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Patellofemoral Pain Syndrome / Anterior Knee Pain
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 anterior knee pain, and also "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 non-athletes, as well. The pain and stiffness it causes can make it difficult to climb stairs, kneel down, and perform other everyday activities.
Symptoms include a generalized dull, aching pain in the knee or pain around the kneecap. Running, going down stairs, squatting, or sitting for a long time with knees bent usually increases pain. Flexing the knee back completely is often painful. Crepitus (a crackling noise under the patella) may occur during knee movement. Slight swelling may be noted. Some patients have decreased kneecap motion, others can have a hyper-mobile kneecap, or history of kneecap dislocations.
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.
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 rubber like layer 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.
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.
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. This change can be in the frequency of activity—such as increasing the number of days you exercise each week. It can also be in the duration or intensity of activity—such as running longer distances. 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. 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.
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.
- Activity Changes - Stop doing the activities that make your knee hurt until your pain is resolved. This may mean changing your training routine or switching to low-impact activities that will place less stress on your knee joint. Biking and swimming are good low-impact options. If you are overweight, losing weight will also help to reduce pressure on your knee.
- The RICE Method - RICE stands for Rest, Ice, Compression, and Elevation. Avoid putting weight on the painful knee. Use cold packs for 20 minutes at a time, several times a day. To prevent additional swelling, lightly wrap the knee in an elastic bandage, leaving a hole in the area of the kneecap. Make sure that the bandage fits snugly and does not cause additional pain. As often as possible, rest with your knee raised up higher than your heart.
- Medications - If your pain affects your daily routine, or is not relieved by other nonsurgical methods, there are medications that can help relieve some of the symptoms.
- Acetaminophen (Tylenol) is an over-the-counter pain reliever that can be effective in reducing mild pain.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen (Aleve) and ibuprofen (Advil / Motrin) may relieve pain and reduce inflammation.
- Glucosamine and chondroitin sulfate, substances found naturally in joint cartilage, can be taken as dietary supplements. Although it has not been shown to decrease or reverse the progression of arthritis over time, patient reports indicate that these supplements may relieve pain.
If your pain persists or it becomes more difficult to move your knee, contact us please contact us for further evaluation. During the examination, your general health and the symptoms you are experiencing will be reviewed. You will be asked when your knee pain started and about the severity and nature of the pain (dull vs. sharp), and about what activities cause the pain to worsen. We will check your knee for problems in patellar tracking. To help diagnose the cause of your pain and to rule out any other physical problems we will 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)
- Problems with your gait that may be contributing to your knee pain.
Usually, patellofemoral pain syndrome can be diagnosed with a physical examination. X-rays will also be performed to rule out damage to the structure of the knee and to the tissues that connect to it.
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. In addition to activity changes, the RICE method, and anti-inflammatory medication, the following may be recommended:
- Physical therapy 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 or 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." Shoe inserts take stress off your lower leg by aligning your foot and ankle.
- Braces can help align and stabilize your knee cap as you bend and straighten the leg taking stress off the patellofemoral joint. Braces can either be custom-made or purchased "off the shelf."
- Prescription anti-inflammatory medications can be effective in reducing symptoms. For those with side effects prescription COX-2 inhibitors are a special type of NSAID that may cause fewer gastrointestinal side effects. Common brand names include Celebrex (celecoxib) and Mobic (meloxicam, which is a partial COX-2 inhibitor).
- Corticosteroids (also known as cortisone) are powerful anti-inflammatory agents that can be injected into the joint These injections provide pain relief and reduce inflammation; however, the effects do not last indefinitely. We recommended limiting the number of injections, due to possible side effects.
- Viscosupplementation involves injecting a gel containing Hyaluronic acid, a molecule found in healthy joint fluid and cartilage, into the joint to lubricate and improve the quality of the joint fluid.
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 is based on the underlying factors identified on exam, and may include:
- Arthroscopy. During arthroscopy, small camera called an arthroscope, is inserted into your knee joint. The camera displays pictures on a monitor. These images are used to guide miniature surgical instruments to address the symptoms in the knee.
- 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.
- Medial Patellofemoral ligament reconstruction. Another way to help stabilize a kneecap that does not track well is by reconstructing the ligament on the inside of the knee. This can help pull the kneecap into proper alignment and hold it in place throughout the range of motion.
- 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). The tibial tubercle is detached 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.
- Osteotomy In some cases improper alignment is due to internal or external rotation in the thigh bone or shin bone. An osteotomy is a procedure where the bone can be cut and rotated into better alignment and held in place with a plate and screws to heal.
- Patellofemoral replacement In cases where severe cartilage damage results, this type of knee replacement can be effective in relieving the symptoms long term. During this "partial" knee replacement, damaged bone and cartilage surfaces are removed and replaced with metal and polyethylene (plastic) components. A thin metal shield is used to resurface the trochlear groove at the end of the femur. A plastic “button” or cover is used to resurface the backside of the patella. These components are typically held to the bone with cement.
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. 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 over-stressing your knees