Histological score for degrees of severity in an implant-associated infection model in mice.

INTRODUCTION: Several scores were introduced to diagnose and to classify osteomyelitis in practice. Mouse models are often used to study the pathophysiology of bone infection and to test therapeutic strategies. Aim of the present study was to design a score to diagnose and quantify implant-associated infection in a murine experimental model. MATERIALS AND METHODS: Four independent parameters were developed: existence of callus, consolidation of the fracture, structural changes of the medullary cavity and number of bacteria. The score was assessed in a standardized implant-associated mouse model with 35 BALB/c-mice. The left femur was osteotomized, fixed by a titanium locking plate and infection was induced by inoculation of Staphylococcus aureus into the fracture gap. For the sham group, the procedure was performed without inoculation of bacteria. The score was assessed on days 7, 14 and 28. Each item of the score showed lower values for the infection group compared to the controls after 4 weeks. RESULTS: Regardless of the assessed time point, the overall total score was significantly higher in the control group compared to the infection group (p < 0.0001). Analysis revealed a sensitivity of 0.85, specificity of 1.0, negative predictive value of 0.67 and positive predictive value of 1.0. CONCLUSION: The proposed score assessing severity of fracture-related infection in an implant-associated murine model was easy to access, feasible to diagnose and estimate bone healing and infection in a murine bone infection with a high sensitivity. Therefore, this score might be a useful tool to quantify infection-related changes after fracture in further future preclinical studies.

Inflammation and vascularisation markers of arthroscopically-guided finger joint synovial biospies reflect global disease activity in rheumatoid arthritis.

OBJECTIVES: To analyse whether synovial markers of the clinically dominant metacarpophalangeal (MCP) joint reflect global disease activity measures in rheumatoid arthritis (RA). METHODS: Arthroscopically-guided synovial biopsies from the dominant metacarpophalangeal (MCP) joint of 10 patients with RA (DAS28 >3.2) were stained for determination of the synovitis score, CD68, vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1α (HIF-1α). MRI and ultrasound were used to calculate the RAMRIS and US7 score respectively. Arthroscopy of the same joint was repeated in 6 patients after 6 months. RESULTS: The synovitis score significantly correlated to DAS28 (Spearman r=0.74), CRP (r=0.69), and US7 (r=0.66); sublining CD68 macrophages to CRP (r=0.6); HIF-1α to DAS28 (r=0.77), CRP (r=0.73); and VEGF to DAS28 (r=0.753) and RAMRIS (r=0.663). All patients showed a reduction of the DAS28 after 6 months (mean±SD: 5.2±1.5 vs. 2.75±1.1; p<0.05). There were three patients with a good EULAR response, and only these showed declining sublining CD68 macrophages in the control biopsy (χ2 test: LR 8.3, p=0.05). Two of the remaining patients with increasing CD68 sublining macrophages showed a deterioration of the RAMRIS. CONCLUSIONS: Some histological findings in arthroscopically-guided biopsies of the dominantly affected MCP joint reflect global disease activity measures and their changes in RA patients. Moreover, repeated MCP synovial biopsy may distinguish true responders from individuals with residual disease activity, who are not readily recognized by clinical means.

[Scaphoid fractures : Current diagnostic and treatment concepts]. / Skaphoidfrakturen : Aktuelle diagnostische und therapeutische Konzepte.

Scaphoid fractures are by far the most frequent fractures of the carpal bones of the hand and often lead to problematic healing processes if the diagnostics and treatment are inadequate. The main complication of a scaphoid fracture is pseudarthrosis, which leads to carpal collapse and degenerative arthritis of the wrist if left untreated. Early diagnosis and individualized differentiated treatment aim to achieve bony healing with restoration of the scaphoid shape and preservation of the function of the wrist. The anatomical and biomechanical characteristics of the scaphoid can impede bony healing after a fracture and, in contrast to the diagnostics and treatment, cannot be influenced. A history of trauma and typical clinical signs of a scaphoid fracture should lead to systematic imaging diagnostics with obligatory computed tomography. Only by determining the exact fracture morphology can an appropriate treatment concept be established. Conservative treatment should be restricted to stable fractures without relevant displacement. Fractures of the proximal scaphoid pole are considered unstable even if they are not displaced. Operative treatment is indicated for all unstable fractures. The favored surgical procedure is osteosynthesis with a cannulated double-threaded screw, which can be used in a retrograde or antegrade manner and in a minimally invasive or open technique, depending on the fracture type. Surgical treatment results in earlier bony healing and quicker restoration of function but can be associated with a higher complication rate. Posttraumatic osteoarthritis after healing in malalignment is usually asymptomatic.

