Autologous iliac crest bone graft: should it still be the gold standard for treating nonunions?

Growth factors and bone regeneration: how much bone can we expect?

A large body of research has investigated the use of growth factors for bone regeneration, as a potential alternative to autogenous bone grafting. The bone morphogenetic proteins (BMPs) represent the most extensively investigated growth factors to date, as potential therapeutic agents for bone regeneration. Despite decades of research, the ideal growth factor or combination of growth factors for bone regeneration remains undefined. This article reviews the current available evidence for the application of growth factors for bone regeneration, with a focus on the clinical evidence for BMP use. Emerging pre-clinical and clinical evidence for growth factors other than the BMPs is also discussed.

Treatment of long bone non-unions with polytherapy: indications and clinical results

The incidence of long bone non-unions has been estimated to range between 5 and 10%. Autologous bone graft usually harvested from the iliac crest continues to be the gold standard for biological enhancement of atrophic non-unions. However, its use has been hampered by minor and major donor site complications. Moreover despite possessing the properties of osteogenecity, osteoconductivity and some osteoinductivity the overall results of treatment have not been consistent with disappointing success rates at times. The concept of polytherapy for the treatment of non-unions, namely the simultaneous application of the three fundamental elements of the diamond concept, osteoprogenitor cells, growth factor and osteoconductive scaffold, appears to be an attractive alternative but more studies are desirable to validate this strategy.

Application of locking plate in long-bone atrophic nonunion following external fixation

The treatment of atrophic fracture nonunion continues to represent a therapeutic challenge. Large segmental osteopenia is often seen in patients who received uniplanar or hybrid external fixators as the definitive method of fixation for high-energy fractures, and this adds more difficulties to the treatment of fracture nonunion. This retrospective study was designed to assess the outcome of locking compression plating with autologous bone grafting in patients with long-bone atrophic nonunion following external fixation.From January 2004 to December 2009, a series of consecutive patients with atrophic nonunion of the long bone following external fixation were treated with this method in our institution. The clinical outcomes and complications of these patients were retrospectively analyzed. Twenty-seven patients with 28 fracture nonunions were involved in this study. Mean follow-up was 14.2±3.4 months. Bony union was achieved in all 27 patients within a mean 18.6±4.8 weeks after revision surgery. Two patients developed superficial wound infections. No deep infections were found, and no implant failure was seen. Three patients reported minor pain in the donor site of the bone graft, and no other donor site complications were found.Revision osteosynthesis of long-bone atrophic nonunion following external fixation by locking compression plating with autologous iliac crest bone grafting represents a safe and efficacious modality for the treatment of these challenging conditions.

The combined bone forming capacity of human periosteal derived cells and calcium phosphates

Current knowledge suggests that the periosteum, a fibrous tissue which covers the surface of all bones, contains a population of progenitor cells which mediate the repair of bone defects. In an effort to optimise the utilisation of this source of cells for bone engineering, herein we describe the rational selection of calcium phosphate (CaP) containing materials, based on biomaterial properties, and evaluation of their combined bone forming capacity. Five different commercially available orthopaedic 3D matrices composed of CaP particles in an open collagen network (NuOss™, CopiOs™, Bio-Oss(®), Collagraft™ and Vitoss(®)) were evaluated in vitro and in vivo with human periosteal derived cells (hPDCs). It was found that the cell-material combinations behaved quite differently in vivo, despite apparent in vitro similarities in gene expression profiles. Bone formation was highest within the NuOss™/hPDC implant at 13.03%, which also contained the highest incidence of bone marrow formation. The bone formed in this implant was chimeric with approximately 65% originating from implanted cells. Upon analysis of human specific gene expression, although it was found that predominantly osteogenic differentiation was observed within NuOss™/hPDC implants, a lesser induction of chondrogenic genes was also observed. The formation of a cartilage intermediate was confirmed by histology. Additionally the NuOss™/hPDC implant integrated into the mouse environment with apparent active scaffold resorption. This study demonstrates the importance of matching a cell support/biological matrix with a cell type and subsequently has outlined parameters which can be used for the rational selection of biomaterials for bone engineering.

Polytherapy in Bone Regeneration: Clinical Applications and Preliminary Considerations

Polytherapy, namely the simultaneous application of three fundamental elements necessary for bone regeneration (growth factors, osteogenic cells and osteocnductive scaffolds) seems to lead to a very high success rate in the treatment of complex non-union (NU) cases and critical bone defects. NU are reported in 5–10% of long bone fractures. The use of autologous bone grafts has been long-considered the gold standard for the treatment of these cases. However the harvesting procedure from the iliac crest increases surgery time and presents some donor site complications which may be elevated. In recent years, surgeons have some alternatives to autologous grafting such as: application of organic or synthetic bone substitute, application of mesenchymal stromal cells (MSC) or growth factors (GF). In the literature there are many studies available about their application in monotherapy, but unfortunately the healing rate doesn't exceed 90%. Polytherapy seems to be a logical option to improve the healing rate, nevertheless, there are not still extensive studies that validate this strategy and moreover, some questions are not resolved.

Comparison between the effects of platelet-rich plasma and bone marrow concentrate on defect consolidation in the rabbit tibia

OBJECTIVE

To perform a comparative analysis of the effects of platelet-rich plasma and centrifuged bone marrow aspirate on the induction of bone healing in rabbits.

