Autogenous bone graft: donor sites and techniques

Percutaneous Harvest of Calcaneal Bone Autograft: Quantification of Volume and Definition of Anatomical Safe Zone

Bone grafting is commonly used in reconstructive foot and ankle surgery. The calcaneus provides an excellent site for graft harvest due to its rich vascularity and access to corticocancellous or strictly cancellous bone. The relatively thin soft tissue envelope makes dissection easy compared to more proximal autograft sites. In this investigation we quantified cancellous autograft volume from the calcaneus while simultaneously defining anatomical safe zones and identifying anatomical structures at risk. Nine matched-pair (18 total) fresh-frozen cadaveric below-knee limbs were utilized. All limbs were thawed at room temperature prior to the procedure. Calcaneal autograft was harvested following the senior author's (D.J.E.) technique. Bone graft was packed and quantified by podiatric medical students (B.R. and J.T.). An independent investigator (K.S.) meticulously dissected the lateral calcaneal soft tissue envelope to determine rates of neurovascular compromise. Anatomical safe zones were defined by measurements of the harvest site compared to vital anatomical structures. Cancellous autograft averaging 0.85 cc was obtained through an average cortical opening of 0.77 cm. The stab incision is approximately 2.2 cm anterior to the posterior aspect of the calcaneus and 1.6 cm superior to the inferior aspect of the calcaneus. This incision is an average 1.8 cm from the main branch of the sural nerve. No neurovascular damage was found. This study details percutaneous harvest of calcaneal autograft for use in forefoot or midfoot surgeries with an emphasis on feasibility of this additional procedure. The technique proposed is valuable based on simplicity, wide anatomic safe zone, and potential improvement of surgical outcomes.

Reconstruction of the coronoid process with the olecranon tip for chronic elbow dislocation in children: A rare case report and literature review

The coronoid process of the ulna, as a key part of the elbow joint, plays an important role in maintaining elbow joint stability. Reconstruction of the coronoid process is necessary in both acute and chronic coronoid defects to restore elbow stability and avoid early joint degeneration. The olecranon tip may be a useful autologous osteochondral graft for reconstructing the same shape of the ulna coronoid process. The purpose of this report was to verify if reconstruction of the coronoid process with the olecranon tip can restore elbow stability and kinematics. Here, we report a 13-year-old boy who had undergone Kirschner-wire fixation for a left supracondylar fracture of the left humerus 9 years previously. After that, the right elbow dislocation and varus deformity gradually appeared. Imaging revealed posterolateral dislocation of the left elbow due to the absence of the coronoid process of the ulna. We reconstructed the ulnar coronoid process by intercepting the ipsilateral olecranon tip. After 22 months of follow-up, the range of motion of the left elbow joint was normal, and the cubitus varus deformity disappeared. The results of this report suggest that olecranon tip autografts are suitable to replace transverse coronoid defects. Given the patient's satisfactory clinical results, this reconstruction technique is safe and effective for the treatment of chronic elbow instability due to coronoid process defects of the ulna.

3D-bulk to nanoforms of modified hydroxyapatite: Characterization and osteogenic potency in an in vitro 3D bone model system

Synthetic bioceramics are replacing conventional methods of treating bone defects with autografts owing to the high demand of bone substitutes, with their Surface topography and size contributing to favor cytocompatibility in tissue regeneration. This experimental study deals with the comparative evaluation of the physical characterizations of four different in-house synthesized bioceramics from 3D-bulk to nanoforms of hydroxyapatite (HA), Biphasic calcium phosphate (BCP), Strontium doped hydroxyapatite (SrHA) and Silica coated hydroxyapatite (HASi) and also simultaneously evaluates adhesion, proliferation and osteogenic differentiation of rabbit adipose derived mesenchymal stem cells (RADMSCs) on these biomimetic ceramic niches. The osteogenic induced cells grown on 3D scaffolds for a period of 7, 14, 21, and 28 days were analyzed for their viability (MTT, LDH, live-dead assays), morphology (SEM), proliferation (Cytox-Red) and osteogenic differentiation (ALP, osteocalcin expression). Cellular activities and differentiation of RADMSCs were significantly higher on SrHA indicating the role of strontium in the differentiation of mesenchymal stem cells on this ceramic platform to the bone lineage. In order to reinforce the materials for hard tissue implantation and drug delivery, nano-SrHA (nSrHA) became the nanoparticle of choice based on its non-toxicity, cytocompatibility and osteogenic properties (nSrHA > nHASi > nBCP > nHA).

Treatment for subtrochanteric fracture and subsequent nonunion in an adult patient with osteopetrosis: A case report and review of the literature

BACKGROUND

As a congenital metabolic bone disease caused by defective osteoclastic resorption of immature bone, osteopetrosis is characterized by diffused sclerosis of bones, brittle bones, easy fracturing, narrow medullary canals, and a weak fracture healing ability. At present, clear standards and principles for the treatment of fractures in patients with osteopetrosis are lacking. Non-operative treatment can prevent fracture hematoma and preserve the blood supply to the bone fragments, while being associated with frequent failures and higher mortality rates. Meanwhile, closed reduction and internal fixation with intramedullary nail (CRIF + IMN) approaches can also protect blood supply to the fracture site. However, IMN cannot be used for the vast majority of patients with osteopetrosis due to the narrowing of medullary canals. Thus, open reduction and internal fixation with plate remains the most appropriate surgical method for treating fractures in patients with osteopetrosis, but this approach is complicated by the lack of intramedullary hematopoiesis in such patients. Fracture healing primarily depends on the blood supply to the external periosteum. Open reduction can also easily destroy the periosteum and cause delayed fracture healing or even nonunion; however, CRIF may be the most practical approach. As a result, it would be prudent to solve the difficulty of drilling during the operation and the problem of postoperative nonunion.

CASE SUMMARY

In 2018, we treated an adult patient with osteopetrosis presenting with a subtrochanteric fracture. The fracture was fixed using a femoral locking compression plate. Because of delayed consolidation, at 12 mo postoperatively the patient was further treated with platelet-rich plasma (PRP) combined with radial extracorporeal shock wave therapy (rESWT). Antero-posterior and lateral radiographs obtained at the latest follow-up (10 mo) showed that the callus had grown at the original fracture site, and the medial fracture line almost disappeared.

CONCLUSION

Osteosynthesis remains the first choice of treatment approach for fractures in patients with osteopetrosis, especially peritrochanteric fractures. Preoperative preparation is necessary to avoid risks such as drill bit breakage and iatrogenic fracture during the operation. Moreover, fractures in a patient with osteopetrosis present with a high risk of delayed union and nonunion, which can be potentially cured with PRP + rESWT.

Tunable and Controlled Release of Cobalt Ions from Metal-Organic Framework Hydrogel Nanocomposites Enhances Bone Regeneration

Cobalt (Co) ions, which can mimic hypoxia to promote angiogenesis, exhibit great potential for bone repair. However, a key point for the use of Co ions is that their release profile should be controllable and, more importantly, suitable for the bone regeneration process. Here, 2-ethylimidazole (eIm) was introduced into zeolitic imidazolate framework-67 (ZIF-67) to slow down Co-ion release and fabricate eIm-doped ZIF-67 (eIm/ZIF-67), which was combined into gelatin methacrylate (GelMA) to obtain an in situ photo-cross-linking nanocomposite hydrogel as a tunable Co-ion controlled release system. A tunable and controlled release of Co ions from the nanocomposite hydrogel was achieved by variation of linker composition, and GelMA with 75% eIm/ZIF-67 (with 75% eIm in the precursor solutions) could maintain a 21-day sustained release of Co ions, which is matched with early-stage angiogenesis during the bone formation process. Our in vitro study also showed that the GelMA@eIm/ZIF-67 hydrogel could reduce cytotoxicity and effectively promote the angiogenic activity of human umbilical vein endothelial cells (HUVECs) and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Moreover, an in vivo rat calvarial defect model demonstrated that the GelMA@eIm/ZIF-67 hydrogel exhibited remarkably enhanced bone formation and neovascularization abilities and had good biocompatibility as shown in organ histopathological examinations. Therefore, this novel nanocomposite hydrogel has strong therapeutic potential as a desirable Co-ion controlled release system and a powerful proangiogenic/osteogenic agent for the treatment of bone defects.