Molecular mechanisms underlying delayed apoptosis in neutrophils from multiple trauma patients with and without sepsis.

Delayed neutrophil apoptosis and overshooting neutrophil activity contribute to organ dysfunction and subsequent organ failure in sepsis. Here, we investigated apoptotic signaling pathways that are involved in the inhibition of spontaneous apoptosis in neutrophils isolated from major trauma patients with uneventful outcome as well as in those with sepsis development. DNA fragmentation in peripheral blood neutrophils showed an inverse correlation with the organ dysfunction at d 10 after trauma in all patients, supporting the important role of neutrophil apoptosis regulation for patient's outcome. The expression of the antiapoptotic Bcl-2 protein members A1 and Mcl-1 were found to be diminished in the septic patients at d 5 and d 10 after trauma. This decrease was also linked to an impaired intrinsic apoptosis resistance, which has been previously shown to occur in neutrophils during systemic inflammation. In patients with sepsis development, delayed neutrophil apoptosis was found to be associated with a disturbed extrinsic pathway, as demonstrated by reduced caspase-8 activity and Bid truncation. Notably, the expression of Dad1 protein, which is involved in protein N-glycosylation, was significantly increased in septic patients at d 10 after trauma. Taken together, our data demonstrate that neutrophil apoptosis is regulated by both the intrinsic and extrinsic pathway, depending on patient's outcome. These findings might provide a molecular basis for new strategies targeting cell death pathways in apoptosis-resistant neutrophils during systemic inflammation.

Depletion of neutrophil extracellular traps in vivo results in hypersusceptibility to polymicrobial sepsis in mice.

INTRODUCTION: Although the formation of neutrophil (PMN) extracellular traps (NETs) has been detected during infection and sepsis, their role in vivo is still unclear. This study was performed in order to evaluate the influence of NETs depletion by administration of recombinant human (rh)DNase on bacterial spreading, PMN tissue infiltration and inflammatory response in a mouse model of polymicrobial sepsis. METHODS: In a prospective controlled double-armed animal trial, polymicrobial sepsis was induced by cecal ligation and puncture (CLP). After CLP, mice were treated with rhDNase or phosphate buffered saline, respectively. Survival, colony forming unit (CFU) counts in the peritoneal cavity, lung, liver and blood were determined. PMN and platelet counts, IL-6 and circulating free (cf)-DNA/NETs levels were monitored. PMN infiltration, as well as organ damage, was analyzed histologically in the lungs and liver. Capability and capacity of PMN to form NETs were determined over time. RESULTS: cf-DNA/NETs were found to be significantly increased 6, 24, and 48 hours after CLP when compared to the levels determined in sham and naïve mice. Peak levels after 24 hours were correlated to enhanced capacity of bone marrow-derived PMN to form NETs after ex vivo stimulation with phorbol-12-myristate-13-acetate at the same time. rhDNase treatment of mice resulted in a significant reduction of cf-DNA/NETs levels 24 hours after CLP (P < 0.001). Although overall survival was not affected by rhDNase treatment, median survival after 24 hours was significantly lower when compared with the CLP group (P < 0.01). In mice receiving rhDNase treatment, CFU counts in the lung (P < 0.001) and peritoneal cavity (P < 0.05), as well as serum IL-6 levels (P < 0.001), were found to be already increased six hours after CLP. Additionally, enhanced PMN infiltration and tissue damage in the lungs and liver were found after 24 hours. In contrast, CFU counts in mice without rhDNase treatment increased later but more strongly 24 hours after CLP (P < 0.001). Similarly, serum IL-6 levels peaked after 24 hours (P < 0.01). CONCLUSIONS: This study shows, for the first time, that depletion of NETs by rhDNase administration impedes the early immune response and aggravates the pathology that follows polymicrobial sepsis in vivo.