METHOD

Twenty adult, male New Zealand rabbits were randomly separated into two equal groups, and surgery was performed to create a bone defect (a cortical orifice 3.3 mm in diameter) in the proximal metaphysis of each rabbit's right tibia. In the first group, platelet-rich plasma was implanted in combination with β-tricalcium phosphate (platelet-rich plasma group), and in the second group, centrifuged bone marrow in combination with β-tricalcium phosphate (centrifuged bone marrow group) was implanted. After a period of four weeks, the animals were euthanized, and the tibias were evaluated using digital radiography, computed tomography, and histomorphometry.

RESULTS

Seven samples from each group were evaluated. The radiographic evaluation confirmed the absence of fractures in the postoperative limb and identified whether bone consolidation had occurred. The tomographic evaluation revealed a greater amount of consolidation and the formation of a greater cortical bone thickness in the platelet-rich plasma group. The histomorphometry revealed a greater bone density in the platelet-rich plasma group compared with the centrifuged bone marrow group.

CONCLUSION

After four weeks, the platelet-rich plasma promoted a greater amount of bone consolidation than the bone marrow aspirate concentrate.

Comparison between Platelet-Rich Plasma and Autologous Iliac Grafts for Tibial Osteotomy

OBJECTIVE

Platelet-rich plasma (PRP) has the capacity to improve the bone-healing process. The aim of this pilot study was to investigate the occurrence of bone healing and the time taken to achieve this in patients submitted to medial opening wedge high tibial osteotomy (MOWHTO), comparing platelet-rich plasma with bone marrow aspirate to autologous iliac graft.

DESIGN

Twenty-five patients who underwent tibial osteotomy were randomly divided into 2 groups: a control group, which received autologous iliac grafts (14 patients), and a study group, which received a compound of PRP and bone marrow aspirate (11 patients).

RESULTS

The bone-healing rates achieved were 100% in the control group and 91% in the study group. There was no difference in the time taken to achieve bone healing between the groups.

CONCLUSIONS

The use of a combination of PRP and bone marrow aspirate, as a bone substitute, did not demonstrate any advantage over the use of an autologous iliac graft in MOWHTO.

Bone regeneration mediated by biomimetic mineralization of a nanofiber matrix

Rapid bone regeneration within a three-dimensional defect without the use of bone grafts, exogenous growth factors, or cells remains a major challenge. We report here on the use of self-assembling peptide nanostructured gels to promote bone regeneration that have the capacity to mineralize in biomimetic fashion. The main molecular design was the use of phosphoserine residues in the sequence of a peptide amphiphile known to nucleate hydroxyapatite crystals on the surfaces of nanofibers. We tested the system in a rat femoral critical-size defect by placing pre-assembled nanofiber gels in a 5mm gap and analyzed bone formation with micro-computed tomography and histology. We found within 4 weeks significantly higher bone formation relative to controls lacking phosphorylated residues and comparable bone formation to that observed in animals treated with a clinically used allogenic bone matrix.

Prospective clinical pilot trial in a single cohort group of rhPDGF in foot arthrodeses

BACKGROUND

Augment Bone Graft, a fully synthetic bone graft material composed of recombinant human PDGF and a calcium phosphate matrix (rhPDGF/TCP), has been considered as a possible alternative to autogenous bone graft. Before proceeding with randomized control studies comparing rhPDGF/TCP to autograft bone, a human trial to assess efficacy and safety was required.

MATERIALS AND METHODS

The current study was a prospective, open-label, multi-center trial designed to evaluate rhPDGF in a calcium phosphate matrix (Augment Bone Graft). Sixty patients requiring hindfoot or midfoot fusion were prospectively followed for 36 weeks. All patients received 0.9 to 2.7 mg of rhPDGF at the fusion sites and returned for clinical and radiographic review at Day 7 to 14 and Weeks 6, 9, 12, 16, 24, and 36. Computerized tomography (CT) scans of the fusion site were obtained at the 6- and 12-week postoperative appointment, with an additional CT scan at 16 weeks if required.

RESULTS

No patients suffered a serious adverse event caused by rhPDGF. CT scan evaluation at 12- to 16-week time periods revealed moderate or complete osseous bridging of 75% (44/59) at 36 weeks.

CONCLUSION

These results indicate that rhPDGF is a safe product and provides clinical/radiographic outcomes that justify the pursuit of randomized controlled studies comparing rhPDGF/TCP to autograft.

rBMP represses Wnt signaling and influences skeletal progenitor cell fate specification during bone repair

Bone morphogenetic proteins (BMPs) participate in multiple stages of the fetal skeletogenic program from promoting cell condensation to regulating chondrogenesis and bone formation through endochondral ossification. Here, we show that these pleiotropic functions are recapitulated when recombinant BMPs are used to augment skeletal tissue repair. In addition to their well-documented ability to stimulate chondrogenesis in a skeletal injury, we show that recombinant BMPs (rBMPs) simultaneously suppress the differentiation of skeletal progenitor cells in the endosteum and bone marrow cavity to an osteoblast lineage. Both the prochondrogenic and antiosteogenic effects are achieved because rBMP inhibits endogenous beta-catenin-dependent Wnt signaling. In the injured periosteum, this repression of Wnt activity results in sox9 upregulation; consequently, cells in the injured periosteum adopt a chondrogenic fate. In the injured endosteum, rBMP also inhibits Wnt signaling, which results in the runx2 and collagen type I downregulation; consequently, cells in this region fail to differentiate into osteoblasts. In muscle surrounding the skeletal injury site, rBMP treatment induces Smad phosphorylation followed by exuberant cell proliferation, an increase in alkaline phosphatase activity, and chondrogenic differentiation. Thus different populations of adult skeletal progenitor cells interpret the same rBMP stimulus in unique ways, and these responses mirror the pleiotropic effects of BMPs during fetal skeletogenesis. These mechanistic insights may be particularly useful for optimizing the reparative potential of rBMPs while simultaneously minimizing their adverse outcomes.

