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

The Role Of BMPs in the Regulation of Osteoclasts Resorption and Bone Remodeling: From Experimental Models to Clinical Applications

In response to mechanical forces and the aging process, bone in the adult skeleton is continuously remodeled by a process in which old and damaged bone is removed by bone-resorbing osteoclasts and subsequently is replaced by new bone by bone-forming cells, osteoblasts. During this essential process of bone remodeling, osteoclastic resorption is tightly coupled to osteoblastic bone formation. Bone-resorbing cells, multinuclear giant osteoclasts, derive from the monocyte/macrophage hematopoietic lineage and their differentiation is driven by distinct signaling molecules and transcription factors. Critical factors for this process are Macrophage Colony Stimulating Factor (M-CSF) and Receptor Activator Nuclear Factor-κB Ligand (RANKL). Besides their resorption activity, osteoclasts secrete coupling factors which promote recruitment of osteoblast precursors to the bone surface, regulating thus the whole process of bone remodeling. Bone morphogenetic proteins (BMPs), a family of multi-functional growth factors involved in numerous molecular and signaling pathways, have significant role in osteoblast-osteoclast communication and significantly impact bone remodeling. It is well known that BMPs help to maintain healthy bone by stimulating osteoblast mineralization, differentiation and survival. Recently, increasing evidence indicates that BMPs not only help in the anabolic part of bone remodeling process but also significantly influence bone catabolism. The deletion of the BMP receptor type 1A (BMPRIA) in osteoclasts increased osteoblastic bone formation, suggesting that BMPR1A signaling in osteoclasts regulates coupling to osteoblasts by reducing bone-formation activity during bone remodeling. The dual effect of BMPs on bone mineralization and resorption highlights the essential role of BMP signaling in bone homeostasis and they also appear to be involved in pathological processes in inflammatory disorders affecting bones and joints. Certain BMPs (BMP2 and -7) were approved for clinical use; however, increased bone resorption rather than formation were observed in clinical applications, suggesting the role BMPs have in osteoclast activation and subsequent osteolysis. Here, we summarize the current knowledge of BMP signaling in osteoclasts, its role in osteoclast resorption, bone remodeling, and osteoblast–osteoclast coupling. Furthermore, discussion of clinical application of recombinant BMP therapy is based on recent preclinical and clinical studies.

Effect of Bone Morphogenetic Protein-2 in the Treatment of Long Bone Non-Unions

Background: Delayed fracture healing continues to cause significant patient morbidity and an economic burden to society. Biological stimulation of non-unions includes application of recombinant bone morphogenetic protein-2 (rhBMP-2). However, rhBMP-2 use continues to be a matter of controversy as literature shows scarce evidence for treatment effectiveness. Questions: The objective of this study was to evaluate the effectiveness of rhBMP-2 treatment on long bone non-unions measuring union rate and time to union. Furthermore, we assess risk factors for treatment failure. Methods and patients: A total of 91 patients with non-unions of long bones were treated with rhBMP-2 (n = 72) or standard care without BMP (n = 19) at our institution. Patient characteristics, comorbidities, nicotine consumption, and complications were recorded. Bone healing was assessed by plane X-rays and clinical examination. Patients were followed up with for 24 months. Results: Overall, there was significantly faster bone healing after rhBMP-2 application compared to the no-BMP group (p < 0.001; HR = 2.78; 95% CI 1.4–5.6). Union rates differed significantly between rhBMP-2 compared to the no-BMP group (89% vs. 47%; p < 0.001). At the humerus, there was neither a significantly higher union rate in the rhBMP-2 (83%) compared to the no-BMP group (50%) (p = 0.26; n = 12) nor a faster bone healing with a median time of 9 months in both groups (HR = 2.01; 95% CI 0.49–8.61; p = 0.315). The 33 femora treated using rhBMP-2 healed significantly faster than 9 femora in the no-BMP group (HR = 2.93; 95% CI 1.00–8.4; p = 0.023) with significant differences in union rate with 85% and 44%, respectively (p = 0.022). Regarding tibia non-unions, 25 out of 27 (93%) healed with a median of 9 months after rhBMP-2 application with no significant difference in the no-BMP group (33%) in time to union (p = 0.097) but a significantly higher union rate (p = 0.039). There was no effect of comorbidities, age, sex, soft tissue damage, or nicotine use on time to union, union rate, or secondary interventions. Conclusion: Consistent with the literature, overall, significantly higher union rates with reduced time to union were achieved after rhBMP-2 application. Femoral and tibial non-unions in particular seem to profit from rhBMP-2 application.

Clinical, functional and radiological outcomes of the use of fixed angle volar locking plates in corrective distal radius osteotomy for fracture malunion

Background and aim:

Fractures of the distal radius are a common injury and mal-union can occur in those managed non-operatively. This can cause significant functional limitations along with pain. A corrective osteotomy with the use of a volar locking plate aims to restore articular surface congruency and improve outcomes. We present our local experience with clinical, functional and radiological outcomes of corrective osteotomy using a fixed angle volar locking plate and bone graft for management of distal radius mal-union.

Methods:

Retrospective study. All adult patients. Both pre and post operatively clinical range of motion was recorded. Post operative PROMS was measure by DASH, MAYO and SF-12 and pain by means of a VAS measured from 0-10. Mean follow up period was at 15 months.

