Objectives

The purpose of this study was to evaluate in vivo biocompatibility of novel single-walled carbon nanotubes (SWCNT)/poly(lactic-co-glycolic acid) (PLAGA) composites for applications in bone and tissue regeneration.

Aim. Aim of this monocentric, prospective study was to evaluate the safety, efficacy, clinical and radiographical results at 24-month follow-up (N = 6 patients) undergoing hip revision surgery with severe acetabular bone defects (Paprosky 2C-3A-3B) using a combination of a novel phase-pure betatricalciumphosphate - collagen 3D matrix with allograft bone chips. Method. Prospective follow-up of 6 consecutive patients, who underwent revision surgery of the acetabular component in presence of massive bone defects between April 2018 and July 2019. Indications for revision included mechanical loosening in 4 cases and history of hip infection in 2 cases. Acetabular deficiencies were evaluated radiographically and CT and classified according to the Paprosky classification. Initial diagnosis of the patients included osteoarthritis (N = 4), a traumatic fracture and a congenital hip dislocation. 5 patients underwent first revision surgery, 1 patient underwent a second revision surgery. Results. All patients were followed-up radiographically with a mean of 25,8 months. No complications were observed direct postoperatively. HHS improved significantly from 23.9 preoperatively to 81.5 at the last follow-up. 5 patients achieved a defined good result, and one patient achieved a fair result. No periprosthetic joint infection, no dislocations, no deep vein thrombosis, no vessel damage, and no complaint about limbs length discrepancy could be observed. Postoperative dysmetria was found to be + 0.2cm (0cm/+1.0cm) compared to the preoperative dysmetria of − 2.4 cm (+0.3cm/−5.7cm). Conclusions. Although used in severe acetabular bone defects, the novel phase-pure betatricalciumphosphate - collagen 3D matrixshowed complete resorption and replacement by newly formed bone, leading to a full implant integration at 24 months follow-up and thus represents a promising method with excellent bone regeneration capacities for complex cases, where synthetic bone grafting material is used in addition to autografts

Bone regeneration includes a well-orchestrated series of biological events of bone induction and conduction. Among them, the Wnt/β-catenin signaling pathway is critical for bone regeneration. Being involved in several developmental processes, Wnt/β-catenin signaling must be safely targeted. There are currently only few specific therapeutic agents which are FDA-approved and already entered clinical trials. A published work has shown that Tideglusib, a selective and irreversible small molecule non-ATP-competitive glycogen synthase kinase 3-β(GSK-3β) inhibitor currently in trial for Alzheimer's patients, can promote tooth growth and repair cavities. [1]Despite some differences, they are some similarities between bone and tooth formation and we hypothesise that this new drug could represent a new avenue to stimulate bone healing. In this work, we locally delivered Tideglusib (GSK3β inhibitor) in the repair of femoral cortical window defects and investigated bone regeneration. A biodegradable FDA-approved collagen sponge was soaked in GSK-3βinhibitor solution or vehicle only (DMSO) and was implanted in 1 × 2 mm unicortical defects created in femora of 35 adult wild-type male mice. Bone defect repair on control and experimental (GSK-3βinhibitor) groups was assessed after 1 week (n=22), 2 weeks (n=24) and 4 weeks (n=24) with microCT and histological analysis foralkaline phosphatase (ALP, osteoblast activity), tartrate resistant acid phosphatase (TRAP, osteoclasts), and immunohistochemistry to confirm the activation of the Wnt/β-catenin pathway. Our results showed that Tideglusib significantly enhanced cortical bone bridging (20.6 ±2.3) when compared with the control (12.7 ±1.9, p=0.001). Activity of GSK-3β was effectively downregulated at day 7 and 14 resulting in a higher accumulation of active β-catenin at day 14 in experimental group (2.5±0.3) compared to the control (1.1±0.2, p=0.03). Furthermore, the onset of ALP activity appears earlier in the experimental group (day 14, 1.79±0.28), a level of activity never reached at any end-point by the control defects. At 4 weeks treatment, we observed a significant drop in ALP in the experimental group (0.47±0.05) compared to the control (1.01±0.19, p=0.02) and a decrease in osteoclast (experimental=1.32±0.36, control=2.23±0.67, p=0.04). Local downregulation of GSK-3β by tideglusib during bone defect repair resulted in significant increase in amount of new bone formation. The early upregulation of osteoblast activity is one explanation of bone healing augmentation. This is likely the effect of upregulation of β-catenin following pharmaceutical inhibition of GSK-3β since β-catenin activation is known to positively regulate osteoblasts, once committed to the osteoblast lineage. As a GSK-3β inhibitor, Tideglusib demonstrates a different mechanism of action compared with other GSK-3β antagonists as treatment was started immediately upon injury and did not interfere with precursor cells recruitment and commitment. This indicates that tideglusib could be used at the fracture site during the initial intraoperative internal fixation without the need for further surgery. This safe and FDA-approved drug could be used in prevention of non-union in patients presenting with high risk for fracture-healing complications

