9. Sports and joints Flashcards
What forces promote and restrict growth at growth plates?
- Tension promotes growth
* Compression restricts growth
When does the bone start to ossify from the middle of the bone?
From 11 weeks in utero
What fuses when a growth plate fuses?
Diaphysis and epiphysis
What is varus?
Deformity where the knees are far apart and ankles are close together - bow leg
What is valgus?
Deformity where the knees are close together (knocked knees) and ankles are further apart
What type of leg deformity are footballers prone to?
Varus - unnatural load placed on knee as they kick with one foot and rotate on the other fixed knee
What type of leg deformity are models prone to?
Valgus - due to gait when walking
What are the 3 compartments to the knee and which parts take the most weight?
- Medial
- Lateral
- Patella femoral
Medial and lateral take the most weight
Which compartment of the knee does varus (and valgus) cause excess weight to be applied to and offloading?
Weight - medial compartment
Offloading - lateral compartment
(Valgus is the opposite)
Does varus and valgus change the likelihood of developing osteoarthritis?
Varus = 2x more likely Valgus = 1.5x more likely
How can varus/valgus be treated?
- 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
What is Wolff’s law?
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
How does being in space affect bone density?
Decreases bone density
What is developmental dysplasia of the hip and when does it occur?
• 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
What are CAM and pincer hips?
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
Is CAM and pincer more common in males or females?
CAM - males
Pincer - females
How can CAM be treated?
Removing the lump before damage to the hip - if there is pain in the groin, it is too late
ACL injury is common in football - what does this cause?
- 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)
What is the tidemark line in cartilage?
Determines where the cartilage is vascularised:
• Bone side is vascularised
• Joint side is not
What happens if superficial damage occurs to the cartilage superficial and past the tidemark line?
- Superficial - cannot repair as it is not vascularised
* Past - repaired by stem cells, but hyaline cartilage is not replaced - stem cells produce fibrocartilage
What is the role of a meniscus in the knee?
Shock absorber - spreads the load across the whole articular surface
What happens if a meniscus is not present?
Force is applied across a point at the joint - more pressure => more damage => OA
