Autograft and nonunions: morbidity with intramedullary bone graft versus iliac crest bone graft

Comparison of reamer irrigator aspirator (RIA) suspension versus bone marrow aspirate concentrate (BMC) for percutaneous treatment of long bone nonunions-A preclinical canine model

OBJECTIVE

To compare the bone healing effects of percutaneously delivered bone marrow aspirate concentrate (BMC) versus reamer irrigator aspirator (RIA) suspension in a validated preclinical canine ulnar nonunion model. We hypothesized that BMC would be superior to RIA in inducing bone formation across a nonunion site after percutaneous application. The null hypothesis was that BMC and RIA would be equivalent.

METHODS

A bilateral ulnar nonunion model (n= 6; 3 matched pairs) was created. Eight weeks after segmental ulnar ostectomy, RIA from the ipsilateral femur and BMC from the proximal humerus were harvested and percutaneously administered into either the left or right ulnar defect. The same volume (3 ml) of RIA suspension and BMC were applied on each side. Eight weeks after treatment, the dogs were euthanized, and the nonunions were evaluated using radiographic, biomechanical, and histologic assessments.

RESULTS

All dogs survived for the intended study duration, formed radiographic nonunions 8 weeks after segmental ulnar ostectomy, and underwent the assigned percutaneous treatment. Radiographic and macroscopic assessments of bone healing at the defect sites revealed superior bridging-callous formation in BMC-treated nonunions. Histologic analyses revealed greater amount of bony bridging and callous formation in the BMC group. Biomechanical testing of the treated nonunions did not reveal any significant differences.

CONCLUSION

Bone marrow aspirate concentrate (BMC) had important advantages over Reamer Irrigator Aspirator (RIA) suspension for percutaneous augmentation of bone healing in a validated preclinical canine ulnar nonunion model based on clinically relevant radiographic and histologic measures of bone formation.

Murine iPSC-Loaded Scaffold Grafts Improve Bone Regeneration in Critical-Size Bone Defects

In certain situations, bones do not heal completely after fracturing. One of these situations is a critical-size bone defect where the bone cannot heal spontaneously. In such a case, complex fracture treatment over a long period of time is required, which carries a relevant risk of complications. The common methods used, such as autologous and allogeneic grafts, do not always lead to successful treatment results. Current approaches to increasing bone formation to bridge the gap include the application of stem cells on the fracture side. While most studies investigated the use of mesenchymal stromal cells, less evidence exists about induced pluripotent stem cells (iPSC). In this study, we investigated the potential of mouse iPSC-loaded scaffolds and decellularized scaffolds containing extracellular matrix from iPSCs for treating critical-size bone defects in a mouse model. In vitro differentiation followed by Alizarin Red staining and quantitative reverse transcription polymerase chain reaction confirmed the osteogenic differentiation potential of the iPSCs lines. Subsequently, an in vivo trial using a mouse model (n = 12) for critical-size bone defect was conducted, in which a PLGA/aCaP osteoconductive scaffold was transplanted into the bone defect for 9 weeks. Three groups (each n = 4) were defined as (1) osteoconductive scaffold only (control), (2) iPSC-derived extracellular matrix seeded on a scaffold and (3) iPSC seeded on a scaffold. Micro-CT and histological analysis show that iPSCs grafted onto an osteoconductive scaffold followed by induction of osteogenic differentiation resulted in significantly higher bone volume 9 weeks after implantation than an osteoconductive scaffold alone. Transplantation of iPSC-seeded PLGA/aCaP scaffolds may improve bone regeneration in critical-size bone defects in mice.

4D Printing of Personalized-Tunable Biomimetic Periosteum with Anisotropic Microstructure for Accelerated Vascularization and Bone Healing

An ideal biomimetic periosteum is expected to wrap various bone surfaces to orchestrate an optimal microenvironment for bone regeneration, including facilitating local vascularization, recruiting osteoblasts, and mineralizing the extracellular matrix (ECM). To mimic the role of the natural periosteum in promoting bone repair, a 4D printing technique to inlay aligned cell sheets on shape-shifting hydrogel is used, containing biophysical signals and spatially adjustable physical properties, for the first time. The outer hydrogel layer endows the biomimetic periosteum with the ability to digitally coordinate its 3D geometry to match the specific macroscopic bone shape to maintain a bone healing microenvironment. The inner aligned human mesenchymal stem cells (hMSCs) layer not only promotes the migration and angiogenesis of co-cultured cells but also exhibits excellent osteogenic differentiation properties. In vivo experiments show that apart from morphing preset shapes as physical barriers, the aligned biomimetic periosteum can actively facilitate local angiogenesis and early-stage osteogenesis. Altogether, this present work provides a novel route to construct a personalized biomimetic periosteum with anisotropic microstructure by introducing a tunable shape to maintain the bone reconstruction microenvironment and this strategy can be extended to repair sophisticated bone defects.

A review of the Masquelet technique in the treatment of lower limb critical-size bone defects

The need for bone tissue to heal effectively is paramount given its role in the mechanical support of tissues. Bone has a very good natural healing potential in comparison with most other tissue types, largely regenerating to its pre-injury state in the vast majority of cases. Certain factors such as high energy trauma, tumour resection, revision surgery, developmental deformities and infection can lead to the formation of bone defects, where the intrinsic healing potential of bone is diminished owing to bone loss. Various approaches to resolving bone defects exist in current practice, each with their respective benefits and drawbacks. These include bone grafting, free tissue transfer, Ilizarov bone transport and the Masquelet induced membrane technique. This review focuses on evaluating the Masquelet technique, discussing its method and underlying mechanisms, the effectiveness of certain modifications, and its potential future directions.

Management of bone loss in acute severe open tibial fractures: a retrospective study of twenty nine cases-a treatment strategy with bone length preservation

PURPOSE

The present study investigated the outcomes of bone loss associated with acute open tibial fractures classified as Gustilo-Anderson classification grade III B (GIIIB) using a bone length preservation strategy.

METHODS

Among acute GIIIB open tibial fractures, 29 limbs of 29 patients requiring bone loss treatment were included. The reconstruction methods for bone loss were selected among the Masquelet technique (MT), bone transport (BT), acute shortening followed by gradual lengthening (ASGL), and free vascularized fibula graft (FVFG). Primary outcome measures were the rate of bone union and time to bone union.

RESULTS

The median radiographic apparent bone gap (RABG) was 46.75 mm. Bone loss was treated with ASGL only in two patients in whom it was not possible to cover large soft tissue defects by a single free latissimus dorsi (LD) myocutaneous flap (with the serratus anterior (SA) muscle). The other 27 patients underwent soft tissue reconstruction and bone loss treatment with the preservation of bone length, including the MT for 23, BT for six, and FVFG for one. The bone union rate was 75.9%, and the median time to bone union was six months. Salvage surgeries were performed on all seven patients with nonunion; all of whom eventually achieved bony union.

CONCLUSION

Bone loss associated with acute GIIIB open tibial fractures were treated with "bone length preservation" if the size of the soft tissue defect was less than the size that was covered by a single LD myocutaneous flap (with the SA muscle).

Transfusion after harvesting bone graft with RIA: Practice changes reduced transfusion rate by more than half

INTRODUCTION

The Reamer Irrigator Aspirator (RIA) is frequently used as a tool for bone graft harvesting procedures. The initial use of this instrument for bone grafting was met with significant blood loss and high transfusion rates. However, the RIA remains an excellent tool to obtain large volumes of viable autologous graft. The aim of this study was to investigate how changes in the technical use of the RIA may affect blood loss.

MATERIALS AND METHODS

We conducted a retrospective chart review of all patients who underwent RIA bone graft harvest over a 12-year study period. The patients were divided into two cohorts based upon changes in the technique used to obtain autograft harvest with the RIA. The traditional cohort (2008-2012) connected the RIA to dilation and curettage suction and selected reamer size based on radiographic parameters. The modified cohort (2012-2020) connected the RIA to wall suction, used improved techniques for reamer head sizing, and more diligence was paid toward the time the RIA was suctioning in the canal. Demographic information, surgical details, pre- and post-operative hematocrit (HCT), transfusion rate, intra-operative blood loss, reported volume of graft harvested, and iatrogenic fracture were recorded.