Results:

32 patients underwent the studied procedure. 24F-8F. Mean age: 56. Radiological union of corrective osteotomy: 28 (88%) of patients. 4 patients required further operative treatment to achieve corrective union. No other reported complications post-op. Post-operatively flexion improved by 24 and extension 20. Pronation was improved by 24 and supination 22. Pain was improved from an average VAS pre-operative of 5.6 to 1.6 post-operatively. Mean DASH scored improved from 57.8 to 16.2 post-operatively and MAYO 38.5 to 58.6. The mean post-operative SF-12 score was 46.2 from 31.

Conclusions:

In this series of 32 patients (the biggest reported in the literature in our knowledge) a corrective osteotomy with fixed-angle volar locking plate for mal-united distal radius has shown to improve both clinical-radiological and patient reported outcomes and provide good results of the very few complications’ treatments. (www.actabiomedica.it)

Growth Factors, Carrier Materials, and Bone Repair

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

Supramolecular self-assembling peptides to deliver bone morphogenetic proteins for skeletal regeneration

Recombinant human bone morphogenetic proteins (BMPs) have shown clinical success in promoting bone healing, but they are also associated with unwanted side effects. The development of improved BMP carriers that can retain BMP at the defect site and maximize its efficacy would decrease the therapeutic BMP dose and thus improve its safety profile. In this review, we discuss the advantages of using self-assembling peptides, a class of synthetic supramolecular biomaterials, to deliver recombinant BMPs. Peptide amphiphiles (PAs) are a broad class of self-assembling peptides, and the use of PAs for BMP delivery and bone regeneration has been explored extensively over the past decade. Like many self-assembling peptide systems, PAs can be designed to form nanofibrous supramolecular biomaterials in which molecules are held together by non-covalent bonds. Chemical and biological functionality can be added to PA nanofibers, through conjugation of chemical moieties or biological epitopes to PA molecules. For example, PA nanofibers have been designed to bind heparan sulfate, a natural polysaccharide that is known to bind BMPs and potentiate their signal. Alternatively, PA nanofibers have been designed to synthetically mimic the structure and function of heparan sulfate, or to directly bind BMP specifically. In small animal models, these bio-inspired PA materials have shown the capacity to promote bone regeneration using BMP at doses 10-100 times lower than established therapeutic doses. These promising results have motivated further evaluation of PAs in large animal models, where their safety and efficacy must be established before clinical translation. We conclude with a discussion on the possiblity of combining PAs with other materials used in orthopaedic surgery to maximize their utility for clinical translation.

A novel autologous bone graft substitute comprised of rhBMP6 blood coagulum as carrier tested in a randomized and controlled Phase I trial in patients with distal radial fractures

Bone morphogenetic proteins (BMPs) are known to induce new bone formation in vivo but treating trabecular bone defects with a BMP based therapeutic remains controversial. Here, we evaluated the safety and efficacy of a novel Autologous Bone Graft Substitute (ABGS) comprised of recombinant human BMP6 (rhBMP6) dispersed within an autologous blood coagulum (ABC) as a physiological natural carrier in patients with a closed distal radial fracture (DRF). We enrolled 32 patients in a randomized, standard of care (SoC) and placebo (PBO) controlled, double-blinded Phase I First in Human (FiH) clinical trial. ABGS was prepared from peripheral blood as 250 μg rhBMP6/mL ABC or PBO (1 mL ABC containing excipients only) and was administered dorsally via a syringe injection into the fracture site following closed fracture fixation with 3 Kirschner wires. Patients carried an immobilization for 5 weeks and were followed-up for 0 to 26 weeks by clinical examination, safety, serial radiographic analyses and CT. During the 13 weeks follow-up and at 26 weeks post study there were no serious adverse reactions recorded. The results showed that there were no detectable anti-rhBMP6 antibodies in the blood of any of the 32 patients at 13- and 26-weeks following treatment. Pharmacokinetic analyses of plasma from patients treated with ABGS showed no detectable rhBMP6 at any time point within the first 24 h following administration. The CT image and radiographic analyses score from patients treated with AGBS showed significantly accelerated bone healing as compared to PBO and SoC at 5 and 9 weeks (with high effect sizes and P = 0.027), while at week 13 all patients had similar healing outcomes. In conclusion, we show that intraosseous administration of ABGS (250 μg rhBMP6/mL ABC) into the distal radial fracture site demonstrated a good tolerability with no serious adverse reactions as well as early accelerated trabecular bone healing as compared to control PBO and SoC patients.

Proteomics of regenerated tissue in response to a titanium implant with a bioactive surface in a rat tibial defect model

Due to their excellent mechanical and biocompatibility properties, titanium-based implants are successfully used as biomedical devices. However, when new bone formation fails for different reasons, impaired fracture healing becomes a clinical problem and affects the patient's quality of life. We aimed to design a new bioactive surface of titanium implants with a synergetic PEG biopolymer-based composition for gradual delivery of growth factors (FGF2, VEGF, and BMP4) during bone healing. The optimal architecture of non-cytotoxic polymeric coatings deposited by dip coating under controlled parameters was assessed both in cultured cells and in a rat tibial defect model (100% viability). Notably, the titanium adsorbed polymer matrix induced an improved healing process when compared with the individual action of each biomolecules. High-performance mass spectrometry analysis demonstrated that recovery after a traumatic event is governed by specific differentially regulated proteins, acting in a coordinated response to the external stimulus. Predicted protein interactions shown by STRING analysis were well organized in hub-based networks related with response to chemical, wound healing and response to stress pathways. The proposed functional polymer coatings of the titanium implants demonstrated the significant improvement of bone healing process after injury.

