Microbiological and ultrastructural evaluation of bacteriophage 191219 against planktonic, intracellular and biofilm infection with Staphylococcus aureus.

Infections of orthopaedic implants, such as fracture fixation devices and total-joint prostheses, are devastating complications. Staphylococcus aureus (S. aureus) is a predominant pathogen causing orthopaedic-implant biofilm infections that can also internalise and persist in osteoblasts, thus resisting antibiotic therapy. Bacteriophages are a promising alternative treatment approach. However, data on the activity of bacteriophages against S. aureus, especially during intracellular growth, and against in vivo biofilm formation on metals are scarce. Therefore, the present study evaluated the in vitro efficacy of S. aureus bacteriophage 191219, alone as well as in combination with gentamicin and rifampicin, to eradicate S. aureus strains in their planktonic stage, during biofilm formation and after internalisation into osteoblasts. Further, the invertebrate model organism Galleria mellonella was used to assess the activity of the bacteriophage against S. aureus biofilm on metal implants with and without antibiotics. Results demonstrated the in vitro efficacy of bacteriophage 191219 against planktonic S. aureus. The phage was also effective against in vitro S. aureus biofilm formation in a dose-dependent manner and against S. aureus internalised in an osteoblastic cell line. Transmission electron microscopy (TEM) analysis showed bacteriophages on S. aureus inside the osteoblasts, with the destruction of the intracellular bacteria and formation of new bacteriophages. For the Galleria mellonella infection model, single administration of phage 191219 failed to show an improvement in survival rate but appeared to show a not statistically significant enhanced effect with gentamicin or rifampicin. In summary, bacteriophages could be a potential adjuvant treatment strategy for patients with implant-associated biofilm infections.

Dental follicle cell differentiation towards periodontal ligament-like tissue in a self-assembly three-dimensional organoid model.

Periodontitis remains an unsolved oral disease, prevalent worldwide and resulting in tooth loss due to dysfunction of the periodontal ligament (PDL), a tissue connecting the tooth root with the alveolar bone. A scaffold-free three-dimensional (3D) organoid model for in vitro tenogenesis/ligamentogeneis has already been described. As PDL tissue naturally arises from the dental follicle, the aim of this study was to investigate the ligamentogenic differentiation potential of dental follicle cells (DFCs) in vitro by employing this 3D model. Human primary DFCs were compared, in both two- and three-dimensions, to a previously published PDL- hTERT cell line. The 3D organoids were evaluated by haematoxylin and eosin, 4',6-diamidino-2-phenylindole and F-actin staining combined with detailed histomorphometric analyses of cell-row structure, angular deviation and cell density. Furthermore, the expression of 48 tendon/ligament- and multilineage-related genes was evaluated using quantitative polymerase chain reaction, followed by immunofluorescent analyses of collagen 1 and 3. The results showed that both cell types were successful in the formation of scaffold-free 3D organoids. DFC organoids were comparable to PDL-hTERT in terms of cell density; however, DFCs exhibited superior organoid morphology, cell-row organisation (p < 0.0001) and angular deviation (p < 0.0001). Interestingly, in 2 dimensions as well as in 3D, DFCs showed significantly higher levels of several ligament- related genes compared to the PDL-hTERT cell line. In conclusion, DFCs exhibited great potential to form PDL-like 3D organoids in vitro suggesting that this strategy can be further developed for functional PDL engineering.

Vertebral osteomyelitis is characterised by increased RANK/OPG and RANKL/OPG expression ratios in vertebral bodies and intervertebral discs.

