Arthropathies are called polyarticular (multiarticular) when involving many joints and monoarticular when involving only a single joint. Arthritis is the leading cause of disability in people over the age of 55. There are many different forms of arthritis, each of which has a different cause. The most common form of arthritis, osteoarthritis (also known as degenerative joint disease), occurs following trauma to the joint, following an infection of the joint or simply as a result of aging and the deterioration of articular cartilage. Furthermore, there is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis. Other forms of arthritis are rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases in which the body is attacking itself. Septic arthritis is caused by joint infection. Gouty arthritis is caused by deposition of uric acid crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout that is caused by the formation of rhomboidal-shaped crystals of calcium pyrophosphate. This form of gout is known as pseudogout. Temporomandibular joint syndrome (TMJ) involves the jaw joints and can cause facial pain, clicking sounds in the jaw, or limitation of jaw movement, to name a few symptoms. It is caused by psychological tension and misalignment of the jaw (malocclusion), and may be affecting as many as 75 million Americans. History
Etymology
The English word joint is a past participle of the verb join, and can be read as joined.
There are four structural classifications of joints:
fibrous joint – joined by dense regular connective tissue that is rich in collagen fibers
cartilaginous joint – joined by cartilage. There are two types: primary cartilaginous joints composed of hyaline cartilage, and secondary cartilaginous joints composed of hyaline cartilage covering the articular surfaces of the involved bones with fibrocartilage connecting them. synovial joint – not directly joined – the bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule that is normally associated with accessory ligaments. facet joint – joint between two articular processes between two vertebrae. Functional classification (movement)
Joints can also be classified functionally according to the type and degree of movement they allow: Joint movements are described with reference to the basic anatomical planes. synarthrosis – permits little or no mobility. Most synarthrosis joints are fibrous joints (e.g., skull sutures). amphiarthrosis – permits slight mobility. Most amphiarthrosis joints are cartilaginous joints (e.g., intervertebral discs). synovial joint (also known as a diarthrosis) – freely movable. Synovial joints can in turn be classified into six groups according to the type of movement they allow: plane joint, ball and socket joint, hinge joint, pivot joint, condyloid joint and saddle joint.Joints can also be classified, according to the number of axes of movement they allow, into nonaxial (gliding, as between the proximal ends of the ulna and radius), monoaxial (uniaxial), biaxial and multiaxial.