Arthritis Flashcards
What are the five broad categories of arthritis?
Osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, gout, infection
What are the subtypes of rheumatic disease?
Soft Tissue: Tennis elbow, Mechanical back pain, Repetitive strain Inflammatory: Rheumatoid arthritis, Seronegative SpA Crystal arthritis, Connective tissue disease Degenerative: Osteoarthritis, Cervical spondylosis Other: Fibromyalgia Normality Metabolic disease
What does the synovium do?
Synovium produces the lubricating synovial fluid, which also passes nutrients to the cartilage, which contains no blood vessels or nerve cells.
What’s happens in osteoarthritis?
It’s caused by cartilage death. The cartilage dies in patches. As a result, the bones sit more closely together (joint space narrowing) and eventually rub against each other.
There is a bony reaction shown in two ways:
• the bone just under the cartilage surface (the ‘subchondral’ bone) becomes thick and sclerotic – represented here by a deeper yellow colour
• the bone at the edges of the joint grows out as if to support the failing joint. These outgrowths are called osteophytes
• In addition, the capsule becomes thickened and fibrotic and the synovium may develop small areas of inflammation. Often additional synovial fluid is also produced.
Joint space narrowing, osteophytes and subchondral sclerosis can all be seen on x-rays of the joints.
OA occurs more in women than men, starts any time after the age of 50 years, and is more common in the elderly
What happens in rheumatoid arthritis?
In RA the synovium becomes inflamed with a mixture of acute and chronic changes (synovitis). This leads to pain, stiffness and destruction.
Persistent inflammation causes generalised cartilage loss (resulting in joint space narrowing) and also thinning (osteoporosis) of the bone close to the joint (juxta-articular osteoporosis)
Synovial cells themselves become overgrown and invasive, and eat into the corners of the bones, forming ‘erosions’.
The joint and the joint capsule will become deformed by these changes.
Joint space narrowing, erosions and juxta-articular osteoporosis can all be seen on x-rays of the joints.
RA occurs more frequently in women than men, and most commonly starts in the 30-50 year age range, although it can begin at any age.
What happens in ankylosing spondylitis?
Inflammation and new bone formation at entheses (the connective tissue between tendon or ligament and bone. The main site of this pathology is in the spine, where enthuses abound. However, the pathology can occur at many other sites, including important entheses that are not close to joints, such as where the plantar fascia of the foot joins to the anterior margin of the calcaneus.
Can cause back which can’t be bent as intervertebral discs fuse together.
In addition to inflammatory episodes (with pain and stiffness) there is a progressive loss of range of motion and, in the worst cases, the whole spine can become ankylosed and immovable.
Much more common in men than women, and usually starts between the ages of 15 and 30 years.
What is gout?
In gout, sodium urate crystals form in the synovial fluid and attract a major onslaught from polymorphonuclear leucocytes which migrate into the joint and set up a severe acute inflammatory response.
• In humans, serum urate levels are at or even above crystalisation concentrations, and are probably kept soluble by serum (and synovial fluid) proteins.
• Either when these systems fail or urate levels rise too high, gout can occur. In half of patients, the joint first involved is the proximal interphalangeal joint of the big toe – inflammation here is called podagra. (In the other half it can be any joint.)
• If no treatment is given, an attack usually settles within two or three weeks. It is very painful.
Gout is best diagnosed by seeing sodium urate crystals in the synovial fluid. They can be seen using an ordinary microscope, but they are best seen using a polarising light microscope.
Gout does not occur in children or women before the menopause, and usually starts over the age of 40 years. It therefore occurs much more in men than women, although in older people the balance is closer.
Can be seen as ‘tophi’ (bumps)
What is joint infection?
Joint infection is rare but making the diagnosis is extremely important as left untreated it can rapidly destroy a joint. Clues to the presence of joint infection are the severity of inflammations, systemic symptoms such as night sweats and pyrexia, and a raised white blood cell count.
• Infection occurs most commonly in joints that are already damaged by arthritis.
• Infection is diagnosed by microscopy and culture of synovial fluid.
In the UK most joint infections are caused by staphylococci or streptococci, but any organism can find its way into joints.
In the USA half of joint infections are caused by
gonococci.
Is there a link between rheumatoid arthritis and periodontitis?
Has been shown that there could be a link as they have similarities in immune response and tissue degradation.
