O&T: Knee Osteoarthritis

Question 1

History taking in knee pain

Answer 1

1. Location (knee have different compartments)
   - Back of knee: Popliteal cyst, Referred pain from spine
2. Mechanical vs Inflammatory
3. Acute vs Chronic
   - Acute: Trauma, Septic arthritis, Gouty arthritis
4. Traumatic vs Non-traumatic
   - Traumatic: Ligament, Meniscus injury
5. Exacerbation factors
   - Seafood (gouty arthritis)
   - Walking / Stair climbing (osteoarthritis)
6. Intensity, Provoking / Alleviating factors, Radiation, Progression, ADL

Question 2

Associated symptoms of Knee joint

Answer 2

1. Swelling
   - Diffuse: Effusion, Haemarthrosis, Synovitis
   - Localised: Bursa, Meniscal cyst, Tumour, Skin pathology (e.g. Lipoma)
2. Deformity
   - Valgus / Varus
   - Fixed flexion / hyperextension
3. Stiffness
   - Early morning stiffness: Inflammatory
   - After inactivity: OA
4. Instability / Giving away
   - Muscle weakness
   - Ligament instability
5. Locking
   - Loose body / Torn meniscus jammed between articular surfaces

Question 3

DDx of Knee pain by anatomical site in knee

Answer 3

Anterior knee:
1. Patellar subluxation / dislocation
2. Tibial apophysitis (Osgood-Schlatter lesion)
3. Patellar tendonitis (Jumper’s knee)
4. Patellofemoral pain syndrome (chondromalacia patellae)

Medial knee:
1. MCL sprain
2. Medial meniscal tear
3. Pes anserine bursitis
4. Medial plica syndrome

Lateral knee:
1. LCL sprain
2. Lateral meniscal tear
3. Iliotibial band tendonitis

Posterior knee:
1. Popliteal cyst (Baker’s cyst)
2. PCL injury

Question 4

Comorbidities in OA

Answer 4

1. CVS disease (due to immobility / obesity)
2. Metabolic syndrome
3. Psychosocial
4. Sleep disturbance
5. Peptic ulcer disease (due to NSAID use)

Question 5

Importance of exercise

Answer 5

1. Muscle
   - Prevent atrophy of muscle
2. Cartilage health
   - Repeated cyclical loading important for cartilage health

Question 6

Risk factors for OA

Answer 6

1. Obesity
2. Injury
3. Occupation

Question 7

(Investigations of OA (From MSS03))

Answer 7

1. Plain radiographs (Kellgren Lawrence classification)
   - **narrowing of joint space
   - **marginal osteophyte
   - **subchondral sclerosis
   - **subchondral cyst
   - body contour change / defect
2. MRI
   - Meniscal tear (cannot be seen on X-ray)
   —> traumatic
   —> degenerative
   - **Loose bodies
   - **Cysts
   —> Baker’s cyst / Popliteal cyst
3. Blood tests
   - **normal white cell count
   - **normal ESR (↑ ESR / CRP —> inflammatory rather than degenerative causes)
   - normal bone profiles (Ca, PO4, alkaline phosphatase)
4. Joint aspiration
   - clear straw colour
   - total cell count <1000 / mm3
   - **gram smear -ve, culture -ve
   - **crystals -ve
   —> urate crystal (Gouty arthritis)

Question 8

Management of OA

Answer 8

1. **Education, **Exercise, ***Weight control (ALL patients)
2. ***Physiotherapy
3. Pharmacological
   - Paracetamol
   - NSAID / COX2 selective (short term basis due to CVS + GI risk, lowest dose possible, prescribed with PPI)
   - Topical NSAID (comparable efficacy with oral NSAID with lower GI SE)
   - Opioid
   - Analgesic balm (menthol-6%, methyl salicylate-14%)
   - Intra-articular injections
   —> Corticosteroids (short benefit in pain, repeated injection may predispose to cartilage / joint damage)
   —> Viscosupplements / Hyaluronic acid (***NO clinically meaningful benefit over placebo)
   —> Platelet rich plasma (need higher quality studies, MOA uncertain)
   - Glucosamine (required for synthesis of mucopolysaccharides found in tendons, ligaments, cartilage, synovial fluid, placebo effect)
   - DMOAD (future)
4. Surgery
   - Arthroscopy
   —> limited indication: frequency locking symptoms caused by ***meniscal tears / loose bodies —> short term relief of locking symptoms
   —> complications: DVT, PE
   —> increase rate of progression of OA
   —> shorten time to joint replacement

• Total / Partial Knee replacement (>65 yo)
  —> mainstay of treatment for end-stage OA
  —> effective: improve pain, QoL, function
• High tibial osteotomy (<55 yo)
  —> preserve native knee
  —> unload diseased compartment
  —> shift load to healthy compartment
  —> aim at slight overcorrect ~3-6o valgus alignment

Question 9

Severe valgus

Answer 9

• TKA indicated for knee pain + instability
• Limited role for non-surgical management for severe valgus knee
• Difficulty TKA surgery
  —> Ligament balancing
  —> Bone loss management
  —> Deformity correction
• Specific complication: ***Peroneal nerve palsy (due to stretching of lateral knee after surgery)

Question 10

RA Atlantoaxial instability

Answer 10

Flexion + Extension X-ray of C-spine:
Atlanto-dens interval (ADI)
- distance between odontoid process of C2 and posterior border of anterior arch of atlas (C1)
- ***>3.5mm —> unstable

Question 11

Surgery for RA

Answer 11

Descending priorities:
1. Urgent / Early surgical treatment: C1/2 subluxation
2. Patient’s preference + expectation
3. More painful joint first
4. Simple procedure with higher success rate first
5. Lower limb before upper limb
- Lower limb: distal to proximal
- Upper limb: proximal to distal