Introduction. “Bioexpandable” prostheses after resection of malignant bone tumors in children to lengthen the bone using the method of callus distraction may offer new perspectives and better long-term results. Materials and Methods. The bioexpandable prosthesis is equipped with an encapsulated electromotor which enables the device to perform distraction in an osteotomy gap with about 1mm/day. The new bone is improving the ratio from bone to prosthesis and therewith the potential stability of the final stem. The device is indicated, when limb length discrepancy is getting more than 3 cm or at maturity and can be used in a minimal invasive way for femur lengthening. Results. 11 patients were treated with the bioexpandable prosthesis. The mean age of the patients was 13,5 years and the mean amount of lengthening was 74mm. In 2 cases lengthening was performed in 2 steps and in 1 case in 3 steps. All lengthening procedures could be finished without complications. There was no infection and no technical problem. The bone regenerate in one tibia case was poor so that bone grafting from the iliac crest was necessary. Conclusions. The “bioexpandable” prosthesis is a new concept for limb lengthening after tumor resection in children. The latest patented version of the prosthesis under development allows all lengthening manoeuvres and the placement of the final stem via small incisions not only for the femur but also for the tibia

Introduction. Fibrous dysplasia is a pathological condition, where normal medullary bone is replaced by fibrous tissue and small, woven specules of bone. Fibrous dysplasia can occur in epiphysis, metaphysis or diaphysis. Occationally, biopsy is necessary to establish the diagnosis. We present a review of operative treatment using the Ilizarov technique. The management of tibial fibrous dysplasia in children are curettage or subperiosteal resection to extra periosteal wide resection followed by bone transport. Materials and Methods. A total of 18 patients were treated between 2010 – 2020; 12 patients came with pain and 6 with pain and deformity. All patients were treated by Ilizarov technique. Age ranges from 4–14 years. 12 patients by enbloc excision and bone transportation and 6 patients were treated by osteotomy at the true apex of the deformity by introducing the k/wires in the medullary cavity with stable fixation by Ilizarov device. The longest duration for bone transport was 16 weeks (14–20 weeks) for application, after deformity correction was 20 weeks. We have never used any kind of bone grafts. Results. All the 18 patients were treated successfully by Ilizarov compression distraction device. The patients with localized tibial pathology with deformity had the shortest period on the Ilizarov apparatus, 14 weeks. Conclusions. Preservation and bone regeneration by distraction histogenesis constitutes a highly conservative limb saving surgery. Patients with bone defects of <10 cm, a great deal of preserved healthy tissue and good prognosis are good candidates for these methods