Efficacy of minimally invasive techniques for enhancement of fracture healing: evidence today

The successful treatment of nonunions represents a major challenge for orthopaedic surgeons. Lately, ongoing advances made in the field of molecular medicine and molecular biology have increased our understanding of the pathways and involvement of mediators surrounding the bone healing process. As a result, the surgeon's armamentarium has been increased in terms of options for intervention. This article aims to provide an overview of minimally invasive techniques applicable in the treatment of nonunions of fractures.

Electrical stimulation for fracture healing: current evidence

This article provides an overview of the biology behind the use of electrical stimulation in fracture healing and discusses the current methods of electrical bone growth stimulation. In addition, we review the best available clinical evidence for the use of electrical stimulation in the treatment of delayed and nonunions of fractures. Our search identified 4 meta-analyses on the use of electrical stimulation on fracture healing. The most methodologically rigorous and recent meta-analysis suggests that the current evidence is insufficient to conclude a benefit of electromagnetic stimulation in improving the rate of union in patients with a fresh fracture, osteotomy, delayed union, or nonunion. The other 3 meta-analyses that we identified suggested a more significant treatment effect from electrical stimulation. Although the evidence supporting electrical stimulation does trend in favor of its use to help achieve bony union, further large, multicenter, randomized, controlled trials are required to resolve the current uncertainty surrounding the use of electrical stimulation and fracture healing.

Gene therapy for fracture healing

Traumatic bone defects and nonunion represent a significant source of morbidity and socioeconomic burden in trauma patients. The treatment of these conditions is currently hampered by inadequate therapies. This has prompted a new era of investigation into biologic therapies for augmenting fracture healing. Within this body of research, gene therapy has arisen as a novel and effective method of delivering therapeutic proteins at a site of desired bone regeneration. Gene therapy has shown tremendous potential in preclinical studies of fracture healing, but to date, no clinical trials have occurred. This article reviews the scientific basis for gene therapy in fracture healing, provides an overview of important preclinical studies that have been performed to date, and discusses the current barriers and future directions of gene therapy as it applies to fracture healing.

A novel biomimetic polymer scaffold design enhances bone ingrowth

There has been recent interest in treating large bone defects with polymer scaffolds because current modalities such as autographs and allographs have limitations. Additionally, polymer scaffolds are utilized in tissue engineering applications to implant and anchor tissues in place, promoting integration with surrounding native tissue. In both applications, rapid and increased bone growth is crucial to the success of the implant. Recent studies have shown that mimicking native bone tissue morphology leads to increased osteoblastic phenotype and more rapid mineralization. The purpose of this study was to compare bone ingrowth into polymer scaffolds created with a biomimetic porous architecture to those with a simple porous design. The biomimetic architecture was designed from the inverse structure of native trabecular bone and manufactured using solid free form fabrication. Histology and muCT analysis demonstrated a 500-600% increase in bone growth into and adjacent to the biomimetic scaffold at five months post-op. This is in agreement with previous studies in which biomimetic approaches accelerated bone formation. It also supports the applicability of polymer scaffolds for the treatment of large tissue defects when implanting tissue-engineering constructs. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.

Viable bone and circulatory factors required for survival of bone grafts

The healing of fractures and nonunions has significant science background to it; however, the application of the products in the surgeon's hands should be considered an art in the science of bone healing. The surgeon must choose adequate fixation for stability and to promote healing by not making the construct too stiff. If a bone graft substitute is necessary, the surgeon must choose the type of bone graft substitute depending on patient factors and surgeon factors involving the treatment of the fracture.

In vitro testing of the osteoinductive potential of different bony allograft preparations

INTRODUCTION

Bony allografts are used frequently in the clinic for bone defect filling, however, less comparative data concerning their osteoinductive potential are available.

AIM

The purpose of the present study was the comparative analysis of different allograft preparations. From five donors, we investigated fresh-frozen cancellous bone (native), peracetic acid–ethanol sterilized (PES) cancellous bone, cortical bone and demineralised bone matrix (DBM). In addition, two commercially available DBM products from five different donors were analyzed: Allomatrix® (Wright Medical Technology Inc.) and DBX putty® (Synthes GmbH). For positive control and as a clinically used growth factor, BMP-2 was chosen.

METHOD

To investigate the osteoinductivity C2C12 cells were cultured with the different materials and the effect on cell proliferation and alkaline phosphatase activity were measured.