The Impact of Nano-Crystal Hydroxyapatites on the Regeneration of Bone Defects

Calcium hydroxyapatite is a widely used material for replacing bone defects. However, the effectiveness of nano-crystalline calcium hydroxyapatite produced from eggshells in the replacement of bone defects has not been investigated yet. The study aimed to evaluate the effectiveness of using nano-crystalline calcium hydroxyapatite made from eggshell for the healing of bone defect of the femur in rats. Forty-eight (n=48) rats underwent a surgical procedure to simulate femoral defect. The animals were sub-divided into 4 groups (each with n=12) depending on the methods of bone defect replacement: I control group (CG) (without bone defect replacement); II intervention group (the bone defect was replaced by PRP (PRP); III intervention group (the bone defect was replaced by nano-crystalline hydroxyapatite obtained from eggshell) (HA) and IV interventional group (the bone defect was replaced by a combination of hydroxyapatite and PRP) (HA+PRP). The degree of effectiveness of studied methods was assessed using radiological (on the 14th day), histological (on the 61st day), and biomechanical analysis (on the 61st day). According to radiographic data, the CG group had the lowest level of bone regeneration after 14 days (4.2 ±1.7%). In the HA + PRP group, the level of bone regeneration was 22.1±7.1 %, which was higher in comparison with the rates of consolidation of bone defects in the HA group (20.7± 9.3) (p = 0.023). According to the histo-morphometry data, the rates of bone tissue regeneration in the PRP group (19.8 ±4.2%) were higher in comparison with the CG group (12.7 ± 7.3%), (p>0.05). In the HA+PRP group, bone regeneration rates (48.9±9.4 %) were significantly higher (p=0.001) than in the HA group (35.1±9.8%). According to the results of biomechanical assessment under the maximum stress (121.0722), the maximum bending deformation of the contralateral bone without defect was 0.028746, which was higher than the indicators of the HA+PRP group, where at the maximum stress (90.67979) the bending deformation was 0.024953 (p>0.05). Compared to CG, PRP, and HA, biomechanical bone strength was significantly higher in the HA + PRP group (p≤0.01). At the maximum stress (51.81391), the maximum bending strain in the CG group was 0.03869, which was lower than in the PRP group, where the maximum stress and bending strain were 59.45824 and 0.055171, respectively (p>0.05). However, the bone strength of the HA group was statistically significantly higher compared to the CG and PRP groups (p<0.01).

The results demonstrated the effectiveness of the use of nanocrystalline calcium hydroxyapatite obtained from eggshell in the healing of a bone defect. The best results were observed in the group of the combined use of nano-crystalline calcium hydroxyapatite and PRP.

Effects of a novel self-assembling peptide scaffold on bone regeneration and controlled release of two growth factors

RADA16 is a self-assembling peptide material with good bioactivity. To improve the bioactivity of a material, some specific functional motifs can be added to its peptide sequence. Here, we report a self-assembling peptide nanogel, RADA16-RGD, that has better bioactivity than RADA16 and can simultaneously carry and control the release of two growth factors, VEGF and BMP-2, which have synergistic effects on bone formation. The peptide materials were characterized by transmission electron microscopy and scanning electron microscopy. The mechanical properties of the peptides were evaluated by the rheology test. The biocompatibility of the materials was evaluated via the use of the CCK-8 test, live/dead staining and confocal laser scanning microscopy. Osteogenesis capability in vitro was evaluated by means of ALP staining, extracellular matrix mineralization and detection of osteogenic markers. The controlled release of growth factors was examined by ELISA. The results showed that RADA16-RGD exhibited a better ability than RADA16 to promote cell proliferation, adhesion and bone formation. In addition, RADA16-RGD had good biocompatibility and exhibited effective controlled release of VEGF and BMP-2. More importantly, compared with RADA16-RGD loaded with single growth factor or without growth factors, RADA16-RGD loaded with two growth factors exhibited a stronger ability to promote cell proliferation and osteogenesis. This study provides a promising strategy for the application of self-assembling peptides to promote osteogenesis and controlled release of proteins.

Outcomes and complications of the reamer irrigator aspirator versus traditional iliac crest bone graft harvesting: a systematic review and meta-analysis

BACKGROUND

The reamer irrigator aspirator (RIA) is a relatively recent device that is placed in the medullary canal of long bones to harvest a large volume of bone marrow, which is collected in a filtered canister. This study compares outcomes and complications of the RIA versus a traditional iliac crest bone graft (ICBG) for the treatment of bone defects.

METHODS

This meta-analysis was conducted according to the PRISMA guidelines. The Embase, Google Scholar, PubMed, and Scopus databases were accessed in June 2021. All clinical trials comparing the RIA and ICBG with a minimum of 6 months follow-up were included.

RESULTS

Data from 4819 patients were collected. The RIA group demonstrated lower site pain (P < 0.0001), fewer infections (P = 0.001), and a lower rate of adverse events (P < 0.0001). The ICBG group demonstrated a greater rate of bone union (P < 0.0001). There was no difference between groups in VAS (P = 0.09) and mean time to union (P = 0.06).

CONCLUSION

The current evidence supports the use of the RIA, given its low morbidity and short learning curve.

Proximal tibia with an inserted nail can be an available donor site for harvesting cancellous bone

INTRODUCTION

A pre-existing implant at the harvesting site might dissuade the surgeon from considering the site as available for bone harvesting. This study aimed to investigate the quantity of cancellous bone graft that can be harvested from a proximal tibia with an inserted nail and to report the clinical outcomes of this bone graft harvesting technique.

HYPOTHESIS

Our hypothesis was that a certain amount of cancellous bone graft could be harvested from a proximal tibia with an inserted nail without compromising the surrounding environment and outcome of nonunion treatment.

MATERIAL AND METHODS

Bone grafting from an ipsilateral proximal tibia with an inserted nail was performed in 32 patients for treating defect nonunion. The amount of harvested bone was measured using three parameters (weight, height, and volume). The effects of the proximal locking screw position on the quantity and location of bone graft harvest were analyzed. Clinical outcomes were evaluated by assessing the radiologic healing of the bone graft site and by assessing the donor site complications.

RESULTS

The mean bone defect volume in the nonunion site was 31.1±18.3 (range, 10.6-87.0) cm³. The mean quantity of harvested bone from proximal tibias with an inserted nail was 21.2g, height was 3.9cm, and volume was 26.3 cm³. A positive correlation was found between the quantity of harvested bone and the level of the lateral oblique interlocking screw hole in the tibial nail. All grafted bone successfully consolidated in all cases at an average of 5.8 months postoperatively. However, joint penetration during bone harvesting occurred in one case.

DISCUSSION

The bony defect, which measured about 14.3 cm³ could be filled with cancellous bone from a PT with an existing IM nail, without additional bone graft requirements. Even if an intramedullary nail exists inside the proximal tibia, harvesting cancellous bone at this site can be a viable option without serious complications.

LEVEL OF EVIDENCE

IV; Retrospective descriptive study.

Scaffold-guided bone regeneration in large volume tibial segmental defects

Large volume losses in weight bearing long bones are a major challenge in clinical practice. Despite multiple innovations over the last decades, significant limitations subsist in current clinical treatment options which is driving a strong clinical demand for clinically translatable treatment alternatives, including bone tissue engineering applications. Despite these shortcomings, preclinical large animal models of large volume segmental bone defects to investigate the regenerative capacity of bone tissue engineering strategies under clinically relevant conditions are rarely described in literature. We herein present a newly established preclinical ovine animal model for the treatment of XL volume (19 cm³) segmental tibial defects. In eight aged male Merino sheep (age > 6 years) a mid-diaphyseal tibial segmental defect was created and stabilized with a 5.6 mm Dynamic Compression Plate (DCP). We present short-term (3 months) and long-term (12-15 months) results of a pilot study using medical grade Polycaprolactone-Tricalciumphosphate (mPCL-TCP) scaffolds combined with a dose of 2 mg rhBMP-7 delivered in Platelet-Rich- Plasma (PRP). Furthermore, detailed analyses of the mechanical properties of the scaffolds as well as interfragmentary movement (IFM) and DCP-surface strain in vitro and a comprehensive description of the surgical and post-surgery protocol and post-mortem analysis is given.

