What is the patella and what is its main function?

The patella is the largest sesamoid bone in the body, embedded in the quadriceps femoris tendon. It lies anterior to the knee joint and functions to increase leverage for the quadriceps during knee extension.

How can you determine the side of a patella bone?

To determine the side, hold it with the base upward and apex downward, with the articular surface facing posteriorly. The larger lateral facet on the posterior surface indicates the side. A trick is to place it on a flat surface with the base toward you; it tilts toward its side.

What are the key features and attachments of the patella?

Key features include the apex attaching to ligamentum patellae, the base attaching to rectus femoris and vastus intermedius, a rough anterior surface covered by prepatellar bursa, and a posterior articular surface with lateral and medial facets.

How does the patella articulate with the femur?

The posterior articular surface has a large lateral facet and a smaller medial facet, divided by a vertical ridge. The lateral facet articulates with the lateral femoral condyle in all knee positions, while the medial facet contacts the medial condyle only in full flexion.

What are common clinical issues associated with the patella?

Common issues include dislocation (often lateral), fracture (from direct blows or forceful quadriceps contraction, with risk of non-union), and abnormal ossification (like bipartite or tripartite patella, distinguished from fractures by smooth margins).

When does the patella ossify?

The patella ossifies from multiple centres appearing between 3–6 years of age. These fuse to form a single bone by puberty.

Patella (Kneecap) – Anatomy, Attachments & Injury