The use of bone morphogenic protein-7 (OP-1) in the management of resistant non-unions in the upper and lower limb

Progress of research on the surface functionalization of tantalum and porous tantalum in bone tissue engineering

Tantalum and porous tantalum are ideal materials for making orthopedic implants due to their stable chemical properties and excellent biocompatibility. However, their utilization is still affected by loosening, infection, and peripheral inflammatory reactions, which sometimes ultimately lead to implant removal. An ideal bone implant should have exceptional biological activity, which can improve the surrounding biological microenvironment to enhance bone repair. Recent advances in surface functionalization have produced various strategies for developing compatibility between either of the two materials and their respective microenvironments. This review provides a systematic overview of state-of-the-art strategies for conferring biological functions to tantalum and porous tantalum implants. Furthermore, the review describes methods for preparing active surfaces and different bioactive substances that are used, summarizing their functions. Finally, this review discusses current challenges in the development of optimal bone implant materials.

Bone Morphogenic Protein for Upper Extremity Fractures: A Systematic Review

BACKGROUND

This review discusses success, time to healing, and complications of bone morphogenic proteins (BMPs) 7 and 2 in treating upper extremity nonunions.

METHODS

Systematic review identified 26 of 479 studies that met inclusion criteria. Publications described application of BMPs to acute and chronic upper extremity delayed unions/nonunions. Unions, complications, patient demographics, and fracture/healing patterns were pooled and analyzed.

RESULTS

Nonunions treated with BMP-7 (n=302) involved the humerus (64%), forearm (22%), clavicle (11%), and hand/wrist (3%), with prior surgical correction attempted in 84%. Nonunions treated with BMP-2 (n=96) involved the humerus (58%), hand/wrist (27%), forearm (14%), and clavicle (1%), with prior surgical correction attempted in all. Most nonunions (80%) were present for over 12 months before BMP application. Union rates of BMP-7 varied according to site: hand/wrist (95%), humerus (74%), forearm (29%), and clavicle (6.2%) nonunions achieved union as defined by study authors in 232 days (confidence interval=96-369, Q<0.001) on average. While not significant across studies, BMP-2 union rates were 71% of hand/wrist and 75% of humerus nonunions. Comparison of the BMPs demonstrates different proportions of success in humerus and hand/wrist fractures (P<.001) but not forearm fractures (P<.77) and longer time to radiographic union with BMP-7 (P<.011).

CONCLUSIONS

Most hand/wrist and humerus nonunions treated with BMP-7 and BMP-2 achieved union, with significant similarity among BMP-7 studies not observed in BMP-2 studies. Nonunions treated with BMP-7 have longer healing times yet similar complication rates compared with BMP-2. Overall, BMPs are an effective adjunct to fracture healing with acceptable complication profile.

Therapeutic Efficacy and Safety of Osteoinductive Factors and Cellular Therapies for Long Bone Fractures and Non-Unions: A Meta-Analysis and Systematic Review

Background: Long bone fractures display significant non-union rates, but the exact biological mechanisms implicated in this devastating complication remain unclear. The combination of osteogenetic and angiogenetic factors at the fracture site is an essential prerequisite for successful bone regeneration. The aim of this study is to investigate the results of the clinical implantation of growth factors for intraoperative enhancement of osteogenesis for the treatment of long bone fractures and non-unions. Methods: A systematic literature review search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in the PubMed and Web of Science databases from the date of inception of each database through to 10 January 2022. Specific inclusion and exclusion criteria were applied in order to identify relevant studies reporting on the treatment of upper and lower limb long bone non-unions treated with osteoinductive or cellular factors. Results: Overall, 18 studies met the inclusion criteria and examined the effectiveness of the application of Bone Morphogenetic Proteins-2 and -7 (BMPs), platelet rich plasma (PRP) and mesenchymal stem cells (MSCs). Despite the existence of limitations in the studies analysed (containing mixed groups of open and close fractures, different types of fractures, variability of treatment protocols, different selection criteria and follow-up periods amongst others), their overall effectiveness was found significantly increased in patients who received them compared with the controls (I² = 60%, 95% CI = 1.59 [0.99–2.54], Z =1.93, p = 0.05). Conclusion: Administration of BMP-2 and -7, PRP and MSCs were considered effective and safe methods in fracture treatment, increasing bone consolidation, reducing time to repair and being linked to satisfactory postoperative functional scores.