Vertebral osteomyelitis (VO) is an infection of the spine mainly caused by bacterial pathogens. The pathogenesis leading to destruction of intervertebral discs (IVDs) and adjacent vertebral bodies (VBs) is poorly described. The present study aimed at investigating the connection between infection and bone/disc metabolism in VO patients. 14 patients with VO (infection group) and 14 patients with burst fractures of the spine (fracture group; control) were included prospectively. Tissue biopsies from affected IVDs and adjacent VBs were analysed by RT-qPCR for mRNA-expression levels of 18 target genes including chemokines, adipokines and genes involved in bone metabolism. Most importantly, the receptor activator of NF-κB/osteoprotegerin (RANK/OPG) expression ratio was drastically elevated in both VBs and IVDs of the infection group. In parallel, expression of genes of the prostaglandin-E2-dependent prostanoid system was induced. Such genes regulate tissue degradation processes via the triad OPG/RANK/RANKL as well as via the chemokines IL-8 and CCL-20, whose expression was also found to be increased upon infection. The gene expression of the adipokine leptin, which promotes inflammatory tissue degradation, was higher in IVD tissue of the infection group, whereas the transcription of omentin and resistin genes, whose functions are largely unknown in the context of infectious diseases, was lower in infected VBs. In summary, similar expression patterns of pro-inflammatory cytokines and pro-osteoclastogenic factors were identified in VBs and IVDs of patients suffering from VO. This suggests that common immuno-metabolic pathways are involved in the mechanisms leading to tissue degradation in VBs and IVDs during VO.

New quantitative automated model to simulate bacterial dissemination in human tissue during irrigation of contaminated wounds.

This study presents a simple and cost-effective model using microparticles to simulate the bacterial distribution pattern in soft tissue after low- and high-pressure irrigation. Silica coated iron microparticles [comparable diameter (1 µm) and weight (0.8333 pg) to Staphylococcus aureus] were applied to the surface of twenty fresh human muscle tissue samples in two amputated lower legs. Particle dissemination into deep tissue layers as an undesired side effect was investigated in four measuring fields as positive control (PC) as well as after performing pulsatile high-pressure (HP, 8 measuring fields) and low-pressure flushing (LP, 8 measuring fields). Five biopsies were taken out of each measuring field to get a total number of 100 biopsies. After histological and digital image processing, the specimens were analysed, and all incomplete sections were excluded. A special detection algorithm was parameterised using the open source bioimage analysis software QuPath. The application of this detection algorithm enabled automated counting and detection of the particles with a sensitivity of 95 % compared to manual counts. Statistical analysis revealed significant differences (p < 0.05) in our three different sample groups: HP (M = 1608, S = 302), LP (M = 2176, SD = 609) and PC (M = 4011, SD = 686). While both HP and LP flushing techniques are able to reduce the number of bacteria, a higher effectiveness is shown for HP irrigation. Nevertheless, a challenge for the validity of the study is the use of dead tissue and therefore a possible negative influence of high-pressure irrigation on tissue healing and further dispersion of particles cannot be evaluated.

Establishment of a clinically relevant large animal model to assess the healing of metaphyseal bone.

Despite the high incidence of metaphyseal bone fractures in patients, the mechanisms underlying the healing processes are poorly understood due to the lack of suitable experimental animal models. Hence, the present study was conducted to establish and characterise a clinically relevant large-animal model for metaphyseal bone healing. Six female adult Merino sheep underwent full wedge-shaped osteotomy at the distal left femur metaphysis. The osteotomy was stabilised internally with a customised anatomical locking titanium plate that allowed immediate post-operative full-weight bearing. Bone healing was evaluated at 12 weeks post-fracture relative to the untouched right femur. Histological and quantitative micro-computed tomography results revealed an increased mineralised bone mass with a rich bone microarchitecture. New trabeculae healed by direct intramembranous ossification, without callus and cartilaginous tissue formation. Stiffness at the cortical and trabecular regions was comparable in both groups. Functional morphological analysis of the osteocyte lacunae revealed regularly arranged spherically shaped lacunae along with the canalicular network. Bone surface biochemical analysis using time-of-flight secondary-ion mass spectrometry showed high and homogeneously distributed levels of calcium and collagenous components. Ultrastructure imaging of the new trabeculae revealed a characteristic parallel arrangement of the collagen fibrils, evenly mineralised by the dense mineral substance. The specialised bone cells were also characterised by their unique structural features. Bone remodelling in the fractured femur was evident in the higher expression levels of prominent bone formation and resorption genes. In conclusion, the novel metaphyseal fracture model is beneficial for studying healing and treatment options for the enhancement of metaphyseal bone defects.

