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Contact stress distribution in the articular surface of the hip is considered a factor in the development of osteoarthritis, a common complication in hips with aseptic necrosis of the femoral head. We present evidence supporting the hypothesis that osteoarthritis in hips with aseptic necrosis of the femoral head can be caused by elevated contact stress related to the reduced load-bearing ability of the necrotic bone. By using a previously validated mathematical model, we observed that hip contact stress may increase considerably if the load-bearing capacity of the necrotic lesion is decreased, if the size of the necrotic segment is increased, and if the necrotic segment is located more laterally. These effects are affected by the intrinsic shape of the hip. As the estimated values of stress in hips with osteonecrosis are in the range obtained by the same method in dysplastic hips, osteoarthritis in hips with osteonecrosis can be caused by elevated contact stress.

Summary:Clostridium difficile (C. difficile) pseudomembraneous colitis was diagnosed in a 13-year-old boy with Hodgkin's disease 3 months after autologous bone marrow transplantation. Hematopoiesis was fully reconstituted at the time. C. difficile infection occurred after gall bladder empyema had been treated conservatively with i.v. antibiotics and prophylactic 4-week administration of oral amoxicillin. C. difficile colitis was diagnosed early and intensive supportive therapy combined with administration of i.v. and subsequently oral vancomycin therapy failed. It is a phenomenon rarely seen and successful eradication of the clostridium infection was only achieved by a combination of higher dose vancomycin with metronidazole. During the post-colitis recovery the patient experienced a relapse of Hodgkin's disease and died following further surgical intervention 137 days post-transplantation.

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Intervertebral cages are used in orthopaedics for stabilization of injured lumbar parts of vertebral columns. Our study provides preliminary results of tests of the biological properties of titanium cages with a variously modified carbon/carbon composite (C/C) core. This core was produced from a C/C composite modified by hydrogel materials based on poly(2-hydroxyethyl methacrylate) (HEMA) enriched with 1% collagen or 35% methylmethacrylate or 30% terc-butylmethacrylamide. We evaluated the adhesion of the cells to the tested material coating using an in vitro study of the metabolic activity and cytokine production of the cells (TNF-alpha, IL-8). We studied the biocompatibility of intervertebral cages coated with different copolymers under in vivo condition and in an implantation experiment in the porcine femurs. Both in vitro and in vivo results revealed favourable biotolerance of the use system. Modification of the composite HEMA with the use of collagen seems to have a more positive effect on the new bone tissue formed around the implanted devices than HEMA copolymerized with methylmethacrylate or terc-butylmethacrylamide.