1.111 Knee Joint

Question 1

What are the two joints of the knee?

Answer 1

Tibio-femoral - weight bearing

Patello-femoral joint - saddle

Question 2

Does the knee joint include the fibula?

Answer 2

No

Question 3

Which muscles are the flexors of the knee?

Answer 3

Gracilis, Hamstrings, Sartorius, Gastrocnemus, and Plantaris

Question 4

Which muscles are stabilisers of the knee?

Answer 4

Gluteus maximus, Tensor fascia latae

Popliteus - locking

Question 5

What does the popliteal artery give branches to?

Answer 5

Branches to give rise to tibial, fibular, sural and genicular arteries

Question 6

What is the nerve supply to the knee?

Answer 6

Femoral – Branches to vasti
Sciatic – Genicular branches
Obturator – Posterior division (sometimes absent)

Question 7

What ar the menisci form from?

Answer 7

Dense fibrous articular cartilage

Question 8

What are the menisci?

Answer 8

• C-shaped (Wedge-shaped in cross-section)
• Vascular at margins
• Attached to tibia by meniscotibial ligaments
• Inside synovial cavity
Move in flexion, extension and rotation of knee

Question 9

Which meniscus is more likely to rupture?

Answer 9

Medial lemniscus is attached to capsule - more likely to rupture
Lateral lemniscus partially attached to popliteus

Question 10

What is the knee capsule bordered by?

Answer 10

Fibrous membrane
Attached posteriorly and sides
At articular margins of tibia and femur - not fibula
Posterior opening to allow popliteaus tendon to attach to the femur

Question 11

With which bones does the arcuate ligament attach with?

Answer 11

Both tibia and fibula

Question 12

What is the anterior cruciate ligament?

Answer 12

• Arises from anterior part of intercondylar area of tibia
• Passes to medial side of lateral femoral condyle
• Slack when knee flexed
• Tight when knee extended
• Prevents anterior displacement of tibia on femur
• Helps to medially rotate femur to ‘lock’ knee in standing

Question 13

What is the posterior cruciate ligament?

Answer 13

• Arises from posterior part of intercondylar area of tibia and passes to lateral side of medial femoral condyle
• Tightens during knee flexion
• (opposite to anterior cruciate)
Prevents posterior displacement of tibia on femur, particularly when climbing stairs or landing a jump

Question 14

What is the anterior draw test?

Answer 14

Positive sign - tibia can be displaced anteriorly

Indicates anterior cruciate ligament, menisci, and meniscotibial ligament damage

Question 15

What is the posterior draw test?

Answer 15

Positive sign - tibia can be displaced posteriorly

Indicates posterior cruciate ligament damage

Question 16

What is Bachmann’s test?

Answer 16

Movement of tibia on femur does not stop suddenly - indicates anterior cruciate ligament damage

Question 17

What is the Patellar bursa?

Answer 17

• Synovial membrane lines non-articular areas
• Extends superiorly between anterior femur and quadriceps tendon to form large suprapatellar bursa
• Muscles inserting around
knee joint have associated bursa:
Popliteus, gracilis hamstrings, sartorius gastrocnemieus
Infrapetellar and pre-patellar

Question 18

What is the Q angle?

Answer 18

Line from anterior superior iliac spine to mid patella

Vertical line through mid patella and tibial tuberosity

Question 19

What are the normal Q angles?

Answer 19

14±3 for males
17±3 for females
17 - menu valgum - bow legged

Question 20

How many degrees is an active rotation?

Answer 20

15 degrees - when turning in a flexed position

Question 21

What is passive rotation?

Answer 21

Lock knee in extended position when standing

Question 22

What is the angle of flexion?

Answer 22

120-150 degrees
Limited by leg against posterior thigh
In shock absorbing use - lengthening of quadriceps femurs muscle to control flexion

Question 23

What is the extension angle?

Answer 23

5-10 degrees

During propulsion, extension from flexed position uses quadriceps muscles

Question 24

What does the iliotibial tract do to the knee?

Answer 24

Assist in maintain a stable “locked” position

Question 25

What is happens during the ‘unlocking’ of the knee?

Answer 25

Requires popliteus to laterally rotate the femur

Popliteus also pulls lateral lemniscus posteriorly

Question 26

What provides stability to the knee?

Answer 26

• Knee joint is adapted for weight-bearing and stability in any position
• But not particularly strong joint
• Most stability from muscles and ligaments, not bony contours
• Iliotibial tract contributes to stability
• Vastus medialis and lateralis strengthen sides of knee
Physiotherapy can improve stabilising influence of quadriceps femoris

Question 27

What are the injures which can occur to the knee?

Answer 27

3C's - cruciate, collaterals and cartilages 
Blow to lateral knee 
- Rupture to medial collateral ligament 
- Tearing to medial lemniscus 
- tearing to anterior cruciate ligament

Question 28

What is tearing to the lateral collateral ligament usually associated with?

Answer 28

Damage to common peroneal (fibular) nerve

Question 29

What would abnormal ossification of the patella cause?

Answer 29

Embryology

Bipartite or Tripartite patella