Knee joint

Question 1

Which articulation is the weight bearing joint of the knee

Answer 1

Tibiofemoral - particularly medial condyle as it is larger

Question 2

What lines the articulating surfaces

Answer 2

Hyaline cartilage

Question 3

Patella is formed inside which tendon

Answer 3

Quadriceps femoris (main knee extensor) tendon which inserts directly over the knee, increasing the muscle’s efficiency

Question 4

What is between the femoral condyles and what is the significance

Answer 4

Anteriorly - shallow depression to allow knee articulation

Posteriorly - intercondylar fossa

Question 5

Significance of femoral epicondyles (above condyles)

Answer 5

Site of attachment for collateral ligaments

Medial epicondyle of femur has adductor tubercle (insertion of hamstring part of adductor Magnus)

Question 6

Describe surface of tibia

Answer 6

Medial surface is concave
Lateral surface is convex
Medial and lateral surfaces are separated by intercondylar eminence

Question 7

What strengthens the knee joint

Answer 7

Menisci,
Ligaments,
Capsule,
Muscles

Question 8

How does the menisci strengthen the knee joint

Answer 8

Deepens the articulation (of tibial element)

Act as shock absorbers

Question 9

Features and attachments of menisci

Answer 9

Crescentric plates of fibrocartilage,
Thicker at edges (wedge shaped),
Attached to intercondylar areas,
Attached to joint capsule via coronary ligaments,
Anteriorly connected (medial and lateral menisci) by transverse ligament of knee

Question 10

What intracapsular ligaments are involved in the knee joint

Answer 10

Anterior cruciate ligament,

Posterior cruciate ligament

Question 11

How are cruciate ligaments named

Answer 11

Attachment to tibia

Question 12

Course of anterior and posterior cruciate ligaments

Answer 12

Posterior passes anteriorly and inserts medially (posterior intercondylar region of tibia to femoral intercondylar fossa)

Anterior passes posterior and inserts laterally (anterior intercondylar region of tibia to femoral intercondylar fossa)

Pam’s apples!

Question 13

Features of anterior cruciate ligament

Answer 13

Weaker than posterior cruciate ligament,
Relatively poor blood supply,
Limits anterior movement (prevents anterior dislocation) of tibia on femur,
Limits knee hyperextension

Question 14

Features of posterior cruciate ligament

Answer 14

Stronger than anterior cruciate ligament,
Main stabiliser in weight bearing flexed knee,
Limits posterior movement (prevents posterior dislocation) of tibia on femur,
Limits knee hyperflexion

Question 15

Where is joint capsule absent and why

Answer 15

Anteriorly

Allows synovial membrane to extend up beneath patella

Question 16

How is the joint capsule strengthened laterally

Answer 16

Inferior fibres of vastus lateralis and medialis

Question 17

How is the joint capsule strengthened posteriorly

Answer 17

Oblique popliteal ligament (an expansion of semimembranosus)

Question 18

What are the extra capsular ligaments of knee joint

Answer 18

Medial (tibial) collateral ligament,

Lateral (fibular) collateral ligament

Question 19

attachments of lateral collateral ligament

Answer 19

Proximally - lateral epicondyle of femur

Distally - depression on lateral fibular head

Question 20

Attachments of medial collateral ligament

Answer 20

Proximally - medial epicondyle of femur
Distally - medial tibia

Attaches to medial menisci at its midpoint (clinically important)

Question 21

What reinforces the lateral collateral ligament

Answer 21

Ilio-tibial tract

Question 22

What is the patellar ligament

Where does it attach

Answer 22

Continuation of quadriceps femoris tendon, distal to patella.
It attaches to tibial tuberosity

Question 23

What muscles permit knee extension

Answer 23

Quadriceps femoris

Question 24

Which muscles permit knee flexion

Answer 24

Hamstrings, gracilis, sartorius, popliteus

Question 25

Which muscles permit lateral rotation of knee (knee must be flexed)

Answer 25

Biceps femoris

Question 26

Which muscles permit medial rotation of knee (knee must be flexed)

Answer 26

``` Semimembranosus, Semitendinosus, Gracilis, Sartorius, Popliteus ```

Question 27

Benefit of locking knee in extension

Answer 27

Uses less energy to stand

Question 28

How does the knee lock in extension

Answer 28

Femur rotates internally over tibia

Question 29

How does the knee unlock

Answer 29

Popliteus helps to rotate femur externally

Question 30

Why is the lateral menisci injured less than the medial

Answer 30

Smaller and doesn't have any extra attachments (this makes it less likely to be damaged)

Question 31

What is torn in an unhappy triad

Answer 31

Medial collateral ligament, medial menisci, | Anterior cruciate ligament

Question 32

How do you obtain the unhappy triad

Answer 32

Blows to side of extended knee, | Lateral twisting of flexed knee (ACL is taut during flexion)

Question 33

How can ACL be torn

Answer 33

Hyperextension of knee joint, | Large force to back of knee with the joint partly flexed

Question 34

Test for ACL damage

Answer 34

Anterior draw test - | Attempt to pull the tibia forwards, positive test if it moves

Question 35

How can PCL be torn

Answer 35

1. 'Dashboard injury' - large force applied to shins when knee is flexed. This pushes tibia posteriorly 2. Hyperextension of knee joint 3. Damage to upper tibial tuberosity

Question 36

Test for PCL damage

Answer 36

Posterior draw test - | Hold knee in flexed position and attempt to push shin posteriorly, positive test if it moves

Question 37

Why do peripheral menisci tears usually heal easily

Answer 37

Reasonable blood supply

Question 38

Articulating surfaces of knee joint

Answer 38

Tibiofemoral - medial and lateral condyles of femur with tibia Patellofemoral - anterior and distal part of femur with patella

Question 39

Describe patella dislocation

Answer 39

Patella displaced out of patellofemoral groove. | Mostly occurs laterally

Question 40

How do patella dislocations occur

Answer 40

Direct trauma on patella, | Forceful sudden twisting of knee

Question 41

How are patella fractures obtained

Answer 41

Direct trauma to patella, | Sudden contraction of quadriceps femoris

Question 42

Consequence if patella fractures into fragments

Answer 42

Fragments usually separate: Proximal fragment - displaced superiorly by quadriceps femoris tendon Distal fragment - displaced inferiorly by patellar ligament

Question 43

Important bursae in knee

Answer 43

Supra-patellar, Pre-patellar, Superficial infrapatellar

Question 44

Location of supra patellar bursa

Answer 44

Extension of synovial cavity of knee. | Found between quadriceps femoris and femur

Question 45

Location of pre patellar bursa

Answer 45

Between apex of patella and skin

Question 46

Location of superficial infrapatellar bursa

Answer 46

Between patella ligament and skin

Question 47

What is Housemaids knee and how is it caused

Answer 47

Inflammation of pre patellar bursa which produces swelling on anterior side of knee. Caused by chronic friction/direct trauma between skin and patella

Question 48

What is clergyman's knee and how is it caused

Answer 48

Inflammation of superficial infrapatellar bursa | Caused by chronic friction/direct trauma between skin and tibia

Question 49

Arthritis in knee

Answer 49

Osteoarthritis is common as knee is weight bearing | Rheumatoid occurs in severe progression of disease

Question 50

How do you investigate the knee

Answer 50

MRI, Arthroscopy (camera into joint) Aspiration (removal of fluid from joint) Clinical examination