A metaphyseal fracture rat model for mechanistic studies of osteoporotic bone healing.

Most osteoporotic fractures occur at metaphyseal regions of long bones. The present study proposed a clinically relevant animal model that satisfied: i) induction of osteoporosis, ii) unilateral complete osteotomy at metaphysis, iii) internal fixation. 6 months old female Sprague-Dawley rats (n = 64) were randomly divided into the ovariectomised-metaphyseal osteotomy (OVX, n = 32) and metaphyseal osteotomy (SHAM, n = 32) groups. The metaphyseal-osteotomy model was created with a plate-fixation of the osteotomy and assessed by X-ray, micro-computed tomography, histomorphometry and mechanical testing at weeks 1, 3 and 6. X-ray results showed complete healing of metaphyseal osteotomy at week 6. Histology showed 3 stages of metaphyseal healing. Stage 1 was characterised by fibrous tissue, consisting of disorganised orientation of collagen fibres, and infiltration of immune cells. At stage 2, a transitional zone consisting of maturing fibrous tissue and differentiating mesenchymal cells with early trabecular bone formation and disorganised woven bone were observed. During stage 3, cortical bone ends unified and woven bone underwent transformation to lamellar bone. OVX group healing was significantly delayed when compared to SHAM samples. The study demonstrated that healing of osteoporotic osteotomy at the metaphyseal region was delayed in terms of radiography, histomorphometry and mechanical strength. These quantitative evaluations, along with histological features, may provide key references for future studies. The animal model may provide additional clinical relevance as most osteoporotic fracture in humans occurs at metaphyseal regions.

Successful Total Elbow Replacement after Septic Arthritis with Staphylococcus aureus- a Case Report and Review of the Literature.

Septic arthritis of the elbow seems to be a contraindication for total elbow arthroplasty (TEA). We here describe a 65-year-old male, American Society of Anesthesiologists (ASA) class 3 - patient, with a severely destructed right elbow due to septic arthritis with Staphylococcus aureus. His treatment consisted of multiple irrigation and debridement procedures including resection of the distal humerus, soft tissue coverage by local rotational flap and the use of a gentamicin-vancomycin loaded PMMA spacer, i.v. and oral antibiotics. After eradication of infection, a constraint cemented TEA could then successfully be performed eight months after the initial surgery and twenty-five weeks after the last debridement procedure. Twenty-one months after the TEA, the patient remained infect free and shows excellent functional results: Disabilities of the Arm, Shoulder and Hand (DASH) score: 38.3, Broberg and Morrey score: 91/100, Mayo elbow score: 95/100. To the best of our knowledge this is the first case in the literature that demonstrates TEA after septic elbow arthritis with Staphylococcus aureus. Although TEA is known as a typical surgical procedure with a low volume in numbers and higher complication rates, such as elevated infection rates compared to other types of arthroplasty, septic arthritis with Staphylococcus aureuscan successfully be performed after eradication of the infection and targeted antibiotic therapy. Key words:total elbow arthroplasty, total elbow replacement, septic arthritis, Staphylococcus aureus.

Differences in expression of Wnt antagonist Dkk1 in healthy versus pathological bone samples.

Wnt/ß-catenin signalling components was shown to affect bone cells function including chondrocytes.Secreted Dkk1, a potent osteogenesis inhibiting factor mediates bone loss in diseased bones by suppressing the biological actions of Wnt proteins. In addition, increased Dkk1 signalling inhibits chondrogenesis in new bone formation. Recent findings also show there exists a cross-talk between the chondrocytes and the cells of the osteoblast lineage, which are the most affected cell types in muskuloskeletal disorders. This study investigated whether spatial expression of Dkk1 is confined to only osteoblasts, osteocytes or chondrocytes. The second objective was to detect a difference in the Dkk1 expression pattern in healthy subjects when compared to pathological state. To elucidate the cell specificity of Dickkopf-1 (Dkk1) in healthy bones, samples from female Sprague-Dawley rats were tested against two different antibodies with the two most widely accepted visualization system (ABC and Envision). The findings show Dkk1 specificity predominantly for osteoblasts, chondrocytes and osteocytes depending upon the antibody used. In addition, Dkk1 expression was evaluated in different cells of human osteoarthritis (OA) and rheumatoid arthritis (OA) patients. Its overexpression in pathologic state also suggests the role of Dkk1 in bone formation. This is scientifically and clinically important in studying the effect of Dkk1 in bone healing and in designing treatments for patients with compromised bone status. Taking into consideration the paradigm that cartilage and subchondral bone behave as an interconnected functional unit, normalization of cell behaviour in one compartment may have benefits in both tissues.