RESULTS

201 patients were included in the study with 61 patients in the traditional and 140 patients in the modified cohorts respectively. The average age was 51 years (range: 18-97) with 107 (53%) males. There was no difference in the demographic data between the two cohorts. No difference was noted between the traditional and modified cohorts in terms of the amount of average graft harvested (54cc vs 51cc; p = 0.34) or major complications (1 vs 2; p = 0.91). However, when comparing the traditional versus modified cohorts the traditional group demonstrated a larger average blood loss (675cc vs 500cc; p=<0.01) and HCT drop (13.7 vs 9.5; p=<0.01) with a higher transfusion rate (44% vs 19%; p = 0.001).

CONCLUSION

This series demonstrated a significant improvement in blood loss and transfusion with modified techniques used to obtain autologous bone graft with the RIA. Importantly, these techniques do not appear to limit bone graft harvest yield and can therefore be efficiently implemented without limiting the utility of the RIA.

Clinical application of platelet-rich fibrin to enhance dental implant stability: A systematic review and meta-analysis

Objective

To investigate the effect of platelet-rich fibrin application on implant stability.

Study design

Five databases, namely, PubMed, Embase, Web of Science, Wiley, and China National Knowledge Infrastructure, were searched for reports published up to November 20, 2022. Randomized controlled trials (RCT), including parallel RCTs and split-mouth RCTs, with at least 10 patients/sites were considered for inclusion.

Results

After screening based on the inclusion criteria, ten RCTs were included. Low heterogeneity was observed in study characteristics, outcome variables, and estimation scales (I2 = 27.2%, P = 0.19). The qualitative and meta-analysis results showed that PRF increased the effect of implant stabilizers after implant surgery.

Conclusions

The results of the present systematic review and meta-analysis suggest that PRF can increase implant stability after implant surgery. PRF may also have a role in accelerating bone healing and tends to promote new bone formation at the implant site.

Review: cellularity in bone marrow autografts for bone and fracture healing

The use of autografts, as primary cell and tissue source, is the current gold standard approach to treat critical size bone defects and nonunion defects. The unique mixture of the autografts, containing bony compartments and bone marrow (BM), delivers promising results. Although BM mesenchymal stromal cells (BM-MSCs) still represent a major target for various healing approaches in current preclinical research and respective clinical trials, their occurrence in the human BM is typically low. In vitro expansion of this cell type is regulatory challenging as well as time and cost intensive. Compared with marginal percentages of resident BM-MSCs in BM, BM mononuclear cells (BM-MNCs) contained in BM aspirates, concentrates, and bone autografts represent a readily available abundant cell source, applicable within hours during surgical procedures without the need for time-consuming and regulatory challenging cell expansion. This benefit is one reason why autografting has become a clinical standard procedure. However, the exact anatomy and cellularity of BM-MNCs in humans, which is strongly correlated to their unique mode of action and wide application range remains to be elucidated. The aim of this review was to present an overview of the current knowledge on these specific cell types found in human BM, emphasize the contribution of BM-MNCs in bone healing, highlight donor site dependence, and discuss limitations in the current isolation and subsequent characterization procedures. Hereby, the most recent and relevant examples of human BM-MNC cell characterization, flow cytometric analyses, and findings are summarized, with a strong focus on bone therapy.

Strategies to capitalize on cell spheroid therapeutic potential for tissue repair and disease modeling

Cell therapies offer a tailorable, personalized treatment for use in tissue engineering to address defects arising from trauma, inefficient wound repair, or congenital malformation. However, most cell therapies have achieved limited success to date. Typically injected in solution as monodispersed cells, transplanted cells exhibit rapid cell death or insufficient retention at the site, thereby limiting their intended effects to only a few days. Spheroids, which are dense, three-dimensional (3D) aggregates of cells, enhance the beneficial effects of cell therapies by increasing and prolonging cell-cell and cell-matrix signaling. The use of spheroids is currently under investigation for many cell types. Among cells under evaluation, spheroids formed of mesenchymal stromal cells (MSCs) are particularly promising. MSC spheroids not only exhibit increased cell survival and retained differentiation, but they also secrete a potent secretome that promotes angiogenesis, reduces inflammation, and attracts endogenous host cells to promote tissue regeneration and repair. However, the clinical translation of spheroids has lagged behind promising preclinical outcomes due to hurdles in their formation, instruction, and use that have yet to be overcome. This review will describe the current state of preclinical spheroid research and highlight two key examples of spheroid use in clinically relevant disease modeling. It will highlight techniques used to instruct the phenotype and function of spheroids, describe current limitations to their use, and offer suggestions for the effective translation of cell spheroids for therapeutic treatments.

Management of talar lesions with cement augmentation and autologous bone graft

BACKGROUND

Treatment of bone lesions involved with the articular cartilage at the talus is challenging. We report the management of talus lesions, particularly tumors and avascular necrosis (AVN), at the articular surface through treatment with cement augmentation and autologous bone graft.

METHODS

Eight benign bone tumors and three cases of AVN were reviewed retrospectively at a mean follow-up of 56 months (range, 12-162). The mean age of all patients was 36.1 years old (range, 15-73) when assessed between February 2005 and November 2021. Curettage of tumorous and necrotic lesions resulted in significant bone defects filled with bone cement augmentation. Cartilage defects of the talar dome were supported with autologous cancellous bone graft. Tolerable weight-bearing ambulation was permitted immediately after surgery. Radiological and functional evaluations were recorded.

RESULTS

We observed an increase in the average The American Orthopaedic Foot and Ankle Score (AOFAS) (p = .003) and a decrease in the average Visual Analogue Scale pain score (p = .003). There was no statistically significant decrease in ROM before or after surgery (p = .114). Additionally, no talus collapse of the ankle joint occurred. Talar dome status did not aggravate before or after surgery, except for one patient. Despite no radiographic osteoarthritis exacerbation before or after surgery in six patients, five patients had osteoarthritic change.

CONCLUSION

Cement implantation and autologous bone graft performed simultaneously for benign bone tumors with joint cartilage damage and AVN are technically simple, have good outcomes, and may be a suitable alternative to standard treatments.

The Reamer-Irrigator-Aspirator (RIA) System for the treatment of aseptic femoral nonunions: Report of two cases and literature review

Femoral shaft nonunions are disabling complications of fractures, with relevant socioeconomic and psychological impact. The incidence of femoral shaft nonunions is not negligible, ranging between 1% and 10% after intramedullary nailing, but can exceed 20% in case of subtrochanteric fractures. Treatment options are influenced by pathomechanical, anatomical, and clinical factors. Hypertrophic nonunions are usually treated by enhancing stability of fixation, while atrophic nonunions require additional biological stimulation to achieve bone union. The Reamer-Irrigator-Aspirator (RIA) System® was developed to reduce intramedullary pressure and heat generation during intramedullary reaming, thus preventing thermal necrosis and decreasing the risk of fat embolism. The RIA System allows to provide large volumes of high-quality morselized autologous bone, that has shown high osteogenetic and osteoinductive properties. Therefore, its use has been expanded as a valuable source of autologous bone graft for the treatment of large bone defects of different nature. In this article, we present two cases of complex femoral nonunions treated with the use of the RIA System. A review of the published literature on the treatment of femoral nonunions with RIA was also performed. Core tip: In case of atrophic nonunions, the RIA System can be used to obtain biologically active tissue to enhance bone healing. Despite the absence of high-quality studies focused on femoral nonunions, the efficacy of RIA is well-known and orthopaedic surgeons should be aware of this powerful tool.

