Osteroarthritis (OA)

Question 1

Define osteoarthritis in simple terms.

Answer 1

Often described as “wear and tear” in the joints.

= NON-INFLAMMATORY DEGENERATIVE ARTHRITIS!

It is not an inflammatory condition like rheumatoid arthritis.
The –itis ending is misleading.

Question 2

Is osteoarthritis an inflammatory condition?

Answer 2

NO!

Question 3

Define osteoarthritis.

Answer 3

A non-inflammatory degenerative disorder of moveable joints characterised by the deterioration of articular cartilage and the formation of new bone.

Question 4

Describe the epidemiology of OA.

Answer 4

1. Most common type of arthritis
2. Most common cause of disability in the Western world in older adults
3. Prevalence increases with age - uncommon before the age of 50

Question 5

Describe the usual onset of OA.

Answer 5

> 50yrs, slow and gradual

Question 6

Give the key points in the pathophysiology of OA.

Answer 6

General wear and tear -> a chronic degenerative disease.

Loss of articular cartilage - exposed bone becomes sclerotic.

Attempts at repair produces osteophytes (nodules).

Question 7

Describe the disease process behind OA in detail (pathophysiology).

Answer 7

1. Normal physiology - there is a dynamic balance between cartilage degradation by wear and its production by
   chondrocytes.
2. In OA: initial imbalance in cartilage homeostasis
3. Leads to cartilage degradation, remodelling of the bone + associated inflammation of the joint
4. Over time, continuous ‘wear’/trauma to the joint
   = local inflammation
   = stimulates chondrocytes
   = they release degradative enzymes
   = enzymes break down collagen + proteoglycan
   = lead to the destruction of the articular cartilage
5. Over time, cartilage thins a lot:
   = exposes the underlying subchondral bone
   = causes subchondral sclerosis
   = continuous remodelling of subchondral bone
   = this forms subchondral cysts and osteophytes.
   = this eventually leads to a progressive loss of joint space.

Question 8

What are the most important cells responsible for OA?

Answer 8

Chrondrocytes.

Question 9

What are the 2 key pathological features of OA?

Answer 9

Main pathological features:
* Loss of cartilage
* Disordered bone repair

Question 10

Which tissues gets most affected in OA?

Answer 10

Articular cartilage

Question 11

What disease lowers your risk of developing osteoarthritis?

Answer 11

Osteoporosis

Question 12

Give 5 risk factors for developing OA.

Answer 12

1. Genetic predisposition.
2. Local Trauma.
3. Abnormal biomechanics e.g. joint hypermobility.
4. Occupation e.g. manual labour.
5. Obesity; pro-inflammatory state.
6. Increasing age.
7. Being female.
8. Inflammatory arthritis e.g. RA.

Question 13

OA risk factor: Occupation - what joints can manual labour be associated with?

Answer 13

The small joints of the hand

Question 14

OA risk factor: Occupation - what joints can being a farmer be associated with?

Answer 14

OA of the hips

Question 15

OA risk factor: Occupation - what joints can being a footballer be associated with?

Answer 15

OA of the knees

Question 16

Why does the prevalence of OA increase with age?

Answer 16

Due to the cumulative effect of trauma and a decrease in neuromuscular function.

Question 17

What joints might be affected in osteoarthritis? Give 5.

Answer 17

BASICALLY - Those that are used a lot!

Weight-bearing joints:
- Hips
- Knees
- Sacro-iliac joints in the cervical spine
- Veterbra

• Distal-interphalangeal joints in the hands (DIPs - Heberden’s nodes)
• The 1st carpometacarpal joints at the base of the thumb of the hands
• Wrist

Question 18

Which surface of the knee is most commonly affected by OA?

Answer 18

The medial surface.

Question 19

Name 3 joints of the hand that are commonly affected in osteoarthritis.

Answer 19

1. Distal interphalangeal joint (DIP).
2. Proximal interphalangeal joint (PIP).
3. Carpal metacarpal joint (CMC).

Question 20

Nodal osteoarthritis can affect the DIP and PIP joints. What are the two terms used for nodes on these joints?

Answer 20

1. PIP - Bouchard’s nodes.
2. DIP - Herbeden’s nodes.

Remember: since B is before H, so Bouchard’s are more proximal than Heberden’s.

Question 21

What are Herbeden’s and Bouchard’s nodes?

