The patella (kneecap) is situated at the prior of the knee joint, within the patellofemoral groove the the femur. Its superior element is attached come the quadriceps tendon and also inferior aspect to the patellar ligament.

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It is classified together a sesamoid type bone due to its place within the quadriceps tendon, and is the largest sesamoid bone in the body. In this short article we will look in ~ the anatomy that the patella – its surface ar features, functions and also clinical relevance.

Bony Landmarks

The patella has actually a triangular shape, v anterior and also posterior surfaces. The apex the the patella is positioned inferiorly and is linked to the tibial tuberosity through the patellar ligament. The base creates the superior facet of the bone and provides the attachment area because that the quadriceps tendon.

The posterior surface of the patella articulates v the femur, and is marked by two facets:

Medial facet – articulates v the medial condyle of the femur.Lateral facet – articulates with the lateral condyle of the femur.

Fig 1.0 – Anterior and also posterior surface of the patella.


The patella has two key functions:

Leg expansion – improves the leverage that the quadriceps tendon can exert on the femur, boosting the effectiveness of the muscle.Protection – Protects the anterior element of the knee share from physical trauma.

Clinical relevance – Injury to the Patella

Patellar Dislocation

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

Most dislocations take place laterally and also are led to by high force impact ~ above the patella or forceful sudden twisting the the knee. This mechanisms of injury do patellar dislocation more common in people participating in sporting activities such as: football, rugby and ice hockey.

Patellar Fracture 

Patellar fractures usually result from direct trauma to the bone, or sudden contraction of the quadriceps muscle. They are more common in males, and also in the 20-50 age range. If the patella fractures right into fragments, castle will typically separate; the proximal fragment displaced superiorly by the quadriceps tendon and the distal fragment pulled inferiorly by the patellar ligament.

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Fig 1.1 – Radiograph that patella fracture. Note the displacement that the proximal and also distal fragments.