Patellar Fractures/Broken Kneecap
Patellar fracture involves the breakage of the small bone at the front of the knee known as the kneecap. These are relatively common injuries as the patellar bone sits directly at the front of the knee and takes the brunt of any frontal trauma. A patellar fracture is most often caused by a direct blow to the front of the knee either from a fall, contact sports or severe trauma like a motor vehicle accident.
A fractured patella can take on several different forms. A simple break may occur, during which the bone is simply split in two. This is known as a transverse or vertical fracture. The bone may also split into many pieces, known as a comminuted fracture. The treatment for each of these breaks will vary.
Stable versus Unstable Patellar Fractures
A stable fracture is one where the bones remain relatively close – within a couple millimeters to each other. Stable fractures often stay in place and may not require surgical intervention.
A displaced fracture is one where the bones of the patella have not stayed in place and are not lining up with each other. This type of fracture will often require surgery.
Comminuted fracture is when the patella breaks into three or more pieces. This kind of fracture may be stable or unstable and may or may not require surgery.
An open fracture is one in which the bone is sticking out through the skin or the wound reaches the bone. Open fractures are a particular concern because there is a significant risk of infection.
Signs and Symptoms of a Patellar Fracture
Because of the severity of the injury, patients should expect to have significant pain, swelling and bruising. They will be unable to walk and likely unable to extend the knee to any significant degree. This will necessitate a trip to an orthopedic surgeon who will discuss medical history, as well as recent traumatic events that may have caused the fracture. Because of the location of the patella, Dr. Manning will likely be able to feel the fracture through the skin. During this diagnostic period, we will also check for hemarthrosis, which is the collection of blood within joint that may be causing additional swelling and pain. Diagnostic imaging will include an x-ray, which is very helpful in determining the scope of the fracture.
Treatment for Patellar Fracture
If the bones of the patella are not displaced – in other words, if the fracture is stable, there is a greater likelihood that we can repair the fracture without surgery. A cast or splint may be necessary to keep the leg immobilized and allow for better healing. This will also keep the bones close enough to ensure that they heal properly. In many cases, the knee will not be able to bear weight for several weeks, during which time the patient will have to use crutches or other assistive devices.
On the other hand, if the bones of the patella have been displaced, surgery is often the only available treatment. If the bones are not set close enough, proper healing and fusion will be impossible. Further, the musculature in and around the knee is such that the displaced bone tends to be pulled apart rather than pushed together. Open fractures will be repaired as soon as possible to minimize the risk of infection. Closed fractures will be repaired at your surgeon’s discretion.
There are several surgical procedures that can be used based on the type of fracture. A transverse or vertical fracture, where the patella is essentially split in two is often corrected using screws and pins, as well as special wires that keep the pieces of bone together using tension. This is typically used for fractures near the center of the bone and is not ideal for multiple fractures. Screws and plates may also be used to keep the bone in place for proper healing.
For multiple fractures, known as comminuted fractures, part of the bone may be removed from the knee. Then, to ensure stability of the knee joint, loose tendon must be reattached to the remaining bone. Depending on exactly how the bone is fractured, we may also need to use wires and screws to add stability and improve healing. In very rare cases, the entire kneecap must be removed.
Recovery for a patellar fracture can vary dramatically and is based on the extent of the injury and speed of healing. Many patients will require 3 to 6 months before they can begin performing activities normally. This may be longer for particularly bad fractures.
Prognosis and Outlook for a Patellar Fracture
The prognosis for recovery from a patellar fracture is directly related to the severity of the fracture itself. Simple fractures may be corrected easily and heal very well, while more complex fractures may require extensive surgery and have a higher risk of poor outcomes. All patellar fractures will require some sort of physical therapy or rehabilitation, especially if immobilization of the knee is necessary. Physical therapy can improve range of motion and surrounding muscle strength.
Longer-term, some patients with patellar fractures, no matter how well they heal, may experience post-traumatic arthritis which is possible after any injury to the bone. Mild to moderate arthritis is a distinct possibility, which will be discussed at consultation or after your procedure. Severe arthritis is less likely. Post-traumatic arthritis does come with the risk of chronic pain, which may require occasional pain medication. Many patients find relief with a knee brace.
Some patients may also have some weakness in the muscles at the front of the thigh known as quadriceps. They may also lose some range of motion in the knee. Typically, neither of these conditions are severe enough to cause major disability.