The Bone Morphogenetic Protein Pathway: The Osteoclastic Perspective

Bone health crucially relies on constant bone remodeling and bone regeneration, both tightly controlled processes requiring bone formation and bone resorption. Plenty of evidence identifies bone morphogenetic proteins (BMP) as major players in osteoblast differentiation and thus, bone formation. However, in recent past years, researchers also increasingly reported on the pivotal role of these multi-functional growth factors in osteoclast formation and activity. This review aims to summarize the current knowledge of BMP signaling within the osteoclast lineage, its role in bone resorption, and osteoblast-osteoclast coupling. Furthermore, subsequent clinical implications for recombinant BMP therapy will be discussed in view of recent preclinical and clinical studies.

Recombinant Human BMP6 Applied Within Autologous Blood Coagulum Accelerates Bone Healing: Randomized Controlled Trial in High Tibial Osteotomy Patients

Bone morphogenetic proteins (BMPs) are potent osteogenic proteins that induce new bone formation in vivo. However, their effect on bone healing in the trabecular bone surfaces remains challenging. We evaluated the safety and efficacy of recombinant human BMP6 (rhBMP6) applied within an autologous blood coagulum (ABC) in a surgically created wedge defect of the proximal tibia in patients undergoing high tibial osteotomy (HTO) for varus deformity and medial osteoarthritis of the knee. We enrolled 20 HTO patients in a randomized, placebo-controlled, double-blinded phase I/II clinical trial. RhBMP6/ABC (1.0 mg/10 mL ABC prepared from peripheral blood) or placebo (10 mL ABC containing excipients) was administered into the tibial wedge defects. Patients were followed for 0 to 24 months by clinical examination (safety) and computed tomography (CT) and serial radiographic analyses (efficacy). The results show that there were no detectable anti-rhBMP6 antibodies in the blood of any of the 20 patients at 14 weeks after implantation. During the 24 months of follow-up, there were no serious adverse reactions recorded. The CT scans from defects of patients treated with rhBMP6/ABC showed an accelerated bone healing compared with placebo at 9 weeks (47.8 ± 24.1 versus 22.2 ± 12.3 mg/cm³ ; p = 0.008) and at 14 weeks (89.7 ± 29.1 versus 53.6 ± 21.9 mg/cm³ ; p = 0.006) follow-up. Radiographic analyses at weeks 6 and 24 and months 12 and 24 suggested the advanced bone formation and remodeling in rhBMP6/ABC-treated patients. In conclusion, we show that rhBMP6/ABC at a dose of 100 μg/mL accelerated bone healing in patients undergoing HTO without serious adverse events and with a good tolerability compared with placebo alone. Overall, for the first time, a BMP-based osteogenic implant was examined against a placebo for bone healing efficacy in the trabecular bone surface, using an objective bone mineral density measurement system. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Distal radius correction osteotomy with tricortical bone graft is a successful method in heavy smokers

BACKGROUND

Corrective osteotomy is a technically challenging surgical option to improve wrist function in tilted distal radius malunions. However fracture healing in smokers is adversely affected. The aim of this study was to evaluate the clinical and radiological effect of cigarettes on bone union in heavy-smokers who underwent corrective osteotomy with a triangular bone graft harvested from the iliac crest.

METHOD

Fifteen patients, who were treated using trapezoidal block grafts taken from the iliac crest, who were smokers of 20 or more cigarettes daily (heavy smokers) with no chronic disease, and who consented to participate in the study. Fifteen non-smoker patients of the same age group were determined as the control group. Radiological measurements were made to include radial inclination and ulnar variance in pre-operative and post-operative radiographs. Functional evaluation was performed using Q-DASH and MAYO hand-wrist scores.

RESULTS

In both groups, the mean age of the patients was 49,1 ± 3,92 years. Smokers group the bone union in the osteotomy line was observed after 16,63 (12-24 h) weeks, non-smokers grup 14.1 (12-24) weeks (p = 0.06). Range of motion is found similar clinic between in groups (p > 0.05). Q-DASH for group smokers was 17.54 ± 1.85, nonsmokers 17.20 ± 1.24 (p = 0,878); MAYO was 82.27 ± 6.06 for 82.00 ± 7.74 (p = 0.874). for group B. No statistically significant difference was noted between the groups.

CONCLUSION

Our study showed that cigarette smoking did not have negative effect on union time in the metaphyseal region after correction osteotomy. The time of bone-union in heavy-smokers was 2.5 weeks more than that of non-smokers.

Autogenous Iliac Crest Bone Grafting for the Treatment of Fracture Nonunion Is Equally Effective in Elderly and Nonelderly Patients

INTRODUCTION

Autogenous iliac crest bone graft (ICBG) is considered the benchmark graft for nonunion repair. However, ICBG harvest is invasive and may provide reduced benefit to elderly patients. The purpose of this study was to compare the clinical and functional outcomes of ICBG use in fixation of fracture nonunions between elderly and nonelderly patients.

METHODS

Over a 13-year period, 242 patients who underwent operative repair of a long bone fracture nonunion and received autogenous ICBG were enrolled in a prospective research registry and followed. Data collected included patient demographics, injury information, and nonunion management. All patients had a minimum of 12 months of postoperative follow-up. Patients at least 65 years of age were classified as elderly, whereas younger patients were classified as nonelderly. Functional outcomes were evaluated at routine intervals postoperatively using the short musculoskeletal function assessment (SMFA) and visual analog scale pain scores. Bony union was determined radiographically. All postoperative complications were recorded.

