Knee: arthrology - The patellofemoral joint

Question 1

What type of joint is the patellofemoral joint?

Answer 1

Synovial saddle joint

Question 2

What 2 structures is the patellofemoral joint between?

Answer 2

Articular surface of patella and patellar surface of femur

Question 3

Where is the patella embedded, what is its function and structure?

Answer 3

Patella is embedded in the tendon of the quadriceps

Function: An anatomic pulley, reduced friction between quadriceps tendon and femoral condyles

Structure: Articular surface - Oval-shaped, cartilage covered, vertical ridge separates medial and lateral areas

Question 4

Where is the patellar surface of the femur located, and what movements does it make during flexion and extension of the knee?

Answer 4

Located between articular facets of the medial and lateral condyles of the femur.
Articulates with vertical ridge of patella (accommodates gliding of patella over distal end of femur).

Movements: Moves proximally in extension and distally in flexion

Question 5

What are the shared features between the joints?

Answer 5

All synovial joints have a joint capsule (joint capsule of knee is incomplete)
Reinforced by ligaments and tendons
Bursae - reduce friction

Question 6

What are the 3 movements that can be made at the knee joint?

Answer 6

1) Flexion and extension
2) Medial and lateral rotation
3) Medial and lateral tibial rotation (can’t rotate knee during extension)

Question 7

Where does closed-packed position of the knee occur?

Answer 7

During full extension (no rotation possible at this position)
 Crucial ligaments become taught
 Full extension = Knee locking mechanism