T2 L10: Anatomy of the knee Flashcards
The knee joint is the articulation between which bones?
The distal femur and the proximal tibia
What type of joint is the knee joint?
A synovial bicondylar hinge joint
What forms the synovial capsule around the knee joint?
The tendons that surround the patella
What is the function of the tibial condyles?
Also known as the tibial plateau, they receive the femoral condyles
Which factors provide stability for the knee joint and how?
- Bony expansions: The bones have condyles and fossa’s that all articulate
- Locking mechanism: There is a round and flat surface on either side. Medial rotation tightens ligaments of the knee. The centre of gravity maintains extension
What is the difference between the anatomical and femoral angle of the femur?
Anatomical is the one that passes through the femur (at an angle)
Mechanical is the one that bears the weight (vertical)
What is Genu varum?
There is medial displacement of the tibia causing ‘bow legs’
Knee’s are apart so there is increased stress resulting in degradation in joint
What is genu valgum?
Lateral displacement of the tibia causing the knee’s to be too close together
Causes ‘knock- knee’s’ and increased stress on the joint resulting in degradation knee’s’
What are the types of ligaments at the knee joint?
Extracapsular: medial and lateral collateral ligaments
Intracapsular: anterior and posterior cruciate ligaments
What does tearing of the lateral collateral ligament result in?
Varus deformity
What does tearing if the medial collateral ligament result in?
Valgus deformity
What is the origin and insertion of the cruciate ligaments?
Origin: lateral femoral condyle
Insertion: intercondylar area
How do you know which cruciate ligament in the knee is posterior?
It’s in relation to the tibia
Anterior to their position on the tibia or posterior
What is the function of cruciate ligament?
They prevent anterior and posterior displacement of the tibia on the femur
They maintain the femur against the tibia. At least 1 ligament is always tense
What happens to the cruciate ligaments during medial and lateral rotation of the leg?
Medial: ligaments tighten so there is limited rotation
Lateral: ligaments unwind
Which cruciate ligament is most frequently injured?
The anterior cruciate ligament is weaker. It’s a common sports injury caused by sudden rotation of the knee
What is the Lachman test?
A passive accessory movement test of the knee performed to identify the integrity of the anterior cruciate ligament
It involves moving the tibia up and down while maintaining position of the femur to look for looseness
What is the menisci of the knee joint?
The medial and lateral menisci provide a deepening of the articulating surfaces to increase stability
Which surfaces of the menisci in the knee are mobile?
Only the anterior and posterior bits are attached to the intercondylar area. The rest is mobile
Why is the medial meniscus less mobile than the lateral meniscus?
Because the medial meniscus is attached to the medial collateral ligament
What is an unhappy triad injury?
Twisting on a flexed knee and a blow to the lateral side during contact sports like rugby
Causes rupture of the anterior cruciate ligament, medial collateral ligament, and the medial meniscus
Why is the unhappy triad injury so hard to repair?
Because there is poor blood supply to the intracapsular structures
It generally requires surgery
What is the function of the iliotibial tract?
It’s the deep band of fascia on the leg that stabilises the joint capsule
Which muscles insert onto the iliotibial fascia?
Gluteus maximus and tensor fascia lata