Aim. Bone regeneration following the treatment of Staphylococcal bone infection or osteomyelitis is challenging due to the ability of Staphylococcus aureus to invade and persist within bone cells, which could possibly lead to antimicrobial tolerance and incessant bone destruction. Here, we investigated the influence of Staphylococcal bone infection on osteoblasts metabolism and function, with the underlying goal of determining whether Staphylococcus aureus-infected osteoblasts retain their ability to produce extracellular mineralized organic matrix after antibiotic treatment. Method. Using our in vitro infection model, human osteoblasts-like Saos-2 cells were infected with high-grade Staphylococcus aureus EDCC 5055 strain, and then treated with 8 µg/ml rifampicin and osteogenic stimulators up to 21-days. Results. Immunofluorescence and transmission electron microscopic (TEM) imaging demonstrated the presence of intracellular bacteria within the infected osteoblasts as early as 2 hours post-infection. TEM micrographs revealed intact intracellular bacteria with dividing septa indicative of active replication. The infected osteoblasts showed significant amounts of intracellular bacteria colonies and alteration in metabolic activity compared to the uninfected osteoblasts (p≤0.001). Treatment of S. aureus-infected osteoblasts with a single dose of 8 µg/ml rifampicin sufficiently restored the metabolic activity comparative to the uninfected groups. Alizarin red staining and quantification of the rifampicin-treated infected osteoblasts revealed significantly lower amount of mineralized extracellular matrix after 7-days osteogenesis (p<0.05). Interestingly, prolonged osteogenic stimulation and rifampicin-treatment up to 21 days improved the extracellular matrix mineralization level comparable to the rifampicin-treated uninfected group. However, the untreated (native) osteoblasts showed significantly more quantity of mineral deposits (p≤0.001). Ultrastructural analysis of the rifampicin-treated infected osteoblasts at 21-days osteogenesis revealed active osteoblasts and newly differentiated osteocytes, with densely distributed calcium crystal deposits within the extracellular organic matrix. Moreover, residual colony of dead bacteria bodies and empty vacuoles of the fully degraded bacteria embedded within the mineralized extracellular matrix. Gene expression level of prominent bone formation markers, namely RUNX2, COL1A1, ALPL, BMP-2, SPARC, BGLAP, OPG/RANKL showed no significant difference between the infected and uninfected osteoblast at 21-days of osteogenesis. Conclusions. Staphylococcus aureus bone infection can drastically impair osteoblasts metabolism and function. However, treatment with potent intracellular penetrating antibiotics, namely rifampicin restored the metabolic and bone formation activity of surviving osteoblasts. Delay in early osteogenesis caused by the bacterial infection was significantly improved over time after successful intracellular bacteria eradication

Aim. Osteomyelitis is a difficult-to-treat disease with high chronification rates. The surgical amputation of the afflicted limb sometimes remains as the patients’ last resort. Several studies suggest an increase in mitochondrial fission as a possible contributor to the accumulation of intracellular reactive oxygen species and thereby to cell death of infectious bone cells. The aim of this study is to analyze the ultrastructural impact of bacterial infection and its accompanying microenvironmental tissue hypoxia on osteocytic and osteoblastic mitochondria. Method. 19 Human bone tissue samples from patients with osteomyelitis were visualized via light microscopy and transmission electron microscopy. Osteoblasts, osteocytes and their respective mitochondria were histomorphometrically analyzed. The results were compared to the control group of 5 non-infectious human bone tissue samples. Results. The results depicted swollen hydropic mitochondria including depleted cristae and a decrease in matrix density in the infectious samples as a common finding in both cell types. Furthermore, perinuclear clustering of mitochondria could also be observed regularly. Additionally, increases in relative mitochondrial area and number could be found as a sign for increased mitochondrial fission. Conclusions. The results show that mitochondrial morphology is altered during osteomyelitis in a comparable way to mitochondria from hypoxic tissues. This suggests that manipulation of mitochondrial dynamics in a way of inhibiting mitochondrial fission may improve bone cell survival and exploit bone cells regenerative potential to aid in the treatment of osteomyelitis