The Clinical Application of Porous Tantalum and Its New Development for Bone Tissue Engineering

Porous tantalum (Ta) is a promising biomaterial and has been applied in orthopedics and dentistry for nearly two decades. The high porosity and interconnected pore structure of porous Ta promise fine bone ingrowth and new bone formation within the inner space, which further guarantee rapid osteointegration and bone-implant stability in the long term. Porous Ta has high wettability and surface energy that can facilitate adherence, proliferation and mineralization of osteoblasts. Meanwhile, the low elastic modulus and high friction coefficient of porous Ta allow it to effectively avoid the stress shield effect, minimize marginal bone loss and ensure primary stability. Accordingly, the satisfactory clinical application of porous Ta-based implants or prostheses is mainly derived from its excellent biological and mechanical properties. With the advent of additive manufacturing, personalized porous Ta-based implants or prostheses have shown their clinical value in the treatment of individual patients who need specially designed implants or prosthesis. In addition, many modification methods have been introduced to enhance the bioactivity and antibacterial property of porous Ta with promising in vitro and in vivo research results. In any case, choosing suitable patients is of great importance to guarantee surgical success after porous Ta insertion.

Clavicle nonunion: plate and graft type do not affect healing rates-a single surgeon experience with 71 cases

BACKGROUND

Clavicle nonunions often result after nonoperative treatment for the acute fracture. Those that require >1 surgical procedure in order for a nonunion to heal are termed recalcitrant. The aims of the present study were to (1) determine healing rates of clavicle nonunions after plate osteosynthesis using either a conventional or locked plate, (2) compare iliac crest bone graft vs. bone morphogenetic protein on nonunion healing, and (3) identify risk factors for the development of a recalcitrant nonunion.

METHODS

We performed a retrospective analysis of a prospectively collected database of 78 clavicle nonunions treated with open reduction and plate fixation with or without graft augmentation by a single surgeon over 25 years. Seventy-one patients over the age of 18 with at least 12 months of follow-up comprised the study group. We analyzed healing rates after the index clavicle nonunion surgery comparing plate type and graft technique as well as identifying risk factors for developing a recalcitrant nonunion.

RESULTS

A total of 62 patients (87.3%) healed after their index nonunion surgery at our institution. Three patients (4.2%) required additional surgery but healed, and 6 patients (8.5%) remain un-united; these 9 patients (12.7%) were defined as recalcitrant. There was no statistically significant difference in healing rates between plate type (P = .633) or type of bone graft (P = .157). There were no identifiable risk factors for the development of a recalcitrant nonunion.

CONCLUSIONS

Plate fixation of clavicle nonunions remains a successful method of treatment. The type of plate or the method of bone graft did not produce different results. There were no demographic, patient, or injury characteristics associated with the development of a recalcitrant nonunion.

Low magnitude high frequency vibration promotes chondrogenic differentiation of bone marrow stem cells with involvement of β-catenin signaling pathway

OBJECTIVE

Mesenchymal stem cells (MSCs) are well known to have the capability to form bone and cartilage, and chondrogenesis derived from MSCs is reported to be affected by mechanical stimuli. This research aimed to study the effects of low magnitude high frequency (LMHF) vibration on the chondrogenic differentiation of bone marrow-derived MSCs (BMSCs) which were cultured with chondrogenic medium, and to investigate the role of β-catenin cascade in this process.

METHODS

Rat bone marrow-derived MSCs (BMSCs) were isolated and randomized into vibration and static cultures. The effect of vibration on BMSCs proliferation, differentiation and chondrogenic potential was assessed at the protein level.

RESULTS

LMHFV did not affect the proliferation of BMSCs. However, this was accompanied by increased markers of chondrogenesis. The protein expression of chondrocyte-specific markers of Aggrecan, Sox9, and BMP7 were upregulated and Collagen X was decreased by LMHF vibration introduced at the chondrogenic differentiation in vitro. Specifically, thicker blue-stained particles were observed in Alcian Blue staining and the level of glycosaminoglycan were significantly increased respectively in the vibration culture group by 56.5 % and 93.6 % on the 7th and 14th day. The expression and nuclear translocation of β-catenin were activated in a significant manner. And inhibition of GSK-3β activity with Licl rearranged and intensified the cytoskeleton affected by vibration stimulation.

CONCLUSIONS

Our data demonstrated that LMHF mechanical vibration promotes BMSCs chondrogenic differentiation and implies β-catenin signal acts as an essential mediator in the mechano-biochemical transduction and subsequent transcriptional regulation in the process of chondrogenesis.

