Knee joint

Question 1

Anastomoses between branches of the major arteries at the knee

Answer 1

• Superior medial genicular artery anastomoses with descending genicular artery (from fem a.)
• Superior lateral genicular artery anastomoses with descending branch of lfca
• Inferior medial & inferior lateral genicular arteries anastomose with recurrent branch of anterior tibial artery

Question 2

Motions of the knee

Answer 2

Extend/flex

Rotate

Translate

Question 3

Anatomy of the knee

Answer 3

• Knee joint is a synovial, hinge joint
• Patella is teh largest sesamoid in the body; its articulation with the femur allows for quads to be pulled

Question 4

What artery supplies the cruciate ligament?

Answer 4

Middle genicular artery off the popliteal artery

Question 5

The popliteal artery is the main artery of the knee and it can be injured in femur fracture or knee joint dislocation.

What are the major branches of the popliteal artery?

Answer 5

• Superior lateral genicular a. : deep to biceps femoris tendon
• Superior medial genicular a.: deep to semimembranosus and semitendinosus; enters vastus medialis
• Inferior lateral genicular artery: passes laterally above the fibula head and then deep to teh fibular collateral ligament
• Inferior medial genicular artery: passes medially along the upper border of the popliteus muscle, deep to the popliteus fascia
• Middle genicular artery: pierces the oblique popliteal ligament and enters the knee joint

Question 6

The popliteal artery splits into ___ and __ at the lower border of the popliteal muscle

Answer 6

Anterior and posterior tibial arteries

Question 7

Where are vessels in the knee?

Answer 7

Behind the posterior horn of the lateral meniscus

Question 8

What’s the anterior-to-posterior order of the vessels & nerve behind the knee?

Answer 8

Artery (anterior)

Vein

Nerve (posterior)

You can’t injure the vein or nerve without injuring the ones more anterior to it (if you’re entering anteirorly).

Question 9

The ___ meniscus is shaped like a C.

The ___ meniscus is shaped like an O.

Answer 9

Medial = C

Lateral = O

Question 10

Which meniscus is more prone to injury and why?

Answer 10

Medial meniscus because it’s constrained by attachment to the capsule; whereas, the lateral meniscus is more mobile.

Question 11

What muscles allow knee extension? Which ones allows knee flexion?

Answer 11

Knee extension - quads, innervated by femoral nerve (L2-4)

Knee flexion - hamstrings

• Biceps femoris, innervated by common fibular nerve
• Semitendinosus & semimembranosus, innervated by the tibial branch of the sciatic nerve (L5-S2)

Question 12

“say grace before tea” - pes anserinus

Answer 12

Pes anserinus

• Sartorius (sailor’s crossing); femoral nerve
  
  • Longest muscle in the body
• Gracilis (abduct+ext rotation); anterior branch of obturator a.
• Semitendinosus: tibial branch of sciatic nerve

Question 13

Compartment syndrome

Answer 13

• Fluid enters the fascia between muscles, compressing the muscles so that they die.
• Fatal

Question 14

What is in the anterior compartment of the leg?

Answer 14

• Anterior tibialis artery
• Deep peroneal nerve
• Anterior tibialis muscle, extensor digitorum longus, extensor hallucis longus, peroneal tertius

Question 15

Contents of lateral compartment

Answer 15

• Peroneus longus, peroneus brevis
• Superficial peroneal nerve

Question 16

Contents of posterior deep compartment

Answer 16

• Flexor hallucis longus, flexor digitorum longus, popliteus, tibialis posterior
• Posterior tibilais artery
• Tibial nerve

Question 17

Contents of posterior superficial compartment

Answer 17

• Soleus, plantaris, gastrocnemius
• Sural nerve

Question 18

Static stabilizers of the knee vs dynamic stabilizers

Answer 18

Static stabilizers - architecture of bone

Dynamic stabilizers - ligaments & menisci

Question 19

Femur as a static stabilizer

Answer 19

• Trochlear groove
• Medial condyle
• Lateral condyle
• Intercondylar notch (site of ACL origin
• 5 types of trochlear grooves:
  
