Managing bone defects

Multiscale metal-based nanocomposites for bone and joint disease therapies

Bone and joint diseases are debilitating conditions that can result in significant functional impairment or even permanent disability. Multiscale metal-based nanocomposites, which integrate hierarchical structures ranging from the nanoscale to the macroscale, have emerged as a promising solution to this challenge. These materials combine the unique properties of metal-based nanoparticles (MNPs), such as enzyme-like activities, stimuli responsiveness, and photothermal conversion, with advanced manufacturing techniques, such as 3D printing and biohybrid systems. The integration of MNPs within polymer or ceramic matrices offers a degree of control over the mechanical strength, antimicrobial efficacy, and the manner of drug delivery, whilst concomitantly promoting the processes of osteogenesis and chondrogenesis. This review highlights breakthroughs in stimulus-responsive MNPs (e.g., photo-, magnetically-, or pH-activated systems) for on-demand therapy and their integration with biocomposite hybrids containing cells or extracellular vesicles to mimic the native tissue microenvironment. The applications of these composites are extensive, ranging from bone defects, infections, tumors, to degenerative joint diseases. The review emphasizes the enhanced load-bearing capacity, bioactivity, and tissue integration that can be achieved through hierarchical designs. Notwithstanding the potential of these applications, significant barriers to progress persist, including challenges related to long-term biocompatibility, regulatory hurdles, and scalable manufacturing. Finally, we propose future directions, including machine learning-guided design and patient-specific biomanufacturing to accelerate clinical translation. Multiscale metal-based nanocomposites, which bridge nanoscale innovations with macroscale functionality, are a revolutionary force in the field of biomedical engineering, providing personalized regenerative solutions for bone and joint diseases.

A Comparative Study of Taylor Spatial Frame and Monolateral External Fixator for Treating Infected Tibial Defects With Concomitant Soft Tissue Loss

OBJECTIVE

The management of infectious tibial defects with concomitant soft tissue loss (ITD-STL) continues to pose substantial clinical challenges in orthopedic practice. This study aimed to compare the clinical efficacy of the Taylor Spatial Frame (TSF) versus the Monolateral External Fixator (MEF) in achieving bone and soft tissue reconstruction for ITD-STL.

METHODS

A retrospective cohort study was performed on 49 consecutive patients with ITD-STL admitted between July 2010 and September 2022. The dataset included 25 patients who received treatment with the TSF, whereas 24 patients underwent treatment with the MEF. Demographic information, wound healing time, bone healing index, external fixation index, cost of hospitalization, and complications were recorded and compared between the two groups. Bone healing and functional recovery were assessed at the last follow-up (mean 18.8 months postoperatively; range 12-24 months) using the Association for the Study and Application of the Method of Ilizarov criteria (ASAMI) score. Then, statistical analysis such as independent samples t tests or chi-Square test was performed.

RESULTS

The wound healing time was (89.5 ± 30.6 days) in the TSF group and (86.2 ± 31.8 days) in the MEF group (p > 0.05). The bone healing index was (45.49 ± 11.99 d/cm) in the TSF group and (48.20 ± 13.01 d/cm) in the MEF group (p > 0.05). The external fixation index of the TSF group (52.4 ± 7.2 d/cm) was significantly lower than the MEF group (58.6 ± 10.3 d/cm) (p < 0.05). The total hospitalization cost was significantly higher in the TSF group compared to the MEF group (67.16 ± 2.46 thousand RMB vs. 42.67 ± 2.35 thousand RMB; p < 0.05). The overall complication rate was significantly lower in the TSF group (56%) than in the MEF group (75%). At the final follow-up, no significant differences in the ASAMI scores were observed between the two groups (p > 0.05).

CONCLUSION

The use of TSF and MEF for ITD-STL can achieve bone reconstruction and soft tissue repair via bone transport, yielding a positive therapeutic effect. However, TSF treatment is a superior method, characterized by better biomechanical properties and fewer complications, particularly in the correction of postoperative tibial axial deviation. However, these benefits might be offset by the economic costs they could entail.

Polyphenol-Mediated Electroactive Hydrogel with Armored Exosomes Delivery for Bone Regeneration

Prolonged oxidative stress and reduced activity of mesenchymal stem cells are significant barriers to effective bone repair. Current therapeutic approaches often suffer from limited long-term efficacy due to inefficient exosome delivery and the degradation of biological materials. Here, we present an electroactive gelatin methacryloyl hydrogel incorporating a tannic acid-mediated conductive polypyrrole microfiber network and exosomes armored with a metal-polyphenol network, designed to mitigate chronic inflammation and enhance bone healing. The iron-tannic acid complex forms a protective coating on the surface of exosomes, shielding them from damage in inflammatory environments and promoting osteoblast differentiation. This is achieved by enabling exosomes to evade lysosomal degradation through the proton sponge effect. Additionally, the phenolic hydroxyl groups of tannic acid effectively scavenge reactive oxygen species at injury sites. By delivering electrical stimulation to mimic the native electrophysiological environment, the catechol-quinone redox balance is maintained, providing sustained antioxidant effects. In a rat bone defect model, this multifunctional hydrogel demonstrated robust activity for bone regeneration. These findings demonstrated the ability of this electroactive hydrogel system to enhance exosome delivery, provide long-term antioxidative activity, and promote osteogenic differentiation, offering a promising therapeutic platform for bone tissue engineering.

"Anti-Bios": Can Local Antibiotics Affect Bone Union in Infected Bone Defects Treated with Degradable Bone Substitutes

Background: Segmental bone defects (SBDs) pose significant clinical challenges, often requiring complex reconstructive procedures. Degradable bone substitutes loaded with antibiotics have emerged as promising tools for infection control. However, their impact on bone healing remains uncertain. This study investigates antibiotic-loaded biodegradable scaffolds in infected defects using an in vivo rabbit model. Methods: Thirty New Zealand white rabbits were divided into three groups-antibiotic-loaded GreenBone scaffolds, non-loaded GreenBone scaffolds, and allografts. A critical-size femoral defect was surgically created and inoculated with Staphylococcus epidermidis. Radiographic evaluations were performed over 16 weeks, followed by histological and microbiological analyses. Bone union, infection rates, and callus maturation were assessed. Results: Eight rabbits were excluded for technical errors. Bone union was significantly lower in the antibiotic-loaded group (two rabbits out of seven; 28.6%) compared to the non-loaded scaffold (13 rabbits out of 15; 86.7%; p = 0.006). The antibiotic-loaded group exhibited a higher incidence of chronic osteomyelitis (100%) versus non-loaded implants (60%; p < 0.05). Histological evaluation revealed delayed bone maturation in the antibiotic-loaded group (22.2% HOES grade 3) compared to non-loaded scaffolds (69.5%; p < 0.001). Conclusions: Despite their infection-fighting potential, antibiotic-loaded biodegradable scaffolds may impair bone healing, leading to higher non-union rates and delayed maturation. These findings highlight a critical trade-off between local antibiotic therapy and bone regeneration, warranting careful clinical consideration and further research to optimize treatment strategies for infected bone defects.

Ring Fixator Bone Transport Is Associated With Fewer Unplanned Major Reoperations Than Masquelet in the Treatment of Segmental Bone Defects of the Tibia

OBJECTIVE

To determine whether bone transport or Masquelet results in higher rates of major unplanned reoperations for the treatment of segmental tibial bone defects ≥4 cm in length.

METHODS

DESIGN

Retrospective cohort.

SETTING

Level I trauma center.

PATIENT SELECTION CRITERIA

Adult patients with segmental tibial defects (OTA/AO 41, 42, 43) ≥4 cm who underwent surgical treatment with ring fixator bone transport or Masquelet between 2011 and 2022 with a minimum 1-year follow-up were included.

OUTCOME MEASURES AND COMPARISONS

The primary outcome was a major unplanned reoperation after corticotomy (bone transport) or autografting (Masquelet), including below knee amputation, surgical debridement for deep infection, or surgical intervention for nonunion. Ring fixator bone transport and Masquelet were compared using multivariable logistic regression, adjusting for defect size as a potential confounder.