RESULTS

Of the 242 patients included, 44 were elderly and 198 were nonelderly. No differences were found between groups with respect to postoperative pain scores or SMFA scores. Furthermore, time to union, rate of union, and postoperative complication rate did not differ between groups. Multivariate linear regression demonstrated that older age was not associated with time to union, postoperative pain scores, or postoperative SMFA scores after controlling for possible confounding variables.

DISCUSSION

The use of ICBG in nonunion repair among elderly patients is as effective as use in younger patients with a long bone nonunion. Concerns of increased postoperative complications and decreased rate of union in elderly patients receiving ICBG for treatment of fracture nonunion should be alleviated. ICBG remains the benchmark graft for nonunion repair among all age groups.

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.

Pilot randomized controlled trials in the orthopaedic surgery literature: a systematic review

BACKGROUND

The primary objective of this systematic review is to examine the characteristics of pilot randomized controlled trials (RCTs) in the orthopaedic surgery literature, including the proportion framed as feasibility trials and those that lead to definitive RCTs. This review aim to answer the question of whether pilot RCTs lead to definitive RCTs, whilst investigating the quality, feasibility and overall publication trends of orthopaedic pilot trials.

METHODS

Pilot RCTs in the orthopaedic literature were identified from three electronic databases (EMBASE, MEDLINE, and Pubmed) searched from database inception to January 2018. Search criteria included the evaluation of at least one orthopaedic surgical intervention, research on humans, and publication in English. Two reviewers independently screened the pool of pilot trials, and conducted a search for corresponding definitive trials. Screened pilot RCTs were assessed for feasibility outcomes related to efficiency, cost, and/or timeliness of a large-scale clinical trial involving a surgical intervention. The quality of the pilot and definitive trials were assessed using the Checklist to Evaluate a Report of a Non-Pharmacological Trial (CLEAR NPT).

RESULTS

The initial search for pilot RCTs yielded 3857 titles, of which 49 articles were relevant for this review. 73.5% (36/49) of the orthopaedic pilot RCTs were framed as feasibility trials. Of these, 5 corresponding definitive trials (10.2%) were found, of which four were published and one ongoing. Based on author responses, the lack of a definitive RCT following the pilot trial was attributed to a lack of funding, inadequacies in recruitment, and belief that the pilot RCT sufficiently answered the research question.

CONCLUSIONS

Based on this systematic review, most pilot RCTs were characterized as feasibility trials. However, the majority of published pilot RCTs did not lead to definitive trials. This discrepancy was mainly attributed to poor feasibility (e.g. poor recruitment) and lack of funding for an orthopaedic surgical definitive trial. In recent years this discrepancy may be due to researchers saving on time and cost by rolling their pilot patients into the definitive RCT rather than publish a separate pilot trial.

Healing in peri-implant gap with BMP-2 and systemic bisphosphonate is dependent on BMP-2 dose-A canine study

The bone-implant interface of cementless orthopedic implants can be described as a series of uneven sized gaps with discontinuous areas of direct bone-implant contact. Bridging these voids and crevices by addition of an anabolic stimulus to increase new bone formation can potentially improve osseointegration of implants. Bone morphogenetic protein 2 (BMP-2) stimulates osteoblast formation to increase new bone formation but also indirectly stimulates osteoclast activity. In this experiment, we investigate the hypothesis that osseointegration, defined as mechanical push-out and histomorphometry, depends on the dose of BMP-2 when delivered as an anabolic agent with systemic administration of the anti-resorptive agent zoledronate to curb an increase in osteoclast activity. Four porous coated titanium implants (one with each of three doses of surface-applied BMP-2 (15 µg; 60 µg; 240 µg) and untreated) surrounded by a 0.75 mm empty gap, were inserted into the distal femurs of each of twelve canines. Zoledronate IV (0.1 mg/kg) was administered 10 days into the observation period of 4 weeks. Bone-implant specimens were evaluated by mechanical push-out test and histomorphometry. The 15 µg implants had the best fixation on all mechanical parameters and largest surface area covered with new bone compared to the untreated, 60 and 240 µg implants, as well as the highest volume of new bone in the implant gap compared to 60 and 240 µg implants. The results in a canine implant model demonstrated that a narrow range of BMP-2 doses have opposite effects in bridging an empty peri-implant gap with bone, when combined with systemic zoledronate. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1406-1414, 2018.

Bone grafts and biomaterials substitutes for bone defect repair: A review

Bone grafts have been predominated used to treat bone defects, delayed union or non-union, and spinal fusion in orthopaedic clinically for a period of time, despite the emergency of synthetic bone graft substitutes. Nevertheless, the integration of allogeneic grafts and synthetic substitutes with host bone was found jeopardized in long-term follow-up studies. Hence, the enhancement of osteointegration of these grafts and substitutes with host bone is considerably important. To address this problem, addition of various growth factors, such as bone morphogenetic proteins (BMPs), parathyroid hormone (PTH) and platelet rich plasma (PRP), into structural allografts and synthetic substitutes have been considered. Although clinical applications of these factors have exhibited good bone formation, their further application was limited due to high cost and potential adverse side effects. Alternatively, bioinorganic ions such as magnesium, strontium and zinc are considered as alternative of osteogenic biological factors. Hence, this paper aims to review the currently available bone grafts and bone substitutes as well as the biological and bio-inorganic factors for the treatments of bone defect.

