The Arthritis Eleven Flashcards
- Bones grow from XXXX rather than YY
the ends of bones
the middle
- The growing portion of a bone is known as the
PHYSIS
the outer extremes of The growing portion of bone is known as…
the epiphysis
Why are athletes usually shorter
that bones under compression stop growing
What is middle alignments of knees known as? Where are the knees in relation to the mechanical axis? Who is this common in?
VARUS
centre of knee joints outside of mechanical axis (bowing)
common in Rickets cases and in professional footballers
What is right alignment of the knees known as? Where are the knees in relation to the mechanical axis? Who is this common in?
VALGUS – centre of knee joints inside of mechanical axis (knock-kneed)
What is WOLFF’S LAW?
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
Demonstrations of Wolffs Law? (3)
- 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
What is DEVELOPMENTAL DYSPLASIA OF THE HIP (DDH)? What is the problem, what does it cause dysfunctional development of, what does it lead to?
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
Subchondral sclerosis is a feature of…
OA
Treatment for developmental dysplasia of the hip? (2)
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
what causes a Cam hip?
- 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
What causes a pincer hip?
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
Cam hip is more common in [men/women]
Men
pincer hip is more common in [men/women]
Women
What is the treatment for cam and pincer impingement?
We can treat these conditions using a razor to shave off the extra bone – preventative treatment for OA
- ACL stops the tibia moving X on the femur
forward
- PCL stops the tibia moving X on the femur
backward
What is a synovial joint
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)
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
8=====D
What way do fibres of collagen run at the interface between cartilage and synovial fluid and why, what does this do?
- 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
What way do fibres of collagen run in the middle of the joint surface?
are more criss-cross in nature
What way do fibres of collagen run at the interface between bone and the joint surface?
the collagen fibres become orthogonal (right angled) to those at the joint surface
Why is the tidemark of collagen important?
fundamental in terms of attaching cartilage to bone – very strong attachment
ACL injuries are caused by…
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
Describe the shape of the Menisci (lateral and medial side)
Lateral side has a more C-shaped meniscus and the medial side is more crescent shaped – often injured from a low-impact force
What is often injured from a low impact force?
Menisci
Purpuse of menisci?
help to stabilize the joint
What can cause the failure of menisci? Why?
- Varus knee can cause the meniscus to fail because of uneven balance of force across it – causes medial compartment to fail
