Other

Question 1

Describe the locking mechanism of the knee

Answer 1

> As femur moves - femoral condyles roll anteriorly over tibial condyles
Femoral condyles also glide posteriorly to prevent rolling off front of tibial condyles
Lateral femoral condyle is shorter so stops rolling first
Medial femoral condyle continues - slightly medially rotates knee
Centre of gravity is then anterior to knee - pushing it backwards without muscle work
To unlock the knee the popliteus must laterally rotate the femur on a fixed tibia (med rotate tibia on fixed femur to unlock the knee)

Question 2

Describe the popliteal fossa, mentioning its contents, roof, fascia and borders

Answer 2

The popliteal fossa is a body space on the posterior aspect of the knee joint
> Borders
- Superolateral: Biceps femoris
- Superomedial: Semimembranosus + Semitendinosus
- Inferolateral: Lat. head of gastrocnemius (+Plantaris)
- Inferomedial: Med. head of Gastrocnemius
> Floor
- Popliteal surface of femur
- Proximal aspect of posterior tibia
- Popliteus
> Roof
- Fascia and skin
> Contents
- Popliteal Vessels (artery + vein)
- Tibial nerve and common peroneal nerve (sciatic branches)
- Popliteal Lymph nodes
- Fat

Question 3

Describe the ITB

Answer 3

ITB = thick band of fascia running from iliac crest to gerdy’s tubercle - anterolateral aspect of tibial plateau (from TFL and glute max)

• Covers lateral femoral condyle and inserts to lateral edge of patella
• No attachment from lateral femoral condyle to gerdy’s tubercle allows it to move as knee moves

Question 4

Describe the nerve supply to the knee joint

Answer 4

Innervated by Femoral nerve, Tibial nerve and Obturator nerve (same as hip = referred pain)

Question 5

Describe the blood supply of the knee

Answer 5

Genicular branches of the femoral and popliteal arteries

Question 6

State the bursae of the knee and their purposes

Answer 6

A bursa prevents friction to facilitate movement
> Suprapatellar bursa - between femur and quadriceps tendon
> Subcutaneous prepatellar bursa - between patella and skin
> Subcutaneous infrapatellar bursa - between patella tendon and skin
> Deep infrapatellar bursa - between patella tendon and tibia
> Subsartorial (pes anserinus) bursa - between the mcl and the Pes anserine attachments
> Semimembranosus bursa - between the Semimembranosus and the medial gastrocnemius head

Question 7

Describe Hoffa’s (infrapatellar) fat pad

Answer 7

• Pad of adipose tissue posterior to patella and patella tendon, attaching to anterior aspect of menisci
• Acts as shock absorber between patella and femur