Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFSS) is pain in the patella gliding pathway between the thigh and kneecap. Patients usually speak of pain next to, behind or below the kneecap. Therefore, it is often referred to as the “front knee pain”. Especially when climbing stairs, after long periods of sitting or in connection with exercise, complaints occur. Young, physically active women are particularly often affected.

The patellofemoral pain syndrome

Patellofemoral pain syndrome is a term used to describe pain in the front of the knee and around the patella or knee bone. It is sometimes called “runner’s knee” or “jumper’s knee” because it is common in people who participate in sports, especially women and young adults, but patellofemoral pain syndrome can also occur in people who are not athletes. 

The pain and stiffness it causes can make it difficult to climb stairs, kneel and perform other daily activities.

Many aspects can contribute to the development of patellofemoral pain syndrome. Problems with kneecap alignment and overuse due to vigorous sports or training are often significant factors.

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


Anatomy of a normal knee

The knee is the largest joint in your body and one of the most complex. It is formed by the lower end of the femur, the upper end of the tibia and the patella.

Ligaments and tendons connect the femur to the bones of the lower leg. The four major ligaments of the knee join the bones and act as strong cords to hold the bones together.

The muscles are connected to the bones by the tendons. The quadriceps tendon connects the muscles from the front of the thigh to the patella. The segments of the quadriceps tendon, called patellar retinaculae, join the tibia and help stabilize the patella. The patellar tendon extends from the patella to the tibia.

Several structures of the knee joint make movement easier. For example, the patella rests in a groove in the upper part of the femur called the trochlea. When the knee flexes or straightens, the patella moves back and forth inside this trochlear groove.

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

The synovia also helps the movement; It is 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 there is a small pad of fat that supports the kneecap and acts as a shock absorber.


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

In some cases of patellofemoral pain, a condition called chondromalacia patellae occurs. Chondromalacia patellar is the softening and degradation of the articular cartilage that is in the inner part of the patella. There are no nerves in the articular cartilage, so damage to the cartilage itself can not cause pain directly. However, it can cause inflammation of the synovium and pain in the underlying bone.


Excessive use

In many cases, patellofemoral pain syndrome is caused by vigorous physical activities that apply repeated strain on the knee, such as jogging, squats, and climbing stairs. It can also be triggered by a sudden change in physical activity. This change may be in the frequency of the activity, such as increasing the number of days you exercise each week. It may also be due to the duration or intensity of the activity, such as running longer distances.

Other factors that can contribute to patellofemoral pain include:

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

Patellar misalignment

The patellofemoral pain syndrome can also be caused by an abnormal alignment of the patella in the trochlear groove. In this condition, the kneecap is expelled to the side of the groove when the knee is flexed. This abnormality can cause more pressure between the back of the patella and the trochlea, which irritates the soft tissues.

Factors that contribute to malalignment of the patella include:

  • Problems with the alignment of the legs between the hips and the ankles. Problems in alignment can result in a patella moving too far to the outside or inside of the leg, or a patella that fits well above the trochlear groove, a condition called a high patella.
  • Imbalance or muscle weakness, especially in the quadriceps muscles in the front of the thigh. When the knee flexes and extends, the quadriceps muscles and the quadriceps tendon help keep the patella within the trochlear groove. Weak or unbalanced quadriceps may cause poor alignment of the patella within the groove.


The most common symptom of patellofemoral pain syndrome is mild, tender pain in the front of the knee. This pain, which usually begins gradually and is often related to activity, can occur in one or both knees. Other common symptoms include:

  • Pain during exercise and activities where the knee is repeatedly flexed, such as climbing stairs, running, kneeling or doing squats.
  • Pain after sitting for a long period of time with knees bent, such as at the movies or after traveling by plane.
  • Pain related to a change in the level or intensity of the activity, playing surface or equipment.
  • Cracks or crackling sounds in the knee when climbing stairs or when standing after sitting for a long time.


The most common symptom of patellofemoral pain syndrome is mild, tender pain in the front of the knee. This pain, which usually begins gradually and is often related to activity, can occur in one or both knees. Other common symptoms include:

  • Pain during exercise and activities where the knee is repeatedly flexed, such as climbing stairs, running, kneeling or doing squats.
  • Pain after sitting for a long period of time with knees bent, such as at the movies or after traveling by plane.
  • Pain related to a change in the level or intensity of the activity, playing surface or equipment.
  • Cracks or crackling sounds in the knee when climbing stairs or when standing after sitting for a long time.

Home remedies

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

Changes in activity

Stop activities that cause pain in your knees until the pain resolves. This may mean changing your training routine or switching to low impact activities that will put less stress on the knee joint. Cycling and swimming are good low impact options. If you are overweight, losing weight will also help reduce the pressure on your knees.

The RICE method

RICE is the abbreviation, in English, of rest, ice, compression and elevation.

  • Break. Avoid putting weight on the affected knee.
  • Ice. Use cold compresses for periods of 20 minutes, several times a day. Do not apply ice directly on the skin.
  • Compression. To avoid further inflammation, wrap the knee lightly in an elastic bandage, leaving a hole in the kneecap area. Make sure the bandage is tight and does not cause additional pain.
  • Elevation. Rest, as often as possible, with your knee raised higher than your heart.


Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen can help reduce inflammation and relieve pain.

If your pain persists or your knee becomes more difficult to move, contact your doctor for a full evaluation.

Medical exam

Physical exploration

During the physical examination, your doctor will talk with you about your general health and the symptoms you are having. He or she will ask you when your knee pain began and about the severity and nature of the pain (mild or acute). Your doctor will also ask what activities make the pain worse.

To determine the exact location of the pain, your doctor can gently press and pull the front of your knees and kneecaps. He or she may also ask you to squat, jump or perform a lunge during the examination to test the knee and the strength of your body trunk.

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

  • The alignment of the lower part of the legs and the position of the kneecap
  • The stability of the knee, the rotation of the hips and the range of motion of the knees and hips
  • The patella to look for signs of sensitivity
  • The union of the muscles of the thigh with the kneecap
  • The strength, flexibility, firmness and flexion of the hips, the front muscles of the thigh (quadriceps) and the posterior muscles of the thigh (thighs)
  • The tightness of the Achilles heel and the flexibility of the feet
Finally, your doctor may ask you to walk back and forth to examine your progress (the way you walk). He or she will check if you have problems in your gait that can contribute to the pain of your knees.


Usually, the doctor will be able to diagnose the patellofemoral pain syndrome with only a physical examination. However, in most cases he or she will also order an x-ray to rule out damage to the knee structure and the tissues that connect with it.


The 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 non-surgically.

Non-surgical treatment

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

Physical therapy exercises. Specific exercises will help improve your range of movement, strength and endurance. It is especially important to focus on strengthening and stretching your quadriceps, since these muscles are the main stabilizers of the patella. Exercises for the trunk of the body can also be recommended to strengthen the muscles of the abdomen and lower back.

Orthopedic devices. Shoe inserts can help to align and stabilize your foot and ankle, relieving the tension that is applied to the lower legs. Orthotics can be made to fit the foot or bought ready to use in stores.

Surgical treatment

Very rarely, surgical treatment is required for patellofemoral pain and is only performed for severe cases that do not respond to non-surgical treatment. Surgical treatments may include:

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

  • Debridement In some cases, removing damaged articular cartilage from the surface of the patella can relieve pain.
  • Lateral release. If the tendon of the lateral retinaculum is so tight that it expels the patella of the trochlear groove, a lateral release procedure can loosen the tissue and correct the patellar misalignment.

Transfer of the tibial tubercle. In some cases, it may be necessary to realign the patella by moving the patellar tendon along with a part of the tibial tubercle, the bony protuberance of the tibia.

A traditional open surgery incision is required for this procedure. The doctor partially or totally detaches the tibial tubercle so that the bone and tendon can move towards the inner side of the knee. Then, the bone piece is reattached to the tibia using screws. In most cases, this transfer allows a better alignment of the patella in the trochlear groove.


The patellofemoral pain syndrome is usually completely relieved by simple measures or physical therapy. However, it may reappear if you do not make adjustments to your training routine or activity level. It is essential to maintain proper conditioning of the muscles that surround the knee, especially the quadriceps and the knees.

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

  • Wear appropriate footwear for your activities
  • Warm up thoroughly before physical activity
  • Incorporate stretching and flexibility exercises for the quadriceps and hamstrings in your warm-up routine, and perform stretching after physical activity
  • Gradually increase training
  • Reduce any activity that has hurt your knees in the past
  • Maintain a healthy body mass to avoid overstressing the knees

Synonyms in the broader sense

The pain of the kneecap is also called Patellofemoral pain syndrome called.
Further synonyms are:

  • Retro Patel tab Merz
  • Chondropathia patellae
  • Chondromalacia patellae
  • patello-femoral arthralgia
  • patello-femoral arthrosis
  • PFS
  • PFCS
  • femoropatellar pain syndrome

Differential diagnosis for patellofemoral pain syndrome

Differential diagnosis refers to alternative causes that cause similar symptoms and discomfort:

  • knee osteoarthritis
  • Knee joint arthritis (inflammation of the knee joint )
  • meniscus damage
  • tape damage
  • free joint body
  • Leg length discrepancy
  • Radiation pain from the hip or spine (referred pain)


The PFFS (Patellofemoral Pain Syndrome) is one of the most common complaints in the anterior knee area .
Hidden behind the PFSS is not a uniform clinical picture, but a very complex symptoms, which is discussed very differently in terms of definition, diagnosis and aetiology (causes).

The definition of an Australian research group is: Pain from the anterior knee area and the patello-femoral region (area of ​​the articulation between the patella and the femur) of mostly unclear cause.

The patellofemoral joint suffers as early and frequently from degenerative changes as almost no other joint and there is still no method for the assured repair of cartilage damage . Often, young, physically active, more often female people are affected by PFFS (Patellofemoral Pain Syndrome).

