osteoarthritis Flashcards
What is osteoarthritis?
It is the chronic slowly progressive disorder due to failure of articular cartilage that typically affects joints of the hand (especially those involved in a pinch grip), spine and weight-bearing joints
What are the main parts of the body that are affected by osteoarthritis?
Joints of the hand
- Distal interphalangeal joints (DIP)
- Proximal interphalangeal joints (PIP)
- First carpometacarpal joint (CMC)
Spine
Weight-bearing joints of lower limbs
- esp. knees and hips
- First metatarsophalangeal joint (MTP)
What are Bouchard’s nodes?
Osteophytes at PIP joints (proximal interphalangeal joint)
What are Heberden’s nodes
Osteophytes at DIP joints
What joint pathologies is osteoarthritis associated with?
- Joint pain- worse with activity, better with rest
- Joint crepitus- creaking, cracking grinding sound on moving affected joint
- Joint instability
- Joint enlargement- e.g. Heberden’s nodes
- Joint stiffness after immobility (‘gelling’)
- Limitation of motion
What are the radiographic features of osteoarthritis?
- Joint space narrowing
- Subchondral bony sclerosis
- Osteophytes- bony protrusions associated with degeneration of cartilage at joints
- Subchondral cysts
What are the radiographic changes in rheumatoid arthritis?
Note that joint-space narrowing occurs in both due to different reasons. Rheumatoid arthritis (secondary damage due to synovitis) and osteoarthritis (due to a primary abnormality).
Bone spurs (osteophytes) can also erupt in osteoarthritis on x-rays
What is the pathogenesis behind osteoarthritis?
And why does it occur?
There is defective to the articular cartilage and irreversible damage to the underlying bone.
this develops due to excessive loading on joints (more apparent in the old) and there are abnormal joint components (more apparent in the young).
Describe the synovium
Weight-bearing properties of articular cartilage depend upon the intact collagen scaffold and the high aggrecan content.
Aggrecan is made up of chondroitin sulphate and keratan sulphate
The GAG chains are importnant at absorbing water to be used to resist compressive forces.
What are ECM proteoglycans?
Porteoglycans- glycoprtoteins containing one or more sulphated glycosaminoglycan (GAG)
What are GAGs and give GAGs
GAGs are repeating polymers of disaccharides and examples include:
- Chondroitin sulphate
- Heparan sulphate
- Keratan sulphate
- Dermatan sulphate
- Heparin
- Hyaluronic acid- the only non-sulphated GAG and is a major component of synovial fluid, in order to maintain its viscosity.
What are the cartilage changes in osteoarthritis?
- Reduced proteoglycan
- Reduced collagen
- Chondrocyte changes (e.g. apoptosis)
Describe the bone changes in osteoarthritis
Changes in sub-articular bone:
- the proliferation of superficial osteoblasts resulting in sclerotic bone
- focal stress on the sclerotic bone resulting in focal superficial necrosis
What is the management of osteoarthritis
- Education
- Physical therapy – physiotherapy, hydrotherapy
- Occupational therapy
- Weight loss where appropriate
- Exercise
- •Analgesia: Paracetamol, Non-steroidal anti-inflammatory agents, Intra-articular corticosteroid injection
- joint replacement
What are the therapeutic approaches to osteoarthritis?
There are none in the UK, but:
- Glucosamine and chondroitin sulphate- commonly taken but not approved by NICE.
- Intra-articular injections of hyaluronic acid- to increase lubrication in the knee only not recommended by NICE
- DMOAD drug- disease-modifying osteoarthritis drug- aggrecanase inhibitors, cytokine inhibitors etc.
