Knee > Patellofemoral Pain Syndrome

The kneecap (patella) is a small, triangular bone in the front of your knee that moves and rotates with the knee. It glides up and down along a track at the end of the thighbone (femur). The kneecap gives the front thigh muscles (quadriceps) extra leverage for straightening the leg, and protects the other bones in the knee against collisions and falls. Patellofemoral pain syndrome occurs when legs and hips are not aligned properly or muscles pull unevenly, which forces the kneecap off its track when you move. Instead of sliding smoothly along the thighbone, the kneecap is typically pulled to the outside, putting added pressure on the bones, which results in pain and possible cartilage damage.

A combination of tight or weak leg muscles, overuse, and poor kneecap alignment typically causes patellofemoral pain syndrome. Sports that overload your knees, like football, basketball, soccer, tennis, and running, can aggravate an existing abnormal kneecap alignment. Running on uneven surfaces, like hills or trails, or playing on multiple surfaces – such as changing from grass to hardcourt in tennis – may also increase the likelihood of patellofemoral pain. Your kneecap pain may be caused by other problems, like patellar fractures, osteochondral defects, patellar dislocations, fractures, or arthritis, which should be diagnosed and treated separately.

Patellofemoral pain syndrome may be a sign that the protective cartilage under your kneecap is wearing down, which can eventually cause bone loss and arthritis. Eighty to 90 percent of people suffering patellofemoral pain are able to fully recover and return to activities. Most active people respond to non-operative treatments. Surgery is prescribed only in rare cases when patellofemoral pain cannot be eased with braces, rest, or physical therapy. Depending on the amount of malalignment your physician finds during the exam, you will typically be asked to try a well-supervised rehabilitation program for between six weeks and six months. In most cases, you will need to continue the exercises you learn in physical therapy for your entire life. If your patellofemoral pain continues to bother you, physicians may recommend that the ligaments and tendons around your kneecap be reconstructed.

There are usually three parts to an orthopedic evaluation: medical history, physical examination, and tests your physician may order.

Your doctor will likely ask you when you noticed your knee pain, how it has been feeling since the pain began, and if your knee has been previously injured. Physicians also typically ask about other conditions, such as diabetes and allergies, and medications currently being taken. The doctor may also ask about your physical and athletic goals – information that will help the doctor decide what treatment might be best for you in achieving those goals.

A physician usually can make an early assessment of an injury by feeling around the area. Because the kneecap is easily visible, physicians can quickly test for pain and tenderness. By moving your kneecap around to check how well it tracks as your leg flexes and extends, physicians can often differentiate your patellofemoral pain from other knee problems.

TESTS

Should your physician require a closer look, the following tests may be conducted:

   X-rays taken from different angles can clearly show when your kneecap is off-track.

   MRI (magnetic resonance imaging) test may be used to see if your pain is due to bone, cartilage, or muscle problems. Results from MRI are usually available in two days.

   Arthroscopy, in which the doctor inserts a tiny camera into your knee, may be used to determine the diagnosis in more detail. This is done on an outpatient basis and does not require a hospital stay.

   Imaging techniques