This article is also available in Spanish: El síndrome de dolor patelofemoral (Patellofemoral Pain Syndrome)El síndrome de dolor patelofemoral (Patellofemoral Pain Syndrome) (topic.cfm?topic=A00763).

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.

Many things may contribute to the development of patellofemoral pain syndrome. Problems with the alignment of the kneecap and overuse from vigorous athletics or training are often significant factors.

Symptoms are often relieved with conservative treatment, such as changes in activity levels or a therapeutic exercise program.

Normal knee 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).

Ligaments and tendons connect the femur to the bones of the lower leg. The four main ligaments in the knee attach to the bones and act like strong ropes to hold the bones together.

Muscles are connected to bones by tendons. The quadriceps tendon connects the muscles in the front of the thigh to the patella. Segments of the quadriceps tendon—called the patellar retinacula—attach to the tibia and help to stabilize the patella. Stretching from your patella to your tibia is the patellar tendon.

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.

(Left) The patella normally rests in a small groove at the end of the femur called the trochlear groove. (Right) As you bend and straighten your knee, the patella slides up and down within the groove.

Patellofemoral pain syndrome occurs when nerves sense pain in the soft tissues and bone around the kneecap. These soft tissues include the tendons, the fat pad beneath the patella, and the synovial tissue that lines the knee joint.

In some cases of patellofemoral pain, a condition called chondromalacia patella is present. Chondromalacia patella is the softening and breakdown of the articular cartilage on the underside of the kneecap. There are no nerves in articular cartilage—so damage to the cartilage itself cannot directly cause pain. It can, however, lead to inflammation of the synovium and pain in the underlying bone.

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.

Factors that contribute to poor tracking of the kneecap include:

• Problems with the alignment of the legs between the hips and the ankles. Problems in alignment may result in a kneecap that shifts too far toward the outside or inside of the leg, or one that rides too high in the trochlear groove—a condition called patella alta.
• Muscular imbalances or weaknesses, especially in the quadriceps muscles at the front of the thigh. When the knee bends and straightens, the quadriceps muscles and quadriceps tendon help to keep the kneecap within the trochlear groove. Weak or imbalanced quadriceps can cause poor tracking of the kneecap within the groove.

(Top) In these x-rays taken from above, both kneecaps are normally aligned within the trochlear groove. (Bottom) Here, both kneecaps have shifted out of the trochlear groove and are pulled toward the outside of the knee.

Reproduced with permission from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010

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.

In many cases, patellofemoral pain will improve with simple home treatment.

Physical Examination

During the physical examination, your doctor will discuss your general health and the symptoms you are experiencing. He or she will ask when your knee pain started and about the severity and nature of the pain (dull vs. sharp). Your doctor will also ask you what activities cause the pain to worsen.

To determine the exact location of the pain, your doctor may gently press and pull on the front of your knees and kneecaps. He or she may also ask you to squat, jump, or lunge during the exam in order to test your knee and core body strength.

During the examination, your doctor will check your knee for problems in patellar tracking.

Reproduced with permission from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010

To help diagnose the cause of your pain and to rule out any other physical problems, your doctor may also check:

• Alignment of the lower leg and the position of the kneecap
• Knee stability, hip rotation, and range of motion of knees and hips
• The kneecap for signs of tenderness
• The attachment of thigh muscles to the kneecap
• Strength, flexibility, firmness, and tone of the hips, front thigh muscles (quadriceps), and back thigh muscles (hamstrings)
• Tightness of the heel cord and flexibility of the feet

Finally, your doctor may ask you to walk back and forth in order to examine your gait (the way you walk). He or she will look for problems with your gait that may be contributing to your knee pain.

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.

Nonsurgical Treatment

In addition to activity changes, the RICE method, and anti-inflammatory medication, your doctor may recommend the following:

Shoe inserts take stress off your lower leg by aligning your foot and ankle.

Reproduced with permission from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010

Physical therapy exercises. Specific exercises will help you improve range of motion, strength, and endurance. It is especially important to focus on strengthening and stretching your quadriceps since these muscles are the main stabilizers of your kneecap. Core exercises may also be recommended to strengthen the muscles in your abdomen and lower back.

Orthotics. Shoe inserts can help align and stabilize your foot and ankle, taking stress off of your lower leg. Orthotics can either be custom-made for your foot or purchased “off the shelf.”

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.

If tightness in the lateral retinaculum is pulling your kneecap to the side, your doctor may recommend lateral release surgery to cut the ligament.

Reproduced with permission from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010

• Debridement. 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.

Patellofemoral pain syndrome is usually fully relieved with simple measures or physical therapy. It may recur, however, if you do not make adjustments to your training routine or activity level. It is essential to maintain appropriate conditioning of the muscles around the knee, particularly the quadriceps and the hamstrings.

Leg extension exercises help to strengthen and stretch the quadriceps, the muscles in the front of the thigh.