Intracellular proliferation of S. aureus in osteoblasts and effects of rifampicin and gentamicin on S. aureus intracellular proliferation and survival.

Staphylococcus aureus is the most clinically relevant pathogen regarding implant-associated bone infection and its capability to invade osteoblasts is well known. The aim of this study was to investigate firstly whether S. aureus is not only able to invade but also to proliferate within osteoblasts, secondly to delineate the mechanism of invasion and thirdly to clarify whether rifampicin or gentamicin can inhibit intracellular proliferation and survival of S. aureus. The SAOS-2 osteoblast-like cell line and human primary osteoblasts were infected with S. aureus EDCC5055 and S. aureus Rosenbach 1884. Both S. aureus strains were able to invade efficiently and to proliferate within human osteoblasts. Immunofluorescence microscopy showed intracellular invasion of S. aureus and transmission electron microscopy images could demonstrate bacterial division as a sign of intracellular proliferation as well as cytosolic bacterial persistence. Cytochalasin D, the major actin depolymerisation agent, was able to significantly reduce S. aureus invasion, suggesting that invasion was enabled by promoting actin rearrangement at the cell surface. 7.5 µg/mL of rifampicin was able to inhibit bacterial survival in SAOS-2 cells with almost complete elimination of bacteria after 4 h. Gentamicin could also kill intracellular S. aureus in a dose-dependent manner, an effect that was significantly lower than that observed using rifampicin. In conclusion, S. aureus is not only able to invade but also to proliferate in osteoblasts. Invasion seems to be associated with actin rearrangement at the cell surface. Rifampicin is effective in intracellular eradication of S. aureus whereas gentamicin only poorly eliminates intracellularly replicating bacteria.

Cholinergic nerve fibers in bone defects of a rat osteoporosis model and their regulation by implantation of bone substitution materials.

OBJECTIVES: Bone is innervated by autonomic nervous system that consists of sympathetic and parasympathetic nerves that were recently identified in bone. Thus we asked whether parasympathetic nerves occur in bone defects and at the interface of substitution materials that were implanted for stabilization and improvement of healing in an osteoporosis animal model. METHODS: Osteoporosis was induced in rats by ovariectomy and deficiency diet. A wedge-shaped osteotomy was performed in the metaphyseal area of femur. Eight different implants were inserted that were based on calcium phosphate cement, iron, silica-mineralized collagen, and modifications with strontium. Nerves were identified by immunohistochemistry with antibodies against vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH) and protein gene product 9.5 (PGP 9.5) as neuronal marker. RESULTS: Cholinergic nerves identified with VAChT immunostaining were detected in defects filled with granulation tissue and in surrounding mast cells. No immunolabeling of cholinergic nerves was found after implantation. The general presence of nerves was reduced after implantation as shown by PGP 9.5. Sympathetic nerves identified by TH immunolabeling were increased in strontium functionalized materials. CONCLUSION: Since cholinergic innervation was diminished after implantation a further increase in the compatibility of substitution materials to nerves could improve defect healing especially in osteoporotic bone.

Nanosilver/DCOIT-containing surface coating effectively and constantly reduces microbial load in emergency room surfaces.

