Cartilage Injuries and Arthritis

Question 1

Function of hyaline cartilage?

Answer 1

Covers the surface of bones in synovial joints in order to decrease friction and distribute load

Question 2

Components of hyaline cartilage?

Answer 2

Water, collagen, PGs and chondrocytes (produces collagen, PGs and enzymes to regulate the EC matrix)

HYALINE CARTILAGE IMAGE

Question 3

Nutrition of hyaline cartilage?

Answer 3

From synovial fluid and sunchondral bone

Question 4

Function of collagen and PGs in hyaline cartilage?

Answer 4

Collagen fibres provide tensile strength

PGs are highly hydrophilic and act like balloons to give compressive strength

Question 5

Structures of proteoglycans?

Answer 5

Hyaluronic acid chains with protein cores, etc

HYALURONIC ACID IMAGE

Question 6

Mechanisms of articular cartilage defects?

Answer 6

Traumatic

Atraumatic:
• Osteochondritis dissecans
• Osteoarthritis
• Inflammatory arthritis

Question 7

Briefly describe mechanism of healing of articular cartilage?

Answer 7

Healing is with fibrocartilage, which has greater friction and is less wear-resistant

Only full-thickness injuries can heal

Question 8

What is Osteochonditis Dissecans?

Answer 8

An area of subchondral bone loses its blood supply and cartilage +/- bone can fragment off, commonly at the femoral condyle

Most common in adolescence and should be Ix if they have unexplained knee pain

Question 9

Signs of OCD?

Answer 9

Knee pain, effusion and a crackling sound with joint movement

Question 10

Management of OCD?

Answer 10

Can heal/resolve spontaneously and most people do well, although sportsmen may feel more effects

If detaching on MRI, it can be pinned in place; if detached, it can be fixed or removed

Many need to correct malalignment

Question 11

Describe cartilage regeneration techniques

Answer 11

Various techniques available but they ALL heal with fibrocartilage (higher friction and is less wear resistant); this is better for small defects and most people have an improvement in symptoms, although some are worse after

Unsuccessful in patellofemoral joint

Question 12

Options for cartilage regeneration techniques?

Answer 12

Options:
• Drilling/microfracture
• Osteochondral autograft/allograft
• Mosaicplasty
• MACI (membrane-induced autologus chondrocyte implantation)

Question 13

Contraindications to cartilage regeneration techniques?

Answer 13

Cannot do this if:
• Radiographic changes of OA
• Inflammatory arthritis
• Joint instability

Question 14

Uses of the different cartilage regeneration techniques?

Answer 14

There is not clear benefit of any but microfracture is the simplest/cheapest

Osteochondral allograft for larger defects or bone loss

There is likely to only be about 5 years benefit

Question 15

Describe OA

Answer 15

Imbalance of cartilage breakdown and repair that may be predisposed to by:
• Injury - articular cartilage injury, fractures and joint instability
• Malalignment (genu varum/valgum, fracture malunion)
• Degenerate meniscal tear
• Infection

There may also be familial/genetic influences

Question 16

Non-operative treatments for early OA?

Answer 16

Weight loss, walking stick, exercise (prevents stiffness), analgesics and activity modification

Viscosupplementation (PG injections)/hyaluronic acid injections have no proven benefit and should not be offered (NICE)

Glucosamine, chondroitin have no proven benefit and are not offered (NICE)

Steroid injections are only used for acute flare-ups

Question 17

Operative treatments for early OA?

Answer 17

Osteotomy may be useful in varus knees, with isolated early medial compartment OA

This is good for manual worker but the satisfaction rates are only 70% and it may later affect results of a Total Knee Replacement (TKR)

Question 18

Uses of knee replacement?

Answer 18

Only for older patients with end-stage arthritis (can last 15-20 years) but younger patients have poorer outcomes and failure rates are higher

Partial knee replacement has poorer results than TKR (3X higher re-operation rates)

Question 19

Risks of knee replacement?

Answer 19

• Deep infection can occur
• Pain, stiffness
• DVT/PE