and femur. Nine of the 13 patients (69%) in which the treatment failed were reoperated; 7 of them underwent nonunion treatment (78%) and 2 underwent amputation (22%). The other 4 patients were waiting for an infection to resolve before being reoperated.

CONCLUSION

The induced membrane technique is an effective surgical procedure for large bone defects in both the tibia and femur. However, the time to union was shorter in the femur than the tibia in our cohort.

LEVEL OF EVIDENCE

IV, retrospective study.

[Application of "diamond concept" in treatment of femoral shaft fractures nonunion after intramedullary fixation]

OBJECTIVE

To investigate the effectiveness of the treatment under the guidance of "diamond concept" for femoral shaft fractures nonunion after intramedullary fixation.

METHODS

Between January 2014 and December 2016, 21 cases of femoral shaft fractures nonunion after intramedullary fixation were treated with auxiliary plate fixation combined with autogenous iliac graft, and autologous bone marrow concentrate and platelet-rich plasma (PRP) gel under the guidance of the "diamond concept". There were 13 males and 8 females, with an average age of 32.5 years (range, 17-48 years). All fractures were closed femoral shaft fractures. Four patients underwent internal fixation with plate and resulted in nonunion, then they were fixed with intramedullary nails, but did not heal either. The rest 17 patients were fixed with intramedullary nailing. Fracture nonunion classification: 4 cases of hypertrophic nonunion, 17 cases of atrophic nonunion; the length of bone defect was 1-3 mm; the duration from the last treatment to the current treatment was 10-23 months (mean, 14.3 months). The operation time, intraoperative blood loss, the time between operation and full loading, fracture healing time, and complications were recorded. The visual analogue scale (VAS) score and the imaging system of fracture healing of the extremities (RUST) of patients before operation and at last follow-up were recorded to evaluate the fracture healing; the function of the affected limb was evaluated according to the Schatzker-Lambert efficacy score standard at last follow-up.

RESULTS

The operation time was 105-160 minutes, with an average of 125.6 minutes; the intraoperative blood loss was 160-580 mL, with an average of 370.5 mL. All incisions healed by first intention, without vascular or nerve injury. All patients were followed up 22-46 months (mean, 26.5 months). All the fractures healed, with a fracture healing time of 3-7 months (mean, 4.8 months). During the follow-up, there was no infection, loosening, implant breakage, re-fracture, and other complications. The VAS score at last follow-up was 0.8±0.3, showing significant difference ( t=7.235, P=0.000) when compared with preoperative score (5.2±3.7); the RUST score was 3.4±0.3, which was significantly higher than the preoperative score (1.5±0.7) ( t=8.336, P=0.000). According to the Schatzker-Lambert effectiveness evaluation standard, the limb function was excellent in 16 cases, good in 4 cases, fair in 1 case, and the excellent and good rate was 95.42%.

CONCLUSION

Nonunion after intramedullary fixation of femoral fracture treated with auxiliary plate combined with autogenous iliac graft, autogenous bone marrow concentration and PRP gel in accordance with the "diamond concept" can not only restore the stability of the fracture ends, but also improves the biological environment of the fracture site, and can improve the rate of fracture healing.

[Diamond concept for treatment of nonunions and bone defects]

Nonunions represent a very heterogeneous, rare and sometimes very complex disease picture. The causes, localization and degree of expression show a very high variability, which makes it difficult to establish uniform treatment standards. Nevertheless, the process of bone healing is subject to some essential factors, which should be ensured for a successful treatment. Over the years these factors have been better researched and were taken into consideration for the diamond concept, which was first published by Giannoudis et al. in 2007. This provides the physician with a concept that does not neglect the heterogeneity of the disease picture and is an aid to decision making for the treatment regimen in individual cases in order to guarantee the best biological and mechanical conditions. The diamond concept is nowadays widely used and many studies have already demonstrated a successful application. It must be understood as a framework, in which the various treatment options available (bone substitute materials, mesenchymal stem cells, osteosynthesis procedures etc.) are incorporated into the individual factors and therefore provides the physician with a certain freedom of choice in the selection of tools. Additionally, it is not a rigid corset and subject to medical scientific progress in its factors, so that it is exciting to see which new developments will be incorporated in the future.