RESULT

Proliferation was significantly enhanced by the native cancellous bone, Allomatrix, and BMP-2 and decreased by the PES-processed cancellous bone. The osteogenic differentiation was significantly enhanced by BMP-2 and the two commercial DBM products and decreased by PES-sterilized cancellous bone. All tested materials revealed a high donor-dependent variability. This is the first comparative study on the osteoinductivity of bony allografts frequently used in clinic.

Technical tricks when using the reamer irrigator aspirator technique for autologous bone graft harvesting

This report describes technical tricks for using the reamer irrigator aspirator to harvest autologous bone graft from the femur. This device is a focus of interest in orthopaedics because it can be used to harvest bone graft from the femoral canal and medial condyle in voluminous quantities. Moreover, according to some authors, the osteogenic potential of this graft is at least as effective as that of autogenous bone obtained from the iliac crest. The reamer irrigator aspirator device has substantially different design characteristics and technicalities compared with those of a standard reamer. First, a guidewire must be redirected into multiple areas, including the center of the distal femur and into both condyles, to harvest ample bone graft. This is accomplished by prebending the guidewire in a stronger fashion than required for regular reaming in the case of femoral nailing procedures. This bend can increase the risk for eccentric reaming as well as lodging of the suctioning device within the femoral canal. Second, the front and lateral drilling surfaces of this device are very sharp and further cleaned and maintained sharp by the irrigation process to permit the surgeon to obtain significant volumes of graft with a single passage of this device. At the same time, however, this sharp front-end cutting design can increase the risk of iatrogenic fracture if reaming is performed without caution. Third, a powerful suctioning device is connected to the reamer such that the blood loss that can occur during continuous reaming, irrigation, and aspiration must be considered with this technique. We hereby discuss these potential dangers and describe the correct use of this device with technical tricks to minimize the risk of unexpected intraoperative events.

Direct write assembly of calcium phosphate scaffolds using a water-based hydrogel

The development of materials to support bone regeneration requires flexible fabrication technologies able to tailor chemistry and architecture for specific applications. In this work we describe the preparation of ceramic-based inks for robotic-assisted deposition (robocasting) using Pluronic F-127 solutions. This approach allows the preparation of pseudoplastic inks with solid contents ranging between 30 and 50 vol.%, enabling them to flow through a narrow printing nozzle while supporting the weight of the printed structure. Ink formulation does not require manipulation of the pH or the use of highly volatile organic components. Therefore, the approach can be used to prepare materials with a wide range of compositions, and here we use it to build hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and biphasic (HA/beta-TCP) structures. The flow of the inks is controlled by the Pluronic content and the particle size distribution of the ceramic powders. The use of wide size distributions favors flow through the narrow printing nozzles and we have been able to use printing nozzles as narrow as 100 microm in diameter, applying relatively low printing pressures. The microporosity of the printed lines increases with increasing Pluronic content and lower sintering temperatures. Microporosity can play a key role in determining the biological response to the materials, but it also affects the strength of the structure.

Free vascularised fibular grafting with OsteoSet®2 demineralised bone matrix versus autograft for large osteonecrotic lesions of the femoral head

The aim of this study was to compare the safety and efficacy of OsteoSet®2 DBM with autologous cancellous bone in free vascularised fibular grafting for the treatment of large osteonecrotic lesions of the femoral head. Twenty-four patients (30 hips) with large osteonecrotic lesions of the femoral head (stage IIC in six hips, stage IIIC in 14, and stage IVC in ten, according to the classification system of Steinberg et al.) underwent free vascularised fibular grafting with OsteoSet®2 DBM. This group was retrospectively matched to a group of 24 patients (30 hips) who underwent free vascularised fibular grafting with autologous cancellous bone during the same time period according to the aetiology, stage, and size of the lesion and the mean preoperative Harris hip score. A prospective case-controlled study was then performed with a mean follow-up duration of 26 months. The results show no statistically significant differences between the two groups in overall clinical outcome or the radiographic assessment. Furthermore, no adverse events related to the use of the OsteoSet®2 DBM were observed. The results demonstrate that OsteoSet®2 DBM combined with autograft bone performs equally as well as that of autologous bone alone. Therefore, OsteoSet®2 DBM can be used as a safe and effective graft extender in free vascularised fibular grafting for large osteonecrotic lesions of the femoral head.

The synergistic effect of autograft and BMP-7 in the treatment of atrophic nonunions

Combining autologous bone graft and recombinant human bone morphogenetic protein-7 (BMP-7) to treat long-bone fracture aseptic atrophic nonunions theoretically could promote bone healing at higher rates than each of these grafting agents separately. We retrospectively reviewed prospectively collected data on patient general characteristics, clinical outcomes, and complications over 3 years to determine the healing rates and the incidence of complications and adverse events of this "graft expansion rationale." There were 45 patients (32 male) with a median age of 43 years (range, 19-76 years). Minimum followup was 12 months (mean, 24.5 months; range, 12-65 months). There were seven humeral, 19 femoral, and 19 tibial nonunions. The median number of prior operations was two (range, 1-7). All fractures united. Clinical and radiographic union occurred within a median of 5 months (range, 3-14 months) and 6 months (range, 4-16 months), respectively. Thirty-nine (87%) patients returned to their preinjury occupation at a mean of 4.2 months (range, 3-6 months). The median visual analog scale pain score was 0.9 (range, 0-2.8; maximum 10), and the median functional score was 86 (range, 67-95; maximum 100) at the final followup. BMP-7 as a bone-stimulating agent combined with conventional autograft resulted in a nonunion healing rate of 100% in these 45 patients.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Application of bone morphogenetic proteins to femoral non-unions: a 4-year multicentre experience

