The knee cap or patella is the largest sesamoid bone in the body and one of the components of the knee joint, present at the front of the knee. The undersurface of the kneecap and the lower end of the femur are coated with articular cartilage, which helps in smooth movement of the knee joint. The knee cap protects the knee and provides attachment to various muscle groups of the thigh and leg. Fracture of knee cap is rare and is more common in adult males.
The most common cause of fracture is a direct blow to the knee cap such as a fall or a motor vehicle accident. The patella can also be fractured indirectly, due to a sudden contraction of the thigh muscles.
Pain and swelling are the predominant symptoms of a patella fracture. A few patients may also experience inability to walk and difficulty in straightening the knee. Sometimes bruising may also be seen around the fracture site.
The diagnosis of a patella fracture comprises of a physical examination, history of the injury and X-ray imaging to determine the nature and severity of the fracture. X-ray is the most common and widely used diagnostic tool for identification of fractures.
The treatment of patellar fracture depends upon the severity and nature of the fracture.
Non-surgical treatment can be used when the patella has not been fragmented or displaced. Casts or splints may be used to straighten the knee and help in the healing process. Immobilization of the affected limb for 6 to 8 weeks may also be recommended.
Surgical treatment is needed if there is displacement of fractured fragments of the bone or the distance between the fractured parts is too far and would fail to heal. Immediate surgery is recommended in case of open fracture where the fractured site is exposed through the skin. The type of procedure to be conducted depends on the nature of the fracture. Transverse fractures are fixed with the help of wires and pins and a "figure-of-eight" configuration tension band where as in a comminuted fracture, the small bone fragments are removed from the knee joint.
Rehabilitation plays a vital role in helping patients resume their daily activities, after healing of the fracture. Treatment of the fracture may cause stiffness of the joint and weakness of the muscles. Physical therapy, joint mobilization and muscle strengthening exercises or weight bearing exercises are helpful in regaining strength and preventing deformities.
Peer Reviewed Publications:
- Melvin JS, Mehta S. Patella Fractures in Adults. J Am Academy Orthop Surg 2011;19:198-207.