Deoxyribonuclease is a potential counter regulator of aberrant neutrophil extracellular traps formation after major trauma.

INTRODUCTION: Neutrophil extracellular traps (NET) consist of a DNA scaffold that can be destroyed by Deoxyribonuclease (DNase). Thus DNases are potential prerequisites for natural counter regulation of NETs formation. In the present study, we determined the relationship of NETs and DNase after major trauma. METHODS: Thirty-nine major trauma patients, 14 with and 25 without sepsis development were enrolled in this prospective study. Levels of cell-free (cf)-DNA/NETs and DNase were quantified daily from admission until day 9 after admission. RESULTS: Levels of cf-DNA/NETs in patients who developed sepsis were significantly increased after trauma. In the early septic phase, DNase values in septic patients were significantly increased compared to patients without sepsis (P < 0.05). cf-DNA/NETs values correlated to values of DNase in all trauma patients and patients with uneventful recovery (P < 0.01) but not in septic patients. Recombinant DNase efficiently degraded NETs released by stimulated neutrophils in a concentration-dependent manner in vitro. CONCLUSIONS: DNase degrades NETs in a concentration-dependent manner and therefore could have a potential regulatory effect on NET formation in neutrophils. This may inhibit the antibacterial effects of NETs or protect the tissue from autodestruction in inadequate NETs release in septic patients.

Mcl-1-mediated impairment of the intrinsic apoptosis pathway in circulating neutrophils from critically ill patients can be overcome by Fas stimulation.

The systemic inflammatory response syndrome and subsequent organ failure are mainly driven by activated neutrophils with prolonged life span, which is believed to be due to apoptosis resistance. However, detailed underlying mechanisms leading to neutrophil apoptosis resistance are largely unknown, and possible therapeutic options to overcome this resistance do not exist. Here we report that activated neutrophils from severely injured patients exhibit cell death resistance due to impaired activation of the intrinsic apoptosis pathway, as evidenced by limited staurosporine-induced mitochondrial membrane depolarization and decreased caspase-9 activity. Moreover, we found that these neutrophils express high levels of antiapoptotic Mcl-1 and low levels of proapoptotic Bax protein. Mcl-1 up-regulation was dependent on elevated concentrations of GM-CSF in patient serum. Accordingly, increased Mcl-1 protein stability and GM-CSF serum concentrations were shown to correlate with staurosporine-induced apoptosis resistance. However, cross-linking of neutrophil Fas by immobilized agonistic anti-Fas IgM resulted in caspase-dependent mitochondrial membrane depolarization and apoptosis induction. In conclusion, the observed impairment of the intrinsic pathway and the resulting apoptosis resistance may be overcome by immobilized agonistic anti-Fas IgM. Targeting of neutrophil Fas by immobilized agonistic effector molecules may represent a new therapeutic tool to limit neutrophil hyperactivation and its sequelae in patients with severe immune disorders.

Increased serum soluble Fas after major trauma is associated with delayed neutrophil apoptosis and development of sepsis.

