Tendon and degeneration or weakening of the tendons, which may eventually lead to tendon rupture. Tendinopathies can be caused by a number of factors relating to the tendon extracellular matrix (ECM), and their classification has been difficult because their symptoms and histopathology often are similar. The first category of tendinopathy is paratenonitis, which refers to inflammation of the paratenon, or paratendinous sheet located between the tendon and its sheath. Tendinosis refers to non-inflammatory injury to the tendon at the cellular level. The degradation is caused by damage to collagen, cells, and the vascular components of the tendon, and is known to
Tendon last is tendinitis, which refers to degeneration with inflammation of the tendon as well as vascular disruption. Tendinopathies may be caused by several intrinsic factors including age, body weight, and nutrition. The extrinsic factors are often related to sports and include excessive forces or loading, poor training techniques, and environmental conditions. In some organisms, notable ones being birds and ornithischian dinosaurs, portions of the tendon can become ossified. In this process, osteocytes infiltrate the tendon and lay down bone as they would in sesamoid bone such as the patella. In birds, tendon ossification primarily occurs in the hindlimb, while in