Thomas Fuchs

A Novel Mouse Model of Staphylococcus aureus Chronic Osteomyelitis That Closely Mimics the Human Infection: An Integrated View of Disease Pathogenesis

Osteomyelitis is a serious bone infection typically caused by Staphylococcus aureus. The pathogenesis of osteomyelitis remains poorly understood, mainly for lack of experimental models that closely mimic human disease. We describe a novel murine model of metastatic chronic osteomyelitis initiated after intravenous inoculation of S. aureus microorganisms. The bacteria entered bones through the bloodstream and, after an acute phase with progressive growth (first 2 weeks after infection), they remained at constant numbers for up to 56 days (chronic phase). Clinical signs of illness and systemic inflammation were apparent only during the acute phase. Bone destruction and remodeling processes were readily detectable by magnetic resonance and X-ray imaging 3 weeks after infection, and high levels of bone deformation were observed during the chronic phase. Histological examination of infected bones demonstrated suppurative inflammation with foci of intense bacterial multiplication and necrosis during acute infection and osteoclastic resorption accompanied by new woven bone formation during chronic infection. Transmission electron microscopy revealed S. aureus microorganisms forming microcolonies within the nonmineralized collagen matrix or located intracellularly within neutrophils. In summary, our mouse model of staphylococcal hematogenous osteomyelitis precisely reproduces most features of the human disease. Although the extent of lesions in the chronic phase was subject to variation, this model is ideal for testing and monitoring novel treatment modalities via noninvasive imaging.

Beckenringfrakturen im Alter

The incidence of pelvic fractures at 0.3-8% is low compared to all fractures. Nevertheless, the number of pelvic fractures in the elderly is increasing. Due to the increased age of the patient differences in trauma mechanism, fracture pattern and therapy occur. Most pelvic fractures in the elderly are caused by low-energy trauma. This makes it difficult to find the right diagnosis especially in insufficiency fracture of the pelvis. The time until the right treatment is started is prolonged significantly. Elderly patients who suffer from a high-energy fracture have a significantly higher risk of haemorrhage. At the same time emergency stabilisation of the pelvis using a C-clamp is dangerous due to the special fracture morphology with transiliac instabilities and the combination with osteoporosis. Low-energy trauma leads to simple fractures of the pubis, which often can be treated without operation. In these cases fractures of the dorsal pelvic ring need to be excluded using CT scan. Fracture of the dorsal part of the pelvic ring such as insufficiency fractures of the sacrum should be stabilized by 3D-guided percutaneous iliosacral screw fixation to reduce pain and allow early mobilisation.

Pelvic ring fractures in the elderly. Underestimated osteoporotic fracture

The incidence of pelvic fractures at 0.3-8% is low compared to all fractures. Nevertheless, the number of pelvic fractures in the elderly is increasing. Due to the increased age of the patient differences in trauma mechanism, fracture pattern and therapy occur. Most pelvic fractures in the elderly are caused by low-energy trauma. This makes it difficult to find the right diagnosis especially in insufficiency fracture of the pelvis. The time until the right treatment is started is prolonged significantly. Elderly patients who suffer from a high-energy fracture have a significantly higher risk of haemorrhage. At the same time emergency stabilisation of the pelvis using a C-clamp is dangerous due to the special fracture morphology with transiliac instabilities and the combination with osteoporosis. Low-energy trauma leads to simple fractures of the pubis, which often can be treated without operation. In these cases fractures of the dorsal pelvic ring need to be excluded using CT scan. Fracture of the dorsal part of the pelvic ring such as insufficiency fractures of the sacrum should be stabilized by 3D-guided percutaneous iliosacral screw fixation to reduce pain and allow early mobilisation.