Healing the Index Humeral Shaft Nonunion: Risk Factors for Development of a Recalcitrant Nonunion in 125 Patients

BACKGROUND

Humeral shaft nonunions are challenging to treat, and those that require >1 surgical procedure in order for a nonunion to heal are termed recalcitrant. Most studies on nonunion have evaluated the union rate independent of the number of procedures required to achieve union. The aims of the present study were (1) to compare the healing rates after the index operation for the treatment of a nonunion with conventional versus locked plating with or without graft augmentation, (2) to report the prevalence of recalcitrant nonunion, and (3) to identify risk factors that predict a recalcitrant nonunion.

METHODS

We performed a retrospective analysis of a prospectively collected database of 125 humeral shaft nonunions treated with open reduction and plate fixation by a single surgeon over 25 years. Univariate and multivariate regression analyses were performed to compare healing rates by type of plate fixation and biological augmentation and to identify demographic, injury, and treatment-related risk factors for the development of a recalcitrant nonunion.

RESULTS

One hundred and five patients (84%) had healing after the index procedure for the treatment of nonunion. Twenty patients (16.0%) required secondary procedures and were defined as having a recalcitrant nonunion. Eight of these patients (6.4% of the overall group) healed after the secondary interventions, and 12 (9.6% of the overall group) had a failure to unite. There were no significant differences in healing rates between conventional and locked plates or between the types of bone graft (autogenous or recombinant human bone morphogenetic protein). Risk factors for the development of a recalcitrant nonunion were plate fixation of the acute humeral fracture, a history of deep infection, and ≥2 prior procedures.

CONCLUSIONS

Plate fixation with bone graft augmentation remains a successful method for the treatment of humeral shaft nonunions. Neither plate type nor graft type reduced the risk of a recalcitrant nonunion. Factors that predicted a recalcitrant nonunion were operative fixation of the acute fracture with a plate, a history of deep infection, and ≥2 surgical procedures.

LEVEL OF EVIDENCE

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

Clinical Applications of Bone Tissue Engineering in Orthopedic Trauma

Purpose of Review

Orthopaedic trauma is a major cause of morbidity and mortality worldwide. Although many fractures tend to heal if treated appropriately either by nonoperative or operative methods, delayed or failed healing, as well as infections, can lead to devastating complications. Tissue engineering is an exciting, emerging field with much scientific and clinical relevance in potentially overcoming the current limitations in the treatment of orthopaedic injuries.

Recent Findings

While direct translation of bone tissue engineering technologies to clinical use remains challenging, considerable research has been done in studying how cells, scaffolds, and signals may be used to enhance acute fracture healing and to address the problematic scenarios of nonunion and critical-sized bone defects. Taken together, the research findings suggest that tissue engineering may be considered to stimulate angiogenesis and osteogenesis, to modulate the immune response to fractures, to improve the biocompatibility of implants, to prevent or combat infection, and to fill large gaps created by traumatic bone loss. The abundance of preclinical data supports the high potential of bone tissue engineering for clinical application, although a number of barriers to translation must first be overcome.

Summary

This review focuses on the current and potential applications of bone tissue engineering approaches in orthopaedic trauma with specific attention paid to acute fracture healing, nonunion, and critical-sized bone defects.

Application of combined porous tantalum scaffolds loaded with bone morphogenetic protein 7 to repair of osteochondral defect in rabbits<sup/>

PURPOSE

Porous tantalum (PT) has been widely used in orthopaedic applications for low modulus of elasticity, excellent biocompatibility, and the microstructures similar to cancellous bone. In order to improve the biological activity of PT, biologically active factors can be combined with the material. The purpose of this study was to investigate if bone morphogenetic protein 7 (BMP-7) modifications could enhance the repairing of cartilage of PT in osteochondral defect in medial femoral condyle of rabbits.

METHODS

A cylindrical osteochondral defect model was created on the animal medial femoral condyle of and filled as follows: PT modified with BMP-7 for MPT group, non-modified PT for the PT group, while no implants were used for the blank group. The regenerated osteochondral tissue was assessed and analyzed by histological observations at four, eight and 16 weeks post-operation and evaluated in an independent and blinded manner by five different observers using a histological score. Osteochondral and subchondral bone defect repair was assessed by micro-CT scan at 16 weeks post-operation, while the biomechanical test was performed at 16 weeks post-operation.

RESULTS

Briefly, higher overall histological score was observed in the MPT group compared to PT group. Furthermore, more new osteochondral tissue and bone formed at the interface and inside the inner pores of scaffolds of the MPT group compared to PT group. Additionally, the micro-CT data suggested that the new bone volume fractions and the quantity and quality of trabecular bone, as well as the maximum release force of the bone, were higher in the MPT group compared to PT group.