Bioprinting of Stem Cells in Multimaterial Scaffolds and Their Applications in Bone Tissue Engineering

Bioprinting stem cells into three-dimensional (3D) scaffolds has emerged as a new avenue for regenerative medicine, bone tissue engineering, and biosensor manufacturing in recent years. Mesenchymal stem cells, such as adipose-derived and bone-marrow-derived stem cells, are capable of multipotent differentiation in a 3D culture. The use of different printing methods results in varying effects on the bioprinted stem cells with the appearance of no general adverse effects. Specifically, extrusion, inkjet, and laser-assisted bioprinting are three methods that impact stem cell viability, proliferation, and differentiation potential. Each printing method confers advantages and disadvantages that directly influence cellular behavior. Additionally, the acquisition of 3D bioprinters has become more prominent with innovative technology and affordability. With accessible technology, custom 3D bioprinters with capabilities to print high-performance bioinks are used for biosensor fabrication. Such 3D printed biosensors are used to control conductivity and electrical transmission in physiological environments. Once printed, the scaffolds containing the aforementioned stem cells have a significant impact on cellular behavior and differentiation. Natural polymer hydrogels and natural composites can impact osteogenic differentiation with some inducing chondrogenesis. Further studies have shown enhanced osteogenesis using cell-laden scaffolds in vivo. Furthermore, selective use of biomaterials can directly influence cell fate and the quantity of osteogenesis. This review evaluates the impact of extrusion, inkjet, and laser-assisted bioprinting on adipose-derived and bone-marrow-derived stem cells along with the effect of incorporating these stem cells into natural and composite biomaterials.

Arthroscopic Distal Clavicular Autograft for Congruent Glenoid Reconstruction

Arthroscopic distal clavicular autograft (DCA) is effective in shoulder instability with glenoid bone loss. The original technique uses an osteochondral autograft, fixed with screws or suture anchors. We developed a modified procedure called "congruent arc DCA" characterized by (1) use of drilling guides to optimize graft positioning and make the all-arthroscopic procedure safer and reproducible; (2) rotation of the DCA of 90° to reach a congruent arc with its undersurface; (3) fixation of the graft with cortical buttons to simplify its intra-articular passage, avoid hardware problems, and facilitate possible revision surgery; and (4) intraoperative use of a suture tensioner to achieve satisfactory compression of the graft and increase its consolidation.

Strategies for large bone defect reconstruction after trauma, infections or tumour excision: a comprehensive review of the literature

Large bone defects resulting from musculoskeletal tumours, infections, or trauma are often unable to heal spontaneously. The challenge for surgeons is to avoid amputation, and provide the best functional outcomes. Allograft, vascularized fibular or iliac graft, hybrid graft, extracorporeal devitalized autograft, distraction osteogenesis, induced-membrane technique, and segmental prostheses are the most common surgical strategies to manage large bone defects. Given its optimal osteogenesis, osteoinduction, osteoconduction, and histocompatibility properties, along with the lower the risk of immunological rejection, autologous graft represents the most common used strategy for reconstruction of bone defects. However, the choice of the best surgical technique is still debated, and no consensus has been reached. The present study investigated the current reconstructive strategies for large bone defect after trauma, infections, or tumour excision, discussed advantages and disadvantages of each technique, debated available techniques and materials, and evaluated complications and new perspectives.

Reconstruction of traumatic tubular bone defects using vascularized fibular graft

Large segmental bone defects due to major trauma constitute a major challenge for the orthopaedic surgeon, especially when combined with poor or lost soft tissue envelope. Vascularized fibular transfer is considered as the gold standard for the reconstruction of such defects of the extremities due to its predictable vascular pedicle, long cylindrical shape, and tendency to hypertrophy, and resistance to infection. Vascularized bone grafts remain viable throughout the healing period and are capable of inducing rapid graft union without prolonged creeping substitution, osteogenesis and hypertrophy at the reconstruction site, and fight with infection. The fibular graft can be transferred solely, or as a composite flap including muscle, subcutaneous tissue, skin and even a nerve segment in order to reconstruct both bone and soft tissue components of the injury at single stage operation. Such a reconstruction can even be performed in the presence of local infection, since vascularized bone and adjacent soft tissue components enhances the blood flow at the traumatized zone, allowing for the delivery of antibiotics and immune components to the infection site. In an effort to preserve growth potential in pediatric patients; the fibular head and proximal growth plate can be included to the graft. This practice also enables to reconstruct the articular ends of various bones, including distal radius and proximal ulna. Apart from defect reconstruction, vascularized fibular grafts also proved to be a reliable in treating atrophic nonunions, reconstruction of osteomyelitic bone segments. These grafts are superior to alternative reconstructive techniques, as bone grafts with intrinsic blood supply lead to higher success rates in reconstruction and accelerate the repair process at the injury site in cases where blood supply to the injury zone is defective, poor soft tissue envelope, and local infection at the trauma zone.

Surgical Management of Enchondromas of the Hand: A 12-Year Experience

Objective Enchondromas are benign tumours of hyaline cartilage most frequently arising in the bones of the hand and the optimum surgical management strategy for these is debated. We present an audit of the surgical management of 57 enchondromas referred to our tertiary hand surgery department over a period of 12 years (2008–2020) and describe our surgical technique for this procedure as well as a comparison with other studies in the literature.

Materials and Methods Retrospective audit of our practice. Data were extracted from our institutional operative database to identify all patients undergoing surgical management of enchondromas during the time period. The individual electronic patient records were then evaluated to extract demographics and outcome data.

Results Our results demonstrate excellent clearance of enchondroma (74% Tordai group 1 radiological resolution) with very low complication rates and no recurrence. Our results also emphasize the importance of surgical management of enchondromas to allow diagnosis of rare chondrosarcoma (3.5% in this study).

Conclusion A larger randomized controlled trial is still required to adequately determine the differences between the surgical options available and determine the best possible surgical approach to these cases. Level of evidence is III.

Autologous Bone Grafting in Trauma and Orthopaedic Surgery: An Evidence-Based Narrative Review

Autologous bone grafting is common in trauma and orthopaedic surgery. Both the Reamer Irrigator Aspirator (RIA) and Iliac Crest Bone Graft (ICBG) aim to obtain autologous bone graft. Although the process of harvesting a bone graft is considered simple, complications may occur. This study examined morbidity and pain at the donor site, blood loss, and iatrogenic fractures, comparing RIA and ICBG. The source of the autologous bone graft, the alternative graft sites, and the storage modalities of the harvested bone marrow were also evaluated. In May 2021, PubMed, Embase, Scopus, and Google Scholar were accessed, with no time constraints. RIA may produce greater blood loss, but with less morbidity and complications, making it a potential alternative source of bone grafting.

Structural Bicortical Autologous Iliac Crest Bone Graft Combined with the Tunnel Bone Tamping Method for the Depressed Tibial Plateau Fractures

Background

Clinically, autologous iliac crest bone grafts (ICBG) and bone tamping methods are often applied to manage depressed tibial plateau fractures (DTPFs). The purpose of this study was to describe and evaluate the technique of using structural bicortical autologous ICBG combined with the tunnel bone tamping method (TBTM) for treating DTPFs.

Methods

All patients with DTPFs who underwent structural bicortical autologous ICBG combined with TBTM from January 2016 to February 2018 were prospectively analysed. Demographics, injury, surgery, postoperative complications, and clinical outcomes were recorded. All patients were followed up for more than 30 months. Postoperative radiography and CT were employed to assess fracture healing and the reduction quality.

Results

Forty-three of the included patients completed the follow-up. No malreduction was observed. Based on the immediate postoperative imaging, the intra-articular step-off was significantly reduced (8.19 mm preoperatively vs. 1.30 mm immediate postoperatively, P < 0.001). From the immediate operation to the latest follow-up, the reduction was maintained significantly well, with a nonnegligible absolute difference (0.18 mm, P = 0.108). A remarkable secondary loss of reduction (intra-articular step off > 3 mm) was found in two elderly patients (2/43, 4.65%). The incidence of complications related to the bone-graft donor and bone-graft site was 2.33% and 4.65%, respectively. At the final follow-up, the mean Hospital for Special Surgery (HSS) score of the knee was 98.19 ± 2.89, and the mean 36-Item Short-Form Health Survey (SF-36) score was 95.65 ± 4.59.