Periprosthetic fractures. An interdisciplinary challenge

ZusammenfassungDie demografische Entwicklung und zunehmende Anzahl implantierter Gelenkendoprothesen zusammen mit einer erhöhten Mobilität und Aktivität im Alter wird die Zahl periprothetischer Frakturen in der Zukunft überproportional ansteigen lassen. Wegen der oft schlechten Knochenqualität, geriatrischen Begleiterkrankungen und häufig mehrfacher endoprothetischer Versorgung besitzen hochbetagte Patienten zum einen ein erhöhtes Risiko für periprothetische Frakturen, zum anderen stellt die Behandlung dieser Frakturen beim geriatrischen Patienten ein Problem dar, das ein interdisziplinäres Herangehen an die Behandlung erforderlich macht.Die folgende Arbeit beschreibt unter dem Blickwinkel der speziellen Situation des geriatrischen Patienten zum einen Aspekte der Epidemiologie, Risikofaktoren und Prävention periprothetischer Frakturen, zum anderen die verschiedenen Möglichkeiten der Therapie.AbstractDemographic changes and rising numbers of implanted prostheses accompanied by increasing demands on mobility and activities of the elderly will lead to an increasing number of periprosthetic fractures in the future. Poor bone quality, geriatric comorbidities and multiple prostheses result in an increased risk for this type of fracture in the old patient. Management of these patients is challenging and demanding and needs an interdisciplinary approach.The present work describes the different aspects of periprosthetic fractures in the geriatric patient with regard to epidemiology, risk factors, prevention and treatment options.Demographic changes and rising numbers of implanted prostheses accompanied by increasing demands on mobility and activities of the elderly will lead to an increasing number of periprosthetic fractures in the future. Poor bone quality, geriatric comorbidities and multiple prostheses result in an increased risk for this type of fracture in the old patient. Management of these patients is challenging and demanding and needs an interdisciplinary approach. The present work describes the different aspects of periprosthetic fractures in the geriatric patient with regard to epidemiology, risk factors, prevention and treatment options.

Das präformierte LCP®-Plattenfixateursystem bei distalen Humerusfrakturen AO-Typ 13C3

In distal intraarticular humerus fractures primary stable osteosynthesis is essential for early mobilization of the elbow joint. Double-plate osteosynthesis techniques using different configurations are the gold standard. In the literature plate position is sometimes discussed controversially. In cases of distal humerus fractures (type AO 13C3) with metaphyseal comminution, as well as in elderly patients with poor bone quality, utilizing locking plates with angular stability was found to have increased structural properties with regard to primary fixation stability. The dorsal approach with osteotomy of the olecranon seems to be very effective in open reduction and internal fixation of this type of fracture. One new development is the anatomically preformed plate-fixation systems such as the LCP-System for distal humerus (Synthes). This study presents our first experience with this system in 11 cases of open reduction and internal fixation of type AO 13C3 distal humerus fractures. The system-specific features and intraoperative options were analyzed.

[Preformed plate-fixation system for type AO 13C3 distal humerus fractures: clinical experiences and treatment results taking access into account].

In distal intraarticular humerus fractures primary stable osteosynthesis is essential for early mobilization of the elbow joint. Double-plate osteosynthesis techniques using different configurations are the gold standard. In the literature plate position is sometimes discussed controversially. In cases of distal humerus fractures (type AO 13C3) with metaphyseal comminution, as well as in elderly patients with poor bone quality, utilizing locking plates with angular stability was found to have increased structural properties with regard to primary fixation stability. The dorsal approach with osteotomy of the olecranon seems to be very effective in open reduction and internal fixation of this type of fracture. One new development is the anatomically preformed plate-fixation systems such as the LCP-System for distal humerus (Synthes). This study presents our first experience with this system in 11 cases of open reduction and internal fixation of type AO 13C3 distal humerus fractures. The system-specific features and intraoperative options were analyzed.

Limb salvage or amputation? The use of a gentamicin coated nail in a severe, grade IIIc tibia fracture

IntroductionSevere grade IIIc tibial fractures have limited treatment options. The decision between limb salvage or amputation depends on many factors, including the age and health status of the patient, as well as the soft tissue status and associated injuries. Until recently, intramedullary nailing was not a favoured treatment option in such tibial fractures, since it is associated with an increased risk of deep wound infections and osteomyelitis.Material and methodsHere we present a case where a novel polylactic acid/gentamicin coated unreamed tibial nail (UTN-PROtect®) has been used to successfully salvage the limb of a 17-year-old man, where prolonged external fixation or amputation would have been the standard treatment.ResultsThis case demonstrates that treating severe grade IIIc tibial fractures with the acid/gentamicin coated unreamed tibial nail (UTN-PROtect®) is a viable alternative to prolonged external fixation or amputation.ConclusionThe gentamicin-loaded coating of the UTN-PROtect® nail, which releases the antimicrobial agent directly at the bone–implant inter-face, overcomes the limitation of insufficient antibiotic delivery. Awareness of this case and the existing literature supporting the use of an antibiotic coated nail may assist surgeons in their decisions on how to treat severe grade IIIc fractures.