RESULTS

Twenty-four patients treated with bone transport [mean age 40 years (18-66), 100% men] and 22 patients treated with Masquelet [mean age 42 years (22-71), 91% men] were included. Defect etiology was identified as acute traumatic in 25 patients (54%) and postinfectious in 21 patients (46%) ( P = 0.23). The median defect size was 7.2 cm (interquartile range 6.1-10.1) for transport and 5.8 cm for Masquelet (interquartile range 4.7-8.0) ( P = 0.08). Bone transport was associated with an 85% reduction in the odds of a major unplanned reoperation compared to treatment with the Masquelet technique (odds ratio, 0.15; 95% confidence interval, 0.03-0.58; P = 0.01). Bone transport patients underwent a mean of 0.38 major unplanned reoperations compared to 0.91 in the Masquelet group. Reoperation for deep infection occurred significantly less in the bone transport group (21%) compared to the Masquelet group (46%) (odds ratio, 0.18; 95% confidence interval, 0.03-0.76; P = 0.03).

CONCLUSIONS

Bone transport was associated with a reduction in major reoperations compared to Masquelet for segmental tibial bone defects. This finding may have been driven by fewer surgeries for infection in the bone transport group.

LEVEL OF EVIDENCE

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

Gene-activation of surface-modified 3D printed calcium phosphate scaffolds

Large volume bone defects that do not spontaneously heal despite surgical stabilization ("critical-sized" defects) remain a challenge to treat clinically. Recent research investigating bone regenerative implants made from 3D printed materials have shown promise as a potential alternative to current treatment methods, such as autografting, allografting, and multi-step surgical interventions. Recent work has shown that implanting 3D printed calcium phosphate cement (CPC) scaffolds loaded with bone morphogenetic protein-2 (BMP-2) can provide a one-step surgical intervention that has similar bone healing outcomes to a popular two-step intervention: the Masquelet technique. The aim of this study was to investigate whether a 3D printed CPC scaffold loaded with a lyophilized polyplex gene-delivery formulation could serve as an alternative to loading BMP-2 protein onto such scaffolds. We 3D printed CPC scaffolds, hardened them with multiple methods, and explored the impact of these hardening methods on surface texture, mechanical strength, osteogenic differentiation, and ion flux. We then gene-activated these materials with cationic polyplexes containing plasmid DNA encoding reporter genes to investigate transfection from the gene-activated scaffolds. We found that incubating CPC scaffolds in aqueous solutions after initial hardening in a humid environment could enhance scaffold mechanical strength (compressive strength of 21.28 MPa vs. 6.54 MPa) and osteogenic differentiation. We also found that when we increased the total surface area of the CPC material exposed to polyplex solutions, there was a reduction in transfection via adsorption of polyplexes to the CPC surface. This study shows that 3D printed, gene-activated CPC scaffolds are a promising avenue for future exploration in the field of bone regeneration, though the level of gene expression induced by the scaffolds must be improved.

Tetrafocal Bone Lengthening by Ilizarov Frame Application in a Patient With Segmental Tibial Bone Loss: A Case Report

CASE

Thirty-five-year-old man presented with 14 cm segmental tibial defect after crush injury (Gustilo Anderson type-IIIA). Tetrafocal bone transport using Ilizarov frame was performed with 3 osteotomies. Two minor complications-skin invagination and failure at proximal docking site-were addressed. At 18 months, patient exhibited excellent functional outcomes with full range of motion and no signs of limb length discrepancy, infection, or nonunion.

CONCLUSION

This case highlights the potential of tetrafocal bone transport as an effective treatment for segmental tibial defects, even in resource-limited settings, demonstrating that complex orthopedic challenges can achieve excellent outcomes with proper technique and care.

Enhanced osteogenesis and antibacterial activity of dual-functional PEEK implants via biomimetic polydopamine modification with chondroitin sulfate and levofloxacin

Polyetheretherketone (PEEK) implants have emerged as a clinically favored alternative to titanium alloy implants for cranial bone substitutes due to their excellent mechanical properties and biocompatibility. However, the biological inertness of PEEK has hindered its clinical application. To address this issue, we developed a dual-functional surface modification method aimed at enhancing both osteogenesis and antibacterial activity, which was achieved through the sustained release of chondroitin sulfate (CS) and levofloxacin (LVFX) from a biomimetic polydopamine (PDA) coating on the PEEK surface. CS was introduced to promote cell adhesion and osteogenic differentiation. Meanwhile, incorporation of antibiotic LVFX was essential to prevent infections, which are a critical concern in bone defect repairing. To our delight, experiment results demonstrated that the SPKD/CS-LVFX specimen exhibited enhanced hydrophilicity and sustained drug release profiles. Furthermore, in vitro experiments showed that cell growth and adhesion, cell viability, and osteogenic differentiation of mouse calvaria-derived osteoblast precursor (MC3T3-E1) cells were significantly improved on the SPKD/CS-LVFX coating. Antibacterial assays also confirmed that the SPKD/CS-LVFX specimen effectively inhibited the growth of Escherichia coli and Staphylococcus aureus, attributable to the antibiotic LVFX released from the PDA coating. To sum up, this dual-functional PEEK implant showed a promising potential for clinical application in bone defects repairing, providing excellent osteogenic and antibacterial properties through a synergistic approach.

Prognostic factors of extracorporeal shockwave therapy in the treatment of nonunion in long bones: a retrospective study

BACKGROUND

Nonunion of long bone fractures is a significant complication following surgical fixation, with an incidence ranging from 5 to 10%. Surgical intervention is the standard treatment for nonunions, but it may come with potential complications. Nonoperative approaches, such as Extracorporeal Shockwave Therapy (ESWT), have been advocated as alternatives.

METHODS

In the retrospective study conducted between January 2004 and January 2018, 91 patients who underwent ESWT for tibia or femur nonunions were included. Nonunion was defined based on radiographic criteria and clinical symptoms. The nonunion morphology was categorized as hypertrophic, oligotrophic, or atrophic. ESWT was administered using the OssaTron device in a single treatment session. Bony union was defined as the presence of a bridging callus over the fracture site with more than three-fourths of the circumference in both planes within the 12-month postoperative period.

RESULTS

The study included 91 patients, with an overall union rate of 62.6%. A higher healing rate was observed in trophic nonunion(69.9%) than in atrophic nonunion(33.3%). Multivariate analysis identified the number of surgeries, maximum fracture gap, and atrophic nonunion as independent factors influencing the risk of fracture nonunion after ESWT. The receiver operating characteristic curves were generated for these factors, providing more than one surgical intervention, and fracture gap greater than 3.94 mm as negative predictors of ESWT for long bone nonunions.

CONCLUSION

The study's primary findings suggest that ESWT is effective in achieving bony union for nonunions in long bones(62.6%). Despite the overall positive results, the study highlights that atrophic nonunions, larger fracture gaps of more than 3.94 mm, and multiple surgeries are associated with poorer outcomes.

Unleashing innovation: 3D-printed biomaterials in bone tissue engineering for repairing femur and tibial defects in animal models - a systematic review and meta-analysis

Introduction

3D-printed scaffolds have emerged as an alternative for addressing the current limitations encountered in bone reconstruction. This study aimed to systematically review the feasibility of using 3D bio-printed scaffolds as a material for bone grafting in animal models, focusing on femoral and tibial defects. The primary objective of this study was to evaluate the efficacy, safety, and overall impact of these scaffolds on bone regeneration.

Methods

Electronic databases were searched using specific search terms from January 2013 to October 2023, and 37 relevant studies were finally included and reviewed. We documented the type of scaffold generated using the 3D printed techniques, detailing its characterization and rheological properties including porosity, compressive strength, shrinkage, elastic modulus, and other relevant factors. Before incorporating them into the meta-analysis, an additional inclusion criterion was applied where the regenerated bone area (BA), bone volume (BV), bone volume per total volume (BV/TV), trabecular thickness (Tb. Th.), trabecular number (Tb. N.), and trabecular separation (Tb. S.) were collected and analyzed statistically.