Is induced membrane technique effective in reconstruction of mandibular segmental bone defects? An experimental study

This study aimed to compare the effectiveness of different graft materials using induced membrane technique for reconstruction of mandibular segmental bone defects. New Zealand rabbits were used as the experimental animal. As first-stage surgical procedure, segmental bone defects were created at the lower border of the mandibula in all groups. Polymethylmethacrylate (PMMA) cement was inserted into the defects. After 6 weeks, PMMA cement was removed in all groups. In the Control group, defect areas were left empty. Defects were filled with autogenous graft in the Autograft group, xenograft in the Xenograft group, and a mixture of autogenous graft and xenograft in the Autograft + Xenograft group. Histopathological, stereological, and immunohistochemical analyses were performed. A total of 40 New Zealand rabbits were used. Rabbits were randomly divided into four subgroups as Control, Autograft, Xenograft and Autograft + Xenograft groups (n = 10). When the groups were compared in terms of newly formed bone tissue volumes, significant difference was found between the Control group and Autograft group, Xenograft group and Autograft + Xenograft group (p < 0.001, p < 0.001, p = 0.003). The results of immunohistochemical examination were consistent with this finding. Stereological and immunohistochemical results can be used as a justification to adopt the induced membrane technique on an experimental basis in humans when it comes to the reconstruction of small segmental mandibular defects.

Masquelet technique in post-traumatic infected femoral and tibial segmental bone defects. Union and reoperation rates with high proportions (up to 64%) of allograft in the second stage

Introduction The aim of this study was to describe union, reoperation and failure rates after using the induced membrane (IM) technique with ≥50% allograft over autograft to treat infected femoral and tibial segmental bone defects (SBD). Materials and methods We retrospectively analyzed patients with femoral and tibial SBD treated in our center between 2012 and 2019 using ≥50% allograft over autograft during the second stage of the Masquelet technique. We analyzed the affected bone, defect size, osteosynthesis technique used, time elapsed between the first and second stage of the technique, graft proportions, union time, reoperations, and non-union rates. Results We included 21 patients (61.90% men) with a median age of 41 (range 18-68) years. The tibia was affected in 61.90% (n:13) and the femur in 38.09% (n:8) of the cases. SBD length was 4.5 (range 3.5-14) cm. The median interval between both stages of the technique was 10 (range 6-28) weeks. The proportion of allograft used was 50 % in 10 patients, 51 to 55% in 5 patients, 56 to 59% in 4 patients, and 60 to 64% in 2. The union rate was 95.23% over a median time of 7 (range 6-12) months. There were 3 (14.28%) reoperations: 2 for relapse of infection and 1 for mechanical instability. There was one failure (4.76%). One patient presented non-union and nail break. The median follow-up after the second stage of the technique was 26 (range 13-54) months. Conclusion The use of the induced membrane technique and a high proportion of allograft (up to 64%) achieved similar union and failure rates than those reported for similar series that relied on lower allograft proportions.

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.

Editorial Commentary: A Functional Capsule, Not the Type of Bone Graft, Determines Outcome After Shoulder Stabilization in Cases of Anterior Glenoid Bone Deficiency

Many clinical results of surgical treatment of recurrent anterior shoulder instability confirm the importance of anterior bone grafting of the glenoid defect. Some studies even propose to perform a graft, even when there is no bony defect. Short- and middle-term studies report comparable results between bone grafting and Latarjet procedure. But one of the main questions that still remains is the quality and efficiency of the capsule. If Latarjet is the gold standard in anterior shoulder stabilization with very good results at very long follow-up, it is probably because the capsule is replaced by the conjoint tendon. Because Latarjet is a difficult surgery and has some complexes and/or challenging complications and because it is a nonanatomic procedure, there is a true place for anterior bone grafting. This anterior grafting under arthroscopy provides excellent results, but it is mandatory to be sure that the shoulder capsule is working. Clinical, functional, and imaging studies of this capsule need to be performed for a better understanding of the unstable shoulder function and treatment.

Investigation of a Prevascularized Bone Graft for Large Defects in the Ovine Tibia

In vivo bioreactors are a promising approach for engineering vascularized autologous bone grafts to repair large bone defects. In this pilot parametric study, we first developed a three-dimensional (3D) printed scaffold uniquely designed to accommodate inclusion of a vascular bundle and facilitate growth factor delivery for accelerated vascular invasion and ectopic bone formation. Second, we established a new sheep deep circumflex iliac artery (DCIA) model as an in vivo bioreactor for engineering a vascularized bone graft and evaluated the effect of implantation duration on ectopic bone formation. Third, after 8 weeks of implantation around the DCIA, we transplanted the prevascularized bone graft to a 5 cm segmental bone defect in the sheep tibia, using the custom 3D printed bone morphogenic protein 2 (BMP-2) loaded scaffold without prior in vivo bioreactor maturation as a control. Analysis by micro-computed tomography and histomorphometry found ectopic bone formation in BMP-2 loaded scaffolds implanted for 8 and 12 weeks in the iliac pouch, with greater bone formation occurring after 12 weeks. Grafts transplanted to the tibial defect supported bone growth, mainly on the periphery of the graft, but greater bone growth and less soft tissue invasion was observed in the avascular BMP-2 loaded scaffold implanted directly into the tibia without prior in vivo maturation. Histopathological evaluation noted considerably greater vascularity in the bone grafts that underwent in vivo maturation with an inserted vascular bundle compared with the avascular BMP-2 loaded graft. Our findings indicate that the use of an initial DCIA in vivo bioreactor maturation step is a promising approach to developing vascularized autologous bone grafts, although scaffolds with greater osteoinductivity should be further studied. Impact statement This translational pilot study aims at combining a tissue engineering scaffold strategy, in vivo prevascularization, and a modified transplantation technique to accelerate large segmental bone defect repair. First, we three-dimensional (3D) printed a 5 cm scaffold with a unique design to facilitate vascular bundle inclusion and osteoinductive growth factor delivery. Second, we established a new sheep deep circumflex iliac artery model as an in vivo bioreactor for prevascularizing the novel 3D printed osteoinductive scaffold. Subsequently, we transplanted the prevascularized bone graft to a clinically relevant 5 cm segmental bone defect in the sheep tibia for bone regeneration.

Autologous bone graft: Is it still the gold standard?

Bone grafting has over 100 years of successful clinical use. Despite the successes of autograft bone transplantation, complications of bone grafting are significant, mostly at the donor site. This article reviews the biology of fracture healing, the properties of bone grafts, and reviews the specific advantages and problems associated with autograft bone. Recent techniques such as the Reamer Irrigator Aspirator are described, which has dramatically reduced complications of bone autograft harvesting.

Comparison of the inner side and two-sided approaches for iliac crest bone graft harvesting for pediatric pelvic osteotomy

Background

The iliac crest is one of the most used bone graft sources. In this study, we aimed to identify the effects of inner side and two-sided approaches for iliac crest bone harvesting on post-surgery ilium growth in children.

Materials and methods

We retrospectively analyzed 47 patients who underwent pelvic osteotomy and iliac crest bone graft (ICBG) procedures from January 2015 to September 2018. The patients were divided into an inner table ilium exposure group (group A) and the inner-outer table ilium exposure group (group B) and were followed up with radiography in postoperative months 1, 3, 6, and 12, and the growth areas were measured using PACS software. Complications such as damage to the arteries or nerves, ureteral injury, gastrointestinal hernia, ileus, abnormal cosmetic appearance, sensory disturbances, and functional limitations were recorded based on clinical records.

Results

There were 22 patients aged 5.3±1.5 years in group A and 25 patients aged 5.9±1.8 years in group B. There were no significant differences in demographics between the two groups, or in growth in the first month. However, bone graft growth at months 3, 6, and 12 was significantly better in group A than in group B. There was no significant difference in complications between the two groups.

Conclusion

Exposure of only the inner table of the ilium resulted in faster recovery of the bone defect than two-sided exposure in pelvic osteotomy. Therefore, we suggest protecting the outer side of the ilium during surgery.

