Basic Science and Injury in Growing Athletes: Cartilage, Menisci, and Bone

Injuries to the growing skeleton are very common in young athletes, and the result could be a damage to the articular cartilage, menisci, and/or bone. Understanding of the basic science and principles of these tissues is important to understand their healing processes and to anticipate the results to the patients and their family. Articular cartilage is composed by hyaline cartilage, which is formed by a solid phase (chondrocytes and proteins of the extracellular matrix with a tridimensional organization) and a fluid phase (water and ions), that gives its biomechanical properties of rigidity, elasticity, and resiliency to the tissue. Injuries to the articular cartilage are very problematic due to its limited healing potential. Several menisci are present in the body, increasing the contact surfaces between incongruent bones, improving load distribution and stability. The knowledge of their gross and microscopic anatomy and biochemical composition is fundamental to understand their function and their pathology. Structural and histological features of menisci change during pre- and postnatal development. Meniscal tears are very common in athletes requiring surgical treatment. Repair of meniscal lesions is limited to the outer part due to its vascularization. Most of the cases require partial meniscectomy. In the growing athlete, bone is composed by cartilaginous and bone tissues. Bone growth occurs by several mechanisms different from long bones to short and flat bones. Furthermore, particular mechanisms are involved in epiphyseal and apophyseal growth and development. Genetic, hormonal, and environmental factors modulate bone growth during childhood and adolescence, and the awareness of the knowledge of the morpho-functional aspects of the epiphysio-metaphyseal growing cartilages mechanisms and speed of bone growth is important for understanding the treatment and prognosis of many injuries in these patients.