Results

3D bio-printed ceramic-based composite scaffolds exhibited the highest capacity for bone tissue regeneration (BTR) regarding BV/TV of femoral and tibial defects of animal models. The ideal structure of the printed scaffolds displayed optimal results with a total porosity >50% with a pore size ranging between 300- and 400 µM. Moreover, integrating additional features and engineered macro-channels within these scaffolds notably enhanced BTR capacity, especially observed at extended time points.

Discussion

In conclusion, 3D-printed composite scaffolds have shown promise as an alternative for addressing bone defects.

Collagen-hydroxyapatite based scaffolds for bone trauma and regeneration: recent trends and future perspectives

Regenerative therapy, a key area of tissue engineering, holds promise for restoring damaged organs, especially in bone regeneration. Bone healing is natural to the body but becomes complex under stress and disease. Large bone deformities pose significant challenges in tissue engineering. Among various methods, scaffolds are attractive as they provide structural support and essential nutrients for cell adhesion and growth. Collagen and hydroxyapatite (HA) are widely used due to their biocompatibility and biodegradability. Collagen and nano-scale HA enhance cell adhesion and development. Thus, nano HA/collagen scaffolds offer potential solutions for bone regeneration. This review focuses on the use and production of nano-sized HA/collagen composites in bone regeneration.

A Novel Method to Assess Healing of Segmental Bone Defects using the Induced Membrane Technique

OBJECTIVE

Clinical concerns exist regarding the quality of bony consolidation in the context of the induced membrane technique. This study evaluates the clinical process of bone grafting in the second stage of induced membrane bone union in patients with tibial bone defects to infer the possibility of non-union and establish a reliable and effective evaluation method combined with computed tomography (CT) to assess fracture healing.

METHODS

Patients with tibial bone defects who underwent the induced membrane technique at our hospital between February 2017 and February 2020 were retrospectively analyzed. The Hounsfield unit (HU) values of the patients were evaluated at different times during the second stage of bone grafting. Bone healing at the boundary value of the 120 HU output threshold (-1024 HU-3071 HU) was directionally selected, and the changes in the growth volume of union (new bone volume [selected according to HU value]/bone defect volume) were compared with analyzing individual class bone union. Method 1 involved X-rays revealing that at least three of the four cortices were continuous and at least 2 mm thick, with the patient being pain free. For Method 2, new bone volume (selected according to HU value/bone defect volume) at the stage was compared with analyzing individual class healing. Receiver operating characteristic curve analysis was used for Methods 1 and 2.

RESULTS

A total of 42 patients with a segmental bone defect with a mean age of 40.5 years (40.5 ± 8.3 years) were included. The relationship between bone graft volume and time variation was analyzed by single factor repeated variable analysis (F = 6.477, p = 0.016). Further, curve regression analysis showed that the change in bone graft volume over time presented a logarithmic curve pattern (Y = 0.563 + 0.086 × ln(X), Ra2 = 0.608, p = 0.041). ROC curve analysis showed that Method 2 is superior to Method 1 (AUC: 86.3% vs. 68.3%, p < 0.05).

CONCLUSION

The induced membrane technique could be used to treat traumatic long bone defects, with fewer complications and a higher healing rate. The proposed imaging grading of HU (new bone volume/bone defect volume) can be used as a reference for the quality of bony consolidation with the induced membrane technique.

Successful Reimplantation of Extruded Ulnar Diaphyseal Segment: A Case Report and Review of Literature

CASE

A 32-year-old man presented with a type II open both-bone forearm fracture and segmental bone loss because of complete extrusion of a diaphyseal fragment (3 cm) of ulna. The patient presented to our level 1 trauma center after a motor vehicle collision. The extruded segment underwent sterilization and immediate reimplantation with internal fixation approximately 6 hours after arrival. Our patient achieved union by 7-month follow-up, demonstrated excellent functional outcomes, and was free from infection at 1-year follow-up.

CONCLUSION

In select cases, successful reimplantation can be achieved by meticulous debridement, sterilization, and immediate reimplantation with internal fixation.

Treatment of Large Femoral and Tibial Bone Defects With Plate-Assisted Bone Segment Transport

OBJECTIVES

The purposes of this study were to assess clinical and radiographic outcomes following plate-assisted bone segment transport (PABST) in large bone defects of the lower extremities.

METHODS

DESIGN

Retrospective study of prospectively collected data.

SETTING

Level-1 trauma center located in Germany.

PATIENT SELECTION CRITERIA

Patients who underwent PABST and were at least 1 year postoperatively were included.

OUTCOME MEASURES AND COMPARISONS

Demographic data were collected. Radiographic apparent bone gap (RABG), time to consolidation, time to full weight-bearing, and consolidation index were calculated. Numeric rating scale, lower extremity functional scale (LEFS), and complications were assessed.

RESULTS

Fifteen patients [13 male; mean age 51 years (range, 20-75)] underwent PABST and had follow-up at a mean of 29.1 months. The tibia was affected in 8 and the femur in 7 patients. Preoperative RABG was 60 mm [interquartile range (IQR): 40-125], and bone defects were caused by septic nonunions in 73% of patients. Fourteen patients (93%) demonstrated consolidated transport callus at 7.3 months [95% confidence interval (95% CI), 6-8.5], and 9 patients (60%) demonstrated complete consolidation of both docking site and transport callus at 11.5 months (95% CI, 7.3-15.3). Postoperative RABG was 0.1 mm (IQR: 0-0.8), and consolidation index was 1.9 months/cm (95% CI, 1.3-2.5). All patients achieved full weight-bearing at 8.7 months (IQR: 6.5-10.3). LEFS was 42 (95% CI, 34-50), and numeric rating scale was 3 (95% CI, 2-4). Patients treated for tibial defects had a significantly higher consolidation rate compared with patients treated for femoral defects ( P = 0.040).

CONCLUSIONS

PABST demonstrated high consolidation of transport callus with few complications. Although full weight-bearing was achieved in all patients, complete consolidation of the docking site was only present in 60% of cases.

LEVEL OF EVIDENCE

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

The effects of allogeneic and xenogeneic lyophilized leukocyte-and platelet-rich fibrin on bone healing in rat

BACKGROUND

Critical size defects are one of the challenges in the treatment of fractures in humans and animals. Blood products such as leukocyte-SAand platelet-rich fibrin (L-PRF) are one of the alternatives to bone autograft to solve this challenge. This study aims to evaluate the effects of allogeneic and xenogeneic lyophilized L-PRF on bone healing in a critical defect of radius bone in rat.

METHODS

A defect with a diameter of 5 mm was created in the radius bone of 60 rats in four groups. The defect was left empty in the untreated group, and it was filled with autogenous bone graft, allogeneic, and xenogeneic lyophilized L-PRF, respectively, in the other three groups. Radiographic evaluation was done every two weeks, and histopathological evaluation in the 14th, 28th, and 56th days after surgery.

RESULTS

The radiographic scores of allogeneic and xenogeneic lyophilized l-PRF groups were significantly higher than the untreated group in all times (P<0.05). In connection with histopathological Emery's scoring system, the score of allogeneic lyophilized L-PRF was significantly higher than the untreated group (P<0.05) in the 14th and 28th days after surgery. The score of the xenogeneic lyophilized L-PRF group was also higher than the untreated group, but the difference was not significant (P>0.05). The allogeneic and xenogeneic lyophilized L-PRF scores were significantly higher than the untreated group (P < 0.05) on the 56th day.

CONCLUSION

The results of the present study showed that the allogeneic and xenogeneic lyophilized L-PRF can improve bone healing in the critical radius bone defect in rat model of study.