Level of evidence

Level III

Radiographic and clinical outcomes of silicate-substituted calcium phosphate (SiCaP) bone grafts in spinal fusion: Systematic review and meta-analysis

Pseudarthrosis continues to affect a nontrivial proportion of spine fusion patients. Given its ties to poorer patient outcomes and high reoperation rates, there remains great interest in interventions aimed at reducing the rates of nonunion. Recently, silicate-substituted calcium phosphate (SiCaP) bone grafts have been suggested to improve fusion rates, yet there exists no systematic review of the body of evidence for SiCaP grafts. Here, we present the first such review along with a meta-analysis of the effect of SiCaP bone grafts on fusion rates. Using the PubMed, Embase, and Web of Science databases, we queried the English-language literature for all studies examining the effect of SiCaPs on spinal fusion. Primary endpoints were: 1) radiographic fusion rate at last follow-up and 2) postoperative improvements in Visual Analog Scale (VAS) pain scores and Oswestry Disability Index (ODI) at last follow-up. Meta-analyses were performed for each endpoint using random effects. Ten articles (694 patients treated with SiCaP bone grafts) were included. Among SiCaP-treated patients, 93% achieved radiographic fusion (range: 79-100%), with comparable rates across subgroups. Meta-analysis of the three randomized controlled trials demonstrated no difference in fusion rates between SiCaP-treated patients and patients receiving grafts with recombinant human bone morphogenetic protein-2 (rhBMP-2) (OR: 1.11; p = 0.83). Patients treated with SiCaP bone grafts experienced significant improvements in VAS back pain (-3.3 points), VAS leg pain (-4.8 points), and ODI (-31.6 points) by last follow-up (p < 0.001 for each). Additional high-quality research is needed to evaluate the relative cost-effectiveness of SiCaP bone grafts in spinal fusion.

18F- based Quantification of the Osteogenic Potential of hMSCs

In bone tissue engineering, there is a constant need to design new methods for promoting in vitro osteogenic differentiation. Consequently, there is a strong demand for fast, effective and reliable methods to track and quantify osteogenesis in vitro. In this study, we used the radiopharmacon fluorine-18 (¹⁸F) to evaluate the amount of hydroxylapatite produced by mesenchymal stem cells (MSCs) in a monolayer cell culture in vitro. The hydroxylapatite bound tracer was evaluated using µ-positron emission tomography (µ-PET) scanning and activimeter analysis. It was therefore possible to determine the amount of synthesized mineral and thus to conclude the osteogenic potential of the cells. A Student's t-test revealed a highly significant difference regarding tracer uptake between the osteogenic group and the corresponding control group (µ-PET p = 0.043; activimeter analysis p = 0.012). This tracer uptake showed a highly significant correlation with the gold standard of quantitative Alizarin Red staining (ARS) (r² = 0.86) as well as with the absolute calcium content detected by inductively coupled plasma mass spectrometry (r² = 0.81). The results showed that ¹⁸F labeling is a novel method to prove and quantify hydroxyapatite content in MSC monolayer cultures. The mineral layer remains intact for further analysis. This non-destructive in vitro method can be used to rapidly investigate bone tissue engineering strategies in terms of hydroxylapatite production, and could therefore accelerate the process of implementing new strategies in clinical practice.

Bone-Targeting Liposome-Encapsulated Salvianic Acid A Improves Nonunion Healing Through the Regulation of HDAC3-Mediated Endochondral Ossification

AIM

Nonunion is a major complication in fracture repair and remains a challenge in orthopaedics and trauma surgery. In this study, we aimed to evaluate the effectiveness of treatment of nonunion with a large radial defect using a bone-targeting liposome-encapsulated salvianic acid A (SAA-BTL)-incorporated collagen sponge and further elucidate whether the effects were closely related to histone deacetylase 3 (HDAC 3)-mediated endochondral ossification in nonunion healing process.

METHODS

Fifteen New Zealand female rabbits were randomly divided into three groups. Segmental radius critical size defects (15 mm) were created via surgery on both the forelimbs of the rabbits. The SAA-BTL/SAA/saline-incorporated collagen sponges were implanted into the defects in the three groups, respectively, for four weeks of treatment. X-ray imaging, micro-computed tomography (CT) analysis, histology, and immunofluorescence analysis (HDAC3, collagen II, VEGFA, and osteocalcin) were performed to determine the effects of the treatments. In addition, a short interfering RNA was applied to induce HDAC3 knockdown in the chondrogenic cell line ATDC5 to investigate the roles of HDAC3 and SAA intervention in endochondral ossification in nonunion healing.

RESULTS

X-ray imaging and micro-CT results revealed that SAA-BTL-incorporated collagen sponges significantly stimulated bone formation in the nonunion defect rabbit model. Furthermore, immunofluorescence double staining and histology analysis confirmed that SAA-BTL significantly increased the expression of P-HDAC3, collagen II, RUNX2, VEGFA, and osteocalcin in vivo; accelerated endochondral ossification turnover from cartilage to bone; and promoted long bone healing of nonunion defects. ATDC5 cells knocked down for HDAC3 showed significantly decreased expression of HDAC3, which resulted in reduced expression of chondrogenesis, osteogenesis, and angiogenesis biomarker genes (Sox9, Col10a1, VEGFA, RUNX2, and Col1a1), and increased expression of extracellular matrix degradation marker (MMP13). SAA treatment reversed these effects in the HDAC3 knockdown cell model.

CONCLUSION

SAA-BTL can improve nonunion healing through the regulation of HDAC3-mediated endochondral ossification.

USP1 inhibitor ML323 enhances osteogenic potential of human dental pulp stem cells

LIM homeobox 8 (LHX8) is expressed during embryonic development of craniofacial tissues, including bone and teeth. In a previous study, the overexpression of LHX8 inhibited osteodifferentiation of human dental pulp stem cells (DPSCs). In this study, a cDNA microarray analysis was performed to reveal the molecular changes which occur in response to LHX8 overexpression in DPSCs and discover possible targets for an osteoinductive agent. There were 345 differentially expressed genes (DEGs) in response to osteoinductive signaling and 53 DEGs in response to LHX8 overexpression and osteoinductive signaling, respectively. Thirty-eight genes were common in both conditions, and among these, genes upregulated in LHX8 DPSCs but downregulated in osteodifferentiated DPSCs were chosen. Five of them had commercial inhibitors available. Among the tested inhibitors, ML323, which target DNA-binding protein inhibitor ID-1, promoted osteodifferentiation of DPSCs. In conclusion, inhibition of ID-1 led to increased osteogenesis of human DPSCs.

Determination of the effective dose of bone marrow mononuclear cell therapy for bone healing in vivo

Introduction

Cell-based therapy by bone marrow mononuclear cells (BMC) in a large-sized bone defect has already shown improved vascularization and new bone formation. First clinical trials are already being conducted. BMC were isolated from bone marrow aspirate and given back to patients in combination with a scaffold within some hours. However, the optimal concentration of BMC has not yet been determined for bone healing. With this study, we want to determine the optimal dosage of the BMC in the bone defect to support bone healing.

Material and methods

Scaffolds with increasing BMC concentrations were inserted into a 5 mm femoral defect, cell concentrations of 2 × 10⁶ BMC/mL, 1 × 10⁷ BMC/mL and 2 × 10⁷ BMC/mL were used. Based on the initial cell number used to colonize the scaffolds, the groups are designated 1 × 10⁶, 5 × 10⁶ and 1 × 10⁷ group. Bone healing was assessed biomechanically, radiologically (µCT), and histologically after 8 weeks healing time.

Results

Improved bone healing parameters were noted in the 1 × 10⁶ and 5 × 10⁶ BMC groups. A significantly higher BMD was observed in the 1 × 10⁶ BMC group compared to the other groups. Histologically, a significantly increased bone growth in the defect area was observed in group 5 × 10⁶ BMC. This finding could be supported radiologically.

Conclusion

It was shown that the effective dose of BMC for bone defect healing ranges from 2 × 10⁶ BMC/mL to 1 × 10⁷ BMC/mL. This concentration range seems to be the therapeutic window for BMC-supported therapy of large bone defects. However, further studies are necessary to clarify the exact BMC-dose dependent mechanisms of bone defect healing and to determine the therapeutically effective range more precisely.

