The normal mobility of a joint, or the distance between flexion and extension, is determined by the structure of the bones and cartilage, the joint capsule and ligaments, tendons and muscles, while respecting individual - and breed dependent variations. Pain, swelling and stiffness of a joint lead to a decreased ROM. Testing of the joint ROMs is part of the orthopaedic examination. The active ROM is assessed during gait inspection, and the passive ROM is tested during the clinical examination.