CONCLUSIONS

We demonstrated that the applied modified PT with BMP-7 promotes excellent subchondral bone regeneration and may serve as a novel approach for osteochondral defects repair.

Clinical application of bone morphogenetic proteins for bone healing: a systematic review

PURPOSE

This paper documents the existing evidence on bone morphogenetic proteins (BMPs) use for the treatment of bone fractures, non-union, and osteonecrosis, through a review of the clinical literature, underlying potential and limitations in terms of cost effectiveness and risk of complications.

METHODS

A systematic review was performed on the PubMed database using the following string: (bone morphogenetic proteins OR BMPs) and (bone repair OR bone regeneration) including papers from 2000 to 2016. The search focused on clinical trials dealing with BMPs application to favor bone regeneration in bone fractures, non-union, and osteonecrosis, in English language, with level of evidence I, II, III, and IV. Relevant data (type of study, number of patients, BMPs delivery material, dose, site, follow-up, outcome, and adverse events) were extracted and analyzed.

RESULTS

Forty-four articles met the inclusion criteria: 10 randomized controlled trials (RCTs), 7 comparative studies, 18 case series, and 9 case reports. rhBMP-2 was documented mainly for the treatment of fractures, and rhBMP-7 mainly for non-unions and osteonecrosis. Mixed results were found among RCTs and comparative papers: 11 reported positive results for BMPs augmentation, 3 obtained no significant effects, and 2 showed negative results. The only study comparing the two BMPs showed a better outcome with rhBMP-2 for non-union treatment.

CONCLUSION

Clinical evidence on BMPs use for the treatment of fractures, non-union, and osteonecrosis is still controversial, with the few available reports being mainly of low quality. While positive findings have been described in many studies, mixed results are still present in the literature in terms of efficacy and adverse events. The difficulties in drawing clear conclusions are also due to the studies heterogeneity, mainly in terms of different BMPs applied, with different concomitant treatments for each bone pathology. Therefore, further research with well-designed studies is needed in order to understand the real potential of this biological approach to favour bone healing.

Local application of lactoferrin promotes bone regeneration in a rat critical-sized calvarial defect model as demonstrated by micro-CT and histological analysis

Lactoferrin is a multifunctional glycoprotein with therapeutic potential for bone tissue engineering. The aim of this study was to assess the efficacy of local application of lactoferrin on bone regeneration. Five‐millimetre critical‐sized defects were created over the right parietal bone in 64 Sprague–Dawley rats. The rats were randomized into four groups: group 1 (n  =  20) had empty defects; group 2 (n  =  20) had defects grafted with collagen gels (3 mg/ml); group 3 (n  =  20) had defects grafted with collagen gels impregnated with bovine lactoferrin (10 μg/gel); and group 4 (n  =  4) had sham surgeries (skin and periosteal incisions only). The rats were sacrificed at 4 or 12 weeks post‐operatively, and the calvaria were excised and evaluated with micro‐CT (Skyscan 1172) followed by histology. The bone volume fraction (BV/TV) was higher in lactoferrin‐treated animals at both timepoints, with groups 1, 2, 3 and 4 measuring 10.5  ±  1.1%, 8.6  ±  1.4%, 16.5  ±  0.6% and 24.27  ±  2.6%, respectively, at 4 weeks (P  <  0.05); and 12.2  ±  1.3%, 13.6  ±  1.5%, 21.9  ±  1.2% and 29.3  ±  0.8%, respectively, at 12 weeks (P  <  0.05). Histological analysis revealed that the newly formed bone within the calvarial defects of all groups was a mixture of woven and lamellar bone, with more bone in the group treated with lactoferrin at both timepoints. Our study demonstrated that local application of lactoferrin significantly increased bone regeneration in a rat critical‐sized calvarial defect model. The profound effect of lactoferrin on bone regeneration has therapeutic potential to improve the poor clinical outcomes associated with bony non‐union. LF In Vivo JTERM Authors Contributions. Copyright © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons, Ltd.

Limb reconstruction after traumatic bone loss

A variety of options exist to reconstruct limbs following traumatic bone loss. The management of these injuries is challenging and often requires prolonged and potentially painful treatment. The Ilizarov technique of bone transport using circular external fixators is widely used for limb reconstruction of large bone defects. Other techniques include vascularised fibular grafting, the use of induced pseudosynovial membranes combined with cancellous autologous bone grafts and the use of autologous, allogeneic or synthetic bone grafts on their own for smaller defects. Future directions include further research on bone tissue engineering using stem cell therapy and growth factors such as bone morphogenetic proteins. The purpose of this Continuing Medical Education article is to describe the key limb reconstructive techniques that may be employed to treat traumatic bone loss. In particular, this article is intended to serve as a revision tool for those preparing for postgraduate examinations.