BACKGROUND: Colonization of near-patient surfaces in hospitals plays an important role as a source of healthcare-associated infections. Routine disinfection methods only result in short-term elimination of pathogens. AIM: To investigate the efficiency of a newly developed antimicrobial coating containing nanosilver in long-term reduction of bacterial burden in hospital surfaces to close the gap between routine disinfection cycles. METHODS: In this prospective, double-blinded trial, frequently touched surfaces of a routinely used treatment room in an emergency unit of a level-I hospital were treated with a surface coating (nanosilver/DCOIT-coated surface, NCS) containing nanosilver particles and another organic biocidal agent (4,5-dichloro-2-octyl-4-isothiazolin-3-one, DCOIT), whereas surfaces of another room were treated with a coating missing both the nanosilver- and DCOIT-containing ingredient and served as control. Bacterial contamination of the surfaces was examined using contact plates and liquid-based swabs daily for a total trial duration of 90 days. After incubation, total microbial counts and species were assessed. FINDINGS: In a total of 2880 antimicrobial samples, a significant reduction of the overall bacterial load was observed in the NCS room (median: 0.31 cfu/cm2; interquartile range: 0.00-1.13) compared with the control coated surfaces (0.69 cfu/cm2; 0.06-2.00; P < 0.001). The nanosilver- and DCOIT-containing surface coating reduced the relative risk of a critical bacterial load (defined as >5 cfu/cm2) by 60% (odds ratio 0.38, P < 0.001). No significant difference in species distribution was detected between NCS and control group. CONCLUSION: Nanosilver-/DCOIT-containing surface coating has shown efficiency for sustainable reduction of bacterial load of frequently touched surfaces in a clinical setting.

Silver-coated versus uncoated locking plates in subjects with fractures of the distal tibia: a randomized, subject and observer-blinded, multi-center non-inferiority study.

BACKGROUND: Antimicrobial coatings of implants are of interest to reduce infection rate in orthopedic surgery. Demonstration of clinical effectiveness of such coated implants to obtain market approval is challenging. The objective of this article is to define a design for a randomized controlled trial to evaluate the clinical performance of a silver-coating for locking plates for fracture treatment. METHODS: The study design has to respect different criteria, such as feasibility, focus on overall complications, such as functional impairment, fracture healing, and particularly on infection rates. Distal tibia fractures were chosen due to the high prevalence of infections in this type of injuries, which warrants a particular benefit of antimicrobial prophylaxis and thus might allow to see a statistical trend in favor of the coated product. The study design was defined as a randomized, controlled, subject and observer-blinded, multi-center study in subjects with fractures of the distal tibia with a total of 226 patients. A number of 113 patients are planned for each of the two treatment arms with treatment of the fracture with a silver-coated device (first arm) or with an uncoated device (second arm). Inclusion criteria are closed fractures of the distal tibia according to the Tscherne-Oestern classification or open fractures of the distal tibia according to the Gustilo-Anderson classification in subjects older than 18 years. Primary outcome parameter is the Anticipated Adverse Device Effects (AADE) including all typical complications of this type of injury, such as functional impairment of the affected limb, non-union, and infections based on a non-inferiority study design. Also, silver-typical complications, such as argyria, are included. Secondary parameters are infection rates and fracture healing. Follow-up of patients includes five visits with clinical and X-ray evaluations with a follow-up time of 12 months. DISCUSSION: Demonstration of clinical effectiveness of antimicrobial coatings of fracture fixation devices remains a challenge. Definition of a prospective randomized pre-market trial design and recruitment of clinical sites for such a study is possible. A confirmative proof of the expected clinical benefit in terms of reduction of device-related infections will be addressed with a prospective post-market clinical follow-up study in a second step due to the large sample size required. TRIAL REGISTRATION: ClinicalTrials.gov NCT05260463. Registered on 02 March 2022.

[Patient consent for the TraumaRegistry DGU based on the GDPR-A challenge for the hospitals: status quo and solution strategies]. / Patienteneinwilligungen für das TraumaRegister DGU® aufgrund der EU-Datenschutz-Grundverordnung (EU-DSGVO) ­ Eine Herausforderung für die Kliniken: Status quo und Lösungsstrategien.