The Masquelet technique: Current concepts, animal models, and perspectives

Bone reconstruction within a critical-sized defect remains a real challenge in orthopedic surgery. The Masquelet technique is an innovative, two-step therapeutic approach for bone reconstruction in which the placement of a poly (methylmethacrylate) spacer into the bone defect induces the neo-formation of a tissue called "induced membrane." This surgical technique has many advantages and is often preferred to a vascularized bone flap or Ilizarov's technique. Although the Masquelet technique has achieved high clinical success rates since its development by Alain-Charles Masquelet in the early 2000s, very little is known about how the process works, and few animal models of membrane induction have been developed. Our successful use of this technique in the clinic and our interest in the mechanisms of tissue regeneration (notably bone regeneration) prompted us to develop a surgical model of the Masquelet technique in rats. Here, we provide a comprehensive review of the literature on animal models of membrane induction, encompassing the defect site, the surgical procedure, and the histologic and osteogenic properties of the induced membrane. We also discuss the advantages and disadvantages of those models to facilitate efforts in characterizing the complex biological mechanisms that underlie membrane induction.

Femoral bone defect healing using two novel biocompatible degradable materials

This study was conducted as an in vivo experiment in adult miniature pigs with the aim to test two new biomaterials. An iatrogenic defect was made into the central femoral diaphysis in the experimental animals and subsequently fixated by bridging plate osteosynthesis. Into the defect we implanted a cancellous autograft (control group), a pasty injectable scaffold (EXP A), and a porous 3D cylinder (EXP B). Radiological examination was performed in all animals at 0, 10, 20, 30 weeks after surgical procedure and histological assessment was performed. In the newly formed bone the osteoblastic activity was monitored. In terms of radiology, the most effective method was observed in the control group (completely healed 100%) compared to experimental groups EXP A (70.0%) and EXP B (62.5%). Histological assessment showed a higher cell count in the place of bone defect in the control group compared to experimental groups. Between the experimental groups, a higher count of bone marrow cells was found in group EXP B. Both newly developed biomaterials seem to be suitable as replacements for large bone defects, having good workability and applicability. However, compared to the control group treated with a cancellous autograft, the newly formed bone did not reach the same number of cells settling in and in some cases, full radiological healing was not reached. Nevertheless, the material was found to be grown into the original bone in all cases within the experimental groups. The new biomaterials have a great potential as a substitute in the treatment of large bone defects.

Quantifying Vascular Changes Surrounding Bone Regeneration in a Porcine Mandibular Defect Using Computed Tomography

Angiogenesis is a critical process essential for optimal bone healing. Several in vitro and in vivo systems have been previously used to elucidate some of the mechanisms involved in the process of angiogenesis, and at the same time, to test potential therapeutic agents and bioactive factors that play important roles in neovascularization. Computed tomography (CT) is a noninvasive imaging technique that has recently allowed investigators to obtain a diverse range of high-resolution, three-dimensional characterization of structures, such as bone formation within bony defects. Unfortunately, to date, angiogenesis evaluation relies primarily on histology, or ex vivo imaging and few studies have utilized CT to qualitatively and quantitatively study the vascular response during bone repair. In the current study a clinical CT-based technique was used to evaluate the effects of rhBMP-2 eluting graft treatment on soft tissue vascular architecture surrounding a large segmental bone defect model in the minipig mandible. The objective of this study was to demonstrate the efficacy of contrast-enhanced, clinical 64-slice CT technology in extracting quantitative metrics of vascular architecture over a 12-week period. The results of this study show that the presence of rhBMP-2 had a positive effect on vessel volume from 4 to 12 weeks, which was explained by a concurrent increase in vessel number, which was also significantly higher at 4 weeks for the rhBMP-2 treatment. More importantly, analysis of vessel architecture showed no changes throughout the duration of the study, indicating therapeutic safety. This study validates CT analysis as a relevant imaging method for quantitative and qualitative analysis of morphological characteristics of vascular tissue around a bone healing site. Also important, the study shows that CT technology can be used in large animal models and potentially be translated into clinical models for the development of improved methods to evaluate tissue healing and vascular adaptation processes over the course of therapy. This methodology has demonstrated sensitivity to tracking spatial and temporal changes in vascularization and has the potential to be applied to studying changes in other high-contrast tissues as well. Impact Statement Tissue engineering solutions depend on the surrounding tissue response to support regeneration. The inflammatory environment and surrounding vascular supply are critical to determining if therapies will survive, engraftment occurs, and native physiology is restored. This study for the first time evaluates the blood vessel network changes in surrounding soft tissue to a bone defect site in a large animal model, using clinically available computed tomography tools and model changes in vessel number, size, and architecture. While this study focuses on rhBMP2 delivery impacting surrounding vasculature, this validated method can be extended to studying the vascular network changes in other tissues as well.