Upper limb non-unions treated with BMP-7: efficacy and clinical results

The management of upper limb non-unions can be challenging and often with unpredictable outcomes. In this study we present our experience with the use of BMP-7 in the treatment of upper limb non-unions. Between 2004 and 2011 all consecutive patients who were treated with BMP-7 were followed up prospectively until fracture union. Fracture union was assessed with regular radiological and clinical assessment. At the final follow up clinical assessment included the short Disabilities of the Arm, Shoulder and Hand (DASH) score. The minimum follow up was 12 months (12-36). In total 42 patients met the inclusion criteria with a mean age of 47 years. Anatomical distribution of the nonunion sites included 19 cases of mid/proximal forearm, 14 humeri, 6 distal radius and 3 clavicle. 35 patients had atrophic non-union, 11 had previous open fractures, and 10 had bone loss (range 1-3 cm). The mean number of operations performed and the mean time from injury to BMP-7 application was 1.5 and 26 months, respectively. 40 fractures had both clinical and radiological union whereas 2 patients had partial radiological union but a pain free range of motion. BMP-7 was applied in isolation in 1 case and in 41 cases the application was combined with autologous bone grafting. DASH scores were available at final follow up in 23 (55%) patients with a mean of 33 score (range 2-86.4). This study supports the view that the combination of ABG and BMP-7 can be considered as a successful treatment modality for the treatment of recalcitrant upper limb non-unions. Further studies preferably randomised controlled trials are desirable to throw more light into the role of BMP-7 in the treatment of upper limb nonunions.

Treatment of recalcitrant atrophic non-union of the humeral shaft with BMP-7, autologous bone graft and hydroxyapatite pellets

Recalcitrant humeral non-union is a disabling condition that is extremely difficult to treat. The use of BMP-7 has been proposed to improve bone healing. This is a report of the results obtained in 12 patients with recalcitrant humeral non-union treated using stable fixation with a long locking compression plate and BMP-7, autologous bone graft and hydroxyapatite pellets applied at the non-union site. Patients had up to three surgical attempts at non-union healing prior to our treatment. The average time from the initial fracture to our surgery was 5.2 years. Average follow-up was 5.3 years. At follow-up, non-union had healed in all patients by an average of 7.3 months. All the patients were very satisfied with their final results, despite a restricted range of motion of the elbow and a moderate muscular atrophy, which was frequently observed. Our study shows that BMP-7 associated with autologous bone grafting and hydroxyapatite pellets after stable fixation is an effective adjuvant to stimulate bone healing in the treatment of recalcitrant humeral non-union.

Biomimetic composite scaffolds containing bioceramics and collagen/gelatin for bone tissue engineering - A mini review

Bone is a natural composite material consisting of an organic phase (collagen) and a mineral phase (calcium phosphate, especially hydroxyapatite). The strength of bone is attributed to the apatite, while the collagen fibrils are responsible for the toughness and visco-elasticity. The challenge in bone tissue engineering is to develop such biomimetic composite scaffolds, having a balance between biological and biomechanical properties. This review summarizes the current state of the field by outlining composite scaffolds made of gelatin/collagen in combination with bioactive ceramics for bone tissue engineering application.

Sequential delivery of BMP-7 and IGF-I to enhance the osteoinductive property of deproteinized bovine bone

Calcium phosphate coated deproteinized bovine bone with sequential delivery of BMP-7 and IGF-I has osteoinductive property to promote bone regeneration.

