Bones - Patella

Question 1

What type of bone is the patella?

Answer 1

Sesamoid bone.

Question 2

Bony landmarks?

Associated muscles and ligaments?

Answer 2

Triangular shape with anterior and posterior surfaces.

Apex - located inferiorly - connected to the tibial tuberosity via the patellar ligament.

Base - located superiorly - provides attachment area for the quadriceps tendon.

Posterior surface is marked by two facets:

1) Medial facet - articulates with medial condyle of the femur.
2) Lateral facet - articulates with lateral condyle of the femur.

Question 3

Functions of the patella?

Answer 3

1) Leg extension - enhances leverage of the quadriceps tendon that can exert of the femur - enhances efficiency of the muscle.
2) Protection - protects anterior aspect of the knee joint from physical trauma.

Question 4

Clinical relevance - patellar dislocation?

Answer 4

In a dislocation, patella bone is displaced out of the patellofemoral groove. It accounts for 3% of knee injuries.

Most locations occur laterally. Caused by high force impacts on the patella or sudden forceful twisting of the knee. This may occur in football, rugby, and ice hockey.

Question 5

Clinical relevance: patellar fractures?

Answer 5

Usually occurs from direct trauma, or sudden contracture of the quadriceps muscle.

More common in males (aged 20-50 year old).

It the patella fractures into fractures, they will usually separate. The proximal fragments will be displaced by the quadriceps tendon. The distal fragments will be displaced by the patellar tendon.