There are additional steps that you can take to prevent recurrence of patellofemoral knee pain. They include:

• Wearing shoes appropriate to your activities
• Warming up thoroughly before physical activity
• Incorporating stretching and flexibility exercises for the quadriceps and hamstrings into your warm-up routine, and stretching after physical activity
• Increasing training gradually
• Reducing any activity that has hurt your knees in the past
• Maintaining a healthy body weight to avoid overstressing your knees

If you found this article helpful, you may also be interested in Knee ArthroscopyKnee Arthroscopy (topic.cfm?topic=A00299).

© Thinkstock 2016

Sports and exercise are healthy activities for girls and women of all ages. Occasionally, a female athlete who focuses on being thin or lightweight may eat too little or exercise too much. Doing this can cause long-term damage to health, or even death. It can also hurt athletic performance or make it necessary to limit or stop exercise.

Three interrelated illnesses may develop when a girl or young woman goes to extremes in dieting or exercise. Together, these conditions are known as the “female athlete triad.”

The three conditions are:

• Disordered eating
  Abnormal eating habits (i.e., crash diets, binge eating) or excessive exercise keeps the body from getting enough nutrition.
• Menstrual dysfunction
  Poor nutrition, low calorie intake, high-energy demands, physical and emotional stress, or low percentage of body fat can lead to hormonal changes that stop menstrual periods (amenorrhea).
• Premature osteoporosis (low bone density for age)
  Lack of periods disrupts the body’s bone-building processes and weakens the skeleton, making bones more likely to break.

© Thinkstock 2016

Females in any sport can develop one or more parts of the triad. At greatest risk are those in sports that reward being thin for appearance (such as figure skating or gymnastics) or improved performance (such as distance running or rowing).

Fashion trends and advertising often encourage women to try to reach unhealthy weight levels. Some female athletes suffer low self-esteem or depression, and may focus on weight loss because they think they are heavier than they actually are. Others feel pressure to lose weight from athletic coaches or parents.

Female athletes should consider these questions:

• Are you dissatisfied with your body?
• Do you strive to be thin?
• Do you continuously focus on your weight?

If the answers are yes, you may be at risk for developing abnormal patterns of eating food (disordered eating), which can lead to menstrual dysfunction and early osteoporosis.

Disordered Eating

Eating a balanced diet is especially important during teenage years when our bodies are building the bone we will need through life.

© Thinkstock 2016

Although they usually do not realize or admit that they are ill, people with disordered eating have serious and complex disturbances in eating behaviors. They are preoccupied with body shape and weight and have poor nutritional habits.

Disordered eating can take many forms. Some people starve themselves (anorexia nervosa) or engage in cycles of overeating and purging (bulimia).

Others severely restrict the amount of food they eat, fast for prolonged periods of time or misuse diet pills, diuretics, or laxatives. People with disordered eating may also exercise excessively to keep their weight down.

Females are more likely than males to have disordered eating. The illness can cause many problems, including dehydration, muscle fatigue and weakness, an erratic heartbeat, kidney damage, and other serious conditions. Not taking in enough calcium can lead to bone loss. It is especially bad to lose bone when you are a child or teenager because that is when your body should be building bone. Hormone imbalances can lead to more bone loss through menstrual dysfunction.

Recognizing the female athlete triad is the first step toward treating it. See your doctor right away if you miss several menstrual periods, get a stress fracture in sports, or think you might have disordered eating.

Give the doctor your complete medical history, including:

• What you do for physical activity and what you eat for nutrition.
• How old you were when you began to menstruate and whether you usually have regular periods.
• If you are sexually active, use birth control pills, or have ever been pregnant.
• If you have ever had stress fractures or other injuries.
• Any changes (up or down) in your weight.
• Any medications you are taking or symptoms of other medical problems.
• Family history of diseases (i.e., thyroid disease, osteoporosis).
• Factors that cause stress in your life.

Your doctor will give you complete physical examination and may use laboratory tests to check for pregnancy, thyroid disease, and other medical conditions. In some cases, a bone density test will be recommended.

Treatment for female athlete triad often requires help from a team of medical professionals including your doctor (pediatrician, gynecologist, family physician), your athletic trainer, a nutritionist, and a psychological counselor.

A psychological counselor is essential for treating athletes with disordered eating.

© Thinkstock 2016

Treatment of ACL tears may be operative or non-operative. In most instances during the immediate aftermath of the injury, the patient is advised to stay off the leg and elevate it, apply ice, and take medication, such as ibuprofen to reduce pain and inflammation. A course of physical therapy is prescribed to strengthen surrounding muscles, and a brace may be fitted for use during activities that would place special stress on the knee.

• Proper leg muscle strength training and core strengthening
• Proper neuromuscular (balance and speed) training
• Proper coaching on jumping and landing to avoid straight-leg landing
• Proper footwear and orthotics if necessary