Clinical effectiveness of Osigraft in long-bones non-unions

Current evidence, based primarily on case series, suggest that the eptotermin alfa (recombinant bone morphogenetic protein-7 (rhBM-7)), which is commercialized as Osigraft with an indication for tibial non-union, used in monotherapy or polytherapy, is a safe and effective therapy for long bones non-unions of lower and upper limbs. No previous study has compared the safety and the efficacy of Osigraft and the "gold standard" treatment for recalcitrant long-bones non-union, autologous bone graft (ABG). This study aims to compare the effectiveness of Osigraft and ABG in the treatment of post-traumatic, persistent long bone non-unions. In particular, the present study will focus exclusively on complex persistent non-unions, excluding simpler cases, in which it is likely that a simple revision of the osteosynthesis will be sufficient to promote union, and extremely severe cases in which there is an indication for amputation and prosthesis. The study addresses the following research question: 1. Is the effectiveness of eptotermin alfa comparable to that of ABG in the treatment of complex long bone non-unions? 2. Are there significant differences in the prevalence of adverse events between patients treated with eptotermin alfa and those treated with ABG? The study is an observational, retrospective study, located in one Experimental Recruiting Center (Ospedale Universitario G. PINI - Milano). The study was conducted with ethics approval and according with the existing Italian law. Demographic and clinical data were collected from patients Clinical Medical Records and other existing documentation, through a web based eCRF. The treatment (surgery with Osigraft or ABG) effectiveness was evaluated comparing the number of success cases (primary endpoint) and the length for clinical and radiological healing (secondary end-points). The treatment safety was evaluating comparing the prevalence of Adverse Events. Osigraft was demonstrated to be statistically equivalent to ABG with respect to the primary and secondary end point of surgical success. The treatment success was statistically comparable across all the anatomical regions considered, both in patients treated with Osigraft and in patients treated with ABG. The use of Osigraft when compared to autograft was associated with statistically lower intraoperative blood loss and shorter operative times. In addition patients treated with Osigraft developed statistically less peri-operative and late onset adverse events, compared to ABG. The difference was substantially due to the occurrence of pain at donor site in patients treated with ABG.

Fracture non-union epidemiology and treatment

Fracture non-union remains a clinical problem despite advances in the understanding of basic science and technology. Each fracture has a unique personality as does the patient suffering the injury. Thus, each case must be treated on an individual basis. This article defines the problem of fracture non-union and reports recent epidemiological studies. We discuss relevant risk factors and methods for assessing patients who have a tendency toward fracture non-union. There are many treatment options for patients with non-union, where a number of these modalities are still under review. We discuss current evidence with the use of bone morphogenic protein, platelet-rich plasma and low-intensity pulsed ultrasound to augment the treatment of fracture non-union.

The role of pleiotrophin in bone repair

Bone has an enormous capacity for growth, regeneration, and remodelling, largely due to induction of osteoblasts that are recruited to the site of bone formation. Although the pathways involved have not been fully elucidated, it is well accepted that the immediate environment of the cells is likely to play a role via cell–matrix interactions, mediated by several growth factors. Formation of new blood vessels is also significant and interdependent to bone formation, suggesting that enhancement of angiogenesis could be beneficial during the process of bone repair. Pleiotrophin (PTN), also called osteoblast-specific factor 1, is a heparin-binding angiogenic growth factor, with a well-defined and significant role in both physiological and pathological angiogenesis. In this review we summarise the existing evidence on the role of PTN in bone repair.

Investigating a potential biological treatment to prevent pathological fractures caused by unicameral bone cysts in children under 8 years

INTRODUCTION

There is no consensus on when and how to treat unicameral bone cysts (UBCs), partly because of a lack of knowledge of the aetiology.

PURPOSE

To review the different treatment techniques for UBCs and to describe our results with a single injection of autogenous bone marrow (BM) mixed with demineralised bone matrix (DBM) in very young children.

PATIENTS AND METHODS

We reviewed five patients under the age of 8 years with UBCs treated by percutaneous aspiration and a single injection of BM associated with DBM. The cyst was located in the proximal humerus in four patients and in the proximal femur in one patient. Assessment of the need for surgery was based on the clinical and radiographic suspicion of new pathological fractures. The administration of a second injection, when necessary, was based on the surgeon's judgement regarding the risk of fracture. The mean follow-up after first injection was 41 months.

RESULTS

There were no complications related to the procedure, except a non-displaced fracture, which healed without problems. All patients were pain free and progressively resumed their activities without restriction until a new fracture occurred in two cases. According to Capanna's classification, only one case healed completely (grade 1), one lesion was classified as grade 2, and there were three recurrences at 11, 12 and 27 months after initial treatment (grade 3). The final outcome was treatment failure for three out of the five patients. Two patients were treated with a second injection and one patient is waiting for surgery.

CONCLUSION

A single injection of aspirated autogenous BM mixed with DBM in very young children with active UBCs at risk of fracture is very simple, comfortable and safe. Nevertheless, the results seem to be unpredictable and are probably more dependent on the natural evolution of the cyst than on the treatment. Further comparative studies with larger sample numbers are needed.