The potential impact of bone tissue engineering in the clinic

Bone tissue engineering (BTE) intends to restore structural support for movement and mineral homeostasis, and assist in hematopoiesis and the protective functions of bone in traumatic, degenerative, cancer, or congenital malformation. While much effort has been put into BTE, very little of this research has been translated to the clinic. In this review, we discuss current regenerative medicine and restorative strategies that utilize tissue engineering approaches to address bone defects within a clinical setting. These approaches involve the primary components of tissue engineering: cells, growth factors and biomaterials discussed briefly in light of their clinical relevance. This review also presents upcoming advanced approaches for BTE applications and suggests a probable workpath for translation from the laboratory to the clinic.

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.

Unmet needs and current and future approaches for osteoporotic patients at high risk of hip fracture

This review provides a critical analysis of currently available approaches to increase bone mass, structure and strength through drug therapy and of possible direct intra-osseous interventions for the management of patients at imminent risk of hip fracture.

PURPOSE

Osteoporotic hip fractures represent a particularly high burden in morbidity-, mortality- and health care-related costs. There are challenges and unmet needs in the early prevention of hip fractures, opening the perspective of new developments for the management of osteoporotic patients at imminent and/or at very high risk of hip fracture. Amongst them, preventive surgical intervention needs to be considered.

METHODS

A European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO)/International Osteoporosis Foundation (IOF) working group reviewed the presently available intervention modalities including preventive surgical options for hip fragility. This paper represents a summary of the discussions.

RESULTS

Prevention of hip fracture is currently based on regular physical activity; prevention of falls; correction of nutritional deficiencies, including vitamin D repletion; and pharmacological intervention. However, efficacy of these various measures to reduce hip fractures is at most 50% and may need months or years before becoming effective. To face the challenges of early prevention of hip fractures for osteoporotic patients at imminent and/or at very high risk of hip fracture, preventive surgical intervention needs further investigation.

CONCLUSION

Preventive surgical intervention needs to be appraised for osteoporotic patients at imminent and/or at very high risk of hip fracture.

Long bone non-unions treated with the diamond concept: a case series of 64 patients

The aim of this retrospective study with prospectively documented data was to report the clinical results of treatment of long bone non-unions using the "diamond concept". Over a 4-year period, patients that presented with a long bone non-union and were managed with the diamond conceptual framework of bone repair were evaluated. Exclusion criteria were hypertrophic, pathological, and infected non-unions. Fixation was revised as it was indicated whilst biological enhancement included the implantation of RIA graft, BMP-7 and concentrated bone marrow aspirate. Data recorded included patient demographics, initial fracture pattern and type of stabilisation, number of previous interventions, time to reoperation, time to union and functional outcome. Painless full weight bearing defined clinical union. Radiological union was defined as the presence of mature callous bridging to at least 3 bone cortices. The minimum follow up was 12 months (range 12-32). In total 64 patients (34 males) with a mean age of 45 years (17-83) were evaluated. Anatomical distribution of non-unions included the femur (54.68%), tibia (34.38%), humerus (4.68%), radius (3.13%) and clavicle (3.13%). The median number of previous interventions was 1 (range 1-5). The majority of patients (82.62%) underwent revision of fixation whereas only bone grafting was performed 9.38% of patients. Three patients developed superficial wound infection (one was MRSA), 1 had deep vein thrombosis and 1 developed heterotopic bone formation. Union was successful in 63/64 (98.4%) non-unions at a mean time of 6 months (range 3-12). All patients were mobilising pain free and returned to their daily living activities at the final follow up. The application of the "diamond concept" in this cohort of patients was associated with a high union rate by providing an optimal mechanical and biological environment. Such an approach should be considered in the surgeon's armamentarium particularly in such cases where difficulty of bone repair is foreseen.

Recent biological trends in management of fracture non-union

Bone regeneration is a complex, well-orchestrated physiological process of bone formation, which can be seen during normal fracture healing, and is involved in continuous remodelling throughout adult life. Currently, there is a plethora of different strategies to augment the impaired or “insufficient” bone-regeneration process, including the “gold standard” autologous bone graft, free fibula vascularised graft, allograft implantation, and use of growth factors, osteoconductive scaffolds, osteoprogenitor cells and distraction osteogenesis. Improved “local” strategies in terms of tissue engineering and gene therapy, or even “systemic” enhancement of bone repair, are under intense investigation, in an effort to overcome the limitations of the current methods, to produce bone-graft substitutes with biomechanical properties that are as identical to normal bone as possible, to accelerate the overall regeneration process, or even to address systemic conditions, such as skeletal disorders and osteoporosis. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.

Bone regeneration using a freeze-dried 3D gradient-structured scaffold incorporating OIC-A006-loaded PLGA microspheres based on β-TCP/PLGA

To reveal the latent capacity of the growth factor-like low-molecular-weight material OIC-A006 in tissue regeneration, it is essential to design a porous scaffold in order to concurrently accommodate cells and drug release in a controlled manner. Consequently, we fabricated poly (L-lactide-co-glycolide) (PLGA)-based microspheres with an OIC-A006-loaded gradient-structured β-TCP/PLGA scaffold by freeze-drying which could then be used for drug delivery and bone regeneration. The OIC-A006-loaded β-TCP/PLGA scaffold consisted of two parts which loaded different doses of OIC-A006 (6.25 μM, outside; 12.5 μM, inside). The porosity, compressive strength, SEM, degradation, and cumulative amount of drug release in vitro were characterized. Furthermore, we confirmed the incorporation of OIC-A006 into the PLGA-based microspheres within the scaffolds using UV-spectrophotometry, and the amount of drug remaining in the scaffold was maintained by 10 % for up to 28 days. The drug release was slower in the normal-structured drug-loaded scaffold. The OIC-A006 released action from the OIC-A006-loaded β-TCP/PLGA scaffold with ideal therapeutic prospects in tissue regeneration. In vitro cell culture results showed that this gradient-structured composite scaffold can induce the adhesion and proliferation of rat bone marrow stromal cells towards osteoblasts. These results showed that the newly developed OIC-A006-loaded scaffolds with gradient structure can be potentially applied to bone regeneration in clinical applications.