Recent advances in composite hydrogels: synthesis, classification, and application in the treatment of bone defects

Bone defects are often difficult to treat due to their complexity and specificity, and therefore pose a serious threat to human life and health. Currently, the clinical treatment of bone defects is mainly surgical. However, this treatment is often more harmful to patients and there is a potential risk of rejection and infection. Hydrogels have a unique three-dimensional structure that can accommodate a variety of materials, including particles, polymers and small molecules, making them ideal for treating bone defects. Therefore, emerging composite hydrogels are considered one of the most promising candidates for the treatment of bone defects. This review describes the use of different types of composite hydrogel in the treatment of bone defects. We present the basic concepts of hydrogels, different preparation techniques (including chemical and physical crosslinking), and the clinical requirements for hydrogels used to treat bone defects. In addition, a review of numerous promising designs of different types of hydrogel doped with different materials (e.g., nanoparticles, polymers, carbon materials, drugs, and active factors) is also highlighted. Finally, the current challenges and prospects of composite hydrogels for the treatment of bone defects are presented. This review will stimulate research efforts in this field and promote the application of new methods and innovative ideas in the clinical field of composite hydrogels.

The Pitfalls of Difficult Distal Radius Fractures and Provisional Reduction

Distal radius fractures are some of the most common injuries encountered in orthopedics and require careful consideration when determining the appropriate treatment options. These fractures can be difficult injuries to treat surgically based on a large variability of fracture patterns, bone quality, and anatomy. It is important to understand the potential pitfalls associated with the treatment of difficult distal radius fractures to prevent avoidable complications. Some of these pitfalls include but are not limited to appropriate surgical exposure and soft tissue handling, provisional reduction, fixation type, and augmentation of fracture fixation.

Modified-Hydroxyapatite-Chitosan Hybrid Composite Interfacial Coating on 3D Polymeric Scaffolds for Bone Tissue Engineering

Three dimensional (3D) scaffolds have huge limitations due to their low porosity, mechanical strength, and lack of direct cell-bioactive drug contact. Whereas bisphosphonate drug has the ability to stimulate osteogenesis in osteoblasts and bone marrow mesenchymal stem cells (hMSC) which attracted its therapeutic use. However it is hard administration low bioavailability, and lack of site-specificity, limiting its usage. The proposed scaffold architecture allows cells to access the bioactive surface at their apex by interacting at the scaffold's interfacial layer. The interface of 3D polycaprolactone (PCL) scaffolds has been coated with alendronate-modified hydroxyapatite (MALD) enclosed in a chitosan matrix, to mimic the native environment and stupulate the through interaction of cells to bioactive layer. Where the mechanical strength will be provided by the skeleton of PCL. In the MALD composite's hydroxyapatite (HAP) component will govern alendronate (ALD) release behavior, and HAP presence will drive the increase in local calcium ion concentration increases hMSC proliferation and differentiation. In results, MALD show release of 86.28 ± 0.22. XPS and SEM investigation of the scaffold structure, shows inspiring particle deposition with chitosan over the interface. All scaffolds enhanced cell adhesion, proliferation, and osteocyte differentiation for over a week without in vitro cell toxicity with 3.03 ± 0.2 kPa mechanical strength.

Osseointegrability of 3D-printed porous titanium alloy implant on tibial shaft bone defect in rabbit model

Previous studies have demonstrated the ability of osseointegration of porous titanium implants in cancellous bone. Our study was designed to (i) investigate the ability of bone ingrowth into 3D-printed porous titanium alloy implant on the cortical bone of rabbits using CT-scan and histology, and (ii) to identify the consistency of the radiology information between clinical Cone Beam Computed Tomography (CBCT) and Micro Computed Tomography (μCT) in the evaluation of bone ingrowth. The porous titanium alloy implants were 3D-printed employing the Electron Beam Melting (EBM) technology with an intended pore size of 600 μm and porosity of approximately 50 percent. Each implant was inserted into tibial diaphysis in one rabbit and its pores were classified as contacting bone or non-contacting bone. Depending on the time of explantation, the rabbits were divided into two groups: group 1 consisting of 6 rabbits between 13 and 20 weeks and group 2 consisting of 6 rabbits between 26 and 32 weeks. Tissue ingrowth into the non-bone contacting pores were evaluated by CBCT and histology. μCT was used to further investigate the bone ingrowth into four implants (two from each group were randomly chosen). The CBCT detected the present of tissue with bone-like density in both bone-contacting pores and non-bone-contacting pores of all implants. The μCT analysis also supported this result. All the bone-like tissues were then histologically confirmed to be mature bone. The analysis of CBCT data to assess bone ingrowth in porous implants had the sensitivity, specificity, positive and negative predictive values of 85, 84, 93 and 70 percent, respectively, when considering μCT assessment as the gold standard. Fully porous titanium alloy implant has great potential to reconstruct diaphyseal bone defect due to its good ability of osseointegration. CBCT is a promising method for evaluation of bone ingrowth into porous implants.

Treatment of a Ballistic Radius Fracture with Segmental Bone Loss Using the Masquelet Technique in a Child: A Case Report

CASE

A 4-year-old boy sustained an accidental self-inflicted gunshot wound to the left forearm. Radiographs revealed a comminuted mid-diaphyseal ballistic radius fracture with a critical-sized bone defect. The fracture was treated with the placement of a flexible intramedullary nail and antibiotic cement spacer, followed by second-stage bone grafting and open reduction and internal fixation of the radius 6 weeks later. Four months after the second-stage procedure, the radial defect healed appropriately without complications.

CONCLUSION

In this case of a pediatric comminuted mid-diaphyseal radius fracture with bone loss, the induced membrane technique resulted in healing across a critical-sized bone defect.

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective

The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient's age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon's preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.

Open fractures: Current treatment perspective

Severe open fractures present challenges to orthopaedic surgeons worldwide, with increased risks of significant complications. Although different global regions have different resources and systems, there continue to be many consistent approaches to open fracture care. Management of these complex injures continues to evolve in areas ranging from timing of initial operative debridement to the management of critical-sized bone defects. This review, compiled by representative members of the International Orthopaedic Trauma Association, focuses on several critical areas of open fracture management, including antibiotic administration, timing of debridement, bone loss, soft tissue management, and areas of need for future investigation.

[Plate-assisted bone segment transport for bone defects of the lower extremities : Possibilities and limitations of treatment]

Large bone defects of the lower extremities are challenging for both patients and the treating orthopedic surgeons. The treatment is determined by the size and location of the defect; however, patient-specific factors, such as the soft tissue situation and the presence of systemic comorbidities must be taken into consideration in the treatment strategy. Osteodistraction is an excellent technique especially for large bone defects exceeding 3 cm; however, it is time-consuming and required external fixation prior to the development of motorized distraction nails. This article describes the procedure for the treatment of large bone defects of the lower extremities, with its possibilities and limitations, using the novel plate-assisted bone segment transport (PABST) procedure.

Delivery of microRNA-302a-3p by APTES modified hydroxyapatite nanoparticles to promote osteogenic differentiation in vitro

OBJECTIVE

To demonstrate the miRNA delivery by hydroxyapatite nanoparticles modified with APTES (HA-NPs-APTES) and promote osteogenic gene expression.

MATERIALS AND METHODS

Osteosarcoma cells (HOS, MG-63) and primary human mandibular osteoblasts (HmOBs) were co-cultured with HA-NPs-APTES conjugated with miRNA-302a-3p. Resazurin reduction assay was performed to evaluate HA-NPs-APTES biocompatibility. Intracellular uptake was demonstrated by confocal fluorescent and scanning electron microscopy. The miRNA-302a-3p and its mRNA targets expression levels including COUP-TFII and other osteogenic genes were assessed by qPCR on day1 or day5 post-delivery. Calcium deposition induced by the osteogenic gene upregulation was shown by alizarin red staining on day7 and 14 post-delivery.

RESULTS

Proliferation of HOS cells treated with HA-NPs-APTES was similar to that of untreated cells. HA-NPs-APTES was visualized in cell cytoplasm within 24 hours. MiRNA-302a-3p level was upregulated in HOS, MG-63 and HmOBs as compared to untreated cells. As a result, COUP-TFII mRNA expression was reduced, followed by an increase of RUNX2 and other osteogenic genes mRNA expression. Calcium deposition induced by HA-NPs-APTES-miR-302a-3p in HmOBs was significantly higher than in untreated cells.