Fracture non-unions often complicate orthopaedic trauma. BMPs (bone morphogenetic proteins) are currently considered the most appealing osteoinductive agents. Applications of BMP-7 since January 2004 were prospectively recorded in a multicentre registry of aseptic femoral non-unions. The study included 30 patients who had undergone a median of 1 revision operation before BMP-7 application and who were followed up for a median 24 months. In 23/30 cases the application of BMP-7 was combined with revision of the fixation, and in 12 it was combined also with autograft. Non-union healing was verified in 26/30 cases in a median period of 6 months. No adverse events were associated with BMP-7 application. Our case series supports the safety and efficacy of BMP-7 in femoral non-unions. Multicentre networks and systematic, long-term follow-up of patients may improve understanding of this promising osteoinductive bone substitute.

Bone morphogenetic proteins in musculoskeletal medicine

Ongoing research at the molecular level has expanded our understanding of the physiological processes that regulate the complex phenomena of fracture healing and bone regeneration. A number of key molecules have been identified and shown to facilitate the progression of healing from one stage to another, leading to an uneventful outcome. Among these candidate molecules, bone morphogenetic proteins (BMPs) possess potent osteoinductive properties. They interact with osteoprogenitor cells, regulating both mitogenesis and differentiation potential. Since the discovery of BMPs, a number of experimental and clinical trials have supported their safety and efficacy of their use in therapy. Nonetheless, at times their efficacy falls short of expectations. Several factors have been identified as contributing to this result. It is anticipated that, as our knowledge expands and we understand better the complex pathways and cascades of molecular events attributable to BMPs, the application of these molecules in the clinical setting will continue to increase and to show more favourable outcomes.

Bone morphogenetic proteins in critical-size bone defects: what are the options?

The recent development of new orthopaedic devices and advanced techniques for soft-tissue reconstruction have clearly improved the outcome in trauma and orthopaedic surgery. Nevertheless, large bone defects are still difficult to treat and require a careful analysis of the situation. Individual planning of the reconstructive strategy is desirable. Bone morphogenetic proteins (BMPs) have successfully been applied in the clinical setting for the treatment of spinal fusion, fracture healing and delayed and non-unions. Following the 'diamond concept', surgeons have begun using BMPs for treatment of critical-size defects also--in most cases, 'off label'; different treatment strategies are currently being evaluated. BMPs are often used in combination with autogenic, allogenic, xenogenic or synthetic grafting materials and even with mesenchymal stem cells. In addition, gene therapy approaches present an attractive option. Experimental studies and first clinical results are promising in the use of BMPs for treatment of critical-size defects; however, there is obvious need for further controlled studies to define strategies.

[Tissue engineering of bone tissue. Principles and clinical applications]

Complex fractures are still a major clinical challenge. The treatment options of large bony defects either with autografts or allografts are limited in terms of material availability and tissue in-growth. Tissue engineering might offer a solution to this problem. In an interdisciplinary approach artificial bony tissue can be generated which mimics normal bone in terms of function and morphology. So far tissue engineering of bone is mainly confined to laboratory investigations whereas clinical applications are still in the beginning. This manuscript presents the most important scaffolds as well as growth factors and cell systems. Furthermore, it focuses on clinical studies for the treatment of large bony defects using tissue engineered cell-matrix constructs.

Use of bone morphogenetic proteins in arthrodesis: clinical results

Bone grafting is not routinely required in primary arthrodesis in the absence of infection, avascular necrosis, bone defect or previous non-union; when any of the above factors is present, autograft is the gold-standard method. However, donor site morbidity and the quantitative and qualitative limitations of autograft have led to the development of alternatives. This study documents the use of the bone morphogenetic protein BMP-7 in a total of 19 joint fusions (ankle, subtalar, talonavicular, pubic and sacroiliac). Healing rates of 90% and satisfactory subjective functional outcome in 70% of cases were recorded over a minimum follow-up of 15 months. These data should provide a sound foundation for future clinical trials evaluating the application of BMP-7 in the fusion of joints.

Surgical techniques: how I do it? The Reamer/Irrigator/Aspirator (RIA) system

Although reamed intramedullary nailing has long been considered a safe procedure, pulmonary complications have been reported in some groups of patients. Concerns over fat embolisation, adult respiratory distress syndrome (ARDS), and sudden intraoperative death have prompted some authors to question whether the benefits of reaming are outweighed by its potential adverse effects to the patient. In response to these complications, recent evaluations have focused on alternative systems that reduce intramedullary pressure during reaming. The Reamer/Irrigator/Aspirator (RIA) system (Synthes, Inc., West Chester, PA) was developed as a simultaneous reaming and aspiration system to reduce the intramedullary pressure, heat generation, operating time, and systemic effects of reaming. It was designed with an aggressive one-pass reamer head which is connected to a hand-held reamer via a drive shaft, simultaneously irrigating and aspirating femoral canal contents during reaming, thus preventing thermal necrosis and fat embolisation. After its early use, investigators examined the "aspirate" captured by the RIA which appeared to be loaded with osteogenic substrates. This discovery revealed a second potential use for the RIA-a bone graft harvester. The different design characteristics and technicalities of the RIA system necessitate a deep and clear understanding of its technique, a meticulous preoperative planning and a strict adherence to its principles intraoperatively. We present our current approach to the use of the RIA system, including the preoperative planning, the details of the operative procedure, the pitfalls and the potential complications that could be encountered.

