The term “joint” refers to the physical point of connection between two bones. There are numerous joint types throughout the body, these being ball and socket joints, hinge joints, condyloid joints, pivot joints, gliding joints, and saddle joints. A normal joint meets the point of two bones to permit movement. Cartilage is made up of protein that covers the end of bones and aids in protecting the bones and operates as a shock absorber and allows the bones to move effortlessly.
Synovial fluid is inside the joint which lubricates the joint and keeps it functioning efficiently. Osteoarthritis has to do with the loss of articular cartilage, the development of bony spurs at the joint margin, also known as osteophytes, it involves the inflammation of the synovial membrane and alterations to the subchondral bone. The order of which the changes in the bone, synovium and cartilage are influenced on the causes for osteoarthritis, these differ in each tissues effect on surrounding tissues.
The pathophysiology of osteoarthritis has subtypes including inflammatory to a varying extent, pain due to tissue damage, and pain at rest. The bone just underneath the cartilage in the synovial joint is called subchondral bone, and is found in various areas. The subchondral bone plate is the top area. This is made up of somewhat non-porous bone with a restricted blood supply. Underneath the bone plate, is a cushioned layer of bone called trabecular bone. In a healthy individual, bone is continually altered by modelling and resorption.
This permits bone to repair and adjust to changing mechanical requirements. In a handful of individuals, the structure or properties of bone are altered by genetic disorders that can lead to an earlier commencement of osteoarthritis. In most individuals, the bone alterations in osteoarthritis are seen later on in life, and the causes aren’t fully recognised. Changes that define the features of osteoarthritis are the subchondral bone plate thickening, the character of the trabecular bone changing, new bones are formed at the osteophytes and subchondral cysts form.
Cartilage is a fairly weak tissue, and many factors, such as age, influence it to damage. Pressure on the cartilage causes chondrocytes to make a collagen and protein substance. The replacement procedure of the substance is usually slow, but extreme loading can lead to the initiation of enzymes that digest it, which then leads to thinning and damaging it. There are variable factors that contribute to abnormal or excessive loading of the cartilage include obesity, high-level and high-impact sport or occupational activities, and repetitive and long-term occupational factors.
Non-modifiable factors include being a female, congenital joint irregularities, genetic polymorphisms, ethnicity with vulnerability in specific joints varying between ethnic groups, and ageing. Interaction between these factors can make it hard to know the influence of each. There is a higher risk of people attaining osteoarthritis if they are female, obese, have metabolic syndrome, manual jobs that involve kneeling, twisting and carrying, and are from ethnic and/or socioeconomic backgrounds that carry an increased incidence of any of these factors.
If the cartilage is damaged, the particles from the damage are engulfed and broken down by synovial cells. This leads to inflammatory mediators produced, such as pro-inflammatory cytokines interleukin IL-1, IL-6 and IL-8, tumour necrosis factor and prostaglandin PGE2. Cartilage damage activates synovial inflammation, which then adds to the damage to the cartilage. A small amount of synovial inflammation is shown in most people with osteoarthritis and many will experience occasional inflammatory flare-ups, even those without synovial inflammation are at risk of this.
The level of inflammation is crucial to differentiate between osteoarthritis and rheumatoid arthritis. Osteoarthritis isn’t always seen as an inflammatory disease. This is because there are low levels of leucocytes in the synovial fluid. Swelling in osteoarthritis is restricted to a certain area of a joint, however, it can be shown that inflammatory chemicals are seen in the circulation along with the synovial fluid. The level of inflammation is related with how sever and painful the disease is.
It is possible that there are many different of subtypes of osteoarthritis, which cause a greater level of synovitis and inflammation than others. Treatment depends on the patient that is suffering from the disease. The severity of the osteoarthritis and what may have caused it are some of the things that have to be taken into account. Treatment that can help reduce symptoms include weight control, proper exercise, heat and cold therapy, pain medication, other pain relief options, stress control, injections into the joint, or surgery.
Despite all the research that has gone into osteoarthritis, there is still no known cure. There are many factors that possibly set off the cartilage damage. It continues to be unidentified why certain joints are affected if the patient hasn’t experienced any former injury or disease. Scientists have theories what could contribute to cause osteoarthritis. These being joint wear and tear, overuse or prior injuries, inactivity of the joint, excess bodyweight for the joints to handle, and hereditary.
The symptoms for osteoarthritis can differ from one patient to the next and also the joints that are affected. Common symptoms are stiffness of joints, pain in affected area, muscle weakness, and bone enlargement and swelling. These symptoms affect everyday living so the further along osteoarthritis is in the process, the harder it is to do daily activities. Osteoarthritis often occurs in weight bearing joints or joints that are used all the time. These joints usually being in the hips, knees, hands, fingers, and the spine.