CONCLUSION

HA-NPs-APTES may support the delivery of miRNA-302a-3p into bone cells, as assessed by osteogenic gene expression and differentiation improvement once this combination is used on osteoblast cultures.

IL-1Ra gene transfer potentiates BMP2-mediated bone healing by redirecting osteogenesis toward endochondral ossification

An estimated 100,000 patients each year in the United States suffer severe disability from bone defects that fail to heal, a condition where bone-regenerative therapies could provide substantial clinical benefits. Although recombinant human bone morphogenetic protein-2 (rhBMP2) is an osteogenic growth factor that is clinically approved for this purpose, it is only effective when used at exceedingly high doses that incur substantial costs, induce severe inflammation, produce adverse side effects, and form morphologically abnormal bone. Using a validated rat femoral segmental defect model, we show that bone formed in response to clinically relevant doses of rhBMP2 is accompanied by elevated expression of interleukin-1 (IL-1). Local delivery of cDNA encoding the IL-1 receptor antagonist (IL-1Ra) achieved bridging of segmental, critical size defects in bone with a 90% lower dose of rhBMP2. Unlike use of high-dose rhBMP2, bone formation in the presence of IL-1Ra occurred via the native process of endochondral ossification, resulting in improved quality without sacrificing the mechanical properties of the regenerated bone. Our results demonstrate that local immunomodulation may permit effective use of growth factors at lower doses to recapitulate more precisely the native biology of healing, leading to higher-quality tissue regeneration.

Mechanical strain induces ex vivo expansion of periosteum

Segmental bone defects present complex clinical challenges. Nonunion, malunion, and infection are common sequalae of autogenous bone grafts, allografts, and synthetic bone implants due to poor incorporation with the patient's bone. The current project explores the osteogenic properties of periosteum to facilitate graft incorporation. As tissue area is a natural limitation of autografting, mechanical strain was implemented to expand the periosteum. Freshly harvested, porcine periosteum was strained at 5 and 10% per day for 10 days with non-strained and free-floating samples serving as controls. Total tissue size, viability and histologic examination revealed that strain increased area to a maximum of 1.6-fold in the 10% daily strain. No change in tissue anatomy or viability via MTT or Ki67 staining and quantification was observed among groups. The osteogenic potential of the mechanical expanded periosteum was then examined in vivo. Human cancellous allografts were wrapped with 10% per day strained, fresh, free-floating, or no porcine periosteum and implanted subcutaneously into female, athymic mice. Tissue was collected at 8- and 16-weeks. Gene expression analysis revealed a significant increase in alkaline phosphatase and osteocalcin in the fresh periosteum group at 8-weeks post implantation compared to all other groups. Values among all groups were similar at week 16. Additionally, histological assessment with H&E and Masson-Goldner Trichrome staining showed that all periosteal groups outperformed the non-periosteal allograft, with fresh periosteum demonstrating the highest levels of new tissue mineralization at the periosteum-bone interface. Overall, mechanical expansion of the periosteum can provide increased area for segmental healing via autograft strategies, though further studies are needed to explore culture methodology to optimize osteogenic potential.

[Synthetic bone replacement substances]

Bone substitute materials have been successfully used for bone defects in orthopedics and trauma surgery for a long time; however, there are cases, especially in bone defects with a critical size, in which the treatment is complicated. Nowadays, multiple bone substitute materials are available. Autologous cancellous bone grafts remain the gold standard among the bone replacement materials; however, donor site morbidity and the limited availability of autologous cancellous bone represent restrictions for autologous bone grafting. Allogeneic cancellous bone grafts have also been successfully for years in the treatment of bone defects; however, infection rates of more than 10% have been described for the use of allogeneic cancellous bone. By introducing synthetic bone substitutes further alternatives are currently available to the user for the individual treatment of bone defects. The aim of this study is to demonstrate the advantages and disadvantages of various synthetic bone substitute materials.

Comparative Study of the Osteogenic Differentiation Potential of Adipose Tissue-Derived Stromal Cells and Dedifferentiated Adipose Cells of the Same Tissue Origin under Pro and Antioxidant Conditions

Adipose tissue-derived stromal cells (ASCs) play an important role in various therapeutic approaches to bone regeneration. However, such applications become challenging when the obtained cells show a functional disorder, e.g., an impaired osteogenic differentiation potential (ODP). In addition to ASCs, human adipose tissue is also a source for another cell type with therapeutic potential, the dedifferentiated fat cells (DFATs), which can be obtained from mature adipocytes. Here, we for the first time compared the ODPs of each donors ASC and DFAT obtained from the same adipose tissue sample as well as the role of oxidative stress or antioxidative catalase on their osteogenic outcome. Osteogenic potential of ASC and DFAT from nine human donors were compared in vitro. Flow cytometry, staining for calcium accumulation with alizarin red, alkaline phosphatase assay and Western blots were used over an osteogenic induction period of up to 14 days. H₂O₂ was used to induce oxidative stress and catalase was used as an antioxidative measure. We have found that ASC and DFAT cultures' ODPs are nearly identical. If ASCs from an adipose tissue sample showed good or bad ODP, so did the corresponding DFAT cultures. The inter-individual variability of the donor ODPs was immense with a maximum factor of about 20 and correlated neither with the age nor the sex of the donors of the adipose tissue. Oxidative stress in the form of exogenously added H₂O₂ led to a significant ODP decrease in both cell types, with this ODP decrease being significantly lower in DFAT cultures than in the corresponding ASC cultures. Regardless of the individual cell culture-specific ODP, however, exogenously applied catalase led to an approx. 2.5-fold increase in osteogenesis in the ASC and DFAT cultures. Catalase appears to be a potent pro-osteogenic factor, at least in vitro. A new finding that points to innovative strategies and therapeutic approaches in bone regeneration. Furthermore, our results show that DFATs behave similarly to ASCs of the same adipose tissue sample with respect to ODPs and could therefore be a very attractive and readily available source of multipotent stem cells in bone regenerative therapies.

[Application of three-dimensional printed customized prosthesis with preserved epiphysis and articular surface in the reconstruction of large bone defects in treatment of adolescent femoral malignant tumors]

Objective

To investigate the clinical application and effectiveness of three-dimensional (3D) printed customized prosthesis with preserved epiphysis and articular surface in the reconstruction of large bone defects in treatment of adolescent femoral malignant tumors.

Methods

The clinical data of 10 adolescent patients with femoral primary malignant tumor who met the selection criteria and underwent limb salvage surgery with 3D printed customized prosthesis with preserved epiphysis and articular surface between January 2020 and October 2021 were retrospectively analyzed. There were 6 males and 4 females with an average age of 12.5 years ranging from 7 to 18 years. There were 8 cases of osteosarcoma and 2 cases of Ewing's sarcoma. Enneking stage was Ⅱb. The length of the lesions ranged from 76 to 240 mm, with an average of 138.0 mm. The length of osteotomy (i. e. length of customized prosthesis) ranged from 130 to 275 mm, with an average of 198.5 mm; the distance between distal osteotomy end and epiphyseal line ranged from 0 to 15 mm, with an average of 8.8 mm; the bone defect after osteotomy accounted for 37.36% to 79.02% of the total length of the lesion bone, with a mean of 49.43%. The operation time, intraoperative blood loss, complications, tumor outcome (refered to RESIST1.1 solid tumor efficacy evaluation criteria), and limb length discrepancy were recorded. The Musculoskeletal Cancer Society (MSTS) 93 score was used to evaluate the function at 6 months after operation, and visual analogue scale (VAS) score was used to evaluate the pain before and after operation.