Injectable biomaterials for regenerating complex craniofacial tissues

Engineering complex tissues requires a precisely formulated combination of cells, spatiotemporally released bioactive factors, and a specialized scaffold support system. Injectable materials, particularly those delivered in aqueous solution, are considered ideal delivery vehicles for cells and bioactive factors and can also be delivered through minimally invasive methods and fill complex 3D shapes. In this review, we examine injectable materials that form scaffolds or networks capable of both replacing tissue function early after delivery and supporting tissue regeneration over a time period of weeks to months. The use of these materials for tissue engineering within the craniofacial complex is challenging but ideal as many highly specialized and functional tissues reside within a small volume in the craniofacial structures and the need for minimally invasive interventions is desirable due to aesthetic considerations. Current biomaterials and strategies used to treat craniofacial defects are examined, followed by a review of craniofacial tissue engineering, and finally an examination of current technologies used for injectable scaffold development and drug and cell delivery using these materials.

Treatment and outcomes of pelvic malunions and nonunions: a systematic review

Although acute management of pelvic fractures and their long-term functional outcome have been widely documented, important information regarding malunion and nonunion of these fractures is sparse. Despite their relative rarity, malunions and nonunions cause disabling symptoms and have major socioeconomic implications. We analyzed the factors predisposing a pelvic injury to develop malunion/nonunion, the clinical presentation of these complications, and the efficacy of the reported operative protocols in 437 malunions/nonunions of 25 clinical studies. Treatment of these demanding complications appeared effective in the majority of the cases: overall union rates averaged 86.1%, pain relief as much as 93%, patient satisfaction 79%, and return to a preinjury level of activities 50%. Nevertheless, the patient should be informed about the incidence of perioperative complications, including neurologic injury (5.3%), symptomatic vein thrombosis (5.0%), pulmonary embolism (1.9%), and deep wound infection (1.6%). For a successful outcome, a thorough preoperative plan and methodical operative intervention are essential. In establishing effective evidence-based future clinical practice, the introduction of multicenter networks of pelvic trauma management appears a necessity.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Treatment of diaphyseal nonunion of the femur and tibia using an expandable nailing system

INTRODUCTION

We evaluated the efficacy of the expandable nailing system for treating femur and tibia shaft nonunions.

PATIENTS AND METHODS

Records of 24 patients (25 fractures) were retrospectively reviewed: 16 with femur and 8 with tibia nonunions. The bones underwent reaming, and the largest possible nail sizes were inserted during re-operation. Bone debris obtained from the reaming was used for bone graft at the site of the nonunion.

RESULTS

The mean age of the patients was 32 years for the tibia group and 49 years for the femur group. The respective intervals between trauma and re-operation were 11 and 13 months, the operation times 60 and 78 min, and the fluoroscopy times 21 and 32s. Twenty-four of the 25 nonunions healed satisfactorily without requiring additional procedures. In 1 case, demineralised bone matrix was injected percutaneously and the femoral nonunion resolved. Healing time was 23 weeks (6-52) and 17 weeks (6-40) in the tibia and femur groups, respectively. We were able to reduce the need of an autologous bone graft to only two cases by using reamed debris in 17 of the 19 patients who required grafting.

CONCLUSIONS

Our results demonstrated satisfactory healing for the treatment of diaphyseal nonunions of the femur and tibia. The expandable nail offers the theoretical advantages of improved load sharing and rotational control without the need for interlocking screws. We recommend expandable nail systems for femur and tibia shaft nonunions and the use of reamed debris in order to decrease the use of autogenous bone graft.

Skeletal cell fate decisions within periosteum and bone marrow during bone regeneration

Bone repair requires the mobilization of adult skeletal stem cells/progenitors to allow deposition of cartilage and bone at the injury site. These stem cells/progenitors are believed to come from multiple sources including the bone marrow and the periosteum. The goal of this study was to establish the cellular contributions of bone marrow and periosteum to bone healing in vivo and to assess the effect of the tissue environment on cell differentiation within bone marrow and periosteum. Results show that periosteal injuries heal by endochondral ossification, whereas bone marrow injuries heal by intramembranous ossification, indicating that distinct cellular responses occur within these tissues during repair. [corrected] Next, lineage analyses were used to track the fate of cells derived from periosteum, bone marrow, and endosteum, a subcompartment of the bone marrow. Skeletal progenitor cells were found to be recruited locally and concurrently from periosteum and/or bone marrow/endosteum during bone repair. Periosteum and bone marrow/endosteum both gave rise to osteoblasts, whereas the periosteum was the major source of chondrocytes. Finally, results show that intrinsic and environmental signals modulate cell fate decisions within these tissues. In conclusion, this study sheds light into the origins of skeletal stem cells/progenitors during bone regeneration and indicates that periosteum, endosteum, and bone marrow contain pools of stem cells/progenitors with distinct osteogenic and chondrogenic potentials that vary with the tissue environment.

