Knee

Question 1

Medial VS Lateral meniscus

Answer 1

Medial meniscus
- Larger
- shaped like the letter “C”
- more stationary
- attaches to MCL

Lateral meniscus
- smaller
- shaped like the letter “O”.
- Lateral ligament of the knee is not attached
- more mobile and less risk of injury
- Attached to popliteus muscle
- During knee flexion, popliteus pulls lateral meniscus posteriorly to prevent entrapment between femur and tibia

Question 2

Anterior Cruciate Ligament

Answer 2

Insertion/Origin
- Extends superiorly, posteriorly and laterally

• APEX = arises from Anterior condylar area, directed Posteriorly and inserts on lateral (EXternal) condyle

Motion limited
Prevents
- anterior translation of the tibia on the femur
- aids in controlling lateral rotation of the tibia in flexion
- aids in controlling extension and hyperextension at the knee (less extent

Tightened position:
Least amount of stress =30-60 degrees
maximally taut = 0-20 degrees

Question 3

Posterior Cruciate Ligament

Answer 3

Insertion/Origin
- Extends superiorly, anteriorly, and medially from the tibia to the femur.

Motion limited
Prevents
- posterior translation of the tibia on the femur
- aids in controlling extension and hyperextension.

Tightened position:
- tight at 30 degrees

Question 4

Screw Home Mechanism

Answer 4

For knee stability
- at end of full extension (0-20 degrees)

Articular surface of medial condyle–>longer than lateral condyle

tibia is then in external rotation–>maximal stability

Question 5

Patella fracture

Answer 5

Blood supply to the patella: geniculate arteries

S/S:
- sharp, intense pain in anterior knee
- limp to avoid pressure through the knee
- pain++ with knee in bent position: e.g. Sit to stand