Anatomy of the knee

Question 1

Where is the knee joint?

Answer 1

Articulation between distal femur and proximal tibia

Articulation between femur and patella

Question 2

What type of joint is the knee?

Answer 2

Synovial bicondylar hinge joint

Question 3

List the functions of the knee

Answer 3

Unusual

Weight–bearing

Mobility

• Extension/flexion
• Some rotation when flexed

Question 4

List the bony structures which strengthen the knee

Answer 4

• Bony expansions
• Locking mechanism
• Femoral angle

Question 5

List the soft tissue structures which strengthen the knee

Answer 5

• Ligaments
• Menisci
• Muscles

Question 6

List the bony expansions of the knee

Answer 6

Epicondyles
Femoral condyles
Tibial condyles
Intercondylar fossa

Question 7

What is the function of the bony expansions?

Answer 7

Provides a strong base

Question 8

What is the function of the locking mechanism

Answer 8

Reduces amount of energy required when extended

Question 9

Describe the shape of the femoral surfaces in flexion

Answer 9

round

Question 10

Describe the shape of the femoral surfaces in extension

Answer 10

Flat

Question 11

What constitutes the locking mechanism

Answer 11

Shape of the femur
Rotation
Centre of gravity

Question 12

What does medial rotation of the femur on the tibia in extension do?

Answer 12

Tightens the ligaments of the knee

Question 13

Where is the centre of gravity in the knee?

Answer 13

In front of the knee

Question 14

What is the function of the centre of gravity in the knee?

Answer 14

Maintains extension

Question 15

Describe the femoral angle

Answer 15

Adducted femur brings knee joint under pelvis

Critical for weight bearing

Occurs during development

Question 16

What is normal joint alignment in the knee?

Answer 16

Vertical line through centre of femoral head,

Centre of knee and centre of ankle

Question 17

Describe varus deformity (Genu varum)

Answer 17

Deformity in the angle tween the femur and tibia
Medial displacement of the tibia - common in children under 2 and rickets
Pushes the knees apart - bow legged - decrease in Q angle

Question 18

Describe valgus deformity (Genu valgum)

Answer 18

Lateral displacement of the tibia
- Common in children aged 2-4, rickets, arthritis
Brings knees together - ‘Knock-kneed’
Increases Q angle

Question 19

What is the function of the ligaments in the knee?

Answer 19

Provide stability

Question 20

Name the two groups of ligaments in the knee

Answer 20

Intracapsular

Extracapsular

Question 21

Where are the Extracapsular ligaments found?

Answer 21

Outside of the capsule

Question 22

Where are the Intracapsular ligaments found?

Answer 22

Inside the capsule

Question 23

Name the Extracapsular ligaments

Answer 23

• Medial collateral

- Lateral collateral

Question 24

Name the Intracapsular ligaments

Answer 24

• Anterior cruciate

- Posterior cruciate

Question 25

Describe the lateral/fibular collateral ligament

Answer 25

Strong round cord | Prevents medial displacement of the tibia

Question 26

What is a varus deformity?

Answer 26

Tear of the LCL

Question 27

Describe the medial/tibial collateral ligament

Answer 27

Broad flat band - Reinforces joint capsule - Prevents lateral displacement of tibia

Question 28

What is a valgus deformity?

Answer 28

Tear of the MCL

Question 29

Where is the anterior cruciate ligament?

Answer 29

anterior in relation to the tibia

Question 30

Where is the posterior cruciate ligament?

Answer 30

Posterior in relation to the tibia

Question 31

What is the function of the anterior cruciate ligament

Answer 31

Prevents anterior displacement of tibia on femur

Question 32

What is the function of the posterior cruciate ligament?

Answer 32

Prevents posterior displacement of tibia on femur | Stabilizer when knee is flexed

Question 33

What is the function of both cruciate ligaments?

Answer 33

Maintain femur against tibia

Question 34

Which is the weaker cruciate ligament?

Answer 34

Anterior cruciate

Question 35

Describe injury to the anterior cruciate ligament

Answer 35

- Common sports injury - Caused by sharp twisting of knee - Immediate decreased range of movement

Question 36

Describe the lachman test

Answer 36

- Patient in supine position with knee bent 20-300 of flexion - Move tibia anteriorly and posteriorly while maintaining position of femur - Laxity during this manoeuvre indicates anterior cruciate ligament injury

Question 37

What are the menisci of the joints

Answer 37

Crescent-shaped plates of fibrocartilage - Deepen the articulating surfaces/stability - Shock absorbers - Provides smooth viscous film for joint

Question 38

Describe the menisci attachments

Answer 38

Horns of menisci attached to intercondylar area of tibia Mobile - Accommodates rolling of femoral condyles Medial meniscus less mobile- Attached to medial collateral ligament

Question 39

What can be commonly ruptured in the knee?

Answer 39

- Anterior cruciate ligament - Medial collateral ligament - Medial meniscus (attached to MCL)

Question 40

Describe the iliotibial tract

Answer 40

- Reinforces joint capsule | - Stabilizes extended knee gluteus maximus, tensor fascia lata

Question 41

List the 4 heads of the quadriceps

Answer 41

Rectus femoris Vastus lateralis Vastus intermedialis Vastus medialis

Question 42

What is the function of the quadriceps

Answer 42

major stabilizing muscle of the knee | Extends the leg

Question 43

Describe the patellar

Answer 43

- Protects quadriceps tendon from stresses during locomotion | - Smooth oval facet of posterior surface for articulation with femur

Question 44

How can the patella be fractured?

Answer 44

due to fall or blow to the knee

Question 45

How can the patella be dislocated?

Answer 45

sudden twisting/jumping or ligamentous laxity

Question 46

Name the 3 hamstring muscles

Answer 46

- Biceps femoris - Semimembranosus - Semitendinosus

Question 47

What is the function of the hamstring muscles

Answer 47

- Also medially and laterally rotates leg when knee flexed | - And extends thigh

Question 48

Which 2 muscles flex the leg?

Answer 48

Hamstrings and gastrocnemius

Question 49

Describe how the extended leg can be unlocked

Answer 49

Popliteus unlocks knee joint | - Laterally rotates femur on tibia when foot is on ground

Question 50

Describe the synovial membrane

Answer 50

From margins of articular surfaces of femur to tibia Attached to patella Extends superiorly behind quadriceps tendon Cuffs anterior surface of cruciate ligaments

Question 51

What is the function of the infrapatellar fat pad?

Answer 51

separates synovial membrane from patellar ligament

Question 52

What is the function of bursae?

Answer 52

- Protection | - Reduce friction

Question 53

What are bursae?

Answer 53

Synovial fluid filled sac lined by synovial membrane

Question 54

What is bursitis?

Answer 54

Inflammation of bursae | Due to repetitive movements or direct pressure

Question 55

Describe Prepatellar bursitis

Answer 55

Seen in carpet fitters | Leaning forward on the knees brings the prepatellar bursa in contact with floor

Question 56

Describe Infrapatellar bursitis

Answer 56

- After prolonged periods of prayer clergymen sat back on their heels bringing infrapatellar bursa in contact with floor

Question 57

Describe Bakers (popliteal cyst)

Answer 57

Abnormal fluid filled sacs in popliteal fossa - Due to herniation of synovial membrane/bursa Common in patients with chronic inflammatory joint disease (e.g. arthritis) - Presents as swelling in the popliteal fossa - Can affect joint movement

Question 58

How do you treat bakers cyst?

Answer 58

aspiration and cortisone injection

Question 59

Describe the vascular supply to the knee

Answer 59

Anastomosis - femoral artery and popliteal artery