Conclusion

Structural bicortical autologous ICBG combined with TBTM is radiologically effective and stable in terms of complications for the DTPFs.

Replacement Process of Carbonate Apatite by Alveolar Bone in a Rat Extraction Socket

The objective of this study was to investigate a bone graft substitute containing carbonate apatite (CO₃Ap) to analyze bone replacement and the state of bone formation in vitro and in vivo compared with autogenous bone (AB) or control. An osteoclast precursor cell line was cultured with AB or CO₃Ap, and morphological analysis using scanning electron microscopy and a tartrate-resistant acid phosphatase activity assay were performed. The right maxillary first and second molars of Wistar rats were extracted and compensated by AB or CO₃Ap granules. Following implantation, the bone formation state was evaluated after 3, 5, 7, 14, and 28 days of surgery by micro-computed tomography and immunohistostaining. The osteoclast-like cell morphology was typical with many cell protrusions in the AB and CO₃Ap groups. Additionally, the number of osteoclast-like cells formed in the culture increased in each group; however, there was no significant difference between the AB and CO₃Ap groups. Five days after tooth extraction, osteoclasts were observed near CO₃Ap. The bone thickness in the CO₃Ap group was significantly increased than that in the control group and the bone formation in the CO₃Ap group increased by the same level as that in the AB group. CO₃Ap is gradually absorbed by osteoclasts in the extraction socket and is easily replaced by alveolar bone. The process of bone replacement by osteoclasts is similar to that of autologous bone. By observing the process of bone replacement in more detail, it may be possible to gain a better understanding of the bone formation and control the amount of bone after surgery.

[Harvesting cancellous bone or composite corticocancellous bone grafts from the posterior iliac crest]

OBJECTIVE

Harvesting bone-either cancellous bone or composite corticocancellous bone grafts-from the iliac crest is an efficient method for filling or bridging bony defects commonly encountered in comminuted epimetaphyseal fractures (e.g., tibial head fractures), in nonunions or during reconstructive measures as in arthrodesis of major joints or spondylodesis, bone defects due to tumor resection or following eradication of chronic infection.

INDICATIONS

All bone defects with a maximum size of 4-5 cm.

CONTRAINDICATIONS

Rejection of surgery by the patient, infection or evidence of pathological bony changes in the posterior pelvic rim, inexperience of the surgeon with the procedure.

SURGICAL TECHNIQUE

Incision at the posterior iliac crest and removal of a structural or cancellous bone graft of predetermined length. Depending on the bleeding tendency, a suction drain can be inserted.

POSTOPERATIVE MANAGEMENT

After surgery supine positioning is favorable for wound compression to avoid bleeding as well as sufficient analgesia. Mobilization is dictated by the main operation. The pelvis is not compromised in its mechanical integrity and allows for full weight bearing on the operated side.

Bone Graft Harvesting From the Calcaneus Using Lateral Wall Corticotomy Technique by an Osteotome

Background: The aim of this study was to evaluate the complications following calcaneal autologous bone graft harvesting using an osteotome in patients who underwent foot and ankle surgery with follow-up of at least 1 year. Methods: In a cohort study, all consecutive patients underwent forefoot or midfoot surgeries in conjunction with harvesting bone graft from the calcaneus using lateral wall corticotomy technique by an osteotome from 2015 till 2018 were asked to follow. The outcome and morbidity were assessed by visual analogue scale (VAS) pain, numbness in territory of the sural nerve, surgical site numbness or tenderness, infection, hematoma formation, or pathologic fracture. Also any possible restrictions on wearing desired shoes were asked. Results: Totally, 50 patients (11 males, 39 females; 29 right foot, 21 left foot) with the mean age of 48.2 ± 13.8 years (range 8-66 years) were assessed. There were no major complications on donor site such as infection, hematoma formation, or pathologic fracture. The following results were seen; 90% without any pain (VAS 0/10), 96% without numbness at the incision site, 96% without point tenderness on lateral of heel, 98% without paresthesia or numbness in the sural nerve territory, and 84% were able to wear their favorite shoes. Forty-one (82%) cases said if they need another foot surgery, they would permit to harvest bone graft from their heel. Conclusions: Autologous bone graft harvesting from the calcaneus using lateral wall corticotomy technique by an osteotome could be a useful method with very low complications.Levels of Evidence: Therapeutic, level IV: cohort, case series.

Settable Polymeric Autograft Extenders in a Rabbit Radius Model of Bone Formation

Autograft (AG) is the gold standard for bone grafts, but limited quantities and patient morbidity are associated with its use. AG extenders have been proposed to minimize the volume of AG while maintaining the osteoinductive properties of the implant. In this study, poly(ester urethane) (PEUR) and poly(thioketal urethane) (PTKUR) AG extenders were implanted in a 20-mm rabbit radius defect model to evaluate new bone formation and graft remodeling. Outcomes including µCT and histomorphometry were measured at 12 weeks and compared to an AG (no polymer) control. AG control examples exhibited new bone formation, but inconsistent healing was observed. The implanted AG control was resorbed by 12 weeks, while AG extenders maintained implanted AG throughout the study. Bone growth from the defect interfaces was observed in both AG extenders, but residual polymer inhibited cellular infiltration and subsequent bone formation within the center of the implant. PEUR-AG extenders degraded more rapidly than PTKUR-AG extenders. These observations demonstrated that AG extenders supported new bone formation and that polymer composition did not have an effect on overall bone formation. Furthermore, the results indicated that early cellular infiltration is necessary for harnessing the osteoinductive capabilities of AG.

Gene- and RNAi-activated scaffolds for bone tissue engineering: Current progress and future directions

Large bone defects are usually managed by replacing lost bone with non-biological prostheses or with bone grafts that come from the patient or a donor. Bone tissue engineering, as a field, offers the potential to regenerate bone within these large defects without the need for grafts or prosthetics. Such therapies could provide improved long- and short-term outcomes in patients with critical-sized bone defects. Bone tissue engineering has long relied on the administration of growth factors in protein form to stimulate bone regeneration, though clinical applications have shown that using such proteins as therapeutics can lead to concerning off-target effects due to the large amounts required for prolonged therapeutic action. Gene-based therapies offer an alternative to protein-based therapeutics where the genetic material encoding the desired protein is used and thus loading large doses of protein into the scaffolds is avoided. Gene- and RNAi-activated scaffolds are tissue engineering devices loaded with nucleic acids aimed at promoting local tissue repair. A variety of different approaches to formulating gene- and RNAi-activated scaffolds for bone tissue engineering have been explored, and include the activation of scaffolds with plasmid DNA, viruses, RNA transcripts, or interfering RNAs. This review will discuss recent progress in the field of bone tissue engineering, with specific focus on the different approaches employed by researchers to implement gene-activated scaffolds as a means of facilitating bone tissue repair.

Long term results of lower limb posttraumatic acute bone defects treated with masquelet technique

INTRODUCTION

Several alternatives are now available when treating posttraumatic acute bone defects. Masquelet's technique represents a safe procedure to treat lower limb open fractures associated with significant bone defects and allows surgeons to try to reduce complications incidence.

MATERIAL AND METHODS

Retrospective study based on patients´ record files and images (2015-2017). Twelve patients suffering acute bone defect, treated using Masquelet technique, were evaluated. A total of ten patients were finally included after exclusion criteria were applied.

RESULTS

Average time from injury to first stage surgery was 11 days. Free flaps were required in three cases (two latissimus dorsi and one anterolateral thigh flap). Time to second stage surgery was 115 days on average. As bone graft, reaming irrigation-aspiration system was associated to this technique. Consolidation was achieved in all patients but one after an average time of 8.4 months. There was only one case of limb shortening of 20 mm. There was no case of nonunion or infection, and patients could perform daily basic activities independently. VAS mean score was one point one year after final surgery.