Results

The operation was successfully performed in all the 10 patients, and the postoperative pathological results were consistent with the preoperative pathological results. The operation time was 165-440 minutes, with an average of 263 minutes; and the intraoperative blood loss was 100-800 mL, with an average of 350 mL. All patients were followed up 7-26 months, with an average of 11.8 months. No tumor was found on the osteotomy surface; the customized prosthesis were firmly installed and closely matched with the retained articular surface. The tumor outcome of neoadjuvant chemotherapy was stable in 4 cases and partial remission in 6 cases. No local recurrence or distant metastasis was found in 9 cases after postoperative adjuvant chemotherapy; pulmonary metastasis was found in 1 case at 12 months after operation. Two patients had local incision fat liquefaction, superficial infection, and delayed healing at 14 days after operation; 1 patient had local bone absorption at the contact surface of the prosthesis, and the screw and prosthesis did not loosen at 7 months after operation; the other patients had good incision healing, with no infection, prosthesis loosening, fracture, or other complications. At 6 months after operation, the MSTS93 score was 19-28, with an average of 24.1; 8 cases were excellent and 2 cases were good. The VAS score was 0.9±1.0, which significantly improved when compared with before operation (5.9±1.0) ( t=23.717, P<0.001). The height of the patients increased by 1-12 cm, with an average of 4.6 cm. At last follow-up, 4 patients had limb length discrepancy, with a length difference of 1 cm in 2 cases and 2 cm in 2 cases.

Conclusion

The application of 3D printed customized prosthesis in the resection and reconstruction of adolescents femoral primary malignant tumors can achieve the purpose of preserving epiphysis and articular surface, and obtain good effectiveness.

Total flavonoids of Rhizoma Drynariae enhances CD31hiEmcnhi vessel formation and subsequent bone regeneration in rat models of distraction osteogenesis by activating PDGF‑BB/VEGF/RUNX2/OSX signaling axis

Total flavonoids of Rhizoma Drynariae (TFRD), extracted from the kidney‑tonifying Traditional Chinese medicine Rhizoma Drynariae, can be effective in treating osteoporosis, bone fractures and defects. However, the pharmacological effects of TFRD on the specific vessel subtype CD31hiEmcnhi during distraction osteogenesis (DO) remains unclear. The present study aimed to investigate the effects of TFRD on CD31hiEmcnhi vessels in a rat model of DO. In the present study, tibial DO models were established using 60 rats with a distraction rate of 0.2 mm per day for 20 days. Co‑immunofluorescence staining of CD31 and endomucin (Emcn) was conducted to determine CD31hiEmcnhi vessels. Radiographic, angiographic and histological analyses were performed to assess bone and vessel formation. Tube formation, alkaline phosphatase (ALP) and Von Kossa staining assays were performed to test angiogenesis of endothelial precursor cells (EPCs) and osteogenesis of bone marrow‑derived mesenchymal stem cells (BMSCs). Additionally, expression levels of platelet‑derived growth factor (PDGF)‑BB, VEGF, runt‑related transcription factor 2 (RUNX2) and Osterix (OSX) were determined by western blotting and reverse transcription‑quantitative PCR. The in vivo assays demonstrated that TFRD markedly promoted CD31hiEmcnhi vessel formation during DO, whereas PDGF‑BB neutralizing antibody suppressed vessel formation. Furthermore, the ALP, Von Kossa staining and tube formation assays indicated that TFRD notably elevated the angiogenic capacity of EPCs and osteogenic capacity of BMSCs under stress conditions, which was significantly suppressed by blocking PDGF‑BB. The protein and mRNA levels of PDGF‑BB, VEGF, RUNX2 and OSX were upregulated by TFRD, but downregulated by blocking PDGF‑BB. Thus, TFRD could facilitate CD31hiEmcnhi vessel formation and subsequently enhance angiogenic‑osteogenic coupling to regenerate bone defects during DO via the PDGF‑BB/VEGF/RUNX2/OSX signaling axis, which indicated that CD31hiEmcnhi vessels could be a potential novel therapeutic target for DO, and TFRD may represent a promising drug for promoting bone regeneration in DO by increasing CD31hiEmcnhi vessels.

HIF signaling: A new propellant in bone regeneration

Bone tissue destruction leads to severe pain, physical flaws, and loss of motility. Bone repair using biocompatible and osteo-inductive scaffolds is regarded as a viable and potential therapeutic approach. However, for large-scale bone regeneration, oxygen and nutrient supply have become limiting factors. Further, a considerable need exists for recruited cell activities and blood vessel growth. Hypoxia-inducible factor (HIF) signaling pathways induced by hypoxia are involved in angiogenesis and osteogenesis. As an important transcription factor, HIF-1 functions by modulating vital genes, such as VEGF, PDK1, and EPO, and is a crucial regulator that influences the final fate of bone regeneration. Collectively, to achieve better osteogenesis results, the in-depth molecular mechanisms that underpin the links between materials, cells, and HIF signaling pathways must be determined. This review aimed to provide an in-depth insight into recent progress in HIF-regulated bone regeneration. Hypoxia and cellular oxygen-sensing mechanisms and their correlations with osteogenesis were determined, and recent studies on hypoxia-inducing and hypoxia-mimicking strategies were briefly described. Finally, the potential applications of HIF signaling in bone regeneration were highlighted. This review provides theoretical support for establishing a novel and viable bone repair strategy in the clinic by harnessing HIF signaling.

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

OBJECTIVES

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

DESIGN

Retrospective comparative study.

SETTING

Academic level I trauma center.

PATIENTS/PARTICIPANTS

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

INTERVENTION

IMT with or without rhBMP-2/HA augmentation.

MAIN OUTCOME MEASUREMENT

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

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

Regeneration of Articular Cartilage Using Membranes of Polyester Scaffolds in a Rabbit Model

One promising method for cartilage regeneration involves combining known methods, such as the microfracture technique with biomaterials, e.g., scaffolds (membranes). The most important feature of such implants is their appropriate rate of biodegradation, without the production of toxic metabolites. This study presents work on two different membranes made of polyester (L-lactide-co-ε-caprolactone-PLCA) named “PVP and “Z”. The difference between them was the use of different pore precursors—polyvinylpyrrolidone in the “PVP” scaffold and gelatin in the “Z” scaffold. These were implemented in the articular cartilage defects of rabbit knee joints (defects were created for the purpose of the study). After 8, 16, and 24 weeks of observation, and the subsequent termination of the animals, histopathology and gel permeation chromatography (GPC) examinations were performed. Statistical analysis proved that the membranes support the regeneration process. GPC testing proved that the biodegradation process is progressing exponentially, causing the membranes to degrade at the appropriate time. The surgical technique we used meets all the requirements without causing the membrane to migrate after implantation. The “PVP” membrane is better due to the fact that after 24 weeks of observation there was a statistical trend for higher histological ratings. It is also better because it is easier to implant due to its lower fragility then membrane “Z”. We conclude that the selected membranes seem to support the regeneration of articular cartilage in the rabbit model.

An Analysis of Complications and Bone Defect Length With the Use of Induced Membrane Technique in the Upper Limb: A Systematic Review

Background: The induced membrane technique was originally described as a technique for the reconstruction of long bone defects. The authors performed a systematic review to determine whether the use of the induced membrane technique is effective in large bony defects in the upper extremity. Methods: A qualitative systematic review was conducted using PubMed, EBSCO, and Google Scholar databases to record all studies reporting on complications of the induced membrane technique in the upper extremity. Studies written after 1990 in English language journals met the inclusion criteria. Exclusion criteria were non-English language publications, animal studies, failure to identify the location of the bone defect, failure to identify whether complications were associated with the procedure, and failure to define the length of bone defect. Results: A total of 1422 studies were identified in the original search. Twelve studies satisfied the criteria for inclusion. A total of 70 patients with 83 upper extremity cases were reported: 1 proximal interphalangeal joint, 22 phalanges, 8 metacarpals, 37 forearms, 14 humeri, and 1 clavicle. The mean bone defect size was 4.0 cm (SD, 1.5). The most common complication was infection. We found that complication rates were independent of the location of the bone defect. Complication rates in the upper extremity ranged from 0% to 100%, with a total weighted mean of 10%. Conclusion: The induced membrane technique is an emerging possible treatment of large bone defects in the upper extremity. More research is needed to determine the outcomes of the induced membrane technique in the upper extremity.

