Week 8 - Osteoathritis Flashcards
OA
- most common form of arthritis and possesses marked variability of disease expression
- wear and tear on joints
Is there an inflammatory component of OA
Considered non-inflammatory, there is a inflammatory component
Primary OA
Where there is no discernible or identifiable aetiology
Secondary OA
Where the aetiology can be identified
- mechanical factors
- biochemical factors
- destruction of cartilage by other mechanisms
- common after bouts of septic, inflammatory and crystal arthritis
Cartilage breakdown
- horizontal flashing
- superficial fissuring
- horizontal splitting
- deep fissuring
- increase in chondrocytes
- increase in water content
- progressive depletion of proteoglycans
- increase in collagen
- proliferation in collagen production
- proliferation of the synovium
Cartilage breakdown results in
Loss of joint space
Osteophytes
Sclerosis of Subchondral bone
Subchondral cyst
Collapse of bone and subluxation
OA symptoms
- joint pain
- early in disease, pain is episodic, triggered by overreactive
- nocturnal pain normally only occurs in the end stages of the disease
- pain should not be ignored
- joint gelling
- joint instability
- loss of function
- muscle wasting
OA Investigations
- radiographs
- US
- MRI
- Laboratory investigations
X-ray allows detection of (OA)
- Osteophytosis
2 joint space narrowing - Subchondral sclerosis
- Subchondral cyst formation
- Loose osseous body
Osteophytosis
+ An Osteophyte is a bony outgrowth (spur) at the margin of the affected joint
+ frequently in an isolated finding but can present in a combination with any or all of the following 4 findings, especially in more severe cases
+ normal bone density is maintained and trabecular reorganisation occurs in the osteophyte
Joint space narrowing
- The joint space narrowing typically is uneven
- narrowing occurs at the focus of the applied abnormal force or at the site of cartilage or Subchondral bone abnormality
- uniform narrowing may be seen if the entire cartilaginous surface is affected
Subchondral sclerosis
- this finding is represented by periarticular increased bone density
- Subchondral sclerosis is frequently found adjacent to the site of joint space narrowing
- no correlation between Subchondral sclerosis and cartilage degeneration
- Subchondral sclerosis does not increase as the disease progresses
Subchondral cyst formation
- geographic, radiolucent, eccentric lesion frequently associated with the OA joint
- characteristically has a thin, sclerotic margin
- can be mistaken for erosion
Loose osseous body
- the loose body appears as a bone fragment or ossicle within the joint or along it’s margins
- related to a traumatic event
OA classification.
0: no joint space narrowing or osteophyte
1: doubtful joint space narrowing, possible osteophytes
2: definite osteophytes, possible joint space narrowing
3: moderate osteophytes, definite joint space narrowing, some sclerosis, possible bone end deformity
4: large osteophytes, marked joint space narrowing, severe sclerosis, definite bone-end deformity