CONCLUSIONS

Masquelet's technique achieves encouraging results when treating lower limb acute bone defects. Using this technique, surgeons could decrease infection incidence in open fractures with severe bone loss. On the other hand, it is a two-stage surgery process, which makes the process longer.

Mineralized collagen scaffold bone graft accelerate the osteogenic process of HASCs in proper concentration

Purpose

To investigate the feasibility and the optimum condition of human adipose-derived stem cells cultured on the mineralized collagen material; and to further explore the mechanism of osteogenic differentiation of the human Adipose-derived stem cells stimulated by the mineralized collagen material.

Methods

Primary human adipose-derived stem cells (HADSCs) were isolated from human adipose tissue using centrifugal stratification, which had been passed repeatedly to later generations and purified. Human adipose-derived stem cells were cultured on the bone graft material and the optimum concentration was explored by Alamar blue colorimetric method. The rest experiment was conducted according to the result. The experimental groups are shown below: group A (HADSCs + bone graft material); group B (HADSCs). Morphological observation was taken by scanning electronic microscope (SEM). Alkaline phosphatase activities were tested by histochemical method. Calcium deposition was investigated by alizarin red staining. The quantity access of osteogenic-related mRNA: ALP (alkaline phosphatase), BMP2 (bone morphogenetic protein 2) and RUNX2 (runt-related transcription factor 2) were detected using RT-PCR.

Results

The cultured cells grew stably and proliferated rapidly. The optimum condition was 0.5 mg/cm² bone graft material coated on the bottom of medium. After culturing on the material 14 days, the alizarin red staining showed that more calcium deposition was detected in group A and alkaline phosphatase activities of group A was higher than group B (p ˃ 0.05). Similarly, after culturing for 14 days, the ALP, BMP2 and RUNX2 transcription activity of group A was higher than group B (p ˃ 0.05).

Conclusion

Human adipose-derived stem cells cultured on bone graft material were dominantly differentiated into osteoblast in vitro. Thus it provided a new choice for bone tissue engineering.

Vertical mandibular bone augmentation by the osteodistraction of the transplanted fibula free flap: A case series with long-term follow-up

Vertical augmentation of the mandible to prepare dental implant therapy is still a challenge, especially with large mandible defects. Reconstruction with fibula free flap is a regularly applied approach in such cases, but it does not always yield optimal results: the resulting crestal height might differ significantly from the crestal height of the patient's intact bone, which makes esthetic and functional rehabilitation difficult. Osteodistraction of the integrated flap is a known but rarely discussed approach where the already integrated flap undergoes additional distraction. Through the four cases reported here, we would like to demonstrate that the osteodistraction of the transplanted fibula free flap is a useful and efficient method of secondary augmentation for cases where the flap itself fails to produce the desired crestal height, and no other method is applicable. The cases show that the method allows outcomes that are highly satisfactory, both in the functional and esthetic sense.

Mechanical Tension-Stress in Alveolar Cleft Repaired With Autogenous Bone in Canine Models

OBJECTIVE

Cleft lip and/or palate is a common birth defect worldwide, always accompanied by alveolar cleft. However, the success rate of secondary alveolar bone grafting is unsatisfactory. Rapid maxillary expansion (RME) often used after bone transplantation provides functional stimulation for bone graft area. This study aimed to investigate the effect of RME force on the bone graft area and midpalatal suture, and screen out the most suitable loaded force and loaded teeth, so as to provide a reference for clinical treatment.

METHODS

Fourteen 24-week-old male beagles were assigned randomly to 3 groups: blank control, autogenous, and autogenous with RME. Three-dimensional finite element analysis was conducted to evaluate the distribution and value of the stress in the model. The maxillae were collected and subjected to radiography and helical computed tomography to evaluate new bone formation in the graft area. Van Gieson's Picrofuchsin staining was performed for histomorphological observation.

RESULTS

After 8 weeks of RME treatment, new bone formation of the dogs was markedly accelerated, and bone resorption was significantly reduced compared with the untreated dogs or those only treated with autogenous iliac bone. The treatment with RME evidently made the bone trabecula more abundant and the area of bone formation larger. Three-dimensional finite element analysis showed that the clinical effect can be achieved by using canine teeth as the loaded teeth and applying force of 10 MPa.

CONCLUSION

Rapid maxillary expansion after bone grafting had a positive effect on osteogenesis in a canine model of alveolar cleft.

Comparison of Autogenous Tooth Materials and Other Bone Grafts

Autogenous odontogenic materials are a new, highly biocompatible option for jaw restoration. The inorganic component of autogenous teeth acts as a scaffold to maintain the volume and enable donor cell attachment and proliferation; the organic component contains various growth factors that promote bone reconstruction and repair. The composition of dentin is similar to that of bone, which can be a rationale for promoting bone reconstruction. Recent advances have been made in the field of autogenous odontogenic materials, and studies have confirmed their safety and feasibility after successful clinical application. Autogenous odontogenic materials have unique characteristics compared with other bone-repair materials, such as the conventional autogenous, allogeneic, xenogeneic, and alloplastic bone substitutes. To encourage further research into odontogenic bone grafts, we compared the composition, osteogenesis, and development of autogenous odontogenic materials with those of other bone grafts. In conclusion, odontogenic bone grafts should be classified as a novel bone substitute.

Mechanical evaluation of a patient-specific additively manufactured subperiosteal jaw implant (AMSJI) using finite-element analysis

Edentulism with associated severe bone loss is a widespread condition that hinders the use of common dental implants. An additively manufactured subperiosteal jaw implant (AMSJI) was designed as an alternative solution for edentulous patients with Cawood and Howell class V-VIII bone atrophy. A biomechanical evaluation of this AMSJI for the maxilla in a Cawood and Howell class V patient was performed via finite-element analysis. Occlusal and bruxism forces were incorporated to assess the loading conditions in the mouth during daily activities. The results revealed a safe performance of the implant structure during the foreseen implantation period of 15 years when exerting average occlusion forces of 200 N. For the deteriorated state of class VIII bone atrophy, increased stresses on the AMSJI were evaluated, which predicted implant fatigue. In addition, excessive bruxism and maximal occlusion forces might induce implant failure due to fatigue. The models predicted bone ingrowth at the implant scaffolds, resulting in extra stability and secondary fixation. For all considered loading conditions, the maximal stresses were located at the AMSJI arms. This area is most sensitive to bending forces and, hence, allows for further design optimization. Finally, the implant is considered safe for normal daily occlusion activities.

Minimally Invasive Spine Surgery versus Open Posterior Instrumentation Surgery for Unstable Thoracolumbar Burst Fracture

Study Design

Retrospective study.

Purpose

To compare the clinical and radiological results of minimally invasive spine surgery (MISS) and open posterior instrumentation surgery for the treatment of unstable burst fractures.

Overview of Literature

MISS has exhibited postoperative outcomes similar to those obtained using open posterior instrumentation in various spine diseases. There remains no consensus regarding the use of MISS in the treatment of unstable burst fracture.

Methods

We enrolled 40 patients who underwent either MISS (M group, 20 patients) or open posterior instrumentation surgery (O group, 20 patients) for the treatment of traumatic unstable burst fractures. Clinical outcomes were evaluated based on postoperative back pain, operation time, blood loss, hospital stay duration, and perioperative complications. For radiologic evaluation, preoperative magnetic resonance imaging and plain radiography were performed before and after the surgery to evaluate the changes in the kyphotic angle and fracture union.

Results

The change in the kyphotic angle was −8.2°±5.8° in the M group and −8.0°±7.8° in the O group. No significant difference was noted in terms of the change in the kyphotic angle (p=0.94, t-test) after 12 months of surgery. The Visual Analog Scale score was 1.5±0.7 points in the M group, while it was 5.2±1.4 points in the O group. In the M group, back pain has significantly decreased (p<0.01, t-test). The estimated blood loss was 195.5 mL in the M group and 1,077.5 mL in the O group; the operation time was significantly decreased in the O group from 290.7 to 120.7 minutes in the M group (p<0.05, t-test) (p=0.36, t-test). The average duration of hospital stay was 36.0 days in the M group and 41.9 days in the O group (p=0.36, t-test).

Conclusions

For the treatment of unstable burst fractures, MISS showed significant differences in terms of postoperative back pain, operation time, and blood loss as compared to open posterior instrumentation surgery.