A sericin/ graphene oxide composite scaffold as a biomimetic extracellular matrix for structural and functional repair of calvarial bone

Bone defects affect millions of people worldwide each year, leading to severe disabilities. Biomimetic scaffolds mediated tissue regeneration represents a promising alternative for bone repair. However, the major problem associated with most currently clinical available artificial bone substitutes (scaffolds) is that they mainly possess filling function but lack of osteo-induction abilities. Therefore, development of biomaterials with osteo-induction property for effective bone regeneration is highly desired. Methods: We report the design and fabrication of a photo-crosslinked sericin methacryloyl (SerMA)/ graphene oxide (GO) hydrogel (SMH/GO) as a biomimetic scaffold for the functional repair of the bone. The mechanical strength, degradation and biocompatibility behavior of SMH/GO hydrogel were measured in vitro. The effect of SMH/GO hydrogel on BMSCs proliferation, migration, osteogenesis differentiation was assessed. After that, SMH/GO-2 was used as an artificial bone substitute for bone regeneration after calvarial defects and effect on bone repair was evaluated by histological, X-Ray and microCT analysis. Furthermore, the potential mechanism of SMH/GO hydrogel regulating BMSCs migration and differentiation was investigated by RNA sequencing. Results: This scaffold has good biocompatibility, cell adhesive property, proliferation- and migration-promoting effects, and osteogenic induction property. After being implanted in a rat calvarial defect model, this SMH/GO scaffold effectively promotes new bone regeneration and achieves structural and functional repair within 12 weeks by inducing autologous bone marrow-derived mesenchymal stem cells (BMSCs) differentiation. By utilizing cell-biological assays and RNA sequencing, we reveal its possible regeneration mechanisms: the SMH/GO hydrogel regulates BMSCs migration and osteo-differentiation via activating MAPK, TNF, and chemokine signaling for bone regeneration. Conclusion: Aiming to meet clinical demands and overcome current limitations of existing artificial bones, we have developed a new type of sericin/ graphene oxide composite scaffold and provided histological, functional, and molecular evidence demonstrating that it is capable of effectively repairing defective bones by inducing autologous BMSCs directional migration and osteogenic differentiation.

Application of Hydroxycholesterols for Alveolar Cleft Osteoplasty in a Rodent Model

BACKGROUND

Bone morphogenetic proteins (BMPs) have played a central role in the regenerative therapies for bone reconstruction, including alveolar cleft and craniofacial surgery. However, the high cost and significant adverse effect of BMPs limit their broad application. Hydroxycholesterols, naturally occurring products of cholesterol oxidation, are a promising alternative to BMPs. The authors studied the osteogenic capability of hydroxycholesterols on human mesenchymal stem cells and the impact of hydroxycholesterols on a rodent alveolar cleft model.

METHODS

Human mesenchymal stem cells were treated with control medium or osteogenic medium with or without hydroxycholesterols. Evaluation of cellular osteogenic activity was performed. A critical-size alveolar cleft was created and one of the following treatment options was assigned randomly to each defect: collagen sponge incorporated with hydroxycholesterols, BMP-2, or no treatment. Bone regeneration was assessed by means of radiologic and histologic analyses and local inflammation in the cleft evaluated. Moreover, the role of the hedgehog signaling pathway in hydroxycholesterol-mediated osteogenesis was examined.

RESULTS

All cellular osteogenic activities were significantly increased on human mesenchymal stem cells treated with hydroxycholesterols relative to others. The alveolar cleft treated with collagen sponge with hydroxycholesterols and BMP-2 demonstrated robust bone regeneration. The hydroxycholesterol group revealed histologically complete bridging of the alveolar defect with architecturally mature new bone. The inflammatory responses were less in the hydroxycholesterol group compared with the BMP-2 group. Induction of hydroxycholesterol-mediated in vitro osteogenesis and in vivo bone regeneration were attenuated by hedgehog signaling inhibitor, implicating involvement of the hedgehog signaling pathway.

CONCLUSION

Hydroxycholesterols may represent a viable alternative to BMP-2 in bone tissue engineering for alveolar cleft.

Can the Reamer/Irrigator/Aspirator System replace anterior iliac crest grafting when treating long bone nonunion?

INTRODUCTION

Autologous bone graft is the gold standard for filling bone defects associated with diaphyseal nonunions. It is typically harvested from the anterior iliac crest (AIC) despite the high complication rate. The Reamer/Irrigator/Aspirator System (RIA) was developed to recover the reaming aspirate and use it as autograft. Initially described for harvesting bone from the femur, the bone volume available is similar to the AIC site; however, its use directly at nonunion sites has been studied very little.

HYPOTHESES

Compared to AIC harvesting, RIA at a non-union site will result in (1) sufficient bone volume, (2) similar time to union and union rate, (3) lower morbidity.

RESULTS

Two groups of patients received an autograft for aseptic nonunion of the tibia or femur for a bone defect up to 2cm: the RIA group (n=30) was followed prospectively and received an autograft by RIA while the AIC group (n=29) was reviewed retrospectively and received an autograft by AIC. We compared the time to union and union rate, operative time, intake of analgesics, duration of hospital stay and complication rate between groups. The RIA provided sufficient bone, 60cm³ on average in a reliable manner. The union rate was similar between groups: 90% (RIA) and 89.7% (CIA) (p=0.965), while the time to union was shorter in the RIA group (8.63±1.47months vs. 10.08±1.7 months) (p=0.006). The operative time (p<0.0001), analgesic intake (p=0.013), length of stay (p<0.0001) and immediate complication rate (p=0.0195) were higher in the AIC group.

DISCUSSION

For the treatment of aseptic long bone nonunion, autograft harvested by the RIA from the nonunion site results in similar union rate and time to union as AIC grafts without additional complications.

LEVEL OF EVIDENCE

IV, comparative retrospective study.

Lentiviral Gene Therapy for Bone Repair Using Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Umbilical cord blood (UCB) has been increasingly explored as an alternative source of stem cells for use in regenerative medicine due to several advantages over other stem-cell sources, including the need for less stringent human leukocyte antigen matching. Combined with an osteoinductive signal, UCB-derived mesenchymal stem cells (MSCs) could revolutionize the treatment of challenging bone defects. This study aimed to develop an ex vivo regional gene-therapy strategy using BMP-2-transduced allogeneic UCB-MSCs to promote bone repair. To this end, human UCB-MSCs were transduced with a lentiviral vector carrying the cDNA for BMP-2 (LV-BMP-2). In vitro assays to determine the UCB-MSC osteogenic potential and BMP-2 production were followed by in vivo implantation of LV-BMP-2-transduced UCB-MSCs in a mouse hind-limb muscle pouch. Non-transduced and LV-GFP-transduced UCB-MSCs were used as controls. Transduction with LV-BMP-2 was associated with abundant BMP-2 production and induction of osteogenic differentiation in vitro. Implantation of BMP-2-transduced UCB-MSCs led to robust heterotopic bone formation 4 weeks postoperatively, as seen on radiographs and histology. These results, along with the fact that UCB-MSCs can be easily collected with no donor-site morbidity and low immunogenicity, suggest that UCB might be a preferable allogeneic source of MSCs to develop an ex vivo gene-therapy approach to treat difficult bone-repair scenarios.

Comparative Study of Early Health Care Use after Forearm Corrective Osteotomy

Background  Bone reconstruction is frequently required for corrective osteotomy of the forearm long bones. Studies have evaluated long term outcomes but not the impact of these procedures on early postoperative complications and health care utilization. Questions/Purposes  This study evaluated the early postoperative health care utilization following corrective osteotomy of the radius and/or ulna. Patients and Methods  The American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) was the primary data source to perform a comparative statistical analysis of the bone autograft and nonautograft (allograft, graft substitute, or no graft) procedures. We performed a review of the NSQIP database (2005-2013) to evaluate patients who underwent a corrective osteotomy of the radius and/or ulna. Results  There were 362 cases; autograft ( n  = 117) and nonautograft ( n  = 245). There were no significant differences with demographics or comorbidities. The majority of cases were outpatient surgeries and there were no significant differences in anesthesia time, operative time, or hospital length of stay. Overall, the average length of stay was 0.6 days, readmission rate was 2%, and the total complication rate was 1% and there was no statistically significant difference between reconstruction groups. Harvesting of autograft was not associated with the overall 30-day complications and specific markers of health care utilization. Conclusions  Our results are derived from the heterogeneous hospital setting of NSQIP contributing centers. The health care utilization and 30-day complications are low following corrective osteotomy of forearm long bones and autograft harvest did not influence the health care utilization. Level of Evidence  Therapeutic Level II.