INTRODUCTION: Deregulated apoptosis and overshooting neutrophil functions contribute to immune and organ dysfunction in sepsis and multiple organ failure (MOF). In the present study, we determined the role of soluble Fas (sFas) in the regulation of posttraumatic neutrophil extrinsic apoptosis and the development of sepsis. METHODS: Forty-seven major trauma patients, 18 with and 29 without sepsis development during the first 10 days after trauma, were enrolled in this prospective study. Seventeen healthy volunteers served as controls. Blood samples from severely injured patients were analyzed at day 1, day 5 and day 9 after major trauma. sFas levels, plasma levels of neutrophil elastase (PMNE) and levels of interleukin (IL)-6 were quantified by enzyme-linked immunosorbent assay and related to patients' Sequential Organ Failure Assessment (SOFA) score and Multiple Organ Dysfunction Score (MODS). Neutrophil apoptosis was determined by propidium iodide staining of fragmented DNA and flow cytometry. sFas-mediated effects on neutrophil apoptosis were investigated in cells cultured with agonistic anti-Fas antibodies in the presence of recombinant sFas, sFas-depleted serum or untreated serum from septic patients. RESULTS: Serum levels of sFas in patients who later developed sepsis were significantly increased at day 5 (P < 0.01) and day 9 (P < 0.05) after trauma compared with patients with uneventful recovery. Apoptosis of patient neutrophils was significantly decreased during the observation period compared with control cells. Moreover, Fas-mediated apoptosis of control neutrophils was efficiently inhibited by recombinant sFas and serum from septic patients. Depletion of sFas from septic patient sera diminished the antiapoptotic effects. In septic patients, sFas levels were positively correlated with SOFA at day 1 (r = 0.7, P < 0.001), day 5 (r = 0.62, P < 0.01) and day 9 (r = 0.58, P < 0.01) and with PMNE and leukocyte counts (r = 0.49, P < 0.05 for both) as well as MODS at day 5 (r = 0.56, P < 0.01) after trauma. CONCLUSIONS: Increased sFas in patients with sepsis development impairs neutrophil extrinsic apoptosis and shows a positive correlation with the organ dysfunction scores and PMNE. Therefore, sFas might be a therapeutic target to prevent posttrauma hyperinflammation and sepsis.

Osteoarthritis of the distal interphalangeal joint.

Osteoarthritis occurs with the highest prevalence in the distal interphalangeal joint of the hand and has been divided into an erosive and a nonerosive form. The pathogenesis of the early stages of osteoarthritis is poorly understood, but considerable emphasis has been placed on the role of cartilage and subchondral bone as well as soft tissue structures such as collateral ligaments and tendons. Radiographic evaluation represents the most standardized method to quantify disease progression, with different systems having been developed for defining and grading radiographic features. This current concepts article examines the recent knowledge base regarding the etiology, pathogenesis, and evaluation of osteoarthritis of the distal interphalangeal joint.

The influence of talonavicular versus double arthrodesis on load dependent motion of the midtarsal joint.

BACKGROUND: Today the most frequently used operative procedures in advanced arthritis of the hindfoot joints are isolated talonavicular arthrodesis and double arthrodesis (involving the talonavicular and calcaneocuboid joints, i.e. the Chopart joint). This in vitro study investigates whether the fusion of the talonavicular joint alone can provide the hindfoot, as well as a midfoot, with comparable biomechanical stability as the double arthrodesis does. Hence with the less-invasive intervention the same benefit in terms of pain reduction and better functionality could be achieved. METHODS: In a series of ten fresh cadaver feet without any radiological pathologies, we measured the range of motion of different tarsal bones in three planes under axial stress. Every foot was loaded without arthrodesis, after talonavicular and after double arthrodesis, by charging tibia and fibula with a force of 350 N using a calibrated Instron® load frame. Each tarsal bone was marked with a K-wire and its motion was measured by registering the movement of the wire's shade that was projected onto the surrounding walls of the trial box. RESULTS: Both operative procedures led to a considerable reduction of the motion of every marked bone to a mean of 18% of the preoperative value. In direct comparison of the two simulated arthrodeses we found for every bone and in every plane only minimal differences of the mean excursions of 1.0 mm on average. Both fusions lead to equal residual tarsal bone motion postoperatively, and provide the midtarsal joint as well as the subtalar joint with comparable biomechanical stability. CONCLUSIONS: Isolated talonavicular arthrodesis is a useful and effective alternative to double arthrodesis. It is the less complicated, less-invasive and functionally equivalent operative option for arthritic alterations of the hindfoot and transverse tarsal joint.

Extracorporeal cell therapy with granulocytes in a pig model of Gram-positive sepsis.