Fracture non-union can be as high as 20% in certain clinical scenarios and has a high associated socioeconomic burden. Boron has been shown to regulate the Wnt/β-catenin pathway in other bodily processes. However, this pathway is also critical for bone healing. Here we aim to demonstrate that the local delivery of boric acid can accelerate bone healing, as well as to elucidate how boric acid, via the regulationtheWnt/β-catenin pathway, impacts theosteogenic response of bone-derived osteoclasts and osteoblasts during each phase of bone repair. Bilateral femoral cortical defects were created in 32 skeletally mature C57 mice. On the experimental side, boric acid (8mg/kg concentration) was injected locally at the defect site whereas on the control side, saline was used. Mice were euthanized at 7, 14, and 28 days. MicroCT was used to quantify bone regeneration at the defect. Histological staining for ALP and TRAP was used to quantify osteoblast and osteoclast activity respectively. Immunohistochemical antibodies, β-catenin and CD34 were used to quantify active β-catenin levels and angiogenesis respectively. Sclerostin and GSK3β were also quantified and are both inhibitors of the wnt signaling pathway via degradation and inactivation of β-catenin. The boron group exhibited higher bone volume and trabecular thickness at the defect site by 28 days on microCT. ALP activity was significantly higher in boron group at 7 days whereas boron had no effect on TRAP activity. Additionally, CD34 staining revealed increased angiogenesis at 14 days in boron treated groups. β-catenin activity on immunohistochemistry was significantly higher in the boron group at 7 days, GSK3β was significantly higher in the boron group at 14 days and Sclerostin was significantly higher in the boron group at 28 days. Boron appears to increase osteoblast activity at the earlier phases of healing. The corresponding early increase in β-catenin along with ALP likely supports that boron increases osteoblast activity via the wnt/β-catenin pathway. Increased angiogenesis at 14 days could be a separate mechanism increasing bone formation independent of wnt/β-catenin activation. Neither GSK3β or Sclerostin levels correlated with β-catenin activity therefore boron likely increases β-catenin through a mechanism independent of both GSK3β and Sclerostin. The addition of this inexpensive and widely available ion could potentially become a non-invasive, cost-effective treatment modality to augment fracture healing and decrease non-union rates in high risk patients

A novel injectable hydrogel based on DNA and silicate nanodisks was fabricated and optimized to obtain a suitable drug delivery platform for biomedical applications. Precisely, the hydrogel was designed by combining two different type of networks: a first network (type A) made of interconnections between neighboring DNA strands and a second one (type B) consisting of electrostatic interactions between the silicate nanodisks and the DNA backbone. The silicate nanodisks were introduced to increase the viscosity of the DNA physical hydrogel and improve their shear-thinning properties. Additionally, the silicate nanodisks were selected to modulate the release capability of the designed network. DNA 4% solutions were heated at 90°C for 45 seconds and cooled down at 37°C degree for two hours. In the second step, the silicate nanodisks suspension in water at different concentrations (0.1 up to 0.5%) were then mixed with the pre-gel DNA hydrogels to obtain the nanocomposite hydrogels. Rheological studies were carried out to investigate the shear thinning properties of the hydrogels. Additionally, the hydrogels were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron microscopy. The hydrogels were loaded with the osteoinductive drug dexamethasone and its release was tested in vitro in phosphate buffer pH 7.4. The drug activity upon release was tested evaluating the osteogenic differentiation of human adipose derived stem cells (hASCs) in vitro through analysis of main osteogenic markers and quantification of alkaline phosphatase activity and calcium deposition. Finally, the hydrogels were tested in vivo and injected into cranial defects in rats to assess their biocompatibility and bone regeneration potential. The inclusion of the silicate nanodisks increased the viscosity of the hydrogels and the best results were obtained with the highest concentration of the nanoclay (0.5%). The hydrogels possessed shear-thinning properties as demonstrated by cyclic strain sweep tests and were able to recover their original storage modulus G' upon removal of strain. Such improvement in the injectable properties of the formulated hydrogels was mainly attributed to the formation of electrostatic interactions between the silicate nanodisks and the phosphate groups of the DNA backbone as confirmed by XPS analysis of the O, N, and P spectra. Additionally, laponite was able to sustain the release of the osteoinductive drug dexamethasone which was instead completely released from the DNA-based hydrogels after a week. The drug after being released was still active and promoted the osteogenic differentiation of hASCs as confirmed by ALP expression and expression of main osteogenic markers including ALP and COLA1. Finally, the gels proved to be biocompatible in vivo when injected into cranial defects and promoted bone formation at the periphery of the defect after a month post-treatment. A novel injectable shear-thinning DNA-based hydrogel was characterized and tested for its drug delivery properties. The hydrogel can promote the sustain release of a small molecule like dexamethasone and be biocompatible in vitro and in vivo. Due to these promising findings, the designed system could find also applicability for the delivery of growth factors or other therapeutic molecules

