Traumatic Chondral Lesions of the Knee Diagnosis and Treatment

1.1 Anatomy and knee joint function The knee joint is classified as a modified hinge joint, with its structure providing a highly mobile and complex joint (fig.1). It consists of two condylar joints between the medial and lateral condyles of the femur and the corresponding plateaus of the tibia, and anteriorly a synovial plane patellofemoral joint. The articular surface of the knee is covered by Hyaline cartilage that is supported by subchondral bone. This Hyaline cartilage is very soft and yields its interstitial water easily when compressed yet it is very stiff in tension along planes parallel to the articular surface (Buckwalter and Mow, 2003). Intact cartilage provides a smooth, lubricated gliding surface with a coefficient of friction better than most man-made bearing materials (Buckwalter and Mow, 2003). In the knee articular cartilage distributes the loads of articulation, thereby minimizing peak stresses acting on the subchondral bone whilst the tensile strength of the tissue maintains its structural integrity under loading. These biomechanical properties make the tissue remarkably durable and wear resistant, enabling it to last many decades, even under high and repetitive stresses (Buckwalter and Mow, 2003).