Patella Fracture (Broken Knee Cap)

Patella-Fracture-Broken-KneecapA patella fracture is a type of knee fracture where the knee cap (patella) has been broken. The patella is the largest sesamoid bone in the body and it functions to protect the knee joint. It also allows leverage of the knee joint which helps to extend the knee up to 30%.

Although uncommon, a patella fracture (broken knee cap) is considered to be a serious injury and is responsible for about 1% of all bone fractures.

See our Dislocated Patella article for a related but different issue.


There are 5 patella fracture types. These include:

  • Displaced Patella – A displaced patella fracture results when the knee cap breaks and its broken ends are disconnected and misaligned.
  • Non-displaced Patella – Non-displaced which is also known as stable fracture, results when the broken pieces of the knee cap stays in place and are correctly aligned together.
  • Closed fracture – A type of broken knee cap wherein the skin covering the patella hasn’t been broken.
  • Open fracture – An open fracture is characterized with broken skin and thus exposing the underlying bone. Usually, this type of injury involves accompanying damage to the ligaments, muscles or tendons which surround the patella.
  • Comminuted fracture – A very unstable type of fracture wherein the patella is broken or shattered into several pieces.


There are three main causes of a patella fracture – broken knee cap. These include:

  • Direct trauma – A direct blow to the patella, either through a fall or any accident that directly impacts the knee cap which causes it to break. Direct trauma typically damages the skin covering the knee cap as well as the ligaments, muscles or tendons surrounding it.
  • Indirect trauma – Another cause of a patella fracture is through a tense force wherein the quadriceps or thigh muscles contract so forcefully (eccentric contraction) pulling the patella apart.
  • Combinational – A combination of direct and indirect trauma causes other knee cap fracture patterns such as a comminution fracture.


Some signs and symptoms of a patella fracture (broken knee cap) are:

  • Sudden and severe pain on the knee, particularly the knee cap.
  • Knee bruising and swelling.
  • Inability to bend the knee.
  • Inability to walk or stand up using the leg with the affected knee.
  • A sensation of having a gap in the knee cap.


After determining your medical history or past experiences of direct or indirect trauma of the knee, a physical examination will be done by the doctor for any fracture, swelling or hemarthrosis. An accompanying X-ray, MRI, CT scan or bone scans might be used to determine any infection, fractures or dislocated knee bones.


There are two general classifications for patella fracture (broken knee cap) treatment. These include:

Nonsurgical Treatment

  • Ice packs – Ice alleviates symptoms like swelling and pain.
  • Pain relievers – Naproxen, Acetaminophen and Ibuprofen might temporarily relieve some knee pain.
  • Antibiotics – Antibiotics help fight or prevent the development of knee infections.
  • Plaster cast/Knee brace/Splint – A cast, brace or splint help to prevent the knee cap from moving. It also supports the knee and promotes healing.
  • Crutches or cane – Crutches or canes enable the patient to move around in a well-balanced manner.
  • Physical therapy – Physical therapy might be recommended to learn exercises that specifically strengthen the knee and reduce pain.
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Surgical Treatment

  • Patellectomy – A partial or complete knee cap removal.
  • Irrigation/Debridement – A process of removing any debris, dead tissue and other objects found on the fractured knee cap.
  • Closed Reduction – A closed reduction is a simple procedure in which the bones can be put back in place without making any kind of incision.
  • Open Reduction – An open reduction is a procedure by making an incision to place broken knee cap pieces or ligaments together utilizing pins, bands, wires and/or screws.


Sometimes injuries happen and are unavoidable but there are certain measure you can take to prevent a patella fracture (broken knee cap). These include:

Have You Ever suffered a patella fracture – Broken Knee Cap? Please Comment Below.

Article last updated on January 8th, 2019, first published on July 16, 2013.

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