9. Sports and joints

Question 1

What forces promote and restrict growth at growth plates?

Answer 1

• Tension promotes growth

* Compression restricts growth

Question 2

When does the bone start to ossify from the middle of the bone?

Answer 2

From 11 weeks in utero

Question 3

What fuses when a growth plate fuses?

Answer 3

Diaphysis and epiphysis

Question 4

What is varus?

Answer 4

Deformity where the knees are far apart and ankles are close together - bow leg

Question 5

What is valgus?

Answer 5

Deformity where the knees are close together (knocked knees) and ankles are further apart

Question 6

What type of leg deformity are footballers prone to?

Answer 6

Varus - unnatural load placed on knee as they kick with one foot and rotate on the other fixed knee

Question 7

What type of leg deformity are models prone to?

Answer 7

Valgus - due to gait when walking

Question 8

What are the 3 compartments to the knee and which parts take the most weight?

Answer 8

• Medial
• Lateral
• Patella femoral

Medial and lateral take the most weight

Question 9

Which compartment of the knee does varus (and valgus) cause excess weight to be applied to and offloading?

Answer 9

Weight - medial compartment
Offloading - lateral compartment

(Valgus is the opposite)

Question 10

Does varus and valgus change the likelihood of developing osteoarthritis?

Answer 10

Varus = 2x more likely
Valgus = 1.5x more likely

Question 11

How can varus/valgus be treated?

Answer 11

• Surgically corrected before it starts to wear out when patient is in their 20s
• 6 months rehab
• Prevents OA in later life which could require replacement by 30/40s

Question 12

What is Wolff’s law?

Answer 12

Bones adapt to stress/load
• Form in direction of the stress they are under
• Make it stronger and more able to deal with the stress
• Cortical and trabecular bone adapt

Question 13

How does being in space affect bone density?

Answer 13

Decreases bone density

Question 14

What is developmental dysplasia of the hip and when does it occur?

Answer 14

• Femur doesn’t sit in the acetabulum correctly
• Acetabulum is shallower than normal - strain on acetabular labrum - risk of OA
• Occurs in utero
- due to error in programming or lack of mechanical movement
• Kicking applies forces between the femoral head and acetabulum in a range of directions, causing the socket to form

Question 15

What are CAM and pincer hips?

Answer 15

Femur or acetabulum is not round
• Cam impingement - thicker neck of femur, comes into contact with acetabulum when abducting
Pincer impingement - acetabulum is not round, encompasses too much of the femoral head and rubs on the bone

Question 16

Is CAM and pincer more common in males or females?

Answer 16

CAM - males

Pincer - females

Question 17

How can CAM be treated?

Answer 17

Removing the lump before damage to the hip - if there is pain in the groin, it is too late

Question 18

ACL injury is common in football - what does this cause?

Answer 18

• ACL normally prevents anterior movement of tibia on femur
• If damaged, it can move forward more than normal

(damage to cruciate ligaments results in unrestrained movement of synovial joint)

Question 19

What is the tidemark line in cartilage?

Answer 19

Determines where the cartilage is vascularised:
• Bone side is vascularised
• Joint side is not

Question 20

What happens if superficial damage occurs to the cartilage superficial and past the tidemark line?

Answer 20

• Superficial - cannot repair as it is not vascularised

* Past - repaired by stem cells, but hyaline cartilage is not replaced - stem cells produce fibrocartilage

Question 21

What is the role of a meniscus in the knee?

Answer 21

Shock absorber - spreads the load across the whole articular surface

Question 22

What happens if a meniscus is not present?

Answer 22

Force is applied across a point at the joint - more pressure => more damage => OA