Flashcards in AFC Arthritis Deck (30)
Where do bones grow from?
Growth plate (epiphyseal plate)
State Hueter-Volkmann’s Law?
Increased compression at the growth plate slows down longitudinal growth
Increased tension at the growth plate speeds up longitudinal growth
Give an example of where this can be used to correct an abnormality.
Eight Growth Plate – if there is abnormal growth on one side of the distal tibial physis you can inset a metal plate with pins on either side of the growth plate to prevent further growth on that side and allow the other side to catch up
What are the three different types of knee alignment?
Varus – bowed legs
Valgus – knocked knees
What types of athletes get varus alignment?
Which part of the knee joint would be loaded most in varus alignment?
The inner part
What are the consequences of this?
It will wear out the cartilage and cause osteoarthritis
What surgical intervention can be performed before the onset of osteoarthritis to realign the knee joint?
Osteotomy – this involves taking a wedge out of the tibia to realign the knee joint
State Wolff’s Law.
Bone in a healthy person will adapt to the loads under which it is placed
Give an example that illustrates Wolff’s law.
What are the two surfaces of the cortical bone?
Load on the bones causes an increase in cortical thickness – how is this response to loading different in children compared to adults?
Children – have an active periosteum and endosteum so they get increased bone growth at BOTH surfaces
Adults – their periosteum is less active – so the response to increased loading is mainly at the endosteal surface
A lot of problems to do with body shape occur in utero. Give an example of such a problem that is associated with 9-10% of cases of osteoarthritis
Developmental Dysplasia of the Hip (DDH)
Describe the appearance of the hip joint in someone who had DDH.
The hip joint may be higher than normal
The acetabulum is shallow and it doesn’t cover much of the femoral head
This leads to increased load and wear
Why is it important to spot these deformities early?
If these deformities are caught early, they could realign them and cause a remodelling of the joint to allow normal stance
Name and describe two abnormalities of the hip joint.
Cam – bump on the neck
Pincer – the acetabulum tries to capture the hip joint so it is much deeper than normal (mainly seen in females)
What are the negative consequences of Cam abnormality?
Deep flexion will cause repeated impact between the bump on the femoral neck and the acetabular rim leading to the wearing away of thecartilage --> osteoarthritis
What are the negative consequences of Pincer abnormality?
The femoral neck will impact with the deepened acetabular labrum and cause compacting of the femoral head posteriorly (this will cause a contre-coup type erosion of the cartilage on the posterior acetabular surface)
Name the two cruciate ligaments of the knee joints and state their roles with regards to sliding at the knee joint.
Anterior cruciate ligament – stops the tibia from sliding forwards
Posterior cruciate ligament – stops the tibia from sliding backwards
What is a synovial joint?
A joint covered with hyaline cartilage or fibrocartilage that is surrounded by a fibrous capsule with a synovial membrane on the inside producing synovial fluid to lubricate the joint
What is the structural difference between the medial and lateral menisci?
The lateral meniscus has a much tighter C shape
What are the two main functions of cartilage?
Which type of collagen is found in cartilage?
Describe the arrangement of collagen in the superficial layer andexplain why they are arranged like this.
Horizontally – resists shear forces
Describe the arrangement of collagen in the deep layer and explain why they are arranged like this.
Vertically – resists compressive forces
What provides the nutrition to the tissue above the tidemark?
What is the downside to the lack of blood supply above the tidemark?
This means that if the cartilage superficial to the subchondral bone is damaged, it can’t really heal itself
What is the name given to the pattern of fibres that form the collagen network in bone?
What happens to your tibia when the ACL snaps and what other structures will try to hold it in place?
It slides forwards
The meniscus will try to hold it in place
NOTE: if you don’t repair the ACL you will get meniscal tears because they are being strained in trying to keep the femur in place on the tibial plateau