Meniscal repair possibilities using bone morphogenetic protein-7

This study analysed the influence of bone morphogenetic protein-7 (BMP-7) on cells and meniscal structure. The effect of treatment with BMP-7 was assessed in vitro and in vivo in lesions in the avascular area of the meniscus. Cells were extracted from the outer and inner part of eight menisci of four 2-year-old merino sheep. The menisci were digested with a collagenase mix, and meniscus cells of the synovium, vascular area and avascular area were extracted. The expression of genes for collagen (Col1 and Col2A), matrix metalloproteinases (MMP-2 and MMP-13) and aggrecan was analysed by real time quantitative polymerase chain reaction (qPCR) at baseline and after incubation with BMP-7. Eight sheep aged 2 years and weighing 35-40 kg were used for the in vivo study. Surgery was performed in both knees of every animal. Two holes were made in the avascular area of the medial meniscus of both knees and filled using Putty(®) (control groups) or OP-1 Putty(®), which comprises BMP-7 mixed with a cellulose putty carrier (experimental groups). Animals were sacrificed at 6, 12 and 25 weeks. Adding BMP-7 to vascular cells of the meniscus was associated with a 15-fold increase in Col2A expression and a 78-fold increase in BMP-7 expression. BMP-7 inhibited MMP-2 and MMP-13 expression. Adding BMP-7 to synovial cells inhibited the expression of Col1, doubled the expression of Col2A and reduced the expression of BMP-7; the expression of MMP-2 was inhibited, while that of MMP-13 was increased three-fold. Incubation of cells from the avascular region with BMP-7 was associated with a 2.4-fold increase in Col1 expression, and a 4.4-fold increase in Col2A expression compared with the control. The expression of MMP-2 and BMP-7 was inhibited. In the in vivo study, treatment of the holes in the avascular area of the meniscus with BMP-7 was associated with an important cell presence inside the holes and the appearance of fibrous tissue after 12 weeks; these features were not seen in the control groups. BMP-7 may be a suitable growth factor for stimulation of meniscal cell and collagen formation.

Bone morphogenetic proteins: a powerful osteoinductive compound with non-negligible side effects and limitations

Healing and regeneration of large bone defects leading to non-unions is a great concern in orthopedic surgery. Since auto- and allografts have limitations, bone tissue engineering and regenerative medicine (TERM) has attempted to solve this issue. In TERM, healing promotive factors are necessary to regulate the several important events during healing. An ideal treatment strategy should provide osteoconduction, osteoinduction, osteogenesis, and osteointegration of the graft or biomaterials within the healing bone. Since many materials have osteoconductive properties, only a few biomaterials have osteoinductive properties which are important for osteogenesis and osteointegration. Bone morphogenetic proteins (BMPs) are potent inductors of the osteogenic and angiogenic activities during bone repair. The BMPs can regulate the production and activity of some growth factors which are necessary for the osteogenesis. Since the introduction of BMP, it has added a valuable tool to the surgeon's possibilities and is most commonly used in bone defects. Despite significant evidences suggesting their potential benefit on bone healing, there are some evidences showing their side effects such as ectopic bone formation, osteolysis and problems related to cost effectiveness. Bone tissue engineering may create a local environment, using the delivery systems, which enables BMPs to carry out their activities and to lower cost and complication rate associated with BMPs. This review represented the most important concepts and evidences regarding the role of BMPs on bone healing and regeneration from basic to clinical application. The major advantages and disadvantages of such biologic compounds together with the BMPs substitutes are also discussed.

Treatment of AVN using the induction chamber technique and a biological-based approach: indications and clinical results

OBJECTIVE

To determine the efficacy of core decompression (CD) technique combined with recombinant morphogenetic proteins, autologous mesenchymal stem cells (MSCs) and xenograft bone substitute into the necrotic lesion of the femoral head on clinical symptoms and on the progression of osteonecrosis of the femoral head.

PATIENTS AND METHODS

A total of 38 patients (40 hips) with early stage osteonecrosis of the femoral head were studied over a 4-year period.

RESULTS

CD technique combined with recombinant morphogenetic proteins, autologous MSCs and xenograft bone substitute was associated with a significant reduction in both pain and joint symptoms and reduced the incidence of fractural stages. At 36 months, 33 patients achieved clinical and radiographic healing.

CONCLUSION

This long-term follow-up study confirmed that CD technique combined with recombinant morphogenetic proteins, autologous MSCs and xenograft bone substitute may be an effective treatment for patients with early stage osteonecrosis of the femoral head.

Megaprosthesis in large bone defects: opportunity or chimaera?

INTRODUCTION

The development of new megaprosthesis for the treatment of large bone defects provides important options to orthopaedic oncologic surgeons for the replacement of skeletal segments, such as the long bones of the upper and lower limbs and the relative joints. We implanted megaprosthesis using either a one-step or two-step technique depending on the patient's condition. The aim of this study was to evaluate retrospectively both clinical and radiological outcomes in patients who underwent lower limb megaprosthesis implant.