OBJECTIVES: Granulocyte transfusions have been used to treat immune cell dysfunction in sepsis. As granulocyte transfusions can trigger tissue injury via local effects of neutrophils, we hypothesized that extracorporeal treatment of plasma using granulocytes would prove beneficial while having less side effects. DESIGN: Prospective controlled three-armed animal study. SETTING: Research laboratory. SUBJECTS: Twenty-one female immature pigs (7.5-12 kg, 7-9 weeks old). INTERVENTIONS: Three groups of spontaneously breathing, sedated pigs (n = 7 each) received an intravenous lethal dose of live Staphylococcus aureus over 1 hour. Although group I had no specific treatment (control), group II and III were subsequently treated for 4 hours with an extracorporeal device containing either no cells (sham control, group II) or human cell line-derived granulocytic cells (group III). Survival time and physiologic, biochemical, and hematologic parameters were monitored for 7 days. MEASUREMENTS AND MAIN RESULTS: All animals of group I died during the observation time (mean survival time: 70 hours). In group II, two of seven and in group III, six of seven animals survived the observation time (mean survival: 75 and 168 hours, respectively). Survival differences were significant between group I and III (p < 0.001) and between group II and III (p < 0.05) but not between group I and II (p = 0.43). Furthermore, group differences in bacterial blood concentrations, differential blood count, blood gases, lactate, and interleukins were observed. The extracorporeal cell treatment was well tolerated by the animals. CONCLUSIONS: Extracorporeal therapy with granulocytic cells significantly improved survival in a pig model of sepsis. Further studies with this approach are encouraged.

The clinical value of neutrophil extracellular traps.

Neutrophil extracellular traps (NETs) have recently been discovered as a central part of antimicrobial innate immunity. In the meanwhile, evidence accumulated that NETs are also generated upon non-infectious stimuli in various clinical settings. In acute or chronic inflammatory disorders aberrantly enhanced NET formation and/or decreased NET degradation seems to correlate with disease outcome. This review summarizes current knowledge about the relation of NETs in a broad spectrum of clinical settings. Specifically, we focus on the importance of NETs as a predictive marker in severely ill patients and further, we speculate about the potential pathophysiology of NETs.

Blue light irradiation and its beneficial effect on Dupuytren's fibroblasts.

Dupuytren's contracture is a fibroproliferative disorder affecting the palmar fascia of the hand. Most affected are the ring fingers, and little fingers of middle-aged men. Symptomatic for this disease is the increased proliferation and differentiation of fibroblasts to myofibroblasts, which is accompanied by an elevated α-SMA expression. The present study evaluated the therapeutic benefit of blue light (λ = 453 nm, 38 mW/cm2, continuous radiance, spot size 10-12 cm2) as well as the molecular mechanism mediating this effect. It could be determined that blue light significantly diminished the induced α-SMA protein expression in both normal palmar fibroblasts and Duypuytren's fibroblasts. The beneficial effect mediated by this irradiance, radiant exposure and wavelength was associated with an elevated reactive oxygen species generation. Furthermore, the data underlines the potential usefulness of blue light irradiation as a promising therapy option for Dupuytren's disease, especially for relapse prevention, and may represent a useful strategy to treat further fibrotic diseases, such as keloids, hypertrophic scarring, and scleroderma.

Axillary nerve palsy after retrograde humeral nailing: clinical confirmation of an anatomical fear.

INTRODUCTION: Locked antegrade or retrograde nailing of humeral shaft and proximal humerus fractures is a well established treatment option. Anatomic-morphological studies revealed a potential high risk of axillary nerve injury within proximal interlocking screw insertion. However, clinical experiences do not seem to confirm this, as there is a lack of interlocking screw insertion associated axillary lesions in literature. CASE REPORT: We report about a 69-year-old man with a humeral shaft fracture (AO-type 12-A3) stabilized by a retrograde implanted interlocking nail. Proximal interlocking screw insertion was performed in a posterior-to-anterior direction. The fracture healed uneventfully. In a follow-up examination 2 years later, an atrophy and paralysis of the deltoid muscle were visible. Electrophysiological evaluation confirmed an isolated axillary nerve injury. Nevertheless, the patient showed good functional recovery with almost free range of motion. CONCLUSION: Even for clinical practise proximal interlocking screw insertion is associated with a substantial risk of axillary nerve injury. Particularly for posterior-to-anterior screw insertion anatomic conditions should be considered. In spite of axillary nerve lesion, recovery of almost full shoulder function is possible by compensating the loss of deltoid function by rotator cuff muscles.

Proximal Phalanx Fracture Management.