Scaffolds from Self-Assembling Tetrapeptides Support 3D Spreading, Osteogenic Differentiation, and Angiogenesis of Mesenchymal Stem Cells

The apparent rise of bone disorders demands advanced treatment protocols involving tissue engineering. Here, we describe self-assembling tetrapeptide scaffolds for the growth and osteogenic differentiation of human mesenchymal stem cells (hMSCs). The rationally designed peptides are synthetic amphiphilic self-assembling peptides composed of four amino acids that are nontoxic. These tetrapeptides can quickly solidify to nanofibrous hydrogels that resemble the extracellular matrix and provide a three-dimensional (3D) environment for cells with suitable mechanical properties. Furthermore, we can easily tune the stiffness of these peptide hydrogels by just increasing the peptide concentration, thus providing a wide range of peptide hydrogels with different stiffnesses for 3D cell culture applications. Since successful bone regeneration requires both osteogenesis and vascularization, our scaffold was found to be able to promote angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro. The results presented suggest that ultrashort peptide hydrogels are promising candidates for applications in bone tissue engineering.

Vascularized Bone Grafts in Spinal Reconstruction: An Overview of Nomenclature and Indications

Several vascularized bone grafts (VBGs) have been introduced for reconstruction and augmenting fusion of the spine. The expanding use of VBGs in the field of spinoplastic reconstruction, however, has highlighted the need to clarify the nomenclature for bony reconstruction as well as establish the position of VBGs on the bony reconstructive algorithm. In the current literature, the terms "flap" and "graft" are often applied inconsistently when describing vascularized bone transfer. Such inconsistency creates barriers in communication between physicians, confusion in interpreting the existing studies, and difficulty in comparing surgical techniques. VBGs are defined as bone segments transferred on their corresponding muscular attachments without a named major feeding vessel. The bone is directly vascularized by the muscle attachments and unnamed periosteal feeding vessels. VBGs are best positioned as a separate entity in the bony reconstruction algorithm between nonvascularized bone grafts (N-VBGs) and bone flaps. VBGs offer numerous advantages as they supply fully vascularized bone to the recipient site without the microsurgical techniques or pedicle dissection required for raising bone flaps. Multiple VBGs have been introduced in recent years to optimize these benefits for spinoplastic reconstruction.

Unidirectional porous beta-tricalcium phosphate and hydroxyapatite artificial bone: a review of experimental evaluations and clinical applications

In Japan, where allograft bone transplantation is not widespread, prospects for artificial bones are very high. Therefore, artificial bones with various compositions, porous structures, and porosities have been developed and employed for clinical use. Both Affinos^® and Regenos^® (made of beta-tricalcium phosphate and hydroxyapatite, respectively) are artificial bones with a unique unidirectional porous structure, in which pores with a diameter suitable for tissue penetration (25–300 μm) are aligned in one direction. The unidirectional porous structure allows rapid penetration of blood deep into the materials by a capillary effect. In animal experiments, Affinos^® showed well-balanced resorption and was replaced with the host’s own bone from an early stage after implantation and new bone formation and remodeling were observed in the cortical bone and medullary cavity. When implanted for clinical situation, resorption from an early stage and good replacement with the patient’s own bone were also observed. Regenos^® has an internal osteon-like material and a vascular-like structure that is maintained within the pores even after long-term implantation, as noted in an animal experiment. When implanted for clinical situation, good osteoconductivity was observed from an early stage of implantation. In addition, the material was observed to be slowly absorbed over time in some cases. We have discussed the beneficial effects of combining teriparatide and platelet-rich plasma impregnation and the potential prospects of these artificial bones.

In Vitro Prevascularization of Self-Assembled Human Bone-Like Tissues and Preclinical Assessment Using a Rat Calvarial Bone Defect Model

In vitro prevascularization has the potential to address the challenge of maintaining cell viability at the core of engineered constructs, such as bone substitutes, and to improve the survival of tissue grafts by allowing quicker anastomosis to the host microvasculature. The self-assembly approach of tissue engineering allows the production of biomimetic bone-like tissue constructs including extracellular matrix and living human adipose-derived stromal/stem cells (hASCs) induced towards osteogenic differentiation. We hypothesized that the addition of endothelial cells could improve osteogenesis and biomineralization during the production of self-assembled human bone-like tissues using hASCs. Additionally, we postulated that these prevascularized constructs would consequently improve graft survival and bone repair of rat calvarial bone defects. This study shows that a dense capillary network spontaneously formed in vitro during tissue biofabrication after two weeks of maturation. Despite reductions in osteocalcin levels and hydroxyapatite formation in vitro in prevascularized bone-like tissues (35 days of culture), in vivo imaging of prevascularized constructs showed an improvement in cell survival without impeding bone healing after 12 weeks of implantation in a calvarial bone defect model (immunocompromised male rats), compared to their stromal counterparts. Globally, these findings establish our ability to engineer prevascularized bone-like tissues with improved functional properties.

A bone regeneration strategy via dual delivery of demineralized bone matrix powder and hypoxia-pretreated bone marrow stromal cells using an injectable self-healing hydrogel

Demineralized bone matrix (DBM) powder is a potential alternative bone grafting material due to its bone regeneration capacity when the supply of autogenous bone is insufficient. However, the use of DBM powder alone remains challenging in many aspects in the clinic, such as its unstable osteoinductivity due to inactivation of growth factors during the preparation process, lack of bone regeneration cells, and difficulty in handling. Herein, we report a strategy that adopts a dual delivery of DBM powder and hypoxia-pretreated bone marrow stromal cells (BMSCs) using an injectable self-healing hydrogel to enhance bone regeneration and repair a cranial bone defect in a rabbit model. The injectable self-healing hydrogel was prepared based on a double crosslinking architecture, which comprised a dynamically cross-linked Schiff-base network as a self-healing component and a borax ion cross-linked physical network that strengthened its mechanical properties. The handling of the DBM powder was improved by mixing with the hydrogel, and, more importantly, the expression of osteocalcin (OCN) and vascular endothelial growth factor (VEGF) of the encapsulated BMSCs in the hydrogel was significantly up-regulated after hypoxia-pretreatment. The in vivo study demonstrated that the use of the hydrogel alone cannot heal the cranial bone defect, while the hydrogel/BMSC composite could increase the bone formation but was inferior to the hydrogel/DBM composite. Finally, the hydrogel/DBM/BMSC composite exhibited the best bone defect repairing effects among all groups. Overall, our results demonstrate that this dual delivery approach is a promising strategy to enhance bone regeneration for bone defect repair.

More weighted cancellous bone can be harvested from the proximal tibia with less donor site pain than anterior iliac crest corticocancellous bone harvesting: retrospective review

Background

Iliac crest is the most preferred autogenous bone graft harvesting donor site while it has sorts of complications like prolonged pain, hematoma, and fracture. Harvesting cancellous bone from proximal tibia is also increasingly being used because of lower complications and less donor site pain. However, there are lack of studies to compare these two donor sites in detail. Thus, we proposed to investigate the available amount of autogenous bone graft from the proximal tibia.

Methods

Fifty-one patients who underwent simultaneous bone graft harvest from the PT and the AIC to fill up the given critical sized bone defects were enrolled in this study. We prospectively collected data including the weight of the harvested bone, donor site pain using the visual analog scale (VAS) score, and complications between the two sites.

Results

The mean weight of cancellous bone harvested from the PT was greater than AIC (33.2g vs. 27.4g, p = 0.001). The mean VAS score was significantly lesser in the PT up to 60 days after harvesting (p < 0.001). There was persistent pain up to 90 days in four PT patients and in seven AIC patients. The major complication was reported only in AIC patients (11.8%).

Conclusions

Harvesting cancellous bone from the PT is an acceptable alternative to the AIC for autogenous bone grafting owing to availability of more weighted graft bone and less donor site pain.

Clinical and radiological assessment of the induced membrane technique using beta-tricalcium phosphate in reconstructive surgery for lower extremity long bone defects

AIMS

To clarify the effectiveness of the induced membrane technique (IMT) using beta-tricalcium phosphate (β-TCP) for reconstruction of segmental bone defects by evaluating clinical and radiological outcomes, and the effect of defect size and operated site on surgical outcomes.