Bioactive-Coated Implants in Trauma Surgery

Complications still occur in musculoskeletal surgery despite improvements in operating techniques and optimization of implants. Problems include delayed fracture healing, non-unions and extensive osseous infections. Growth factors for local application are in clinical use, but have not become widely accepted. Reasons may be that these proteins are expensive and of limited availability and considerable quantities have to be implanted locally. Coated implants incorporating active ingredients could release drugs locally and thereby generate a high concentration directly in the area of interest without systemic side effects. Compounds that could be used in this way include growth factors for the improvement of fracture healing and antibiotics for prophylaxis of implant-related infections. The biodegradable poly(D,L-lactide) coating of implants can facilitate the local controlled release of incorporated growth factors directly into the fracture and thus serves both as a fracture stabilization device and as a carrier for active components. This review presents different models (fracture healing; intervertebral fusion; infection model) demonstrating the efficiency of the coating technology. These findings seem to justify the transfer of this technology into clinical settings. In a preliminary study, gentamicin-coated intramedullary tibial nails were implanted in patients exhibiting fractures with severe soft tissue damage. The preliminary findings do not allow conclusions to be drawn in respect of therapy of fractures with severe soft tissue damage or revision surgery. However, the coating seems to be suitable as a “key technology” for the incorporation of active ingredients and might be helpful in revision arthroplasty.

Influence of Synovial Fluid on Human Osteoblasts: An In Vitro Study

Osseous graft healing at the tendon bone interface after anterior cruciate ligament (ACL) reconstruction is unsatisfactory in 10—25%, depending on the evaluation criteria or the kind of graft used for reconstruction. Mechanical as well as biological aspects are currently discussed. Since osteoblasts play an important role in the osseous integration of an ACL graft, we hypothesize that synovial fluid (SF), when entering the bone tunnel, has an inhibitory effect on osteoblasts. In order to verify this hypothesis, human osteoblasts (p3) were incubated in the presence of SF or partially purified SF. Proliferation was assayed using MTT or BrdU assay. Gene expression of osteoblast markers (alkaline phosphatase, collagen I, and osteocalcin) were determined by TaqMan analysis. In the control group, SF was exchanged by fetal calf serum (FCS). The results showed osteoblast proliferation in the presence of SF as well as in partially purified heat-pretreated synovial fluid. Native SF induced alkaline phosphatase and collagen I gene expression. No induction of the osteocalcin gene was observed in the experiment. These results were comparable to that obtained with FCS. These findings suggest that SF stimulated proliferation of osteoblasts in vitro. This effect is mediated, in part, by heat-stable components of SF. In addition, the expression of osteoblast marker genes alkaline phosphatase and collagen I, but not osteocalcin, was induced by SF. Therefore, problems associated with cruciate ligament reconstruction might be due to the inhibition of osteoblast differentiation. If so, this is not a specific attribute of SF, but also applies to serum.

Beckenringfrakturen im Alter@@@Pelvic ring fractures in the elderly: Die unterschätzte osteoporotische Fraktur@@@Underestimated osteoporotic fracture

The incidence of pelvic fractures at 0.3-8% is low compared to all fractures. Nevertheless, the number of pelvic fractures in the elderly is increasing. Due to the increased age of the patient differences in trauma mechanism, fracture pattern and therapy occur. Most pelvic fractures in the elderly are caused by low-energy trauma. This makes it difficult to find the right diagnosis especially in insufficiency fracture of the pelvis. The time until the right treatment is started is prolonged significantly. Elderly patients who suffer from a high-energy fracture have a significantly higher risk of haemorrhage. At the same time emergency stabilisation of the pelvis using a C-clamp is dangerous due to the special fracture morphology with transiliac instabilities and the combination with osteoporosis. Low-energy trauma leads to simple fractures of the pubis, which often can be treated without operation. In these cases fractures of the dorsal pelvic ring need to be excluded using CT scan. Fracture of the dorsal part of the pelvic ring such as insufficiency fractures of the sacrum should be stabilized by 3D-guided percutaneous iliosacral screw fixation to reduce pain and allow early mobilisation.