According to the General Data Protection Regulation (GDPR 05/2018), anonymized data sets with a sufficiently high data density are classified as traceable and require a declaration of consent if they are evaluated centrally for research or quality control purposes. Quality assurance and further increases in the quality of care are, however, only possible with a nearly complete survey of seriously injured persons in the sense of health services research. The more than 600 German clinics that take part in the TraumaRegistry DGU® try to obtain the declarations of consent from this special patient population. The study clinic evaluated the rate of consent and the reasons for rejection or failure to obtain consent over a 12-month period. While using a resource-intensive workflow especially for patient education and obtaining the consent, a patient consent rate of 64.5% and an error rate of 35.5% were recorded. Of the 276 potential TraumaRegistry DGU® data records 98 could not be entered and were therefore neither available for quality control nor for multiple trauma research. In order to guarantee the quality control and the further improvement of the quality of care, an approximate total recording of the patient population is necessary; however, this cannot be achieved by requiring a declaration of consent. We therefore advocate creating the possibility of collecting the TraumaRegistry data set without consent, as this ultimately represents a standard data set, comparable to the Hospital Remuneration Act (§21-KHEntgG) data set but pseudonymised.

[Operative treatment of rhizarthritis: comparison of ligament reconstruction according to Epping with trapezectomy and interposition of pyrocarbon spacers as replacement of the trapezium]. / Operative Versorgung der Rhizarthrose: Vergleich der Resektionssuspensionsarthroplastik mit der Trapezektomie und Interposition eines Pyrocarbonspacers als Trapeziumersatz.

BACKGROUND: Rhizarthritis is the most common form of arthritis of the hand with a frequency of 10% and conservative as well as surgical methods of treatment are available. The aim of this study was to compare the results of resection suspension arthroplasty according to Epping with trapezium replacement using pyrocarbon spacers. MATERIAL AND METHODS: Between January 2001 and December 2008 a total of 84 patients were surgically treated for rhizarthritis in our clinic. Of these patients 12 were treated with other surgical procedures, 40 with resection suspension arthroplasty according to Epping and 32 with pyrocarbon spacers as trapezium replacement. The patients were examined in a retrospective study and success of treatment was evaluated according to the Buck-Gramcko criteria. RESULTS: According to the evaluation criteria over 80% of patients in both collectives achieved very good or good operative results with the same degree of satisfaction. CONCLUSION: The results of this study confirm the value of resection suspension arthroplasty according to Epping for surgical treatment of rhizarthritis. Using trapezectomy with interposition of pyrocarbon spacers good or very good results can be achieved in the majority of cases. Essential points of criticism are the current material cost of 930 Euros and 4 dislocations in our collective but with good multiaxial movement and loading capacity. Comparable results using alternative procedures indicate that the results of further studies and long-term results will be decisive for establishment of this operational procedure.

[Intramedullary nailing of periprosthetic femoral fractures after revision for total knee endoprosthesis. Treatment of periprosthetic femoral fractures by inserted knee endoprostheis with intramedullary shaft by in situ lengthening of the prosthesis with specially prepared slotted hollow nails]. / Marknagelung periprothetischer Femurfrakturen nach Revisions-Knietotalendoprothese. Behandlung periprothetischer Femurfrakturen bei einliegender Knieendoprothese mit intramedullärem Stiel durch In-situ-Verlängerung der Prothese mit einem sonderangefertigten geschlitzten Hohlnagel.

BACKGROUND: With the increasing number of revision operations after knee replacement a growing incidence of periprosthetic femoral fractures which are difficult to treat is observed. MATERIAL AND METHODS: This retrospective study describes the operating procedure for osteosynthetic treatment of periprosthetic femoral fractures using a specially made slotted hollow nail which is engrafted with the purpose of in-situ lengthening of the prosthesis and thus becomes stably clamped. From 1999 to 2008 our patients have included 9 who were treated by this method. There were 5 male and 4 female patients with an average age of 63.4 years (range 47­80 years). Prerequisites for the performance of this operation are stability of the prosthesis and knowledge of the type of prosthesis or exact preoperative planning based on CT measurement of the thickness and length relationships. RESULTS: It was possible to conduct a clinical and radiological follow-up examination of all 9 patients after an average time of 29.1 months (range 10­64 months). In all cases load-bearing stabilization of the fracture was confirmed. CONCLUSION: In-situ coupling of an endoprosthesis with a slotted hollow nail represents a valuable treatment option for periprosthetic fractures.

