The patella is a small bone located to the front of the knee joint. You may know it as the kneecap. It is where the thighbone (femur) and shinbone (tibia) meet. The patella protects the knee and connects the muscles in the front of the thigh to the shinbone. A patella fracture can be a simple, clean one in which the bone breaks in two or it can be more complex with the bone breaking into many pieces. The break can occur at the top, center, or lower part of the bone or even in more than one area of the kneecap.
Patella fractures are not very common. They make up about one percent of all broken bones with males affected more often than females. Middle-aged people are most often affected.
Causes and Types of Fracture
Patella fractures typically result from a hard blow to the front of the knee or falling directly onto the knee. They can also occur during vehicular accidents if the knee receives a sharp blow. It is also possible for the kneecap to break due to a strong contraction of the thigh muscles.
Many types of fractures can occur in this bone. In a stable fracture, the broken pieces of bone may remain in contact with each other or be minimally separated. The bones will usually stay in place during healing in this case. On the other hand, if there is a displaced fracture, the broken ends of the bone will separate and will not line up correctly. The joint surface may also be disrupted. Displaced fractures often require surgery to put the pieces of bone back together.
Another type of fracture which can occur is the comminuted fracture in which the bone shatters into three or more pieces. This fracture can be either stable or unstable. One of the most serious patella breaks is the open fracture. This is when the bone breaks in such a way that pieces of bone stick out through the skin or there’s a wound which penetrates down to the bone. Open fractures place the patient at higher risk of infection since the skin is broken and they, therefore, require immediate treatment. They may also take a longer time to heal.
Diagnosis and Treatment
Symptoms of a patella fracture include pain, swelling and bruising to the front of the knee. The injured person may also be unable to straighten the knee, keep the knee extended, or walk. Sometimes the tibia, femur and knee ligaments may also be injured. These symptoms are key to diagnosis and X-rays will be used to confirm the fracture. Sometimes an MRI may be required for children.
Treatment depends on the type of fracture. A stable fracture will usually heal with a cast. Some displaced fractures can also be treated with casting as long as the injured person can straighten their leg without assistance. In such an instance, the leg may be immobilized in a straight position for about three weeks with bending introduced gradually.
A two-part or transverse fracture is often fixed with screws or pins and wire along with a tension band. This is best for treating fractures that are located near the center of the patella since pieces of bone at the ends of the kneecap are too small. Transverse fractures can also be treated by securing the bones using small screws and/or plates.
Other types of patella fractures usually require surgery. In the case of a comminuted fracture, the bottom of the kneecap often breaks into several small pieces. The doctor will remove the bone fragments that are too small to be restored then attach any loose tendons or ligaments to the remaining bone. This is called a partial patellectomy.
If the kneecap is broken in the center and the pieces are separated, the doctor may use wires and screws to hold it together. In some cases, a full patellectomy may be required but this is a solution of last resort.
Patella Fracture Recovery
Recovery time depends on the severity of the patella fracture, whether treatment was surgical or non-surgical and the length of time needed for rehabilitation.
Most patients return to normal activities within three to six months. Patients with severe fractures may take longer.