Lecture: Lower Limb 2: The Knee Joint

Question 1

Which articulations are there at the knee joint?

Answer 1

2 femorotibial (medial and lateral)
1 femoropatellar

fibula not associated with the knee joint

Question 2

what movements are possible at he knee joint?

Answer 2

Extension
Flexion
Medial/Lateral rotation (when knee flexed at 90 degrees)

Question 3

What happens as the knee extends?

Answer 3

as it approaches full extension, femur undergoes a few degrees of medial rotation of the tibia
locks the knee in place
unlocked by the popliteus muscle

Question 4

what increases congruency at the tibial plateau

Answer 4

2 c-shaped wedges of fibrocartilage - the medial and lateral menisci

Question 5

functions of the menicsci?

Answer 5

increase joint congruency
even distribution of weight
shock absorbtion
assist in the locking mechanism
external edges attach to fibrous capsule of the joint

Question 6

How do meniscal tears arise and what is the consequence?

Answer 6

common sports/degenerative injury

displaced cartilage can become trapped during knee movements
can be painful/result in knee locking
damage is associated with osteoarthritis

Question 7

What features contribute to the stability of the knee joint?

Answer 7

Intra-articular ligaments
extra-articular ligaments
the surrounding muscles

Question 8

Describe the posterior cruciate ligament (PCL)

Answer 8

attaches to posterior intercondylar region of tibia and ascends supero-anteriorly to insert on medial femoral condyle
prevents posterior dislocation of tibia on femur
prevents hyperflexion
stronger one
supports weight walking downhill

Question 9

Describe the anterior cruciate ligament (ACL)

Answer 9

attaches to anterior intercondylar region of tibia and ascends supero-posteriorly to attach to lateral femoral condyle
prevents anterior displacement of tibia on femur
prevents hyperextension
weaker one

Question 10

Describe the Tibial (medial) collateral ligament

Answer 10

attached to medial meniscus

prevents abduction of leg at knee

Question 11

Describe the Fibular (lateral) collateral ligament

Answer 11

NOT attached to lateral meniscus

prevents adduction of leg at knee

Question 12

what is the unhappy triad of knee injury?

Answer 12

Torn ACL
Torn Medial Meniscus
Torn Tibial (medial) collateral ligament

Question 13

What typically causes the unhappy triad knee injury?

Answer 13

Excessive lateral twisting of flexed knee

or blow to lateral side of extended knee

Question 14

Which muscles are the main stabilisers of the knee?

Answer 14

Quadriceps
Hamstrings
Sartorius
Gracilis
Iliotibial tract

Question 15

Where are the bursae of the knee located?

Answer 15

Pre-patellar bursae - superficial to knee

Deep and superficial infrapatellar bursae - just inferior to knee

Question 16

common injuries to the knee joint?

Answer 16

bony fractures of any of the 3 bones involved
meniscal tears
ligamentous tears
dislocations of the patella or even whole knee joint

Question 17

Why are patellar dislocations more common in females than males?

Answer 17

Greater angle of femur due to wider, shallower hips
greater Q-angle
full of quads more horizontal

Question 18

Describe abnormal alignment issues of the knee

Answer 18

Bow-Leg - tibia adducted w.r.t femur

Knock-knee - tibia abducted w.r.t femur