Cartilage is a type of connective tissue, supporting tissue and connecting different organs, made up of cells and fibers. In joints , articular cartilage allows sliding of bone surfaces against one another due to its composition of rigid collagen fiber and cells called chondrocytes which create a component in which these fibers and cells are bathed, called the matrix. This articular cartilage wears naturally over time with aging, and cracks appear. In some cases , this degradation can lead to osteoarthritis. The cartilage can also be affected following trauma to the joint. Note that other types of cartilage exist such as the epiphyseal cartilage present in children which enables the bones to grow lengthwise , or fibrous cartilage in certain organs such as the ears or the trachea.