LOCO OA

Question 1

Describe the effect of repetitive mechanical and increased oxidative stress on the chrondrocytes

Answer 1

Chondrocytres hypertrophy and undergo senescence
Release Matrix metalloproteinases (MMPs) and ADAMTS
The degrade the ECM of cartilage

Question 2

General pathophysiology of OA

Answer 2

Cells fail to maintain balance between synthesis and degradation of ECM products in the cartilage resulting in exposed bone

Question 3

What pro-inflammatory cytokines are released after cartilage breakdown and what are the effects

Answer 3

IL-1, IL-6 and TNF alpha
These are released into the synovial cavity and initiate inflammation which triggers the influx of immune cells (macrophages)
These produce growth factors that may contribute to the formation of osteophytes

Question 4

What changes occur in the bone once exposed

Answer 4

Bone becomes softer and of a poorer quality due to hypomineralisation
Osteoblast activity also increase resulting in subchondral schlerosis
Growth factors from synovial macrophages may cause osteophyte formation

Question 5

What are the MICROSCOPIC structural changes to the cartilage

Answer 5

• Chondrocyte necrosis (especially in the superficial layers)
• Focal clumps/clones of chondrocytes (isogenic clusters)
• Changes in cartilage from Type II (hyaline) to type I (fibrocartilage) you can see tidemark duplication (two lines where it changes from type II to type II and to bone

Question 6

What are the BIOCHEMICAL changes to cartilage

Answer 6

• Cartilage thickens and swells so becomes more porous
• Loss of proteoglycans results in less compressible cartilage
  -Cartilage networks breakdown due to MMPs, ADAMTs and collagenases
  Cartilage softens (chondromalacia) which progresses to fibrillation

Question 7

What are the MACROSCOPIC changes to bone

Answer 7

• Fibrillation
• erosion and cracking
• eburnation (exposed bone looks polished)

Question 8

Other than age, name 2 other risk factors for OA (out of 4 others)

Answer 8

• Gender (females are more likely probably due to menopause)
• Obesity (increased loading of the joints)
• Genetic Factors (loss of HMGB2)
• Joint injury or disease (RA or Gout, joint injury more likely in men)

Question 9

Name 2 symptoms of OA other than joint pain

Answer 9

• Morning stiffness (less than 30 minutes)
• Joint instability of buckling
• Loss of function
• Crepitus on motion

Question 10

What might you observe on clinical examination of a patient with OA

Answer 10

• Limited range of motion
• Muscle atrophy/weakness
• Crepitus on motion
• Bony enlargments felt on affected joints
• Malalignment/joint deformity

Question 11

What is involved in the GALS musculoskeletal assesment

Answer 11

Gait, arms, legs and spine
Observe gait
Look, feel, move limbs
inspect joints and spine

Question 12

What features would you on an x-ray of an osteoarthritic joint

Answer 12

• Narrowing of joint space
• Subchondral sclerosis
• Subchondral cysts
• Presence of osteophytes

Question 13

Apart from analgesics, what treatment options are there for OA

Answer 13

• non-pharmacological
• Arthroscopic washout and debridement
• Viscosupplementation
• Chondrocyte grafting
• Total joint replacement

Question 14

What are the non-pharmacological treatment options for OA

Answer 14

• Exercise/diet/weight loss
• Suitable footwear, aids and walking devices
• TENS
• Thermotherapy
• Nutraceuticals