Intrabody application of eptotermin alpha enhances bone formation in osteoporotic fractures of the lumbar spine; however, fails to increase biomechanical stability - results of an experimental sheep model

This study analyses the effect of eptotermin α application into fractured vertebrae. It is hypothesized that eptotermin α is capable to enhance bony healing of the osteoporotic spine. In 10 Merino sheep osteoporosis induction was performed by ovariectomy, corticosteroid therapy and calcium/phosphorus/vitamin D-deficient diet; followed by standardized creation of lumbar vertebral compression fractures (VCFs) type A3.1 and consecutive fracture reduction/fixation using expandable mesh cages. Randomly, intravertebral eptotermin α (G1) or no augmentation was added (G2). Macroscopic, micro-CT, and biomechanical evaluation assessed bony consolidation two months postoperatively: Micro-CT data revealed bony consolidation for all cases with significant increased callus development for G2 (60%) and BV/TV (bone volume/total volume 73.45%, osteoporotic vertebrae 35.76%). Neither group showed improved biomechanical stability. Eptotermin α enhanced mineralisation in VCFs in an experimental setup with use of cementless augmentation via an expandable cage. However, higher bone mineral density did not lead to superior biomechanical properties.

BMP-7 versus BMP-2 for the treatment of long bone nonunion

The authors compared the results of treating nonunion with either bone morphogenetic protein (BMP)-7 or BMP-2. Between 2001 and 2009, 214 limb segments were treated for nonunion with either BMP-7 or BMP-2 at the authors' institution. Sixty-three subjects received 76 units of BMP-7. Radiographic healing occurred in 70% of limb segments at an average of 30 weeks after surgery, and 75% of limb segments were weight bearing at an average of 23 weeks after surgery. In 15.8%, persistent nonunion necessitated additional surgery. Average follow-up was 32 months. One hundred twelve subjects received 138 units of BMP-2. Radiographic healing occurred in 93% of limb segments at an average of 19 weeks after surgery, and 88% were weight bearing at an average of 15 weeks after surgery. In 6.25%, persistent nonunion necessitated additional surgery. Average follow-up was 17 months. Several significant differences were observed. Patients in both BMP-7 and BMP-2 groups were able to fully weight bear at an average of 23 and 15 weeks, respectively (P<.001). Further, both BMP-7 and BMP-2 groups healed at an average of 30 and 19 weeks, respectively (P<.001). Additionally, healing occurred in more limb segments in the BMP-2 group (93%) than in the BMP-7 group (70%) (P<.001). No difference in the complication rate was seen between groups. Patients who received BMP-2 for the treatment of nonunion had a higher rate of radiographic healing, achieved radiographic healing more quickly, and were able to bear weight sooner than those who underwent treatment with BMP-7.

The clinical use of bone morphogenetic proteins revisited: a novel biocompatible carrier device OSTEOGROW for bone healing

PURPOSE

The purpose of this study was to revise the clinical use of commercial BMP2 (Infuse) and BMP7 (Osigraft) based bone devices and explore the mechanism of action and efficacy of low BMP6 doses in a novel whole blood biocompatible device OSTEOGROW.

METHODS

Complications from the clinical use of BMP2 and BMP7 have been systemically reviewed in light of their role in bone remodeling. BMP6 function has been assessed in Bmp6-/- mice by μCT and skeletal histology, and has also been examined in mesenchymal stem cells (MSC), hematopoietic stem cells (HSC) and osteoclasts. Safety and efficacy of OSTEOGROW have been assessed in rats and rabbits.

RESULTS

Clinical use issues of BMP2 and BMP7 have been ascribed to the limited understanding of their role in bone remodeling at the time of device development for clinical trials. BMP2 and BMP7 in bone devices significantly promote bone resorption leading to osteolysis at the endosteal surfaces, while in parallel stimulating exuberant bone formation in surrounding tissues. Unbound BMP2 and BMP7 in bone devices precipitate on the bovine collagen and cause inflammation and swelling. OSTEOGROW required small amounts of BMP6, applied in a biocompatible blood coagulum carrier, for stimulating differentiation of MSCs and accelerated healing of critical size bone defects in animals, without bone resorption and inflammation. BMP6 decreased the number of osteoclasts derived from HSC, while BMP2 and BMP7 increased their number.

CONCLUSIONS

Current issues and challenges with commercial bone devices may be resolved by using novel BMP6 biocompatible device OSTEOGROW, which will be clinically tested in metaphyseal bone fractures, compartments where BMP2 and BMP7 have not been effective.

Cochrane corner: bone morphogenetic protein (BMP) for fracture healing in adults

BACKGROUND

Delay in fracture healing is a complex clinical and economic issue for patients and health services.