Previously, we reported impaired biomechanical bone properties and inferior bone matrix quality in tachykinin1 (Tac1)-deficient mice lacking the sensory neuropeptide substance P (SP). Additionally, fracture callus development is affected by the absence of SP indicating a critical effect of sensory nerve fibers on bone health and regeneration. For α-calcitonin gene-related peptide (α-CGRP)-deficient mice, a profound distortion of bone microarchitecture has also been described. We hypothesize that SP and α-CGRP modulate inflammatory as well as pain-related processes and positively affect bone regeneration during impaired fracture healing under osteoporotic conditions. Therefore, this study investigates the effects of SP and α-CGRP on fracture healing and fracture-related pain processes under conditions of experimental osteoporosis using SP- and α-CGRP-deficient mice and WT controls. We ovariectomized female WT, Tac1−/− and α-CGRP−/− mice (age 10 weeks, all strains on C57Bl/6J background) and set intramedullary fixed femoral fractures in the left femora 28 days later. We analyzed pain threshold (Dynamic Plantar Aesthesiometer Test) and locomotion (recorded at day and night, each for 1 hour, EthoVision®XT, Noldus) at 5, 9, 13, 16 and 21 days after fracture. At each time point, fractured femora were prepared for histochemical analysis of callus tissue composition (alcian blue/sirius red staining). Pain threshold is significantly higher in Tac1−/− mice 13 days after fracture and tends to be higher after 21 days compared to WT controls. In contrast, touch sensibility was similar in α-CGRP−/− mice and WT controls but compared to Tac1−/− mice pain threshold was significantly lower in α-CGRP−/− mice 13 and 16 days and tends to be lower 21 days after fracture. Locomotion of Tac1−/− mice during daylight was by trend higher 9 days after fracture and significantly higher 16 days after fracture whereas nightly locomotion is reduced compared to WT mice. Analysis of locomotion during daylight or night revealed no differences between α-CGRP−/− and WT mice. During early fracture healing phase, 5 and 9 days after fracture, transition of mesenchymal to cartilaginous callus tissue tends to be faster in Tac1−/− mice compared to WT controls whereas no difference was observed during late stage of fracture healing, 13, 16 and 21 days after fracture. In contrast, callus tissue maturation seems to be similar in α-CGRP−/− and WT mice. Our data indicate different effects of SP and α-CGRP on fracture healing under conditions of experimental osteoporosis as a model for impaired bone tissue. Lack of α-CGRP seems to have no effects, but loss of SP affects locomotion throughout osteoporotic fracture healing and fracture-related pain processes during late phases of osteoporotic fracture healing. This indicates a modified role of SP during fracture healing under impaired versus healthy conditions, where SP changed early fracture-related pain processes and had no influence on callus tissue composition

Aims

Distraction osteogenesis with intramedullary lengthening devices has undergone rapid development in the past decade with implant enhancement. In this first single-centre matched-pair analysis we focus on the comparison of treatment with the PRECICE and STRYDE intramedullary lengthening devices and aim to clarify any clinical and radiological differences.