MATERIALS AND METHODS

A total of 32 patients were treated with mono- and bi-articular megaprosthesis subdivided as follows: proximal femur, distal femur, proximal tibia and total femur. The mean follow-up of patients was about 18 months (range 3 months to 5 years). Clinical and serial radiographic evaluations were conducted using standard methods (X-ray at 45 days, 3, 6, 12, 18 and 24 months) and blood parameters of inflammation were monitored for at least 2 months.

RESULTS

Although the mean length of follow-up was only 18 months, the first patients to enter the study were monitored for 5 years and showed encouraging clinical results, with good articulation of the segments, no somato-sensory or motor deficit and acceptable functional recovery. During surgery and, more importantly, in pre-operative planning, much attention should be given to the evaluation of the extensor apparatus, preserving it and, when necessary, reinforcing it with tendon substitutes.

DISCUSSION

Megaprosthesis in extreme cases of severe bone loss and prosthetic failure is a potential solution for the orthopaedic surgeon. In oncological surgery, the opportunity to restore functionality to the patient (although not ad integrum) is important for both the patient and the surgeon. The high mortality associated with cancer precludes long-term patient follow-up; therefore, there is a lack of certainty about the survival of this type of prosthesis and any medium- to long-term complications that may occur. Nevertheless, patients should be considered as an oncologic patient, not because of the disease, but because of the limited therapeutic options available.

CONCLUSIONS

Megaprosthesis provides a valuable opportunity to restore functionality to patients with highly disabling diseases.

Revision of 120 tibial infected non-unions with bone and soft tissue loss treated with epidermato-fascial osteoplasty according to Umiarov

Treatment of tibial infected non-unions with bone and soft tissue loss has to solve three problems: infection, lack of bone continuity and lack of skin coverage. The aims of treatment are infection healing, bone consolidation with preservation of limb length and soft tissue reconstruction. The most important stage in the planning is an accurate débridement. Soft tissue reconstruction can be achieved using plastic surgery, and bone reconstruction is accomplished with bone grafts or induced membrane technique, but these methods may present disadvantages and risks. Epidermato-fascial osteoplasty is a modified procedure of compression-distraction osteosynthesis that was first described by Umiarov in 1982. This procedure offers the advantages of exactly classifying the phases of simultaneous bone and soft tissue regeneration, and of eliminating large tissue losses without previous closure of soft tissues or use of grafts, because the transported fragment takes fascia and skin along during the transport and closes the edges of the soft tissue gap until the epidermic and fascial reconstruction is complete. A total of 120 patients underwent this kind of surgery between 1986 and 2010 and were followed up for 2-26 years. Average age was 34 years (range 21-57 years). Cultures were positive for Staphylococcus in all cases, and for Pseudomonas in 27 cases. Adequate antibiotic therapy was administered in collaboration with the Infectious Diseases Specialist. Tibial bone resection was from 6 to 18cm (average 9.5cm). The Ilizarov apparatus was used with the oblique wire technique for bone transport in all patients. No intraoperative complications were observed. One patient died 40 days after the operation because of pulmonary embolism. The duration of treatment for the remaining 119 patients was 7-18 months. In all cases, infection eradication, healing of regenerate bone, consolidation at the docking site (with the aid of an autoplastic bone graft in only 11 patients), and epidermic and fascial reconstruction were observed, and functional results were very good. These techniques are particularly demanding for the patient and for the surgical team, but our results demonstrate that they can provide excellent outcomes in the management of difficult cases of infected non-unions.

Fracture non-union: Can biomarkers predict outcome?

Delayed bone healing and non-union occurs in approximately 10-15% of long bone fractures. Both pathologies may result in prolonged period of pain, disability and repetitive operative interventions. Despite intense investigations and progress done in understanding the pathophysiologic processes governing bone healing, the diagnostic tools have not been altered. The clinical findings and radiographic features remain the two important landmarks of diagnosing non-union and even when the diagnosis is established there is debate on the ideal timing and mode of intervention. Emerging evidence suggest that there are certain molecules and genes that can serve as predictors of potentially unsuccessful fracture union. This article summarises the current evidence on the available 'bio-markers'to predict fracture non-union.

The influence of environmental factors on bone tissue engineering

Bone repair and regeneration are dynamic processes that involve a complex interplay between the substrate, local and systemic cells, and the milieu. Although each constituent plays an integral role in faithfully recreating the skeleton, investigators have long focused their efforts on scaffold materials and design, cytokine and hormone administration, and cell-based therapies. Only recently have the intangible aspects of the milieu received their due attention. In this review, we highlight the important influence of environmental factors on bone tissue engineering.