Implantable biosensors for musculoskeletal health

PURPOSE

A healthy musculoskeletal system requires complex functional integration of bone, muscle, cartilage, and connective tissues responsible for bodily support, motion, and the protection of vital organs. Conditions or injuries to musculoskeeltal tissues can devastate an individual's quality of life. Some conditions that are particularly disabling include severe bone and muscle injuries to the extremities and amputations resulting from unmanageable musculoskeletal conditions or injuries. Monitoring and managing musculoskeletal health is intricate because of the complex mechanobiology of these interconnected tissues.

METHODS

For this article, we reviewed literature on implantable biosensors related to clinical data of the musculoskeletal system, therapeutics for complex bone injuries, and osseointegrated prosthetics as example applications.

RESULTS

As a result, a brief summary of biosensors technologies is provided along with review of noteworthy biosensors and future developments needed to fully realize the translational benefit of biosensors for musculoskeletal health.

CONCLUSIONS

Novel implantable biosensors capable of tracking biophysical parameters in vivo are highly relevant to musculoskeletal health because of their ability to collect clinical data relevant to medical decisions, complex trauma treatment, and the performance of osseointegrated prostheses.

3D Bioprinted Scaffolds for Bone Tissue Engineering: State-Of-The-Art and Emerging Technologies

Treating large bone defects, known as critical-sized defects (CSDs), is challenging because they are not spontaneously healed by the patient’s body. Due to the limitations associated with conventional bone grafts, bone tissue engineering (BTE), based on three-dimensional (3D) bioprinted scaffolds, has emerged as a promising approach for bone reconstitution and treatment. Bioprinting technology allows for incorporation of living cells and/or growth factors into scaffolds aiming to mimic the structure and properties of the native bone. To date, a wide range of biomaterials (either natural or synthetic polymers), as well as various cells and growth factors, have been explored for use in scaffold bioprinting. However, a key challenge that remains is the fabrication of scaffolds that meet structure, mechanical, and osteoconductive requirements of native bone and support vascularization. In this review, we briefly present the latest developments and discoveries of CSD treatment by means of bioprinted scaffolds, with a focus on the biomaterials, cells, and growth factors for formulating bioinks and their bioprinting techniques. Promising state-of-the-art pathways or strategies recently developed for bioprinting bone scaffolds are highlighted, including the incorporation of bioactive ceramics to create composite scaffolds, the use of advanced bioprinting technologies (e.g., core/shell bioprinting) to form hybrid scaffolds or systems, as well as the rigorous design of scaffolds by taking into account of the influence of such parameters as scaffold pore geometry and porosity. We also review in-vitro assays and in-vivo models to track bone regeneration, followed by a discussion of current limitations associated with 3D bioprinting technologies for BTE. We conclude this review with emerging approaches in this field, including the development of gradient scaffolds, four-dimensional (4D) printing technology via smart materials, organoids, and cell aggregates/spheroids along with future avenues for related BTE.

Resorbable polylactide membrane for the treatment of segmental bone defects

INTRODUCTION

Segmental bone defects are a challenging clinical problem. In animal studies and craniomaxillofacial surgery, resorbable polylactide membrane (OrthoMesh; DePuy Synthes, West Chester, PA) shows promise for treatment of bone defects. This study presents the results of the treatment of segmental bone defects with resorbable polylactide membrane, bone morphogenic protein-2 (BMP-2), and autograft.

METHODS

This study was approved by the institutional review board. All patients with a segmental bone defect treated with a resorbable polylactide membrane by a single surgeon from 2010 to 2019 were retrospectively reviewed. Data related to demographic variables, surgical details, and union were collected.

RESULTS

Eleven patients with median age of 37 years (range 22-62 years) were included in the study with segmental bone defects in the tibia (n = 3), femur (n = 4), or forearm (n = 4). Median bone defect size was 6 cm (range 3-12 cm). Etiology of bone defects included osteomyelitis (n = 7), oncologic resection (n = 3), and post-traumatic aseptic nonunion (n = 1). Flap coverage was performed in two patients. Median radiographic follow-up was 24 months (range 5-75 months). Ten patients (10/11) achieved union at a median of 17 months (range 5-46 months). Seven patients required reoperation for any reason with six patients requiring repeat grafting.

CONCLUSIONS

To our knowledge, this study is the largest series of patients with segmental bone defects treated with resorbable polylactide membrane. Resorbable polylactide membrane in combination with BMP-2 and autograft represents a safe and effective method of bone graft containment in segmental bone defects measuring up to 12 cm in this series. Ten of 11 patients achieved union at a median time of 16 months with 6 patients requiring repeat grafting. These results compare favorably with the induced membrane technique. This study is limited by its retrospective design, absence of control and comparison groups, and low patient numbers. Future prospective randomized study of the induced membrane technique and resorbable polylactide membrane should be undertaken to determine preferred approaches for treatment of segmental bone defects.

Regenerative Approaches for the Treatment of Large Bone Defects

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

3D-printed, bioactive ceramic scaffold with rhBMP-2 in treating critical femoral bone defects in rabbits using the induced membrane technique

Although autogenous bone grafts are an optimal filling material for the induced membrane technique, limited availability and complications at the harvest site have created a need for alternative graft materials. We aimed to investigate the effect of an rhBMP-2-coated, 3D-printed, macro/microporous CaO-SiO2 -P2 O5 -B2 O3 bioactive ceramic scaffold in the treatment of critical femoral bone defects in rabbits using the induced membrane technique. A 15-mm segmental bone defect was made in the metadiaphyseal area of the distal femur of 14 rabbits. The defect was filled with polymethylmethacrylate cement and stabilized with a 2.0 mm locking plate. After the membrane matured for 4 weeks, the scaffold was implanted in two randomized groups: Group A (3D-printed bioceramic scaffold) and Group B (3D-printed, bioceramic scaffold with rhBMP-2). Eight weeks after implantation, the radiographic assessment showed that the healing rate of the defect was significantly higher in Group B (7/7, 100%) than in Group A (2/7, 29%). The mean volume of new bone formation around and inside the scaffold doubled in Group B compared to that in Group A. The mean static and dynamic stiffness were significantly higher in Group B. Histological examination revealed newly formed bone in both groups. Extensive cortical bone formation along the scaffold was found in Group B. Successful bone reconstruction in critical-sized bone defects could be obtained using rhBMP-2-coated, 3D-printed, macro/microporous bioactive ceramic scaffolds. This grafting material demonstrated potential as an alternative graft material in the induced membrane technique for reconstructing critical-sized bone defects.

Effect of surface topography on in vitro osteoblast function and mechanical performance of 3D printed titanium

Critical-sized defects remain a significant challenge in orthopaedics. 3D printed scaffolds are a promising treatment but are still limited due to inconsistent osseous integration. The goal of the study is to understand how changing the surface roughness of 3D printed titanium either by surface treatment or artificially printing rough topography impacts the mechanical and biological properties of 3D printed titanium. Titanium tensile samples and discs were printed via laser powder bed fusion. Roughness was manipulated by post-processing printed samples or by directly printing rough features. Experimental groups in order of increasing surface roughness were Polished, Blasted, As Built, Sprouts, and Rough Sprouts. Tensile behavior of samples showed reduced strength with increasing surface roughness. MC3T3 pre-osteoblasts were seeded on discs and analyzed for cellular proliferation, differentiation, and matrix deposition at 0, 2, and 4 weeks. Printing roughness diminished mechanical properties such as tensile strength and ductility without clear benefit to cell growth. Roughness features were printed on mesoscale, unlike samples in literature in which roughness on microscale demonstrated an increase in cell activity. The data suggest that printing artificial roughness on titanium scaffold is not an effective strategy to promote osseous integration.