OBJECTIVES

To assess the incremental effectiveness and costs of bone morphogenetic protein on fracture healing in fractures and nonunions compared with standards of care.

SEARCH STRATEGY

We searched The Cochrane Library (2008, Issue 4), MEDLINE, and other major health and health economics databases (to October 2008).

SELECTION CRITERIA

Randomized controlled trials (RCTs) and full or partial economic evaluations of bone morphogenetic protein for fracture healing in skeletally mature adults.

DATA COLLECTION AND ANALYSIS

All clinical and economic data were extracted by one author and checked by another.

BMP Signaling in Regenerative Medicine

More than 40 years after the discovery of Bone Morphogenetic Proteins (BMPs) as bone inducers, a whole protein family of growth factors connected to a wide variety of functions in embryonic development, homeostasis, and regeneration has been characterized. Today, BMP2 and BMP7 are already used in the clinic to promote vertebral fusions and restoration of non-union fractures. Besides describing present clinical applications, the authors review ongoing trials highlighting the future possibilities of BMPs in medicine. Apparently, the physiological roles of BMPs have expanded their range from bone growth induction and connective tissue regeneration to cancer diagnosis/treatment and cardiovascular disease prevention.

Recommendations and considerations for the use of biologics in orthopedic surgery

Reconstruction of extensive bone defects remains technically challenging and has considerable medical and financial impact on our society. Surgical procedures often require a bone/substitute graft to enhance and accelerate bone repair. Bone autografts are associated with morbidity related to bone harvesting and are limited in quantity. Alternatively, bone allografts expose the patient to the risk of transmission of infectious disease. Synthetic bone graft substitutes, such as calcium sulfates, hydroxyapatite, tricalcium phosphate, and combinations, circumvent some of the disadvantages of auto- and allografts, but have limited indications. Biomedical research has made possible the stimulation of the body's own healing mechanisms, either by delivering exogenous growth factors locally, or by stimulating their local production by gene transfer. Among all known factors having osteoinductive properties, only two bone morphogenetic proteins (for specific indications) and demineralized bone matrix have been approved for clinical use. In addition, ongoing research is exploring the efficacy of cell therapy and tissue engineering. The present report examines the composition, biological properties, indications, clinical experience and regulations of several of the biotherapeutics employed for bone reconstruction.

Biologic adjuvants for fracture healing

Bone tissue has an exceptional quality to regenerate to native tissue in response to injury. However, the fracture repair process requires mechanical stability or a viable biological microenvironment or both to ensure successful healing to native tissue. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. Preclinical and clinical studies using biologic agents like recombinant bone morphogenetic proteins have demonstrated an efficacy similar or better than that of autologous bone graft in acute fracture healing. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.

Bone graft substitutes

Replacement of missing bone stock is a reconstructive challenge to upper extremity surgeons and decision-making with regards to available choices remains difficult. Preference is often given to autograft in the form of cancellous, cortical, or corticocancellous grafts from donor sites. However, the available volume from such donor sites is limited and fraught with potential complications. Advances in surgical management and medical research have produced a wide array of potential substances that can be used for bone graft substitute. Considerations in selecting bone grafts and substitutes include characteristic capabilities, availability, patient morbidity, immunogenicity, potential disease transmission, and cost variability.

Growth factor delivery: how surface interactions modulate release in vitro and in vivo

Biomaterial scaffolds have been extensively used to deliver growth factors to induce new bone formation. The pharmacokinetics of growth factor delivery has been a critical regulator of their clinical success. This review will focus on the surface interactions that control the non-covalent incorporation of growth factors into scaffolds and the mechanisms that control growth factor release from clinically relevant biomaterials. We will focus on the delivery of recombinant human bone morphogenetic protein-2 from materials currently used in the clinical practice, but also suggest how general mechanisms that control growth factor incorporation and release delineated with this growth factor could extend to other systems. A better understanding of the changing mechanisms that control growth factor release during the different stages of preclinical development could instruct the development of future scaffolds for currently untreatable injuries and diseases.

The use of bone grafts and substitutes in the treatment of distal radius fractures

The interest in developing biomaterials to augment fracture healing continues to grow. New products promise early return to function with minimal morbidity; however, indications to use these products remain unclear. An ideal bone graft material stimulates bone healing and provides structural stability while being biocompatible, bioresorbable, easy to use, and cost-effective. This article reviews the biology of bone grafts and the clinical evidence in the use of bone graft substitutes for the treatment of distal radius fractures.

The role of bone allografts in the treatment of angular malunions of the distal radius

PURPOSE

Two cohorts of patients who had corrective osteotomies and volar platings for malunited fractures of the distal radius were compared retrospectively to determine whether the time to union and the outcome were affected by bone allograft.

METHODS

Patients in the first group (n = 14) did not receive any bone graft; patients in the second group (n = 14) had allograft bone chips following volar plating. Indications for surgery, surgical technique, and postoperative rehabilitation were the same in both groups. Volar cortical contact was maintained using a volar locking plate in all patients. Radiographic parameters of deformity correction, time to union, wrist and forearm range of motion, grip strength, patient-rated wrist evaluation and Disabilities of the Arm, Shoulder, and Hand questionnaire were used to evaluate the outcome before and after the surgery. Average follow-up time was 36 weeks. Patients who had diabetes, who smoked, who had a body mass index of more than 35, and who required lengthening for deformity correction were excluded from the study.

RESULTS

Osteotomies in both groups healed without loss of surgical correction. Final outcome and time to union revealed no significant differences, clinically or statistically, between the 2 groups. The Disabilities of the Arm, Shoulder, and Hand score was improved in both groups.

