L6 - Knee

Question 1

The nerves innervations the periarticular tissues in the knee joint are composed of what?

Answer 1

Both postganglionic autonomic sympathetic and sensory axons, the latter of which end peripherally as encapsulated or free sensory

Question 2

Nerves to any one particular joint in the knee arise from what?

Answer 2

More than one level in the spinal cord

Question 3

What are the two types of synovial fibers in the knee joint?

Answer 3

Postganglionic sympathetic adrenergic fibers and unmyelinated C fibers

Question 4

Describe postganglionic sympathetic adrenergic fibers in the knee joint synovium

Answer 4

Located around blood vessels and are responsible for the control of articular blood flow

Question 5

Describe unmyelinated C fibers in knee joint synovium

Answer 5

Responsible for pain transmission
Typically only fire when there is trauma and are therefore termed nociceptive
Prostaglandin E2 associated with inflammation can induce signaling in the nociceptive fibers causing pain in the normal range of movement

Question 6

What are the cruciate ligaments?

Answer 6

Internal ligaments (within the capsule yet separate from the joint cavity)
Join femur to tibia
Named according to attachment to tibia: ACL and PCL

Question 7

Describe attachments of the anterior cruciate ligament (ACL)

Answer 7

Anterior part of intercondylar area of tibia
Fibers orientated superiorly, posteriorly and laterally
Medial side of lateral condyle of femur

Question 8

When is the ACL taut?

Answer 8

When the leg is extended
Prevents posterior displacement of the femur
Prevents anterior displacement of tibia

Question 9

Describe the attachments of the PCL

Answer 9

Posterior part of intercondylar area of tibia
Fibers directed superiorly, anteriorly and medially
Lateral surface of medial condyle of femur

Question 10

When is the PCL taut?

Answer 10

When the leg is flexed
Prevents anterior displacement of femur
Prevents posterior displacement of tibia

Question 11

What are menisci?

Answer 11

C shaped plates of fibrocartilage on medial and lateral articular surfaces of tibia
Deepens articular surface and absorbs shock

Question 12

What are the external margins of menisci?

Answer 12

Thick and attached to joint capsule (coronary ligaments)

Question 13

What are the anterior edges of menisci?

Answer 13

Joined by transverse ligament of knee

Allows menisci to move together during movements of femur on tibia

Question 14

Describe the medial meniscus

Answer 14

Broader posteriorly
Anterior horn may attach anteriorly to ACL
Posterior horn attaches anterior to PCL
Adherent to deep surface of tibial collateral ligament

Question 15

Describe the lateral meniscus

Answer 15

Nearly circular; anterior and posterior ends closer together
Small and more mobile than medial meniscus
Posterior meniscofemoral ligament joins it to posterior cruciate ligament
Popliteus tendon passes between it and fibular collateral ligament

Question 16

What is Osgood-Schlatter disease?

Answer 16

During activities that involve a lot of running, jumping and blinding a child’s thigh muscles (quads) pull on the tendon that connects the kneecap to the shinbone
The repeated stress can cause the tendon to pull away from the shinbone resulting in pain and swelling
The body may try to close that gap with new bone growth which can result in a bony bump at that spot

Question 17

What is a groin pull?

Answer 17

The groin is the junction between the trunk and thigh

Strain, stretching and probably some tearing of the proximal attachments of thigh adductor/flexor muscles

Question 18

What does Hilton’s law state?

Answer 18

That the same nerve trunks that supply motor branches to muscles crossing a joint likewise provide branches to the skin overlying insertions of the same muscles, and to the periarticular tissues of the joint proper

Question 19

What is the anterior drawer sign?

Answer 19

Pulling of the knee and tibia forward will show an anterior displacement of the tibia showing a tear of the ACL
Can also test for PCL tear with posterior drawer sign

Question 20

Describe meniscal tears

Answer 20

Commonly involves medial meniscus
Lateral meniscus usually does not tear because of mobility (may not be true)
Peripheral meniscal tears can often be repaired or will heal because of blood supply
Meniscal tears that do not heal or cannot be repaired are removed via arthroscopic surgery

Question 21

What is an unhappy triad of injuries?

Answer 21

Occurs when the foot is fixed and twisting of the trunk occurs during a fall (ex. While playing football)
Tears the ACL, tibial collateral ligament and medial meniscus (of O’Donahue)
More recently it has been noted that the lateral meniscus is involved instead