We present the results of a new non-invasive lengthening nail enabling accurate control of the lengthening process and joint rehabilitation. Introduction. The use of intramedullary lengthening nails have gained popularity as they reduce common complications associated with external fixators, including infection, joint stiffness, bone regenerate deformity, late fracture and patient implant acceptance. Current nails however are associated with complications including implant breakage, mechanical failure, runaway nail and requiring MUA to restart or obtain segment lengthening. The Precice nail incorporates magnet technology with a hand held device allowing non-invasive lengthening. The nail is also reversible allowing shortening if required. Physiotherapy can continue throughout treatment to maintain joint range of motion without concern of uncontrolled nail runaway. The lengthening is axial reducing shear/torsional forces on the regenerate. Method. The lengthening of 4 femora was undertaken in 3 patients, mean age 34 yrs for post-traumatic shortening and short stature. A standard technique included an Ilizarov corticotomy followed by a 6 day latent period. Patients were mobilised partial weight bearing and knee range of motion maintained. The femora were lengthened one third of a millimetre three times per day. Radiographic and clinical review was performed every 2 weeks. Results. The desired femoral length was obtained in all patients, mean 5.6 cms (4.5–6.5). There were no complications of infection, poor bone regenerate or premature consolidation. One patient undergoing bilateral femoral lengthening underwent surgical release of a tight Tensor Fascia Lata following completion of lengthening due to hip flexion contracture. One patient required slowing of the lengthening rate due to knee flexion contracture. Physiotherapy corrected the deformity and the normal lengthening rate could be resumed. Conclusion. The Precice nail is a new device that offers accurate control of the lengthening process and rehabilitation. This should reduce complications of poor regenerate formation and soft tissue contractures

We present our experience of lower limb reconstruction for patients with obvious defects in the tibia, by bone transport using a stacked Taylor Spatial Frame. A retrospective review of 40 patients treated between 2003 and 2009. There were 19 cases of infected non union, 9 cases of acute bone loss following fracture, 6 cases of chronic osteomyelitis, 4 cases of aseptic non union, 1 case of neurofibromatosis and 1 case of a loose and infected total ankle replacement. Twenty-eight out of the 40 patients reviewed have completed their treatment. Of these 28 patients, bony union was achieved in 23 patients, of whom 22 were assessed at discharge to have regained good to excellent limb function, a functional assessment was not available for review in the remaining patient. In 5 patients, docking site union failed, 3 of whom then underwent below knee amputation. Two patients required treatment with an intramedullary nail following frame treatment to achieve consolidated union of the docking site. Anatomic sagittal and coronal alignment was achieved in 19 out of 23 patients. The mean bone regenerate was 53.3 mm (range: 15-180mm), with a mean healing index of 9.2 days/mm (range: 4.4-25 days/mm). The majority of patients experienced at least one complication, these included pin site and soft tissue infections, refracture, nerve palsy and joint stiffness. Surgical stimulation of the docking site was required in 12 of the 28 patients to promote union. The use of a stacked Taylor Spatial Frame system is effective for restoring bone length and limb function in patients with bone loss following complex trauma and orthopaedic cases. The computer assisted nature of the spatial frame allows for predictable bone regenerate, minimal residual deformity and accurate bone docking

Introduction. We present our experience of lower limb reconstruction for patients with obvious defects in the tibia, by bone transport using a stacked Taylor Spatial Frame. Methods. A retrospective review of 40 patients treated between 2003 and 2009. There were 19 cases of infected non union, 9 cases of acute bone loss following fracture, 6 cases of chronic osteomyelitis, 4 cases of aseptic non union, 1 case of neurofibromatosis and 1 case of a loose and infected total ankle replacement. Results. 28 out of the 40 patients reviewed have completed their treatment. Of these 28 patients, bony union was achieved in 23 patients, of whom 22 were assessed at discharge to have regained good to excellent limb function; a functional assessment was not available for review in the remaining patient. In 5 patients docking site union failed, 3 of whom then underwent below-knee amputation. Two patients required treatment with an intramedullary nail following frame treatment to achieve consolidated union of the docking site. Anatomic sagittal and coronal alignment was achieved in 19 out of 23 patients. The mean bone regenerate was 53.3 mm (range: 15-180mm), with a mean healing index of 9.2 days/mm (range: 4.4-25 days/mm). The majority of patients experienced at least one complication; these included pin site and soft tissue infections, refracture, nerve palsy and joint stiffness. Surgical stimulation of the docking site was required in 12 of the 28 patients to promote union. Conclusion. The use of a stacked Taylor Spatial Frame system is effective for restoring bone length and limb function in patients with bone loss following complex trauma and orthopaedic cases. The computer assisted nature of the spatial frame allows for predictable bone regenerate, minimal residual deformity and accurate bone docking