[Acute compartment syndrome of the lower leg as an interdisciplinary complication after long duration intervention in the lithotomy position]. / Das lagerungsbedingte Kompartmentsyndrom des Unterschenkels als Komplikation nach Eingriffen in Steinschnitt-Position.

INTRODUCTION: The positioning-related compartment syndrome of the lower leg after long-duration operations in the lithotomy position -represents a rare complication. The aim of this retrospective study was to draft recommendations to avoid this rare complication by reviewing the cases with positioning-related compartment syndromes in our own patient data. PATIENTS / MATERIAL AND METHODS: From January 1996 to February 2009, 3 women and 1 man with an average age of 38 years (24 to 55 years) were treated with a medial and lateral dermatofasciotomy with opening of lower leg loges due to a clinically manifested compartment syndrome of the -lower leg after long-duration operations in the -lithotomy position. RESULTS: In all 4 patients a dermatofasciotomy with opening of the lower leg compartments could -avoid considerable secondary damage of the limb. A long-duration lithotomy position in connection with obesity, a low positioning of the head as well as nicotine abuse are only some of the risk factors contributing to the development of a positioning-related compartment syndrome. An epidural anaesthesia bears the risk of a protracted diagnosis. CONCLUSION: The positioning-related compartment syndrome represents a rare but considerable complication after long-duration operations in the -lithotomy position. It is a clinical complication and the inducing and exponentiation risk factors as well as the clinical symptoms should be known by the treating team. If the operation time is expected to be longer than 3 hours, we recommend written information to the patient concerning this complication. Consequent postoperative controls of risk patients are obligatory. An epidural anaesthesia bears the risk of a protracted diagnosis. In the case of suspected compartment syndrome we recommend early dermatofasciotomy in order to avoid -irreversible damage to the limb.

Colloid, adhesive and release properties of nanoparticular ternary complexes between cationic and anionic polysaccharides and basic proteins like bone morphogenetic protein BMP-2.

Herein we describe an interfacial local drug delivery system for bone morphogenetic protein 2 (BMP-2) based on coatings of polyelectrolyte complex (PEC) nanoparticles (NP). The application horizon is the functionalization of bone substituting materials (BSM) used for the therapy of systemic bone diseases. Nanoparticular ternary complexes of cationic and anionic polysaccharides and BMP-2 or two further model proteins, respectively, were prepared in dependence of the molar mixing ratio, pH value and of the cationic polysaccharide. As further proteins chymotrypsin (CHY) and papain (PAP) were selected, which served as model proteins for BMP-2 due to similar isoelectric points and molecular weights. As charged polysaccharides ethylenediamine modified cellulose (EDAC) and trimethylammonium modified cellulose (PQ10) were combined with cellulose sulphatesulfate (CS). Mixing diluted cationic and anionic polysaccharide and protein solutions according to a slight either anionic or cationic excess charge colloidal ternary dispersions formed, which were cast onto germanium model substrates by water evaporation. Dynamic light scattering (DLS) demonstrated, that these dispersions were colloidally stable for at least one week. Fourier Transform Infrared (FTIR) showed, that the cast protein loaded PEC NP coatings were irreversibly adhesive at the model substrate in contact to HEPES buffer and solely CHY, PAP and BMP-2 were released within long-term time scale. Advantageously, out of the three proteins BMP-2 showed the smallest initial burst and the slowest release kinetics and around 25% of the initial BMP-2 content were released within 14days. Released BMP-2 showed significant activity in the myoblast cells indicating the ability to regulate the formation of new bone. Therefore, BMP-2 loaded PEC NP are suggested as novel promising tool for the functionalization of BSM used for the therapy of systemic bone diseases.

Economic considerations for the use of recombinant human bone morphogenetic protein-2 in open tibial fractures in Europe: the German model.

