Kneecap Fractures (Patella Fractures): Overview

Kneecap Fractures (Patella Fractures): Overview

This video will provide an overview of patella fractures, also called kneecap fractures. The patella, also known as the kneecap, is a round bone positioned in front of the knee joint. This unique bone plays an important role in the extensor mechanism of the knee, the group of structures that allows the knee to straighten. The kneecap allows for a smooth and efficient transfer of force from the quadriceps muscles of the thigh to pull the shinbone to straighten the knee. Without the kneecap, the quadriceps muscles cannot function properly.

Patella fractures, or breaks in the kneecap, are not that common and make up 1% of all fractures. While high-energy traumas like motor vehicle accidents can cause patella fractures, the most common cause is impact to the kneecap from a direct fall onto a bent knee. This frequently occurs in the elderly population.

Symptoms of a patella fracture include: pain in the front of the knee; bruising; swelling; and inability to straighten the knee, stand, or walk. During a physical examination, a health care provider will examine the appearance and range of motion of the knee and see if the knee is tender to the touch. The health care provider will also examine the patient's ability to straighten the knee or lift the leg in a straightened position to check for injury to the other parts of the extensor mechanism, which include the quadriceps muscles, quadriceps tendon, and patellar tendon.

Diagnostic imaging is needed to confirm a diagnosis of a patella fracture. X-rays are taken from the front and from the side to look at the kneecap from multiple angles to check for breaks in the bone. CT scans may also be used to create a 3-D image of the kneecap to see if the bone is broken into multiple pieces. These imaging methods are used to classify the different types of patella fractures, which include: transverse or horizontal; vertical; osteochondral, which affects the cartilage on the underside of the kneecap; and comminuted, also called stellate, due to the star-like appearance. Patella fractures may also be classified as upper pole or lower pole fractures if they affect the top or bottom portions of the kneecap, or displaced fractures if the broken bone pieces have shifted out of place.

The health care provider will use imaging findings along with the patient's symptoms to determine the best treatment option. In summary, the patella or kneecap plays an important role in the extensor mechanism of the knee that allows the knee to straighten. Patella fractures, or breaks in the kneecap, most often result from directly falling onto the knee. Symptoms include knee pain, bruising, and swelling. Imaging, such as x-rays and CT scans, is needed to diagnose a patella fracture and classify the type of fracture.