Patellofemoral pain syndrome

Patellofemoral pain syndrome

Knee ​Condition

Patellofemoral pain syndrome

Patellofemoral pain syndrome is a broad term used to describe pain in the front of the knee and around the patella, or kneecap. It is sometimes called “runner’s knee” or “jumper’s knee” because it is common in people who participate in sports—particularly females and young adults—but patellofemoral pain syndrome can occur in nonathletes, as well. The pain and stiffness it causes can make it difficult to climb stairs, kneel down, and perform other everyday activities.

Anatomy

Your knee is the largest joint in your body and one of the most complex. It is made up of the lower end of the femur (thighbone), the upper end of the tibia (shinbone), and the patella (kneecap).

Several structures in the knee joint make movement easier. For example, the patella rests in a groove on the top of the femur called the trochlea. When you bend or straighten your knee, the patella moves back and forth inside this trochlear groove.

A slippery substance called articular cartilage covers the ends of the femur, trochlear groove, and the underside of the patella. Articular cartilage helps your bones glide smoothly against each other as you move your leg.

Also aiding in movement is the synovium—a thin lining of tissue that covers the surface of the joint. The synovium produces a small amount of fluid that lubricates the cartilage. In addition, just below the kneecap is a small pad of fat that cushions the kneecap and acts as a shock absorber.

Causes

Overuse

In many cases, patellofemoral pain syndrome is caused by vigorous physical activities that put repeated stress on the knee —such as jogging, squatting, and climbing stairs. It can also be caused by a sudden change in physical activity.

Other factors that may contribute to patellofemoral pain include:

  • Use of improper sports training techniques or equipment
  • Changes in footwear or playing surface

 
Patellar malalignment

Patellofemoral pain syndrome can also be caused by abnormal tracking of the kneecap in the trochlear groove. In this condition, the patella is pushed out to one side of the groove when the knee is bent. This abnormality may cause increased pressure between the back of the patella and the trochlea, irritating soft tissues.

Symptoms

The most common symptom of patellofemoral pain syndrome is a dull, aching pain in the front of the knee. This pain—which usually begins gradually and is frequently activity-related—may be present in one or both knees. Other common symptoms include:

  • Pain during exercise and activities that repeatedly bend the knee, such as climbing stairs, running, jumping, or squatting.
  • Pain after sitting for a long period of time with your knees bent, such as one does in a movie theater or when riding on an airplane.
  • Pain related to a change in activity level or intensity, playing surface, or equipment.
  • Popping or crackling sounds in your knee when climbing stairs or when standing up after prolonged sitting.
Treatment

Medical treatment for patellofemoral pain syndrome is designed to relieve pain and restore range of motion and strength. In most cases, patellofemoral pain can be treated nonsurgically by the following methods:

  • Activity modifications
  • RICE method
  • NSAID’s
  • Physical therapy
  • Orthotics
Surgical Treatment

Surgical treatment for patellofemoral pain is very rarely needed and is done only for severe cases that do not respond to nonsurgical treatment. Surgical treatments may include:

Arthroscopy. During arthroscopy, your surgeon inserts a small camera, called an arthroscope, into your knee joint. The camera displays pictures on a television screen, and your surgeon uses these images to guide miniature surgical instruments.

  • In some cases, removing damaged articular cartilage from the surface of the patella can provide pain relief.
  • Lateral release. If the lateral retinaculum tendon is tight enough to pull the patella out of the trochlear groove, a lateral release procedure can loosen the tissue and correct the patellar malalignment.

 
Tibial Tubercle Transfer. In some cases, it may be necessary to realign the kneecap by moving the patellar tendon along with a portion of the tibial tubercle—the bony prominence on the tibia (shinbone).

A traditional open surgical incision is required for this procedure. The doctor partially or totally detaches the tibial tubercle so that the bone and the tendon can be moved toward the inner side of the knee. The piece of bone is then reattached to the tibia using screws. In most cases, this transfer allows for better tracking of the kneecap in the trochlear groove.