Cartilage repair and tissue engineering.

Question 1

The function of articular cartilage is…

Answer 1

distribution and transmission of load, minimisation of peak stress on subchondral bone, and resistance to low friction repeated movements.

Question 2

The main type of collagen in articular cartilage is…

Answer 2

Type 2 Collagen

Question 3

Articular cartilage contains which main components?

Answer 3

Chondrocytes, subchondral bone and an extra cellular matrix made up of collagen, proteoglycan and water.

Question 4

Type 1 Collagen is found where?

Answer 4

In your bones!

Question 5

The articular cartilage proteoglycan, agrican, has what function?

Answer 5

It uses its glycosaminoglycan chains to draw in water - it’s osmotically active.

Question 6

Normal articular cartilage has three zones, what are they called?

Answer 6

Superficial Zone (nearest the surface, releases lubrication into the joint space) and the Deep Zone (formed of more organised columnar chondrocytes). Between these two there is the mid zone where the chondrocytes are more disorganised

Question 7

Loss of joint space, sclerosis, subchondral cysts and osteophytes are X-ray characteristics of which pathology?

Answer 7

Osteoarthritis.

Question 8

Why is articular cartilage so poor at repairing?

Answer 8

Avascular (no fibrin to clot and no chemotactic factors) and slow diffusion of nutrients and waste through the synovial fluid.

Question 9

Cartilage focal lesions are most often the result of what?

Answer 9

Trauma, mainly in young adults as a result of sports and exercise. - either repetitive or traumatic impact.

Question 10

Which type of focal lesion lies entirely within the cartilage and have no spontaneous repair?

Answer 10

Chondral focal lesions.

Question 11

Which type of focal lesion penetrates through vascularised subchondral bone and demonstrates some spontaneous repair?

Answer 11

Osteochondral focal lesions - deeper.

Question 12

Advanced osteoarthritis and large cartilage defects are treated with what?

Answer 12

TKA - total knee replacement.

Question 13

What 5 treatments are used for small localised defects?

Answer 13

Debridement
Microfracture
Osteochondral grafting
Cell-based therapies
Ostotomy

Question 14

Which small lesion treatment relies on stimulation of the healing response by inducing bleeding into the joint space?

Answer 14

Microfracture

Question 15

Which focal lesion treatment is used to re-establish a normal gait pattern?

Answer 15

Osteotomy

Question 16

What is an autograft?

Answer 16

Tissue obtained from a patient for grafting.

Question 17

What is an allograft?

Answer 17

Tissue obtained from donor or cadaver tissue bank.

Question 18

Which focal lesion treatment technique requires a periosteal patch?

Answer 18

ACI - autologous chondrocyte implantation - a privately available technique. Not suitable for OA.

Question 19

What are fibrinogen and thrombin used for in the ACI procedure?

Answer 19

As a ‘glue’ to hold the periosteal patch in place.

Question 20

What is the recovery time after an ACI procedure?

Answer 20

6months to low impact eg swimming
9-12 months to higher impact ie jogging and aerobics
12+months basketball football etc

Question 21

Porcine collagen is used in which advanced ACI procedure?

Answer 21

Matrix induced autologous chondrocyte implantation.

Question 22

Mesenchymal cells give rise to which other cell types?

Answer 22

Chondrocytes
Lipoblasts
fibroblasts
osteoblasts
myoblasts

Question 23

Fibroblasts are the building blocks of what structures?

Answer 23

ligaments, tendons, joint capsules and general supporting tissues.

Question 24

What structure in joints acts as a shock absorber in the joint space and compliments the action of the cartilage?

Answer 24

Meniscus