METHODS

A review of the medical records was conducted of consecutive 35 lower limbs (30 males and five females; median age 46 years (interquartile range (IQR) 40 to 61)) treated with IMT using β-TCP between 2014 and 2018. Lower Extremity Functional Score (LEFS) was examined preoperatively and at final follow-up to clarify patient-centered outcomes. Bone healing was assessed radiologically, and time from the second stage to bone healing was also evaluated. Patients were divided into ≥ 50 mm and < 50 mm defect groups and into femoral reconstruction, tibial reconstruction, and ankle arthrodesis groups.

RESULTS

There were ten and 25 defects in the femur and tibia, respectively. Median LEFS improved significantly from 8 (IQR 1.5 to 19.3) preoperatively to 63.5 (IQR 57 to 73.3) at final follow-up (p < 0.001). Bone healing was achieved in all limbs, and median time from the second stage to bone healing was six months (IQR 5 to 10). Median time to bone healing, preoperative LEFS, or postoperative LEFS did not differ significantly between the defect size groups or among the treatment groups.

CONCLUSION

IMT using β-TCP provided satisfactory clinical and radiological outcomes for segmental bone defects in the lower limbs; surgical outcomes were not influenced by bone defect size or operated part. Cite this article: Bone Joint J 2021;103-B(3):456-461.

Biomaterial Properties Modulating Bone Regeneration

Biomaterial scaffolds have been gaining momentum in the past several decades for their potential applications in the area of tissue engineering. They function as three-dimensional porous constructs to temporarily support the attachment of cells, subsequently influencing cell behaviors such as proliferation and differentiation to repair or regenerate defective tissues. In addition, scaffolds can also serve as delivery vehicles to achieve sustained release of encapsulated growth factors or therapeutic agents to further modulate the regeneration process. Given the limitations of current bone grafts used clinically in bone repair, alternatives such as biomaterial scaffolds have emerged as potential bone graft substitutes. This review summarizes how physicochemical properties of biomaterial scaffolds can influence cell behavior and its downstream effect, particularly in its application to bone regeneration.

Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect

Methods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.

Customized Borosilicate Bioglass Scaffolds With Excellent Biodegradation and Osteogenesis for Mandible Reconstruction

Graft reconstruction of the mandible is an important approach that aims at improving the appearance and functionality of defected mandibles. The traditional implant materials are generally bioinert, non-degradable, and that they lack favorable pore structures for cell proliferation, which limit their clinical application. In this study, we used boron-containing bioactive glass which was combined with a three-dimensional (3D) printing technology to construct an osteoinductive implant scaffold, according to the imaging instructions of CT scan on bone defects. Here, the boron-containing bioglass scaffold (B-BGs) was prepared through sol-gel processing and a 3D print technique. Different boron content of borosilicate bioglass was prepared by incorporating B₂O₃ (molar: 19.4 and 38.8%) into 58S bioglass to replace parts of SiO₂. For fabricated mandible implants through three-dimensional 3D printing of B-BGs (size: 8 × 2 mm; pore size: 250 μm) modified with borosilicate bioglass powder and sodium alginate. Notably, the compressive strength of the B-BGs was about 3.8 Mpa, which supported mandibular activity. Subsequently, the excellent biocompatibility of B-BGs was confirmed using cytotoxicity in vitro studies. Finally, data from in vivo experiments demonstrated that the B-BGs could promote bone regeneration and they could almost get completely degraded within 4 weeks. Our results showed that the boron-containing bioglass could repair mandibular defects.

How much platelet-rich plasma can be soak-loaded onto beta-tricalcium phosphate? A comparison with or without a unidirectional porous structure

Objective: This study aimed to examine differences in platelet-rich plasma (PRP) soak-loaded volumes of β-tricalcium phosphate (β-TCP) with or without a unidirectional porous structure. Materials and Methods: Leukocyte-rich PRP was extracted from 15 healthy volunteers by centrifugation. Two types of artificial bones were soaked for either ten seconds or ten minutes. The volume ratios of PRP soak-loaded onto the artificial bone and soaked area ratios were evaluated. Statistical analyses were performed using the Tukey-Kramer HSD test and the Games-Howell method. A P-value of <0.05 was considered statistically significant. Results: Regardless of the soaking time, the PRP soak-loaded volume ratio and soaked area ratio were significantly higher in the unidirectional porous β-TCP (UDPTCP) group than in the spherical porous β-TCP (SPTCP) group. Conclusion: PRP can be soak-loaded faster and in larger amounts onto UDPTCP compared to SPTCP. Understanding the basic biology of β-TCP soak-loaded with PRP can help develop more novel and effective β-TCP treatments for orthopedic surgery.

Synergy of molecularly mobile polyrotaxane surfaces with endothelial cell co-culture for mesenchymal stem cell mineralization

Stem cell-based bone tissue engineering is a promising strategy for the treatment of bone defects. Since regeneration of bone tissue takes a long time, promoting osteogenesis of stem cells is desired for earlier recovery from dysfunctions caused by bone defects. Here, we combined endothelial cell co-culture using the molecularly mobile sulfonated polyrotaxane (PRX) surfaces to enhance the mineralization of human bone marrow derived mesenchymal stem cells (HBMSCs). Sulfonated PRXs are composed of sulfopropyl ether-modified α-cyclodextrins (α-CDs) threaded on a polyethylene glycol chain. The molecular mobility of PRX, α-CDs moving along the polymer, can be modulated by the number of α-CDs. When osteoblastic differentiation was induced in HBMSCs and human umbilical vein endothelial cells (HUVECs), co-culture groups on sulfonated PRX surfaces with low molecular mobility showed the highest mineralization, which is about two times as high as co-culture groups on sulfonated PRX surfaces with high molecular mobility. Nuclear accumulation of yes-associated proteins in HBMSCs and cell–cell communication via cytokines or cadherin may play an important role in synergistically induced mineralization of HBMSCs.

Molecular mobility of polyrotaxane surfaces promoted mineralization in a co-culture system of mesenchymal stem cells and endothelial cells.

Novel Vacuum-Assisted Method for Harvesting Autologous Cancellous Bone Graft and Bone Marrow From the Proximal Tibial Metaphysis

Background:

Autogenous cancellous bone graft and bone marrow aspirate are commonly used in lower extremity fusion procedures to enhance fusion potential, and frequently in revision situations where bone loss and osteolysis may be a feature. The tibial metaphysis is a common donor site for bone graft, with the procedure typically performed using a curette or trephine to harvest the cancellous bone. Some limitations of this technique include suboptimal harvest of the marrow portion in particular, incomplete graft harvest, and loss of graft material during the harvest process. We describe a novel vacuum-assisted bone harvesting device to acquire cancellous bone and marrow from the proximal tibia.

Methods:

This is a retrospective study of a single surgeon’s consecutive patients who underwent foot and ankle arthrodesis procedures using proximal tibia autograft obtained using a vacuum-assisted bone harvesting device. Descriptive statistics were used to summarize patient and operative characteristics and outcomes. We identified 9 patients with a mean age of 51 years, 4 of whom were female.

Results:

On average, the skin incision was slightly more than 2 cm, and 27 mL of solid graft and 16 mL of liquid phase aspirate were collected. At 6 weeks after the procedure, there was minimal to no pain at the donor site, and we did not observe any fractures or other complications.

Conclusions:

We report the use of a novel vacuum-assisted curette device to harvest bone graft from the proximal tibial metaphysis for use in foot and ankle fusions. This device has been reliable and efficient in clinical practice.

Level of Evidence:

Level IV, retrospective case series.

Trephine Technique for Iliac Crest Bone Graft Harvest: Long-term Results

STUDY DESIGN

Report of surgical technique and long-term outcome; review of prospectively gathered data and follow-up survey of patient cohort.

OBJECTIVE

The aim of this study was to review surgical technique for a trephine graft harvest technique and assess perioperative complications/pain, long-term outcome, and patient satisfaction after anterior iliac crest bone graft (ICBG) harvest for anterior cervical fusion.