  • Large & rounded
  • Small & rounded
  • Tent-shaped (rare)
  • Lateral angled wave -> ACL tears
  • Smaller angled wave -> ACL tears

Question 20

Tibia & patella as static stabilizers

Answer 20

• Tibia
  
  • Medial TP- concave - more stable
  • Lateral TP- convex - more motion
• Patella
  
  • Facets- median, middle, lateral (superior, middle, and inferior of each), and odd
  • If dislocated, it usually dislocates laterally

Question 21

Which horn of the meniscus keeps your knee from dislocating when your cruciate ligament is compromised?

Answer 21

Posterior horn doesn’t allow translation of knee when bending

Question 22

ACL vs PCL direction

Answer 22

ACL: lateral to medial

PCL: medial to lateral

They cross each other, which is why it’s a cruciate ligament.

Question 23

Most common way to get a PCL injury vs an ACL injury

Answer 23

PCL injury: dashboard injury

ACL injury: twisting

Question 24

Baker’s cyst (not an LO)

Answer 24

Swelling behind the knee from arthritis, meniscus injury, herniation, or tear of the joint capsule.

Impairs flexion and extension; pain worsens when the knee is fully extended

Question 25

In an *acute* ACL tear, which meniscus is more likely to get injured?

Answer 25

Lateral meniscus. Medial meniscus for chronic or old ACL injuries.

Question 26

Explain the consequence of a lesion of the tibial nerve in the popliteal fossa.

Answer 26

* Loss of plantar flexion of the foot * Paralyzed tibialis posterior * Impaired inversion * difficulty in getting heel off the ground * Shuffling of the gait. * Results in a characteristic clawing of the toes and sensory loss on the sole of the foot.

Question 27

Hallus valgus vs Hallux varus

Answer 27

**Hallux Valgus:** Lateral deviation of the big toe; bunion **Hallux Varus:** Medial deviation of the big toe

Question 28

Consequence of damaging **superficial fibular nerve**

Answer 28

Via fibularis longus & brevis: --\> Loss of foot eversion --\> Loss of innervation of dorsum of foot an distal 1/3 of anterolateral leg

Question 29

Consequence of damaging deep fibular nerve

Answer 29

Via tibialis anterior, hallucis longus, extensor digitorum longus, and fibularis tertius: * Foot drop * High-stepping gait * Loss of innervation at the skin of the 1st interdigital cleft

Question 30

Anterior vs Posterior drawer sign

Answer 30

**Anterior drawer sign:** Forward sliding of the tibia on the femur due to a rupture of anterior cruciate ligament **Posterior drawer sign:** Backward sliding of the tibia on the femur caused by a rupture of the posterior cruciate ligament

Question 31

What are bursa and what are the major ones of the knee?

Answer 31

**Bursa:** Synovial fluid filled sac, found between moving structures in a joint (purpose is to reduce wear and tear on these structures)

Question 32

Explain the consequence of a lesion of the **tibial nerve in the popliteal fossa**

Answer 32

* Loss of plantar flexion * Impaired inversion (via tibialis posterior) * **Shuffling gait:** hard to get heel of the ground * **Clawing of the toes** * Sensory loss of the sole of the foot

Question 33

Housemaid's knee

Answer 33

Inflammation and swelling of the **prepatellar bursa** (on superficial surface of patella)

Question 34

Clergyman's knee

Answer 34

Inflammation of the superficial **infrapatellar bursa**

Question 35

Lachman's test

Answer 35

Anteiror drawer test in 30 degree flexion

Question 36

the ACL is taut with knee \_\_\_xion. The PCL is taut with knee \_\_\_xion.

Answer 36

ACL taut with extension PCL taut with flexion