Answer 21

Soft tissue swellings on the fingers
Seen in the early stages of OA

Herbedens = DIP
Bouchards = PIP
(HD AND BP)

Question 22

Give 5 symptoms of OA.

Answer 22

1. Morning stiffness (<30 minutes).
2. Pain - aggravated by activity.
3. Tenderness (tender to palpation).
4. Walking and ADLs affected (activities of daily living).
5. Joint effusion (too much fluid builds up around a joint) and bony enlargement.
6. Deformities.
7. Crepitus (a popping, clicking or crackling sound in a joint).

Question 23

Describe the character of the pain from OA.

Answer 23

Increases with movement, worse at the end of the day.

Question 24

How is the pain different in osteroarthritis vs inflammatory arthritis?

Answer 24

Osteoarthritis:
- Morning stiffness only lasting up to 15 mins, generally worsens throughout day

Inflammatory arthritis:
- Stiff for 30+ mins, better with use

Question 25

Describe the pattern of joint involvement of OA.

Answer 25

Asymmetrical: - Arthritis that occurs in just 1 joint or a joint on only 1 side of your body. Finger joints, thumbs + weight bearing joints (hip/knee/big toe)

Question 26

What systemic features are present in osteoarthritis?

Answer 26

NONE

Question 27

A patient complains of 'locking', what is the most likely cause of this?

Answer 27

This is probably due to a loose body e.g. a bone or cartilage fragment.

Question 28

Investigations: What would the lab findings be in OA?

Answer 28

1. Rheumatoid factor = RhF -ve 2. Antinuclear antibodies = ANA -ve 3. Normal ESR/CRP typically normal

Question 29

What is the primary investigation used to make a diagnosis of OA?

Answer 29

X-ray.

Question 30

Investigations: What would be the radiological findings in osteoarthritis?

Answer 30

X-ray - LOSS: Loss of joint space. Osteophytes. Subchondral cysts. Subchondral Sclerosis.

Question 31

What is an osteophyte?

Answer 31

An area of bone which has been reactively laid down in the wrong place.

Question 32

What is sclerosis in relation to arthritis?

Answer 32

Thickening and widening of the bone at the joint.

Question 33

How do you end up with bony changes in OA?

Answer 33

1. Mechanical forces --> cartilege lost. 2. Cartilage loss = cytokines - TNFa, IL-1, NO. 3. Cytokines = cartilage cannot repair properly. 4. Loss of cartilage = bone rubbing on bone. 5. Reactive changes in bone, it is not designed to rub on bone.

Question 34

Describe features of the non-medical management for OA.

Answer 34

- Education. - Exercise. - Weight loss. - Physiotherapy. - Occupational therapy. - Walking aids.

Question 35

Describe the pharmacological management for OA.

Answer 35

Step-wise use of analgesia to control symptoms: 1st line: topical NSAIDs 2nd line: oral paracetamol + topical NSAIDs (consider adding a PPI to protect their stomach) 3rd line: short-term NSAIDs (+PPI) + paracetamol + topical capsaicin 4th line: weak opioid (e.g. dihydrocodeine), NSAIDs (+PPI) + paracetamol + topical capsaicin - Intra-articular corticosteroid injections - DMARDs if there is an inflammatory component

Question 36

Describe the surgical management for OA.

Answer 36

1. Arthroscopy for loose bodies. - Scope inserted into joint to assess damage + remove loose bodies 2. Osteotomy (cut bone to change bone length/shape). 3. Arthroplasty (joint replacement - knee or hip). 4. Arthrodesis - Fusion (usually ankle and foot - to prevent painful grinding of the bones).

Question 37

What is the indication for arthroscopy in OA?

Answer 37

Loose bodies e.g. bone or cartilage fragment that cause ‘knee lock’

Question 38

Give 3 indications for surgery - joint replacement in OA.

Answer 38

1. Significant limitation of function. 2. Uncontrolled pain (particularly at night). 3. Waking at night from pain.

Question 39

What is the disadvantage of having a joint replacement and getting a prosthetic joint?

Answer 39

Prosthetic joint has lifespan of 10-15 years and will need replacement. In a young person, this could be as much as 3 times.

Question 40

What is the treatment for loose bodies?

Answer 40

Arthroscopy.

Question 41

What main features would you use to differentiate between rheumatoid arthritis and osteoarthritis (inflammatory VS degenerative)?

Answer 41

1. Pattern + distribution of joint involvement. 2. Absence of systemic features of OA. 3. RA has marked early morning stiffness lasting >60mins.