CONCLUSIONS

When volar cortical contact was maintained using a volar locked plate, bone allograft at the osteotomy site did not improve the final outcome.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Complications following autologous bone graft harvesting from the iliac crest and using the RIA: a systematic review

Bone grafting is a commonly performed surgical procedure to augment bone regeneration in a variety of cases in orthopaedic and maxillofacial surgery. Autologous bone graft remains to be the 'gold standard' and the iliac crest to be the most common harvesting site. The intramedullary canal of long bones represents another potential site for large volume of autologous bone graft harvesting and is recently being used as an alternative donor site. However, harvesting of autologous bone graft is associated with morbidity and a number of complications. The aim of this systematic review was to collect and summarise the existing data on reported complications after harvesting autologous bone from the iliac crest (anterior and posterior) and the long bone intramedullary canal using the RIA device. We searched the PubMed Medline and Ovid Medline databases, from January 1990 to October 2010, to retrieve all relevant articles. A total of 92 articles (6682 patients) were included in the analysis. Overall, the complication rate following RIA was 6% (14 complications in 233 patients) and 19.37% after iliac crest bone graft harvesting (1249 complications in 6449 patients). The rate of each of the reported complications was assessed and, when the donor site was properly documented, comparison within the anterior and posterior iliac crest donor sites was performed. Although the difference of the overall morbidity rates between the two harvesting sites was not statistically significant (p=0.71); the rates of certain complications were found to significantly differ when anterior or posterior iliac crest was used. The rates of infection (p=0.016), haematoma formation (p=0.002), fracture (p=0.017), and hyperthrophic scar (p=0.017) were significantly higher when the donor site was the anterior iliac crest compared to the posterior iliac crest; whereas the rates of chronic donor site pain (p=0.004) and sensory disturbances (p=0.003) were significantly lower. The incidence of bone graft harvesting related complications can be reduced further if certain principles are followed depending on the performed harvesting methods; but overall the use of RIA device as harvesting method seems a promising alternative with a low complication rate.

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.

Bone morphogenetic protein (BMP) for fracture healing in adults

BACKGROUND

Delay in fracture healing is a complex clinical and economic issue for patients and health services.

OBJECTIVES

To assess the incremental effectiveness and costs of bone morphogenetic protein (BMP) on fracture healing in acute fractures and nonunions compared with standards of care.

SEARCH STRATEGY

We searched The Cochrane Library (2008, Issue 4), MEDLINE, and other major health and health economics databases (to October 2008).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and full or partial economic evaluations of BMP for fracture healing in skeletally mature adults.

DATA COLLECTION AND ANALYSIS

All clinical and economic data were extracted by one author and checked by another.

MAIN RESULTS

Eleven RCTs, all at high risk of bias, and four economic evaluations were included. Apart from one study, the times to fracture healing were comparable between the BMP and control groups. There was some evidence for increased healing rates, without requiring a secondary procedure, of BMP compared with usual care control in acute, mainly open, tibial fractures (risk ratio (RR) 1.19, 95% CI 0.99 to 1.43). The pooled RR for achieving union for nonunited fractures was 1.02 (95% CI 0.90 to 1.15). One study found no difference in union for patients who had corrective osteotomy for radial malunions. Data from three RCTs indicated that fewer secondary procedures were required for acute fracture patients treated with BMP versus controls (RR 0.65, 95% CI 0.50 to 0.83). Adverse events experienced were infection, hardware failure, pain, donor site morbidity, heterotopic bone formation and immunogenic reactions. The evidence on costs for BMP-2 for acute open tibia fractures is from one large RCT. This indicates that the direct medical costs associated with BMP would generally be higher than treatment with standard care, but this cost difference may decrease as fracture severity increases. Limited evidence suggests that the direct medical costs associated with BMP could be offset by faster healing and reduced time off work for patients with the most severe open tibia fractures.

AUTHORS' CONCLUSIONS

This review highlights a paucity of data on the use of BMP in fracture healing as well as considerable industry involvement in currently available evidence. There is limited evidence to suggest that BMP may be more effective than controls for acute tibial fracture healing, however, the use of BMP for treating nonunion remains unclear. The limited available economic evidence indicates that BMP treatment for acute open tibial fractures may be more favourable economically when used in patients with the most severe fractures.

BMPs: Options, indications, and effectiveness

Alteration of the bone healing process with bone morphogenetic proteins offers a new perspective in orthopaedic surgery in those adverse situations that necessitate bone grafting. BMPs have been demonstrated to be effective and safe for human application and have an efficacy comparable with that of autologous bone grafting. Nevertheless, clinical trials with level 1 evidence are still limited in their ability to extrapolate robust and safe clinical conclusions for the possible indications mentioned in this article. Future research should refine issues regarding the relative effectiveness of bone morphogenetic proteins, the interaction between bone morphogenetic protein subtypes, and their specific effect on various target cell populations.

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.

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.

Bone morphogenetic proteins in orthopaedic surgery

Bone healing is a predictable process that has a high rate of success. For some patients, and in certain clinical settings, this process can be delayed or completely inhibited. This leads to significant morbidity and may also result in time lost from work, costs related to prolonged medical treatment, and continued pain at the site of nonunion or failed spinal fusion. Several growth factors, specifically BMP-2 and BMP-7, have been approved in several countries for specific indications. The use of these products and potential complications of their use are reviewed.