Effects of a new allograft processing procedure on graft healing in a canine model: a preliminary study

Graft healing in vivo can be affected by allograft processing. We asked whether a new processing technique influenced graft-host healing compared with autograft and a standard processing technique in a canine ulna model. We used bilateral intercalary allografts or autografts in the ulna of 13 skeletally mature male coonhounds. Each animal received two allografts, either one autograft and one allograft, or two autografts. At term (90 days), the graft sites were harvested. We assessed union with high-resolution xray imaging. Each specimen was processed for nondecalcified histologic analysis to assess the graft-host interface. Quantitative histomorphometric analysis was performed to determine spatial location and area of bone. Radiographic analysis, histologic analysis, and histomorphometric measures revealed no differences in union, mean total bone area, or total endosteal/intramedullary bone for the new process, standard process, and autografts. Our preliminary data suggest the new processing techniques may increase the safety of allograft transplantation without adversely affecting union when compared with standard processing techniques and autograft in a canine model.

Extracorporeal shockwave therapy: A systematic review of its use in fracture management

Extracorporeal shockwave therapy is increasingly used as an adjuvant therapy in the management of nonunions, delayed unions and more recently fresh fractures. This is in an effort to increase union rates or obtain unions when fractures have proven recalcitrant to healing. In this report we have systematically reviewed the English language literature to attempt to determine the potential clinical efficacy of extracorporeal shockwave therapy in fracture management. Of 32 potentially eligible studies identified, 10 were included that assessed the extracorporeal shockwave therapy use for healing nonunions or delayed unions, and one trial was included that assessed its use for acute high-energy fractures. From the included, studies' overall union rates were in favor of extracorporeal shockwave therapy (72% union rate overall for nonunions or delayed unions, and a 46% relative risk reduction in nonunions when it is used for acute high-energy fractures). However, the methodologic quality of included studies was weak and any clinical inferences made from these data should be interpreted with caution. Further research in this area in the form of a large-scale randomized trial is necessary to better answer the question of the effectiveness of extracorporeal shockwave therapy on union rates for both nonunions and acute fractures.

Application of rhBMP-7 and platelet-rich plasma in the treatment of long bone non-unions: a prospective randomised clinical study on 120 patients

The purpose of this prospective randomised clinical study was to compare the efficacy of recombinant bone morphogenetic protein 7 (rhBMP-7) and platelet-rich plasma (PRP) as bone-stimulating agents in the treatment of persistent fracture non-unions. One hundred and twenty patients were randomised into two treatment groups (group rhBMP-7 vs. group PRP). Sixty patients with sixty fracture non-unions were assigned to each group (median age: 44 years, range 19-65, for the rhBMP-7 group and 41 years, range 21-62, for the PRP group, respectively). In the rhBMP-7 group, there were 15 tibial non-unions, 10 femoral, 15 humeral, 12 ulnar, and 8 radial non-unions. In the PRP group, there were 19 tibial non-unions, 8 femoral, 16 humeral, 8 ulnar, and 9 radial non-unions. The median number of operations performed prior to our intervention was 2 (range 1-5) and 2 (range 1-5) with autologous bone graft being used in 23 and 21 cases for the rhBMP-7 and PRP groups, respectively. Both clinical and radiological union occurred in 52 (86.7%) cases of the rhBMP-7 group compared to 41 (68.3%) cases of the PRP group, with a lower median clinical and radiographic healing time observed in the rhBMP-7 group (3.5 months vs. 4 months and 8 months vs. 9 months, respectively). This study supports the view that in the treatment of persistent long bone non-unions, the application of rhBMP-7 as a bone-stimulating agent is superior compared to that of PRP with regard to their clinical and radiological efficacy.

Differentiation potential of multipotent progenitor cells derived from war-traumatized muscle tissue

BACKGROUND

Recent military conflicts have resulted in numerous extremity injuries requiring complex orthopaedic reconstructive procedures, which begin with a thorough débridement of all contaminated and necrotic tissue in the zone of injury. The site of injury is also the site of healing, and we propose that débrided muscle tissue contains cells with robust reparative and regenerative potential.

METHODS

Débrided muscle from soldiers who had sustained traumatic open extremity injuries was collected during surgical débridement procedures at Walter Reed Army Medical Center. With modifications to a previously described stem-cell-isolation protocol, mesenchymal progenitor cells were harvested from traumatized muscle, enriched, expanded in culture, and exposed to induction media for osteogenesis, adipogenesis, and chondrogenesis.

RESULTS

The isolated mesenchymal progenitor cells stained positive for cell-surface markers (CD73, CD90, CD105), which are characteristic of adult human mesenchymal stem cells. Histological identification of lineage-specific markers demonstrated the potential of these cells to differentiate into multiple mesenchymal lineages. Reverse transcription-polymerase chain reaction analysis confirmed multilineage mesenchymal differentiation at the gene-expression level.

CONCLUSIONS

To our knowledge, the present report provides the first description of mesenchymal progenitor cell isolation from traumatized human muscle. These cells may play an integral role in tissue repair and regeneration and merit additional investigation as they could be useful in future cell-based tissue-engineering strategies.

