The Arthritis Eleven

Question 1

• Bones grow from XXXX rather than YY

Answer 1

the ends of bones

the middle

Question 2

• The growing portion of a bone is known as the

Answer 2

PHYSIS

Question 3

the outer extremes of The growing portion of bone is known as…

Answer 3

the epiphysis

Question 4

Why are athletes usually shorter

Answer 4

that bones under compression stop growing

Question 5

What is middle alignments of knees known as? Where are the knees in relation to the mechanical axis? Who is this common in?

Answer 5

VARUS
centre of knee joints outside of mechanical axis (bowing)
common in Rickets cases and in professional footballers

Question 6

What is right alignment of the knees known as? Where are the knees in relation to the mechanical axis? Who is this common in?

Answer 6

VALGUS – centre of knee joints inside of mechanical axis (knock-kneed)

Question 7

What is WOLFF’S LAW?

Answer 7

Lines of force (trabeculae) show you the angle of force going across your joint, and bone at the points of most force thicken (become more dense) and become stronger

Question 8

Demonstrations of Wolffs Law? (3)

Answer 8

• Surfers get thick bones
• Astronauts get thin (osteopaenic) bones
• Tennis players’ dominant arms have higher cortical thickness (less relevant for females as they tend to use double handed grip

Question 9

What is DEVELOPMENTAL DYSPLASIA OF THE HIP (DDH)? What is the problem, what does it cause dysfunctional development of, what does it lead to?

Answer 9

Occurs during utero/fetal development
 Steeply formed acetabular wall, femoral head doesn’t develop, end up with flat adult socket and abnormal shaped femoral head
 Can lead to subchondral sclerosis – thickening of the bone beneath the articular surface, leaving very little joint space

Question 10

Subchondral sclerosis is a feature of…

Answer 10

OA

Question 11

Treatment for developmental dysplasia of the hip? (2)

Answer 11

 Head needs to be put back into socket – abduct the hip to reduce the head back into the socket, and by Wolff’s law the socket will develop around it
 Can also cut the femur in order to put the head back in the socket

Question 12

what causes a Cam hip?

Answer 12

• If the ball (femoral neck) is not ball-shaped, and has an extra piece of developing bone, then the forces going across the hip are different, and hip abduction causes the femoral neck to push against the acetabulum, the extra piece gets bigger and bigger by Wolff’s law

Question 13

What causes a pincer hip?

Answer 13

If the problem is with a misshapen acetabulum, the extra bone on the acetabulum will push against the femoral neck when you abduct your hip, and it’ll keep getting bigger by Wolff’s law

Question 14

Cam hip is more common in [men/women]

Answer 14

Men

Question 15

pincer hip is more common in [men/women]

Answer 15

Women

Question 16

What is the treatment for cam and pincer impingement?

Answer 16

We can treat these conditions using a razor to shave off the extra bone – preventative treatment for OA

Question 17

• ACL stops the tibia moving X on the femur

Answer 17

forward

Question 18

• PCL stops the tibia moving X on the femur

Answer 18

backward

Question 19

What is a synovial joint

Answer 19

capsule, inside of which is a membrane which produces synovial fluid (a lubricant to allow joints to move freely over each other with low friction to protect the joint surfaces)

Question 20

Be able to label on a diagram of the knee:
Articular cartilage
ACL
PCL
Synovial membrane
Capsule
Femur
Tibia
Fibula
Ligaments
Meniscus
Bursa
Patella
Tendon

Answer 20

8=====D

Question 21

What way do fibres of collagen run at the interface between cartilage and synovial fluid and why, what does this do?

Answer 21

• At the top of the joint surface, at the interface between the cartilage and the synovial fluid, the fibres of collagen run parallel because of sheer forces – this reduces friction

Question 22

What way do fibres of collagen run in the middle of the joint surface?

Answer 22

are more criss-cross in nature

Question 23

What way do fibres of collagen run at the interface between bone and the joint surface?

Answer 23

the collagen fibres become orthogonal (right angled) to those at the joint surface

Question 24

Why is the tidemark of collagen important?

Answer 24

fundamental in terms of attaching cartilage to bone – very strong attachment

Question 25

ACL injuries are caused by…

Answer 25

Platarflexed foot rooted to ground, hyperflexed knee – allows tibia to translate anteriorly on the femur causing an unstable knee which can give way when the knee is put down

Question 26

Describe the shape of the Menisci (lateral and medial side)

Answer 26

Lateral side has a more C-shaped meniscus and the medial side is more crescent shaped – often injured from a low-impact force

Question 27

What is often injured from a low impact force?

Answer 27

Menisci

Question 28

Purpuse of menisci?

Answer 28

help to stabilize the joint

Question 29

What can cause the failure of menisci? Why?

Answer 29

• Varus knee can cause the meniscus to fail because of uneven balance of force across it – causes medial compartment to fail