SUMMARY OF BACKGROUND DATA

Rates of complications and residual pain after ICBG harvest have reduced its utility as a source of autograft for spinal fusion. Less invasive options reduce morbidity, and trephine harvest is a simple technique, with low morbidity and perioperative and long-term pain. It has not been presented in the peer-reviewed spine literature, and the long-term experience has not been previously reported.

METHODS

Sixty-eight patients undergoing anterior cervical discectomy and fusion (ACDF), using allograft spacers, underwent ICBG harvest using a 3.5 mm trephine by a minimally invasive approach. Perioperative complications, pain incidence and Visual Analog Scale (VAS) were analyzed. Thirty consecutive patients were subsequently surveyed for long-term follow-up regarding pain, function, and satisfaction.

RESULTS

No perioperative (0-6 weeks) graft-site complications (infection, hematoma, fracture, wound dehiscence) occurred. There were no reoperations, and no treatment required for graft-site complaints. No patient reported clinically significant perioperative pain (>3/10). At long-term follow-up (mean 45 months) no patients reported pain >3/10 at their graft-site, and the mean VAS was 0.20/10. No patient was impaired by graft-site symptoms, and all were satisfied with their graft harvest.

CONCLUSION

Trephine graft harvest minimizes soft tissue dissection, periosteal elevation, and cortical disruption. Outcome using this technique eliminated perioperative complications in this study group, and reduced pain in both perioperative and long-term assessments. Compared to historical outcomes, trephine harvest provides sufficient graft with comparable or improved results relative to other minimally invasive approaches, and significantly improved relative to traditional open techniques.

LEVEL OF EVIDENCE

4.

Strontium-calcium phosphate hybrid cement with enhanced osteogenic and angiogenic properties for vascularised bone regeneration

Vascularized bone tissue engineering is regarded as one of the optimal treatment options for large bone defects. The lack of angiogenic properties and unsatisfactory physicochemical performance restricts calcium phosphate cement (CPC) from application in vascularized bone tissue engineering. Our previous studies have developed a starch and BaSO4 incorporated calcium phosphate hybrid cement (CPHC) with improved mechanical strength and handling properties. However, the bioactivity-especially the angiogenic ability-is still absent and requires further improvement. Herein, based on the reported CPHC and the osteogenic and angiogenic properties of strontium (Sr) ions, a strontium-enhanced calcium phosphate hybrid cement (Sr-CPHC) was developed to improve both biological and physicochemical properties of CPC. Compared to CPC, the initial setting time of Sr-CPHC was prolonged from 2.2 min to 20.7 min. The compressive strength of Sr-CPHC improved from 11.21 MPa to 45.52 MPa compared with CPC as well. Sr-CPHC was biocompatible and showed promotion of alkaline phosphatase (ALP) activity, calcium nodule formation and osteogenic relative gene expression, suggesting high osteogenic-inductivity. Sr-CPHC also facilitated the migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro and up-regulated the expression of the vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1). In vivo evaluation showed marked new bone formation in a rat calvarial defect model with Sr-CPHC implanted. Sr-CPHC also exhibited enhancement of neovascularization in subcutaneous connective tissue in a rat subcutaneous implantation model. Thus, the Sr-CPHC with the dual effects of osteogenesis and angiogenesis shows great potential for clinical applications such as the repair of ischemic osteonecrosis and critical-size bone defects.

Electrical Stimulation of Adipose-Derived Stem Cells in 3D Nanofibrillar Cellulose Increases Their Osteogenic Potential

Due to the ageing population, there is a steadily increasing incidence of osteoporosis and osteoporotic fractures. As conventional pharmacological therapy options for osteoporosis are often associated with severe side effects, bone grafts are still considered the clinical gold standard. However, the availability of viable, autologous bone grafts is limited making alternative cell-based strategies a promising therapeutic alternative. Adipose-derived stem cells (ASCs) are a readily available population of mesenchymal stem/stromal cells (MSCs) that can be isolated within minimally invasive surgery. This ease of availability and their ability to undergo osteogenic differentiation makes ASCs promising candidates for cell-based therapies for bone fractures. Recent studies have suggested that both exposure to electrical fields and cultivation in 3D can positively affect osteogenic potential of MSCs. To elucidate the osteoinductive potential of a combination of these biophysical cues on ASCs, cells were embedded within anionic nanofibrillar cellulose (aNFC) hydrogels and exposed to electrical stimulation (ES) for up to 21 days. ES was applied to ASCs in 2D and 3D at a voltage of 0.1 V/cm with a duration of 0.04 ms, and a frequency of 10 Hz for 30 min per day. Exposure of ASCs to ES in 3D resulted in high alkaline phosphatase (ALP) activity and in an increased mineralisation evidenced by Alizarin Red S staining. Moreover, ES in 3D aNFC led to an increased expression of the osteogenic markers osteopontin and osteocalcin and a rearrangement and alignment of the actin cytoskeleton. Taken together, our data suggest that a combination of ES with 3D cell culture can increase the osteogenic potential of ASCs. Thus, exposure of ASCs to these biophysical cues might improve the clinical outcomes of regenerative therapies in treatment of osteoporotic fractures.

Safety and Efficacy Results of BonoFill First-in-Human, Phase I/IIa Clinical Trial for the Maxillofacial Indication of Sinus Augmentation and Mandibular Bone Void Filling

PURPOSE

The gold standard for bone regeneration of bone deficiencies is still an autologous bone graft, which has considerable disadvantages; namely, the need for a second major surgery and the limited volume of bone available for harvesting. BonoFill (BF) is a novel, tissue-engineered, bone graft with intrinsic osteoinductive, osteoconductive, and osteogenic properties, consisting of the patient's own adipose tissue-derived mesenchymal stem cells, attached to hydroxyapatite particles. Here, we present the safety and efficacy results of BF first-in-human clinical study for maxillofacial bone tissue regeneration.

MATERIALS AND METHODS

Eleven eligible male and female subjects, aged 49-65 years, were enrolled into the clinical study in 2 clinical indications: Bone augmentation and bone void grafting in the jaws. Clinical follow-up was performed throughout a period of 6 months after BF treatment and included clinical examination, blood tests, CT scans, and biopsies collected from the transplantation site to assess chronic bone infection, changes in complete blood count, and adequate bone augmentation for implant placement.

RESULTS

The study results demonstrated that BF promoted adequate bone tissue regeneration without complications. Per our evaluation, there were no incidents of chronic bone infection, or significant changes in complete blood count, and the patients reported overall good health for the duration of the study. At trial end, in the sinus augmentation indication, the BF treated sites residual bone was augmented at an average of 6.36 mm (Δ new bone, n = 10) and the total bone height at the treated area was on average 11.44 mm (n = 10). In the indication of filling of bone voids, the patient's average residual bone height of 2.91 mm was 15.76 mm (n = 1) at trial end.

CONCLUSIONS

BF treatment was shown to be safe and resulted in newly generated bone, which provided adequate bone height for placement of dental implants. Thus, BF is a promising novel autologous bone graft for bone tissue repair.

Growth Factors, Carrier Materials, and Bone Repair

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

Radiographic and clinical assessment of unidirectional porous hydroxyapatite to treat benign bone tumors

Unidirectional porous hydroxyapatite (UDPHAp) was developed as an excellent scaffold with unidirectional pores oriented in the horizontal direction with interpore connections. The purpose of this study was to assess radiographic changes and clinical outcomes and complications following UDPHAp implantation to treat benign bone tumors. We retrospectively analyzed 44 patients treated with intralesional resection and UDPHAp implantation for benign bone tumors between 2010 and 2015. Clinical and radiographic findings were evaluated postoperatively at regular follow-up visits. The mean follow-up was 49 months. Radiographic changes were classified into five stages based on bone formation in the implanted UDPHAp according to Tamai’s classification. All patients showed excellent bone formation inside and around implanted UDPHAp. Absorption of UDPHAp and bone marrow cavity remodeling was identified in 20 patients at a mean of 17 months postoperatively, and was significantly more common in young patients. Preoperative cortical thinning was completely regenerated in 26 of 31 patients on average 10 months after surgery. There were no cases of delayed wound healing, postoperative infection, or allergic reaction related to implanted UDPHAp. UDPHAp is a useful bone-filling substitute for treating benign bone tumor, and the use of this material has a low complication rate.