The addition of recombinant human bone morphogenetic protein (rhBMP-2) to the standard of care, consisting of soft tissue management and intramedullary nailing, in the BMP-2 Evaluation in Surgery for Tibial Trauma (BESTT) study led to a significantly better outcome for the patient. Reductions in fracture healing time, secondary interventions for delayed fracture healing and infection rates were observed with 1.50 mg/mL rhBMP-2 compared with the standard of care alone. In Germany the approximate cost of applying one dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) to an open tibial fracture is euro2970. The current German-Diagnosis-Related Group reimbursement system provides one flat rate per hospital stay or treatment case, and does not take into account the costs of rhBMP-2 application. Therefore there is no reimbursement for the price of rhBMP-2 for hospitals by health insurance companies. However, the above mentioned improvements in medical outcome could lead to important savings for health care systems, particularly for health insurance companies. A sound economic model to assess the cost-effectiveness and budget impact of rhBMP-2 is required. Using medical data from the BESTT study the differences in fracture healing time, in reduction of secondary interventions for fracture healing and infection treatment can be transferred into economic savings. It is anticipated that the overall savings that can be achieved by rhBMP-2 treatment in open tibia fractures, offset the upfront price of rhBMP-2 and lead to net savings for health insurance companies.

Suprapatellar nailing of tibial fractures-Indications and technique.

Intramedullary nailing is the standard procedure for surgical treatment of closed and Gustilo-Anderson Grade I-II° open fractures of the tibial shaft. The use of intramedullary nailing for the treatment of proximal metaphyseal tibia fractures is frequently followed by postoperative malalignment, whereas plate osteosynthesis is associated with higher rates of postoperative infection. Intramedullary nailing of tibial fractures is generally performed through an infrapatellar approach. The injured extremity must be positioned at a minimum of 90° of flexion in the knee joint to achieve optimal exposure of the correct entry point. The tension of the quadriceps tendon causes a typical apex anterior angulation of the proximal fragment. The suprapatellar approach improves reduction of the fracture and reduces the occurrence of malalignment during intramedullary nailing of extra-articular proximal tibial fractures. The knee is positioned in 20° of flexion to neutralise traction forces secondary to the quadriceps muscle, thus preventing an apex anterior angulation of the proximal fragment. An additional advantage of the technique is that it allows the surgeon to avoid or minimise further soft tissue damage because of the distance between the optimal incision point and the usual area of soft tissue damage.

Fixation performance of an ultrasonically fused, bioresorbable osteosynthesis implant: A biomechanical and biocompatibility study.

Bioresorbable implants may serve as an alternative option for the fixation of bone fractures. Because of their minor inherent mechanical properties and insufficient anchorage within bone bioresorbable implants have so far been limited to mechanically nondemanding fracture types. By briefly liquefying the surface of the biomaterial during insertion, bioresorbable implants can be ultrasonically fused with bone to improve their mechanical fixation. The objective of this study was to investigate the biomechanical fixation performance and in vivo biocompatibility of an ultrasonically fused bioresorbable polymeric pin (SonicPin). First, we biomechanically compared the fused pin with press fitted metallic and bioresorbable polymeric implants for quasi-static and fatigue strength under shear and tensile loading in a polyurethane foam model. Second, fused implants were inserted into cancellous bovine bone and tested biomechanically to verify the reproducibility of their fusion behavior. Finally, the fused pins were tested in a lapine model of femoral condyle osteotomies and were histologically examined by light and transmission electron microscopy. While comparable under static shear loads, fixation performance of ultrasonically fused pins was significantly (p = 0.001) stronger under tensile loading than press fit implants and showed no pull-out. Both bioresorbable implants withstood comparable fatigue shear strength, but less than the K-wire. In bovine bone the ultrasonic fusion process worked highly reproducible and provided consistent mechanical fixation. In vivo, the polymeric pin produced no notable foreign body reactions or resorption layers. Ultrasonic fusion of polymeric pins achieved adequate and consistent mechanical fixation with high reproducibility and exhibits good short-term resorption and biocompatibility.