Influence of platelet time activation on articular cartilage growth in the rabbit knee: preliminary study.

PURPOSE: The aim of the present article was to study the influence of platelets and different time activation on cartilage growth in articular defects in the rabbit knee. METHODS: Twelve male New Zealand rabbits (12 weeks) were divided in two groups. Under general anaesthesia, a 4 mm diameter and 2 mm deep defect was performed in medial condyles in both knees. The right knee defect was filled with platelet concentrate 5 min after being activated with ClCa in group A, and 2 min afterwards in group B. Platelets were obtained by centrifuging 10 ml arterial blood from the rabbit prior to the surgical procedure. The left knee defect was not filled. Rabbits were sacrificed 6 weeks after surgery. Macroscopic and microscopic studies were performed. RESULTS: In group A, hyaline cartilage was observed in the right knee defect at the end of the experiment in five rabbits. None of the defects of the left knees showed hyaline cartilage growth. In group B, hyaline cartilage was observed in the right knee defect in only one rabbit. Nevertheless, in group B, all rabbits presented better chondral cellularity and regeneration and lower fibrosis in defects treated with platelets than in non-treated ones. CONCLUSIONS: This technique for articular defect reconstruction with platelets is simple and easy, and has shown satisfactory results in our study. Platelets may be useful as an autologous source of multiple growth factors for articular defect reconstruction. Nevertheless, this is a preliminary study and further research is required.

Interleukin-1, interleukin-6, and interleukin-10 responses after antibiotic treatment in experimental chronic Staphylococcus aureus osteomyelitis.

BACKGROUND: Staphylococcal implant infections' response to treatment may be correlated with cytokine production. We investigated the effect of certain antibiotics on the cytokine response in experimental osteomyelitis. METHODS: A stainless steel needle with an adherent slime-producing Staphylococcus aureus was implanted intramedullarly in the left tibia of 40 adult male Wistar rats. At 42 days after implantation, cefuroxime, vancomycin, tobramycin, and ciprofloxacin were administered intramuscularly every 12 h for 21 days. The control group was given no antibiotic. At the end of the treatment, implants and tibias were retrieved, and the bacterial numbers were estimated. Cytokines [interleukin-1alpha (IL-1alpha), IL-6, and IL-10] were determined (ELISA) in the tibial extract. RESULTS: Vancomycin and cefuroxime inhibited bone colonization in all tibias, and tobramycin and ciprofloxacin inhibited it only partially. Cefuroxime reduced the number of bacteria that adhered to the implants more than the other antibiotics. IL-1alpha and IL-6 showed higher levels in the ciprofloxacin-treated group than in the cefuroxime-treated and control groups. IL-6 levels in rats treated with cefuroxime were lower than in rats treated with tobramycin or vancomycin and the control group. Cefuroxime decreased IL-10 levels more than ciprofloxacin or vancomycin or those seen in the control group. CONCLUSIONS: The cefuroxime group showed the greatest decrease of pro-inflammatory cytokines. Different antibiotics produce different cytokine reactions that should be studied to choose the best treatment.

Evaluation of four experimental osteomyelitis infection models by using precolonized implants and bacterial suspensions.

Staphylococcus aureus osteomyelitis, a major problem in orthopedic surgery, often involves biofilm bacteria adhering to implants and surrounding bone and tissues. The inadequacy of therapy or immunological surveillance has encouraged studies using animal models which simulate natural osteomyelitic infections, ensure the development of infections and avoid mortality. We evaluated 4 models for infection (8 animals/model) in rats, using stainless-steel implants in tibiae and a very adherent slime-producing bacterial strain. Each animal received: an implant containing a 12 h-biofilm with about 10(6) cfu (Model 1); an implant containing this biofilm and a suspension with about 10(4) cfu (Model 2): a sterile implant and a suspension with about 10(5) cfu (Model 3); or a sterile implant and a suspension with about 10(6) cfu (Model 4). 63 days after surgery we found 100% rat survival, colonization of bone by implant biofilm bacteria in some animals and local, but not systemic infections. Model 1 (but not Models 2-4) reproduced an infection in both, tibiae and implants, most reliably (in 100% of the animals). Model 3 was the least reliable (p < 0.01, 25% infected implants, 12% infected tibiae).