BACKGROUND: The goal of proximal phalangeal fracture management is to allow for fracture healing to occur in acceptable alignment while maintaining gliding motion of the extensor and flexor tendons. METHODS: We reviewed the most current literature on various treatment methods of proximal phalanx fractures, focusing on the indications and outcomes of nonoperative as well as operative interventions. RESULTS: Stable fractures can be successfully treated nonoperatively, whereas unstable injuries benefit from surgery. Regardless of the surgical intervention employed, the overriding goal is to restore anatomy and impart enough stability to allow for early motion. The surgical dissection contributes to soft tissue scarring and should be minimized. CONCLUSIONS: Clinical success is achieved when acceptable fracture alignment and stability occur in the setting of unobstructed tendon gliding and early active range of motion.

Effect of hyperbaric oxygen therapy (HBO) on implant-associated osteitis in a femur fracture model in mice.

Hyperbaric oxygen therapy (HBO) is applied very successfully in treatment of various diseases such as chronic wounds. It has been already suggested as adjunctive treatment option for osteitis by immune- and fracture modulating effects. This study evaluates the importance of HBO in an early implant-associated localized osteitis caused by Staphylococcus aureus (SA) compared to the standard therapy. In a standardized murine model the left femur of 120 BALB/c mice were osteotomized and fixed by a titanium locking plate. Osteitis has been induced with a defined amount of SA into the fracture gap. Debridément and lavages were progressed on day 7, 14, 28 and 56 to determine the local bacterial growth and the immune reaction. Hyperbaric oxygen (2 ATA, 90%) was applied for 90 minutes on day 7 to 21 for those mice allocated to HBO therapy. To evaluate the effect of HBO therapy the following groups were analyzed: Two sham-groups (12 mice / group) with and without HBO therapy, two osteotomy groups (24 mice / group) with plate osteosynthesis of the femur with and without HBO therapy, and two osteotomy SA infection groups (24 mice / group) with and without HBO therapy. Fracture healing was also quantified on day 7, 14, 28 and 56 by a.p. x-ray and bone healing markers from blood samples. Progression of infection was assessed by estimation of colony-forming units (CFU) and immune response was analyzed by determination of polymorphonuclear neutrophils (PMN), Interleukin (IL) - 6, and the circulating free DNA (cfDNA) in lavage samples. Osteitis induced significantly higher IL-6, cfDNA- and PMN-levels in the lavage samples (on day 7 and 14, each p < 0.05). HBO-therapy did not have a significant influence on the CFU and immune response compared to the standard therapy (each p > 0.05). At the same time HBO-therapy was associated with a delayed bone healing assessed by x-ray radiography and a higher rate of non-union until day 28. In conclusion, osteitis led to significantly higher bacterial count and infection parameters. HBO-therapy neither had a beneficial influence on local infection nor on immune response or fracture healing compared to the standard therapy in an osteitis mouse model.

Interprofessional education as part of becoming a doctor or physiotherapist in a competency-based curriculum.

INTRODUCTION: Interprofessional learning is a critical pre-requisite for future interprofessional work. Structural adaptations in education offer possibilities to introduce new concepts. Rheumatic and musculoskeletal diseases (RMD) are both prevented and treated by physicians and physiotherapists but the development of interprofessional roles is seldom part of curricula. PROJECT DESCRIPTION: A complex, longitudinal interprofessional educational approach for future doctors and physiotherapists was designed and implanted at various stages (anatomy, physical examination, pathology, therapy). Most segments of the RMD curriculum are now based on interprofessional classes. Student satisfaction with learning is continually and comparatively evaluated. Learning success is assessed with practical and written exams. RESULTS: Interprofessional teaching was first introduced in 2013 for 420 first-year and 360 fourth-year medical students, along with 40 first- and third-year physiotherapy majors. The satisfaction with teaching and learning is high and distinctly above average for all teaching areas (satisfaction RMD rated as 2.4; average for all is 3.3). The percentage of those who pass the final exam is 94%. 100% of the students surveyed support the continuation of this interprofessional unit. CONCLUSION: Interprofessional teaching of RMD can be successfully implemented for future physicians and physiotherapists at different learning levels.

Lysostaphin-coated titan-implants preventing localized osteitis by Staphylococcus aureus in a mouse model.