Periosteum is important for bone homoeostasis through the release of bone morphogenetic proteins (BMPs) and their effect on osteoprogenitor cells. Smoking has an adverse effect on fracture healing and bone regeneration. The aim of this study was to evaluate the effect of smoking on the expression of the BMPs of human periosteum. Real-time polymerase chain reaction was performed for BMP-2,-4,-6,-7 gene expression in periosteal samples obtained from 45 fractured bones (19 smokers, 26 non-smokers) and 60 non-fractured bones (21 smokers, 39 non-smokers). A hierarchical model of BMP gene expression (BMP-2 > BMP-6 > BMP-4 > BMP-7) was demonstrated in all samples. When smokers and non-smokers were compared, a remarkable reduction in the gene expression of BMP-2, -4 and -6 was noticed in smokers. The comparison of fracture and non-fracture groups demonstrated a higher gene expression of BMP-2, -4 and -7 in the non-fracture samples. Within the subgroups (fracture and non-fracture), BMP gene expression in smokers was either lower but without statistical significance in the majority of BMPs, or similar to that in non-smokers with regard to BMP-4 in fracture and BMP-7 in non-fracture samples. In smokers, BMP gene expression of human periosteum was reduced, demonstrating the effect of smoking at the molecular level by reduction of mRNA transcription of periosteal BMPs. Among the BMPs studied, BMP-2 gene expression was significantly higher, highlighting its role in bone homoeostasis

In revision surgery of a neglected loose cemented stem, especially if long-standing infection is present, the bone may become extremely thin and fragile. A fracture during implant removal, therefore, occurs readily and the bone may simply disintegrate so that it cannot be reconstructed to produce intrinsic stability. In such cases, rather than try to put together a house of cards, the bail and nail technique may be used. I first described this in 1992. A large bore intramedullary nail is inserted into what is left of the femur and the bone fragments proximally or cerclage wires are around the nail. The patient is left with a Girdlestone. Most patients cannot weight-bear on a Girdlestone for about two months. After that time, they are encouraged to do so as load bearing speeds healing and bone regeneration. Generally, within six to nine months, the femur is reconstituted and a revision can be carried out. This is a simple operation as the medullary canal is already open and the regenerated bone is often of surprising good quality. It may even be possible to use a primary stem as opposed to a long revision stem, but this probably should not be done under nine months. The presence of an IM nail and cerclage wires does not prevent the elimination of infection. As our brothers, the trauma surgeons, will attest the treatment of an infected non-union of the femur is an intramedullary nail. This technique is seldom required. The author has used it in eight cases in the last 30 years. It is, however, extremely valuable in bailing out of an impossible revision, especially if strut allografts or modular long stems are not immediately available

Aim. The demand for a synthetic bone substitute that can build bone and at the same time kill bacteria is high. The aim of this study was to compare the elution of gentamicin from a new synthetic bone substitute in vitro with the performance in clinical applications. Method. Gentamicin release was measured from a synthetic bone graft substitute, comparing in vitro and clinical conditions:. 1). elution in Ringers solution. The bone graft substitute contained 175mg gentamicin per 10mL. The material was introduced either as paste or as pre-set beads with a high or low surface areas, >100cm. 2. and 24cm. 2. respectively. The gentamycin release was measured by daily collection of samples. 2). elution in patients treated for trochanteric hip fractures(n=6) or uncemented hip revisions(n=5) 7,3±1,1mL of substitute was implanted and drainage was collected at 6h,12h,24h,30h,36h post-op. Blood serum was collected every hour for the first 6h and thereafter every 6h until 4 days post-op, urine – daily for the first 7 days post-op. 3). elution in patients treated after bone tumor resection(n=8), 12,1±5,5mL of substitute was implanted and both drainage and blood serum were collected daily until 2 days post-op. Gentamicin concentrations were analyzed using antibody technique. Results. In the in vitro study, there was an initial peak in the gentamicin concentration (GC) for all the samples and at a level above 4mg/L, which is the MIC break point, during the whole test period of 28 days. All gentamicin was released during the test period and more than 95 % had been released after 2–4 days independently of the surface area of the material, or if it was pre-set or paste. In the clinical studies similar results were found. Gentamicin was detected in the drainage until 2 days post-op. and the hip patients 40% less GC – compared to the tumor patients. In the blood serum with higher GC in the tumor patients and non-detectable levels after 2 days post-op for the hip patients. The GC was significantly lower than maximum systemic level recommended of 12 mg/L. In the urine, GC was above the MIC of 4mg/L for the first seven days post-op. Conclusions. A reliable in vitro test method has been identified for the future development of additional new and effective antibiotic containing bone substitutes. The new bone regenerating carrier gives very high local antibiotic release for a controlled short time after surgery and high systemic serum concentrations are avoided

