Current concepts of articular cartilage repair.

Articular cartilage provides a vital function in the homeostasis of the joint environment. It possesses unique mechanical properties, allowing for the maintenance of almost frictionless motion over a lifetime. However, cartilage is vulnerable to traumatic injury and due to its poor vascularity and inability to access mesenchymal stem cells, unable to facilitate a satisfactory healing response. Untreated chondral defects are thus likely to predispose patients to the development of osteoarthritis. Reconstitution and repair of articular cartilage is dependent on the neosynthesis or implantation of cartilage matrix elements, a goal which can be achieved through a variety of surgical means. Commonly used repair techniques include marrow stimulation, structural osteo-articular autografts or chondrocyte implantation. Despite substantial differences in the complexity and technical application of each method, all are united in the endeavour to restore joint function and prevent joint degeneration. Anyone attempting to treat cartilage defects must possess a basic understanding of the physiology of cartilage growth, and relevant factors affecting cartilage healing and repair. Furthermore, knowledge of the biomechanics and kinematics of the knee are essential in order to appreciate the forces acting on joint surfaces and repair tissues. Although clinical success is dependent on appropriate patient selection, accurate clinical assessment, definition of root causes and application of the right choice of treatment modality, the ultimate outcome of any intervention remains heavily reliant on the surgeon's proficiency in the technical aspects of the chosen surgical procedure.