The increasing incidence of implant-associated infections induced by Staphylococcus aureus (SA) in combination with growing resistance to conventional antibiotics requires novel therapeutic strategies. In the current study we present the first application of the biofilm-penetrating antimicrobial peptide lysostaphin in the context of bone infections. In a standardized implant-associated bone infection model in mice beta-irradiated lysostaphin-coated titanium plates were compared with uncoated plates. Coating of the implant was established with a poly(D,L)-lactide matrix (PDLLA) comprising lysostaphin formulated in a stabilizing and protecting solution (SPS). All mice were osteotomized and infected with a defined count of SA. Fractures were fixed with lysostaphin-coated locking plates. Plates uncoated or PDLLA-coated served as controls. All mice underwent debridement and lavage on Days 7, 14, 28 to determine the bacterial load and local immune reaction. Fracture healing was quantified by conventional radiography. On Day 7 bacterial growth in the lavages of mice with lysostaphin-coated plates showed a significantly lower count to the control groups. Moreover, in the lysostaphin-coated plate groups complete fracture healing were observed on Day 28. The fracture consolidation was accompanied by a diminished local immune reaction. However, control groups developed an osteitis with lysis or destruction of the bone and an evident local immune response. The presented approach of terminally sterilized lysostaphin-coated implants appears to be a promising therapeutic approach for low grade infection or as prophylactic strategy in high risk fracture care e.g. after severe open fractures.

Dynamic contrast-enhanced magnetic resonance imaging of metacarpophalangeal joints reflects histological signs of synovitis in rheumatoid arthritis.

INTRODUCTION: Synovial inflammation and joint destruction in rheumatoid arthritis (RA) may progress despite clinical remission. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is increasingly used to detect synovial inflammation in RA. Although small joints such as metacarpophalangeal (MCP) joints are mainly affected by RA, MRI findings have never been directly compared to histological synovitis in MCP synovial tissue. The objective of the current study was therefore to analyse if DCE-MRI relates to histological signs of synovitis small RA joints. METHODS: In 9 RA patients, DCE-MRI (3 Tesla, dynamic 2D T1 weighted turbo-flash sequence) of the hand was performed prior to arthroscopically-guided synovial biopsies from the second MCP of the imaged hand. Maximum enhancement (ME), rate of early enhancement, and maximum rate of enhancement were assessed in the MCP. Synovial biopsies were stained for determination of sublining CD68 and the Synovitis Score. Correlations between MRI and histological data were calculated according to Spearman. RESULTS: ME of the MCP significantly correlated to sublining CD68 staining (r = 0.750, P = 0.02), the Synovitis Score (r = 0.743, P = 0.02), and the subscores for lining layer hypertrophy (r = 0.789, P = 0.01) and cellular density (r = 0.842; P = 0.004). CONCLUSIONS: Perfusion imaging of synovial tissue in RA finger joints employing DCE-MRI reflects histological synovial inflammation. According to our study, ME is the most closely associated parameter amongst the measures considered.

Implant-associated localized osteitis in murine femur fracture by biofilm forming Staphylococcus aureus: a novel experimental model.

Staphylococcus aureus (SA) is the most common causative agent for implant-associated osteitis. The present study characterizes a novel model of a low grade acute SA osteitis with bone defect in the femur which is stabilized by a titanium locking plate. Wild-type Balb/c mice were osteotomized, fixed by a locking plate and infected with SA. Mice underwent debridement 7 and 14 days later and were sacrificed at Day 28. At Days 7, 14, and 28 after inoculation local and systemic cell populations and IL-6 were analyzed. Fracture healing was quantified by radiography. The control group underwent the same procedure without infection. The bacterial load of implant-associated osteitis with biofilm formation was quantified by counting CFU and real-time PCR. Fracture healing determined by radiography was delayed in infected compared to non-infected mice. Throughout the investigation period CFU and leukocyte counts, as well as IL-6 levels were found to be significantly elevated in infected mice at the infection site but not systemically. Our murine model allows the detailed investigation of implant associated localized osteitis with biofilm producing SA and its influence on fracture healing. The model provides a tool to analyze therapeutic or prophylactic approaches to the problem of biofilm-associated osteitis.