Controlled release of insulin-like growth factor-1 and bone marrow stromal cell function of bone-like mineral layer-coated poly(lactic-co-glycolic acid) scaffolds

Controlled release of growth factors or drugs provides great therapeutic advantages for bone defects which do not heal with normal therapeutic treatments. We have accelerated the deposition of bone-like mineral (BLM) on the surface of three-dimensional (3D) poly(lactic-co-glycolic acid) (PLGA) porous scaffolds to 36-48 h by modifying the biomimetic process parameters and applying surface treatments onto PLGA scaffolds. We used simulated body fluid containing insulin-like growth factor-1 (IGF-1; 1 microg/ml) to mineralize the PLGA scaffolds for 48 h. IGF-1 was co-precipitated with mineral on the surface of the PLGA scaffolds. IGF-1-incorporated mineralized scaffolds demonstrated slow controlled release over a 30 day period when they were incubated in phosphate-buffered saline (PBS) at 37 degrees C. Bone marrow stromal cell (BMSC) function on three different types of scaffolds, such as control (non-mineralized) scaffolds, mineralized scaffolds, and IGF-1-incorporated mineralized scaffolds was also investigated. BMSC attachment and proliferation was enhanced for IGF-1-incorporated mineralized scaffolds compared with controls during the culture period. BMSC differentiation was not changed during the culture period among the three groups of scaffolds, as assessed by alkaline phosphatase activity and osteocalcin assay. According to findings from this study, BLM has great potential to be used as a carrier for biological molecules for localized release applications as well as bone tissue-engineering applications.

A comparison of RhBMP-7 (OP-1) and autogenous graft for metaphyseal defects after osteotomy of the distal radius

SUMMARY AIM: The aim of the study was to demonstrate whether RhBMP-7 is an effective alternative to autogenous bone graft in the healing of metaphyseal defects in the distal radius following corrective osteotomies for symptomatic malunion after distal radial fractures.

PATIENTS AND METHODS

Thirty patients were entered into the study and were randomised to receive either RhBMP-7 or autogenous bone graft harvested from the ipsilateral iliac crest. Stabilisation of the osteotomy was either carried out with non- bridging external fixation or the pi-plate. Clinical, radiographic and functional review were carried out at regular intervals up to 1 year.

RESULTS

The first 10 patients were treated using non-bridging external fixation of the osteotomy. Two of the 4 patients treated with RhBMP-7 developed excessive osteolysis around the osteotomy site resulting in loss of the corrected position and non-union of the osteotomy. The other 2 patients healed at 13 weeks. The 6 patients treated with autogenous bone graft all healed at an average of 7 weeks, without any complications. It was postulated that the osteolysis was related to instability of the osteotomy site, and the use of external fixation was abandoned and replaced with internal fixation with a dorsal pi-plate. In the pi-plate group of patients, 10 were treated with autogenous bone graft and 10 with RhBMP-7. The bone graft patients healed at 7 weeks compared to 18 weeks for the RhBMP-7 patients, which was statistically significant (p = 0.019). The patients who received bone graft had complete filling of the metaphyseal defect radiologically. Five patients treated with RhBMP-7 healed at the volar cortex with a dorsal defect remaining at 1 year. Two patients developed non-union radiologically. Ten patients (3 in the RhBMP-7 and 7 in the bone graft groups) required plate removal for soft tissue complications.

CONCLUSION

RhBMP-7 does not confer the same stability as bone graft, allowing shear forces across the osteotomy site when used in conjunction with non-bridging external fixation, reducing the capacity for healing and resulting in osteolysis. Using the RhBMP-7 with a pi-plate resulted in healing of the osteotomy, but at a slower rate than autogenous bone graft.

Application of BMP-7 to tibial non-unions: a 3-year multicenter experience

The effective treatment of the often debilitating, longlasting and large-asset-consuming complication of fracture non-unions has been in the centre of scientific interest the last decades. The use of alternative bone substitutes to the gold standard of autologous graft includes the osteoinductive molecules named bone morphogenetic proteins (BMPs). A multicenter registry and database (bmpusergroup.co.uk) focused on the application of BMP-7/OP-1 was created in December 2005. We present the preliminary results, using the prospective case-series of aseptic tibial non-unions as an example. Sixty-eight patients fulfilled the inclusion criteria for this observational study, with a minimum follow-up of 12 months. The median duration of tibial non-union prior to BMP-7 application was 23 months (range 9-317 mo). Patients had undergone a median of 2 (range 0-11) revision procedures prior to the administration of BMP-7. In 41% the application of BMP-7 was combined with revision of the fixation at the non-union site. Non-union healing was verified in 61 (89.7%) in a median period of 6.5 months (range 3-15 mo). No adverse events or complications were associated with BMP-7 application. The safety and efficacy of BMP-7 was verified in our case series, and was comparable to the existing evidence. The establishment of multicenter networks and the systematic and long-term follow- up of these patients are expected to provide further information and significantly improve our understanding of this promising osteoinductive bone substitute.

Innovations in osteosynthesis and fracture care

Over the years giant steps have been made in the evolution of fracture fixation and the overall clinical care of patients. Better understanding of the physiological response to injury, bone biology, biomechanics and implants has led to early mobilisation of patients. A significant reduction in complications during the pre-operative and post-operative phases has also been observed, producing better functional results. A number of innovations have contributed to these improved outcomes and this article reports on the advances made in osteosynthesis and fracture care.