Rat Calvarial Bone Regeneration by 3D-Printed β-Tricalcium Phosphate Incorporating MicroRNA-200c

Advanced fabrication methods for bone grafts designed to match defect sites that combine biodegradable, osteoconductive materials with potent, osteoinductive biologics would significantly impact the clinical treatment of large bone defects. In this study, we engineered synthetic bone grafts using a hybrid approach that combined three-dimensional (3D-)printed biodegradable, osteoconductive β-tricalcium phosphate (β-TCP) with osteoinductive microRNA(miR)-200c. 3D-printed β-TCP scaffolds were fabricated utilizing a suspension-enclosing projection-stereolithography (SEPS) process to produce constructs with reproducible microarchitectures that enhanced the osteoconductive properties of β-TCP. Collagen coating on 3D-printed β-TCP scaffolds slowed the release of plasmid DNA encoding miR-200c compared to noncoated constructs. 3D-printed β-TCP scaffolds coated with miR-200c-incorporated collagen increased the transfection efficiency of miR-200c of both rat and human BMSCs and additionally increased osteogenic differentiation of hBMSCs in vitro. Furthermore, miR-200c-incorporated scaffolds significantly enhanced bone regeneration in critical-sized rat calvarial defects. These results strongly indicate that bone grafts combining SEPS 3D-printed osteoconductive biomaterial-based scaffolds with osteoinductive miR-200c can be used as superior bone substitutes for the clinical treatment of large bone defects.

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

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

3D Printing of Micro- and Nanoscale Bone Substitutes: A Review on Technical and Translational Perspectives

Recent developments in three-dimensional (3D) printing technology offer immense potential in fabricating scaffolds and implants for various biomedical applications, especially for bone repair and regeneration. As the availability of autologous bone sources and commercial products is limited and surgical methods do not help in complete regeneration, it is necessary to develop alternative approaches for repairing large segmental bone defects. The 3D printing technology can effectively integrate different types of living cells within a 3D construct made up of conventional micro- or nanoscale biomaterials to create an artificial bone graft capable of regenerating the damaged tissues. This article reviews the developments and applications of 3D printing in bone tissue engineering and highlights the numerous conventional biomaterials and nanomaterials that have been used in the production of 3D-printed scaffolds. A comprehensive overview of the 3D printing methods such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and ink-jet 3D printing, and their technical and clinical applications in bone repair and regeneration has been provided. The review is expected to be useful for readers to gain an insight into the state-of-the-art of 3D printing of bone substitutes and their translational perspectives.

Use of Amniotic Membrane and Its Derived Products for Bone Regeneration: A Systematic Review

Thanks to their biological properties, amniotic membrane (AM), and its derivatives are considered as an attractive reservoir of stem cells and biological scaffolds for bone regenerative medicine. The objective of this systematic review was to assess the benefit of using AM and amniotic membrane-derived products for bone regeneration. An electronic search of the MEDLINE-Pubmed database and the Scopus database was carried out and the selection of articles was performed following PRISMA guidelines. This systematic review included 42 articles taking into consideration the studies in which AM, amniotic-derived epithelial cells (AECs), and amniotic mesenchymal stromal cells (AMSCs) show promising results for bone regeneration in animal models. Moreover, this review also presents some commercialized products derived from AM and discusses their application modalities. Finally, AM therapeutic benefit is highlighted in the reported clinical studies. This study is the first one to systematically review the therapeutic benefits of AM and amniotic membrane-derived products for bone defect healing. The AM is a promising alternative to the commercially available membranes used for guided bone regeneration. Additionally, AECs and AMSCs associated with an appropriate scaffold may also be ideal candidates for tissue engineering strategies applied to bone healing. Here, we summarized these findings and highlighted the relevance of these different products for bone regeneration.

Preclinical Evaluation of an Innovative Bone Graft of Marine Origin for the Treatment of Critical-Sized Bone Defects in an Animal Model

Autogenous cancellous bone graft is the current gold standard of treatment for the management of bone defects since it possesses the properties of osteoinduction, osteoconduction, and osteogenesis. Xenografts and synthetic grafts have been widely reported as available and low-cost alternatives, which retain good osteoconductive and mechanical properties. Given the rich biodiversity of ocean organisms, marine sources are of particular interest in the search for alternative bone grafts with enhanced functionalities. The purpose of this paper is to assess the biocompatibility of a marine-derived bone graft obtained from shark tooth, which is an environmentally sustainable and abundant raw material from fishing. This research presents the findings of a preclinical trial—following UNE-EN ISO 10993—that induced a critical-sized bone defect in a rabbit model and compared the results with a commercial bovine-derived bone graft. Evaluation by micro-computed tomography and histomorphometric analysis 12 weeks after implantation revealed good osseointegration, with no signs of inflammatory foreign body reactions, fibrosis, or necrosis in any of the cases. The shark tooth-derived bone graft yielded significantly higher new bone mineral density values (54 ± 6%) than the control (27 ± 8%). Moreover, the percentage of intersection values were much higher (86 ± 8%) than the bovine-derived bone graft (30 ± 1%) used as control. The area of occupancy by bone tissue in the test material (38 ± 5%) also gave higher values than the control (30 ± 6%). The role of physicochemical properties, biphasic structure, and composition on the stimulation of bone regeneration is also discussed.

Classification of Bone Defects: An Extension of the Orthopaedic Trauma Association Open Fracture Classification

OBJECTIVES

To develop a post-traumatic bone defect classification scheme and complete a preliminary assessment of its reliability.

DESIGN

Retrospective classification.

SETTING

Tertiary referral trauma center.

PATIENTS/PARTICIPANTS

Twenty open fractures with bone loss.

INTERVENTION

Assignment of a bone defect classification grade.

MAIN OUTCOME MEASUREMENTS

Open fractures were classified based on orthogonal radiographs, assessing the extent and local geometry of bone loss, including D1-incomplete defects, D2-minor/subcritical (complete) defects (<2 cm), and D3-segmental/critical-sized defects (≥2 cm). Incomplete defects (D1) include D1A-<25% cortical loss, D1B-25%-75% cortical loss, and D1C->75% cortical loss. Minor/subcritical (complete) defects (<2 cm) (D2) include D2A-2 oblique ends allowing for possible overlap, D2B-one end oblique/one end transverse, and D2C-2 transverse ends. Segmental/critical-sized Defects (≥2 cm) include D3A-moderate defects, 2 to <4 cm; D3B-major defects, 4 to <8 cm; and D3C-massive defects, ≥8 cm. Reliability was assessed among 3 independent observers using Fleiss' kappa tests.

RESULTS

Interobserver reliability demonstrated the classification scheme has very good agreement, κ = 0.8371, P < 0.0005. Intraobserver reliability was excellent, κ = 1.000 (standard error 0.1478-0.1634), P < 0.00001. Interobserver reliability for the distinction between categories alone (D1, D2, or D3) was also excellent, κ = 1.000 (standard error 0.1421-0.1679), P < 0.00001.

CONCLUSIONS

This classification scheme provides a robust guide to bone defect assessment that can potentially facilitate selection of the most appropriate treatment strategy to optimize clinical outcomes.

Unprecedented tibial bone lengthening of 33.5 cm by distraction osteogenesis for the reconstruction of a subtotal tibial bone defect. A case report and literature review

Background

We present a case of an immense unprecedented tibial bone lengthening of 33.5 cm. The management of chronic osteomyelitis of the right tibia with subtotal tibial bone defect, talus defect and equinus ankle deformity. We demonstrate limb reconstruction by distraction osteogenesis and correction of ankle deformity with the Ilizarov technique. Limb salvage was preferred as an alternative to amputation to restore basic limb function.

Case presentation

A 16-year-old male patient fell and injured his right lower leg. He attempted to treat the symptoms with traditional home remedies. During 15 months of self-treating, he developed osteomyelitis of the right tibia and had lost function in his foot. Radiology revealed immense bone defect of the right tibia, including talus bone defect and equinus deformity of the calcaneus. The patient’s right tibia was non weight-bearing, had drainage sinus just below his knee and a large scar anteriorly along the entire length of the tibia.

Conclusion

Upon completion of treatment, the patient was able to avoid amputation of his leg with partially restored function for weight-bearing. He carried himself without assistance after 3 years of lost function in his right leg. Tibial bone distraction osteogenesis of 33.5 cm was done after 90% of the tibial length was defected. To the best of our best knowledge, this case is one of a kind to achieve distraction of tibial bone to such length.