Preclinical induced membrane model to evaluate synthetic implants for healing critical bone defects without autograft

Critical bone defects pose a formidable orthopaedic problem in patients with bone loss. We developed a preclinical model based on the induced membrane technique using a synthetic graft to replace autograft for healing critical bone defects. Additionally, we used a novel osteoconductive scaffold coupled with a synthetic membrane to evaluate the potential for single-stage bone regeneration. Three experimental conditions were investigated in critical femoral defects in rats. Group A underwent a two-stage procedure with insertion of a polymethylmethacrylate (PMMA) spacer followed by replacement with a 3D printed polycaprolactone(PCL)/β-tricalcium phosphate (β-TCP) osteoconductive scaffold after 4 weeks. Group B received a single-stage PCL/β-TCP scaffold wrapped in a PCL-based microporous polymer film creating a synthetic membrane. Group C received a single-stage bare PCL/β-TCP scaffold. All groups were examined by serial radiographs for callus formation. After 12 weeks, the femurs were explanted and analyzed with micro-CT and histology. Mean callus scores tended to be higher in Group A. Group A showed statistically significant greater bone formation on micro-CT compared with other groups, although bone volume fraction was similar between groups. Histology results suggested extensive bone ingrowth and new bone formation within the macroporous scaffolds in all groups and cell infiltration into the microporous synthetic membrane. This study supports the use of a critical size femoral defect in rats as a suitable model for investigating modifications to the induced membrane technique without autograft harvest. Future investigations should focus on bioactive synthetic membranes coupled with growth factors for single-stage bone healing. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Proliferative and osteogenic differentiation capacity of mesenchymal stromal cells: Influence of harvesting site and donor age

Human mesenchymal stromal cells (hMSCs) are the cellular source of new bone formation and an essential component of autologous bone grafts. Autologous bone graft harvesting is routinely conducted at the iliac crest, although alternative donor sites with lower complication rates are available. Thus, the aim of this study was to compare hMSCs harvested from the iliac crest and the proximal tibia regarding their proliferative and osteogenic differentiation capacity. Furthermore, we investigated the influence of donor age on these biological properties. HMSCs were isolated from iliac crest or proximal tibia bone grafts of 46 patients. Proliferative capacity was assessed by cumulative population doublings, population doubling time, colony forming units and cell proliferation assays. Osteogenic capacity was assessed by quantification of extracellular calcium deposition and marker gene expression levels. The number of hMSCs per gram harvested tissue was determined. Furthermore, the adipogenic and chondrogenic differentiation capacity were quantified using BODIPY and Safranin Orange staining, respectively. Additional analyses were carried out after grouping young (18-49 years) and aged (≥50 years) donors. HMSCs derived from the proximal tibia featured a comparable proliferative and osteogenic differentiation capacity. No significant differences were found for any analysis conducted, when compared to hMSCs obtained from the iliac crest. Furthermore, no significant differences could be revealed when comparing young and aged donors. This was equally true for hMSCs from both donor sites after comparison within the same age group. Our study demonstrates comparable biological properties of hMSCs derived from both donor sites, the iliac crest and the proximal tibia. Furthermore, aging does not alter proliferative and osteogenic differentiation capacity. Consequently, the proximal tibia should be considered more closely as an alternative donor site in patients of all age groups.

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

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

The periosteum-like effect of fresh human amniotic membrane on bone regeneration in a rabbit critical-sized defect model

OBJECTIVE

The purpose of this study was to investigate the effect of fresh human amniotic membrane (FHAM) as a substitute of periosteum to enhance bone regeneration in critical-sized defects.

METHODS

Tibial diaphyseal bone defects were created in forty New Zealand white rabbits and treated with FHAM or left empty. Treatment groups consisted of: FHAM implanted in the place of removed periosteum (FHAMP group); FHFAM implanted to fill the entire defect (FHAMF group) compared to negative control group; empty defect with removing the periosteum (NC group) and positive control group; and empty defect without removing the periosteum (PC group). Bone regeneration was evaluated by radiographic, micro-computed tomography (μ-CT) and histological analyses at 4 and 8weeks post-surgery.

RESULTS

Radiographic and μ-CT analysis demonstrated clearly enhanced new bone formation in positive control group (PC) and FHAMP group compared to negative control group (NC) and FHAMF group. Histological staining exhibited remaining woven bones and cartilage matrix in the FHAMP group, immature lamellar bone with medellury cavity and marrow bone formation in PC group from 4weeks post-operatively. For FHAMF group, a little new bone formation was detected only from 8weeks post-operatively, and an absence of any sign of healing in NC group at both time points.

CONCLUSION

The results provide that FHAM increases bone regeneration in critical-sized defects when it is implanted in the place of the removed periosteum, but its additive effect does not have the same effect of the natural periosteum.

Complications and risk management in the use of the reaming-irrigator-aspirator (RIA) system: RIA is a safe and reliable method in harvesting autologous bone graft

BACKGROUND

Autologous bone grafting (ABG) remains the gold standard for augmentation of bone defects. The RIA system has become more prevalent, but evidence regarding risk management and complications remain scarce. This study presents the risk management and complications associated with RIA in the largest single-center case series to date.

METHODS

All records, operative notes, lab data and radiographs of patients receiving a RIA procedure at Heidelberg´s University Hospital between 01/01/2010 and 31/12/2016 were reviewed. Multivariate logistic regression models adjusting for clinically relevant covariates were used to examine the respective relevance regarding the presence and absence of prolonged postoperative pain (PPP).

RESULTS

A total of 341 RIA procedures on 306 patients were performed at our level-1 trauma center. The femur was the main donor site (98.53%; N = 336) whereas only in 1.47% (N = 5) the tibia was utilized. A total of 11 patients showed a relevant loss of hemoglobin requiring blood transfusion. A total of 22 patients suffered from PPP directly associated with the RIA procedure resulting in prevalence of 6.45%. The 6 major complications in our study were of diverse origin and all intraoperative complications took place in the early phase of the RIA procedure in our center (2010-2013). Our data revealed influence of sex (p = 0.0459) and age (p = 0.0596) on the criterion PPP. The favored model including sex and age resulted in an AUC of 66.2% (CI: 55.5%-76.9%).

CONCLUSION

Perioperative blood loss remains a prevalent complication during RIA reaming. In addition, PPP occurs with a prevalence of 6.45%. This study showed a complication rate of 1.76%, emphasizing RIA´s overall safety and furthermore highlighting the need for vigilance in its application and prior extensive hands-on training of surgeons. Level of Evidence: II.

Novel, cost-effective, Cu-doped calcium silicate nanoparticles for bone fracture intervention: Inherent bioactivity and in vivo performance

Copper (Cu)-doped calcium silicate nanoparticles were synthesized by a wet precipitation method as economical bone fracture filler. The aim was to improve the overall physicochemical properties, bioactivity, and biological performance of the bone fracture filler prepared herein. The synthesized nanoparticles were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The bioactivity of the prepared nanoparticles was investigated after immersion in simulated body fluid (SBF) by means of inductively coupled plasma (ICP), SEM coupled with energy dispersive X-rays (EDX), and FTIR. The size and bioactivity of the prepared nanoparticles after 15 days of immersion in SBF was dependent on the Cu concentrations. The fracture healing ability of the fabricated nanoparticles on adult aged male Wistar rats was enhanced by the presence of copper. All the obtained results are of high relevance for fabricating improved Cu-doped calcium silicate nanoparticles (∼50 nm) as low cost bone fracture filler. In addition, the in vivo study presented complete healing of the tibiae bone with normal architecture of bone tissue specifically calcium silicate nanoparticles doped with 3% and 5% Cu. Hence, the presence of copper is a promising tactic for improving the biological properties of calcium silicate. Therefore, the designed nanoparticles have huge potential for the treatment of bone fractures. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 388-399, 2019.

