Treatment of articular cartilage lesions in the knee remains a challenge for the practising orthopaedic surgeon. A wide range of options are currently practised, ranging from conservative measures through various types of operations and, recently, use of growth factors and emerging gene therapy techniques. The end result of these methods is usually a fibrous repair tissue (fibrocartilage), which lacks the biomechanical characteristics of hyaline cartilage that are necessary to withstand the compressive forces distributed across the knee. The fibrocartilage generally deteriorates over time, resulting in a return of the original symptoms and occasionally reported progression to osteoarthritis. Our purpose in this study was to review the aetiology, pathogenesis and treatment options for articular cartilage lesions of the knee. At present, autologous cell therapies, growth factor techniques and biomaterials offer more promising avenues of research to find clinical answers.

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Previous studies have demonstrated that male Sprague Dawley (SD) rats experience age-related bone loss with the same characteristics as that in ageing men. As articular cartilage, like bone, is a critical component of the health and function of the musculoskeletal system, the authors hypothesized that articular cartilage in the untreated male SD rats could be a suitable model for studying the age-related deterioration of articular cartilage in men. To test this hypothesis, male SD rats were killed at between 6 and 27 months. The right femur of each rat was removed. The effects of ageing on the structural integrity of the distal femoral articular cartilage were studied by biomechanical testing with a creep indentation apparatus. The aggregate modulus, Poisson's ratio, permeability, thickness, and percentage recovery of articular cartilage were determined using finite element/non-linear optimization modelling. No significant differences were observed in these biomechanical properties of the distal femoral articular cartilage as a function of age. Therefore, untreated male SD rats appear to be unsuitable for studying the age-related changes of articular cartilage as they occur in men. However, and more intriguingly, it is also possible that ageing does not affect the biomechanical properties of articular cartilage in the absence of cartilage pathology.

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Additional information is available at the end of the chapter http://dx.doi.org/10.5772/53250 . IntroductionOne of the most devastating complications of prosthetic knee arthroplasty is a periprosthetic infection. This complication occurs in -% of knee arthroplasties [ , ] and can exceed % in immunocompromized individuals [ ] and % after revision surgery [ ]. Prosthetic infection leads to loosening of the implant, [ , ]. In this circumstances revision surgery is required. Because of the diversity of the clinical presentation, i.e. early, intermediate or late infection [ ], different surgical methods to treat infected knee prostheses were developed [ , ]. Several treatment methods became well accepted but others are still controversial. In the present review we intend to describe mainly the diagnostic tools for detection of infection and commonly used treatment methods in failed total knee arthroplasty due to infection, with special emphasis on the surgical techniques. Additionally we will describe some trends for the future improvement of the treatment modalities. . Pathology and microbiologyThe main infecting pathogens, around %, of knee prostheses, are the different strains of Staphylococci, e.g. coagulase negative Staphylococci cause around % of knee prostheses infections and Staphylococcus aureus is responsible for % of infections, according to pooled data from nine different studies [ ]. Most of the clinically significant infections are caused by biofilm producing microorganisms. The role of biofilms in pathogenesis of periprosthetic infection is the masking of the pathogens from bodily immune response and antibiotic access. Biofilm is a biological