Osteoarthritis (MSK) Flashcards
What is osteoarthritis?
OA is a chronic degenerative joint disorder characterised by non-inflammatory degeneration of the joint complex; prevalence increases with age
Cartilage destruction exceeds repair –> pain and disability
What are the most commonly affected joints in osteoarthritis?
Knee > hip > hands > lumbar and cervical spine
What is the aetiology of osteoarthritis?
- mechanical and biological events that destabilise the normal process of degradation and synthesis of articular cartilage chondrocytes, ECM and subchondral bone
- involves the entire joint including the articular cartilage, subchondral bone, pericapsular muscles, capsule, and synovium
- leads to loss of cartilage, sclerosis and eburnation of subchondral bone, osteophytes and subchondral cysts
What is primary osteoarthritis?
Unknown aetiology, multifactorial causes
What is secondary osteoarthritis? (6)
- developmental abnormalities (e.g. hip dysplasia)
- trauma (e.g. previous fractures)
- inflammatory (e.g. rheumatoid arthritis, gout, septic arthritis)
- metabolic (e.g. haemochromatosis, acromegaly)
- obesity
- occupational
What happens to the chondrocytes in osteoarthritis?
Low yield
- chondrocytes are responsible for maintaining a balance between destruction and production of articular cartilage
- OA = irreversible loss of articular cartilage
- altered chondrocyte activity = increased destruction –> loss of joint volume
- chondrocytes eventually weaken and undergo apoptosis –> immune response –> patchy chronic synovial inflammation
- also fibrotic thickening of joint capsules
- eventually the bone becomes exposed = rubs with neighbouring bone
What are Heberden and Bouchard nodes in osteoarthritis and why do they occur?
Due to damage/inflammation, new bone formation on edges of bone with outward growth –> osteophytes known as Heberden (DIPJs) and Bouchard (PIPJs)
Occur due to osteophyte formation
What are the clinical features of osteoarthritis?
- pain during/after exertion, relieved by rest
- sparing of MCPJs but involves PIPs and DIPs (differentiates OA from RA)
- bony deformities
- Heberden nodes at DIPs
- Bouchard nodes at PIPs
- squaring at base of thumb
- varus deformity
- malalignment (causes varum and valgum deformities)
- crepitus
- asymmetric joint involvement
What bony deformities are seen in osteoarthritis? (4)
- Heberden nodes at DIPs
- Bouchard nodes at PIPs
- squaring at base of thumb
- varus deformity
How does osteoarthritis present (history)?
- joint pain and discomfort
- usually localised to knee, hip or spine
- use-related
- pain on movement (relieved at rest) and crepitus
- worse at end of day
- background pain at rest
- morning stiffness lasting <30 mins
- difficulty with certain movements
- feelings of joint instability
- restriction walking, climbing stairs, manual tasks
- no swelling
How does osteoarthritis present on examination?
- local joint tenderness
- bony swellings along joint margins
- Heberden’s nodes - DIP
- Bouchard’s nodes - PIP
- crepitus and pain on joint movement
- joint effusion
- restriction of range of movement
- antalgic gait (avoiding pain)
What are the risk factors for osteoarthritis? (8)
- age >50 (cartilage thinning)
- females
- obesity (excessive load, metabolic disorders)
- family history/genetic disorders (mutations in cartilage building)
- previous joint injuries
- infection
- neurologic disorders
- excessive joint loading - physically demanding job/sport
What are the 1st line investigations for osteoarthritis?
- X-ray of affected joints
- serum CRP
- serum ESR (erythrocyte sedimentation rate)
What bedside examination can be done for osteoarthritis?
MSK exam
What bloods are taken for osteoarthritis?
- CRP - may be slightly raised
- ESR - normal
- RF - if RA cannot be excluded clinically
- anti-CCP - negative