Biomimetic Tissue-Engineered Bone Substitutes for Maxillofacial and Craniofacial Repair: The Potential of Cell Sheet Technologies

Maxillofacial defects are complex lesions stemming from various etiologies: accidental, congenital, pathological, or surgical. A bone graft may be required when the normal regenerative capacity of the bone is exceeded or insufficient. Surgeons have many options available for bone grafting including the "gold standard" autologous bone graft. However, this approach is not without drawbacks such as the morbidity associated with harvesting bone from a donor site, pain, infection, or a poor quantity and quality of bone in some patient populations. This review discusses the various bone graft substitutes used for maxillofacial and craniofacial repair: allografts, xenografts, synthetic biomaterials, and tissue-engineered substitutes. A brief overview of bone tissue engineering evolution including the use of mesenchymal stem cells is exposed, highlighting the first clinical applications of adipose-derived stem/stromal cells in craniofacial reconstruction. The importance of prevascularization strategies for bone tissue engineering is also discussed, with an emphasis on recent work describing substitutes produced using cell sheet-based technologies, including the use of thermo-responsive plates and the self-assembly approach of tissue engineering. Indeed, considering their entirely cell-based design, these natural bone-like substitutes have the potential to closely mimic the osteogenicity, osteoconductivity, osteoinduction, and osseointegration properties of autogenous bone for maxillofacial and craniofacial reconstruction.

Treatment of critical-sized bone defects: clinical and tissue engineering perspectives

Critical-sized bone defects are defined as those that will not heal spontaneously within a patient's lifetime. Current treatment options include vascularized bone grafts, distraction osteogenesis, and the induced membrane technique. The induced membrane technique is an increasingly utilized method with favorable results including high rates of union. Tissue engineering holds promise in the treatment of large bone defects due to advancement of stem cell biology, novel biomaterials, and 3D bioprinting. In this review, we provide an overview of the current operative treatment strategies of critical-sized bone defects as well as the current state of tissue engineering for such defects.

Bone regeneration in minipigs by intrafibrillarly-mineralized collagen loaded with autologous periodontal ligament stem cells

Biomimetic intrafibrillarly-mineralized collagen (IMC) is a promising scaffold for bone regeneration because of its structural and functional similarity to natural bone. The objective of this study was to evaluate the bone regeneration potential of IMC loaded with autologous periodontal ligament stem cells (PDLSCs) in large bone defects in minipigs. A macroporous IMC with a bone-like subfibrillar nanostructure was fabricated using a biomimetic bottom-up approach. Non-healing full thickness defects were established on the cranial bone in minipigs, and IMC and hydroxyapatite (HA) scaffolds seeded with autologous PDLSCs were implanted into these defects. Computed tomographic imaging, histology staining, and atomic force microscopy were applied to evaluate to the quantity, micro/nano structures, and mechanical performance of the neo-bone after 12 weeks of implantation. Compared with HA, IMC showed superior regeneration properties characterized by the profuse deposition of new bony structures with a normal architecture and vascularization. Immunohistochemistry showed that the runt-related transcription factor 2 and transcription factor Osterix were highly expressed in the neo-bone formed by IMC. Furthermore, the nanostructure and nanomechanics of the neo-bone formed by IMC were similar to that of natural bone. This study provides strong evidence for the future clinical applications of the IMC-based bone grafts.

Is This Autograft Worth It?: The Blood Loss and Transfusion Rates Associated With Reamer Irrigator Aspirator Bone Graft Harvest

OBJECTIVES

To investigate the blood loss and transfusion rate associated with the use of reamer irrigator aspirator (RIA).

DESIGN

Retrospective review.

SETTING

Academic Level-I trauma hospital.

PATIENTS

One hundred eight patients requiring bone graft harvest for surgical reconstruction of nonunion or failed arthrodesis.

INTERVENTION

Bone graft harvest preformed via RIA or iliac crest bone graft (ICBG).

MAIN OUTCOME MEASURE

Blood loss as measured by a change in preoperative and postoperative hematocrit (Hct). In addition, postoperative transfusion reported intraoperative blood loss, volume of graft harvested, and major complications.

RESULTS

The average Hct drop was found to be 13.7 (4.1-27.4) in the RIA cohort of 61 patients and 7.36 (1.2-14.5) in the ICBG cohort of 47 patients (P = 0.013). Operative reports documented an average estimated blood loss of 674 mL (100-2000 mL) in the RIA cohort compared with 255 mL (50-1000 mL) in the ICBG cohort (P < 0.001). Twenty-seven patients (44%) required blood transfusion after RIA, whereas 10 patients (21%) required blood transfusion after ICBG (odds ratio 5.32, 95% confidence interval 2.2-6.3, P < 0.001). RIA procedures collected an average 53 mL (20-100 mL) of bone graft compared with 27 mL (15-50 mL) with ICBG. There was no significant difference between groups regarding age, sex, medical comorbidities, or postoperative major complications.

CONCLUSIONS

This series demonstrated that 44% of patients undergoing RIA bone graft harvest required transfusion, with a mean Hct drop of 13.7 across all subjects, which is significantly greater than that associated with ICBG.

LEVEL OF EVIDENCE

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

Use of Pig as a Model for Mesenchymal Stem Cell Therapies for Bone Regeneration

Bone is a plastic tissue with a large healing capability. However, extensive bone loss due to disease or trauma requires extreme therapy such as bone grafting or tissue-engineering applications. Presently, bone grafting is the gold standard for bone repair, but presents serious limitations including donor site morbidity, rejection, and limited tissue regeneration. The use of stem cells appears to be a means to overcome such limitations. Bone marrow mesenchymal stem cells (BMSC) have been the choice thus far for stem cell therapy for bone regeneration. However, adipose-derived stem cells (ASC) have similar immunophenotype, morphology, multilineage potential, and transcriptome compared to BMSC, and both types have demonstrated extensive osteogenic capacity both in vitro and in vivo in several species. The use of scaffolds in combination with stem cells and growth factors provides a valuable tool for guided bone regeneration, especially for complex anatomic defects. Before translation to human medicine, regenerative strategies must be developed in animal models to improve effectiveness and efficiency. The pig presents as a useful model due to similar macro- and microanatomy and favorable logistics of use. This review examines data that provides strong support for the clinical translation of the pig model for bone regeneration.

Technique for Use of Trabecular Metal Spacers in Tibiotalocalcaneal Arthrodesis With Large Bony Defects

There are many causes of large bone defects in the tibiotalar joint that need to be definitively treated with a tibiotalocalcaneal (TTC) arthrodesis. Some of the challenges of a large defect are its effect on leg length and the complications associated with trying to fill the defect with structural bone graft. We present an operative strategy involving the use of a trabecular metal implant, a TTC nail that utilized 2 forms of compression, and Reamer/Irrigator/Aspirator (RIA) autograft, to address limitations of previous operative approaches and reliably treat this operative challenge.

Histological Evaluation of Hydroxyapatite Granules with and without Platelet-Rich Plasma versus an Autologous Bone Graft: Comparative study of biomaterials used for spinal fusion in a New Zealand white rabbit model

OBJECTIVES

Hydroxyapatite (HA) has osteoconductive properties and is widely used as a bone graft substitute. Platelet-rich plasma (PRP) is an autologous product with osteoinductive effects. Hypothetically, a combination of both would augment the bone formation effect of HA and widen its application in spinal fusion surgeries. This study aimed to compare new bone formation with HA granules alone and in combination with PRP versus an autologous bone graft during a lumbar intertransverse process spinal fusion.

METHODS

A total of 16 adult New Zealand white rabbits underwent single-level bilateral intertransverse process fusion at the L5-L6 vertebrae. One side of the spine received either HA granules alone or a combination of HA granules and PRP, while the contralateral side received an autologous bone graft. Four animals each from the HA group and the HA plus PRP group versus the autograft group were assessed either at six or 16 weeks by undecalcified histology and histomorphometry. The mean percentage of new bone areas over the corresponding fusion masses were compared between groups.

RESULTS

No significant difference in new bone formation was observed between the HA and HA plus PRP groups at six or 16 weeks. The autograft group had significantly more new bone formation at six and 16 weeks (P = 0.004 and <0.001, respectively).

CONCLUSION

An autologous bone graft remains superior to HA granules, with or without PRP. HA granules demonstrated an excellent osteoconductive scaffold but had poor biodegradability. While PRP enhances the properties of HA granules, these biomaterials do not have a synergistic effect.