The physiological effects of 1,25 vitamin D3 (1,25D) are well known and the previously held dogma was that this was the only active vitamin D metabolite. A number of methods have been employed to demonstrate the effects of 24,25-dihydroxyvitamin D3 (24,25D) on osteoblast maturation responses, in the presence of FHBP, ((3S) 1-Fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate), an agonist of lysophosphatidic acid (LPA). These include alkaline phosphatase (ALP) expression and investigation of the role of CYP27B1, which is the enzyme responsible for converting 24,25D to 1,24,25D. Ketoconazole, which inhibits the actions of CYP27B1, as well as an enzyme-linked immunosorbant assay (ELISA) for CYP27B1 were used. The results clearly demonstrate that 24,25D stimulates maturation of MG63 cells when combined with FHBP. It has also been shown that the metabolite is not converted to another active form (for example, 1,24,25D) within osteoblasts, due to the absence of CYP27B1. 24,25D is an active vitamin D metabolite and exerts its effects in a bone fide manner, rather than following conversion to another active metabolite in osteoblasts. Given it is non-calcaemic, this metabolite has the exciting potential of being used in a bone regenerative setting in orthopaedic applications

Gene-activated scaffolds have shown potential in localised gene delivery resulting in bone tissue regeneration. In this study, the ability of two gene delivery vectors, polyethyleneimine (PEI) and nano-hydroxyapatite (nHA), to act as carriers for the delivery of therapeutic genes when combined with our collagen-nHA (coll-nHA) scaffolds to produce gene-activated scaffolds [1, 2], was determined. In addition, coll-nHA-dual gene scaffolds containing both an angiogenic gene and an osteogenic gene were assessed for bone healing in an in vivo Wistar rat calvarial defect model. When cells were applied to the coll-nHA scaffolds under osteogenic conditions in vitro, the dual scaffolds exhibited significantly superior osteogenic potential when analysed using microCT, calcium quantification and histology compared to single-gene scaffolds and gene-free controls. When the dual scaffolds were assessed in vivo, the nHA dual scaffold outperformed all other groups as early as 4 weeks post-implantation as determined using X-ray, microCT, quantification of new bone volume, histology and vessel formation. This research has demonstrated the potential of using novel coll-nHA scaffolds for therapeutic gene therapy while also being capable of simultaneously delivering numerous genes. This study underlines the effect of specifically tailoring gene-activated scaffolds for bone regeneration applications

Failure of the femoral component after a primary or revision THA is commonly associated with some degree of femoral bone loss. Depending on the quantity and quality of the remaining host bone, femoral stem revision can be challenging. Twenty patients with severe proximal femoral bone loss due to prosthetic loosening were treated by Wagner cementless self-locking revision stems with a mean follow up of 24 months (range 18–36 months). The indication of revision surgery was aseptic loosening in 16 patients and septic loosening in 4 cases. At the end of the follow up the mean Harris hip score increased from 35 to 86 points. Definite radiographic evidence of bone regeneration in the bony defects was achieved within 3 months in all patients. Implantation of a Wagner cementless selflocking revision stem provided satisfactory results. The Wagner SL Revision prosthesis, firmly and rotationally stable fixed in the medullary cavity of the healthy bone distal from the original prosthetic bed, with its conical longitudinal ribs and cementless anchorage, bridges the defective prosthetic bed and hereby leads to a condition of relative mechanical stability. With time, there is active ossification in the old prosthetic bed, replacing lost bone