Biomaterials to Facilitate Delivery of RNA Agents in Bone Regeneration and Repair

Bone healing after traumatic injuries or pathological diseases remains an important worldwide problem. In search of safer and more effective approaches to bone regeneration and repair, RNA-based therapeutic agents, specifically microRNAs (miRNAs) and short interfering RNA (siRNA), are beginning to be actively explored. In this review, we summarize current attempts to employ miRNAs and siRNAs in preclinical models of bone repair. We provide a summary of current limitations when attempting to utilize bioactive nucleic acids for therapeutic purposes and position the unique aspects of RNA reagents for clinical bone repair. Delivery strategies for RNA reagents are emphasized and nonviral carriers (biomaterial-based) employed to deliver such reagents are reviewed. Critical features of biomaterial carriers and various delivery technologies centered around nanoparticulate systems are highlighted. We conclude with the authors' perspectives on the future of the field, outlining main critical issues important to address as RNA reagents are explored for clinical applications.

The modulation of stem cell behaviors by functionalized nanoceramic coatings on Ti-based implants

Nanoceramic coating on the surface of Ti-based metallic implants is a clinical potential option in orthopedic surgery. Stem cells have been found to have osteogenic capabilities. It is necessary to study the influences of functionalized nanoceramic coatings on the differentiation and proliferation of stem cells in vitro or in vivo. In this paper, we summarized the recent advance on the modulation of stem cells behaviors through controlling the properties of nanoceramic coatings, including surface chemistry, surface roughness and microporosity. In addition, mechanotransduction pathways have also been discussed to reveal the interaction mechanisms between the stem cells and ceramic coatings on Ti-based metals. In the final part, the osteoinduction and osteoconduction of ceramic coating have been also presented when it was used as carrier of BMPs in new bone formation.

•

The effects of basic physical properties like roughness, topography and porous stucture of ceramic coatings on the stem cells behaviors on Ti-based alloys have been reviewed together.

•

The chemical way to modulate the cell behaviors is also discussed in this review paper; and the related mechanotransduction pathways have been described in this paper.

Periodontal regeneration in swine after cell injection and cell sheet transplantation of human dental pulp stem cells following good manufacturing practice

Background

Periodontitis, one of the most prevalent infectious diseases in humans, results in the destruction of tooth-supporting tissues. The purpose of the present study is to evaluate the effect of cell injection and cell sheet transplantation on periodontal regeneration in a swine model.

Methods

In the present study, human dental pulp stem cells (hDPSCs) were transplanted into a swine model for periodontal regeneration. Twelve miniature pigs were used to generate periodontitis with bone defects of 5 mm in width, 7 mm in length, and 3 mm in depth. hDPSCs were obtained for bone regeneration using cell injection or cell sheet transplantation. After 12 weeks, clinical, radiological, and histological assessments of regenerated periodontal tissues were performed to compare periodontal regeneration treated with xenogeneic cell injection and cell sheet implantation.

Results

Our study showed that translating hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. After 12 weeks, both the hDPSC sheet treatment and hDPSC injection significantly improved periodontal tissue healing clinically in comparison with the control group. The volume of regenerative bone in the hDPSC sheet group (52.7 ± 4.1 mm³) was significantly larger than in the hDPSC injection group (32.4 ± 5.1 mm³) (P < 0.05). The percentage of bone in the periodontium in the hDPSC injection group was 12.8 ± 4.4 %, while it was 17.4 ± 5.3 % in the hDPSC sheet group (P < 0.05).

Conclusion

Both hDPSC injection and cell sheet transplantation significantly regenerated periodontal bone in swine. The hDPSC sheet had more bone regeneration capacity compared with hDPSC injection.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0362-8) contains supplementary material, which is available to authorized users.

Hierarchical Structures of Bone and Bioinspired Bone Tissue Engineering

Bone, as a mineralized composite of inorganic (mostly carbonated hydroxyapatite) and organic (mainly type I collagen) phases, possesses a unique combination of remarkable strength and toughness. Its excellent mechanical properties are related to its hierarchical structures and precise organization of the inorganic and organic phases at the nanoscale: Nanometer-sized hydroxyapatite crystals periodically deposit within the gap zones of collagen fibrils during bone biomineralization process. This hierarchical arrangement produces nanomechanical heterogeneities, which enable a mechanism for high energy dissipation and resistance to fracture. The excellent mechanical properties integrated with the hierarchical nanostructure of bone have inspired chemists and material scientists to develop biomimetic strategies for artificial bone grafts in tissue engineering (TE). This critical review provides a broad overview of the current mechanisms involved in bone biomineralization, and the relationship between bone hierarchical structures and the deformation mechanism. Our goal in this review is to inspire the application of these principles toward bone TE.

Corrective osteotomies of the radius: Grafting or not?

AIM: To review the current literature regarding corrective osteotomies to provide the best evidence of the rule of bone grafting.

METHODS: Our MEDLINE literature search included 280 studies using the following key words “Malunited distal radius fracture” and 150 studies using key words “Corrective osteotomy of the distal radius”. Inclusion criteria were: Malunited distal radial, extra articular fracture, volar locking plate, use of iliac bone graft (cancellous or corticocancellous), non-use of bone graft. Twelve studies met the inclusion criteria.

RESULTS: Seven of the 12 studies considered, described the use of a graft; the remaining five studies didn’t use any graft. Type of malunion was dorsal in most of the studies. The healing time was comparable using the graft or not (mean 12.5 wk), ranging from 7.5 to 16 wk. The mean disabilities of the arm, shoulder and hand score improvement was 23 points both in the studies that used the graft and in those not using the graft.

CONCLUSION: This review demonstrated that corrective osteotomy of extra-articular malunited fractures of the distal radius treated by volar locking plate does not necessarily require bone graft.

Reamer Irrigator Aspirator bone graft harvesting: complications and outcomes in an Asian population

INTRODUCTION

Autologous bone grafting has been accepted as the gold standard in the treatment of non-unions and in definitive filling of segmental bone defects. However, there have been well-recognised complications associated with their harvest. The Reamer Irrigator Aspirator (RIA) system is an alternative technique of autologous bone graft harvesting. Studies have been published in the Western population showing the efficacy and outcome of this technique. No prior studies were done in the Asian population, who has smaller average canals, different femoral geometry as compared to Caucasians and weaker bone density in both genders. We aim to present the findings and discuss its suitability in the Asian population when dealing with segmental bone loss and non-unions requiring reconstruction.

METHODS

We conducted a retrospective analysis of all trauma patients with segmental bone loss and non-unions treated with RIA bone grafting over a 4.5 year period. A total of 57 cases of RIA bone grafting were conducted on 53 patients. The amount of bone graft harvested, blood loss and post-operative pain were measured. Patients were followed up for union rate as well as complications of the procedure.

RESULTS

Union was achieved in 86.8% of patients. The mean time to union was 17.64 weeks. Seven patients did not achieve union after the first RIA surgery, in which six of seven were open fractures initially and six were smokers. One major intra-operative complication was recorded, that being a fractured femoral shaft due to thinning of the cortex by the RIA harvester. There were two patients who developed donor site superficial soft tissue infection that resolved after a course of antibiotics. There were no long-term complications seen in all patients.

CONCLUSIONS

The safety and efficacy of RIA bone graft harvesting for the management of non-union in the Asian population is promising, with adequate graft quantities, high success and low complication rates that are comparable to the Caucasian population. The diameter of the medullary canal in our population is suitable for this procedure. We believe that RIA bone graft harvesting provides a reliable and safe alternative source of autologous bone grafts for bone grafting of non-union sites.

Bone critical defect repair with poloxamine-cyclodextrin supramolecular gels

The aim of this study was to evaluate the osteoinductive capacity of a poloxamine (Tetronic(®) 908, T) and α-cyclodextrin (αCD) supramolecular gel (T-CD) as scaffold in a critical size defect in rat calvaria. The T-CD gel was evaluated solely and after being loaded with simvastatin (SV) and bone morphogenetic protein (BMP-2) separately and in combinations in order to reduce the doses of the active substances. Three doses of SV (7.5, 75, 750 μg) and two doses of BMP-2 (3 and 6 μg) were tested. The histology and histomorphometrical analysis showed improved bone repair with T-CD compared to T, probably due to better release control of both SV and BMP-2. In addition, as T-CD eroded more slowly than poloxamine alone, it remained longer in the defect site. Although synergism was not obtained with BMP-2 and SV, according to the observed regeneration of the defect, the dose of BMP-2 and SV can be reduced to 3 μg and 7.5 μg, respectively.