Symptoms of Patellofemoral Pain Syndrome

  • Pain in the area of ​​the kneecap (behind, beside, under)
  • Temporary pain after prolonged rest of the knee joint
  • Pain intensified after exercise, when climbing stairs, when squatting
  • Limitations of movement, distension of swelling in the patellar area
  • Pain can be unilateral, bilateral or alternating

Causes of pain on the kneecap

  • Bony deviations of the kneecap and knee joint ( O-legs / X-legs )
  • Bony deviations of the hip or ankle
  • Too tight patella leadership by band shortening
  • Muscle weakness of the thigh muscles
  • Muscle shortening of the thigh, hip and calf muscles
  • Classic overload of the knee joint

Pain due to bony deviations of the knee

Due to a lack of training of the patella (patellar dysplasia) , a forward displacement of the thigh or a so-called patella alta (too high standing patella ), there is an incongruent articular surface between the patella and thigh  patella sliding bearing) , resulting in a deteriorated leadership of the patella.Unter Patella alta is understood to mean a long thigh muscle tendon (patellar tendon) that is too long compared to the longitudinal diameter of the kneecap.

The patella moves through these mismatches with increasing knee extension too far outward (lateral), the contact surface of the joint decreases and the pressure load on the patella on the thighincreases. The consequence of this is an irritation of the surrounding soft tissues, damage to the patellar patella and stress pain.

An x-leg position of the knee joint (genu valgus) or an o-leg position (genu varus) alsochange the tension conditions of the thigh extensor ( quadriceps muscle ) and the position of the kneecap in its sliding bearing on the thigh. A osteoarthritis (cartilage degeneration) of the patellar and knee joint cartilage is promoted thereby.

Patellar cartilage needs adequate pressure and discharge to stay healthy. In addition to the structural changes described above, risk factors for cartilage damage include in particular a lack of physical disposition, inadequate exercise and strain, and a mismatch between exercise and exercise tolerance.

Illustration of the kneecap

  1. Patella – patella
  2. Thighbone – femur
  3. Shin – Tibia
  4. Fibula – fibula
  5. Internal meniscus – meniscus medialis
  6. Outer meniscus – lateral meniscus
  7. Patellar ligament – patellar ligament
  8. Straight thigh muscle – Musculus rectus femoris
  9. Iliac tibia tendon – iliotibial tract
  10. Anterior tibial muscle – tibialis anterior muscle

What is the patellofemoral pain syndrome (PFSS)?

The most common causes include a shortened or weakened thigh muscles, a not fully developed patella glacis, a leg-axis deviation (eg X- or O-legs) or a tilt of the kneecap.

The following synonyms are used for the patellofemoral pain syndrome (PFSS):


In the healthy state, the kneecap sits in the so-called sliding bearing of the femur as in a guide trough and is additionally held by lateral straps. The musculature actively supports the central glide. An instability of the kneecap causes it is not exactly in the plain bearing and in the worst case, “jumps out” of the guide channel. This causes a lot of pain.

Basically, three degrees of instability are distinguished:

  1. Lateralization of the kneecap (the kneecap slides laterally on the guide trough)
  2. Subluxation of the kneecap (the kneecap almost disappears)
  3. Dislocation of the kneecap (the kneecap completely decays)

Mostly the cause of the complaints lies in an unfavorable combination of dislocation-promoting components. From an anatomical point of view, these include abnormalities of the gullet or patella. Other risk factors include a loose ligament (patellar hypermobility), a high kneecap, and an imbalance between the outer and inner front thigh muscles. The latter can cause the shortened muscles to pull the kneecap over the tendons to the side. The result: an instability of the kneecap.

Healthy musculature tenses and relaxes again. Overloading can cause the outer thigh muscle to permanently tighten and then shorten. Here, “trigger points” can form that cause and radiate pain. Discomfort in the knee can thus also be related to the formation of a trigger point in the outer, front thigh muscles.

Symptoms and signs

The pain is noticeable behind, next to or below the kneecap. Especially after prolonged sitting or prolonged immobilization of the knee joint (tiring pain), but also in conjunction with exercise or when climbing stairs complaints occur. Young, physically active women are particularly often affected.

risk factors

The following risk factors favor the patellofemoral pain syndrome:

  • Normal deviation of the gullet or the patella – interferes with the central sliding of the kneecap in the plain bearing
  • Loose ligaments (patellar hypermobility)
  • Standing kneecap
  • Imbalance between the outer and inner front thigh muscles – the shortened muscles pull the kneecap over the tendons to the side. The result: an instability of the kneecap.


In the case of lateralization or subluxation of the patella is usually treated conservatively, ie without surgery. To stabilize the patella and knee joint, the patient wears a knee brace (for lateralization) or a knee brace (for luxation). If the kneecap refracts for the first time or several times, surgery may be considered. In addition, it is important to positively influence the pulling direction on the kneecap. Help physiotherapy exercises and regular independent training to strengthen the thigh muscles.

Physio exercises

With the right exercises you can maintain your fitness and mobility and prevent pain. In particular, your thigh muscles should strengthen you with regular, independent training and thus positively influence the direction of pull on the kneecap.

The training program consists of exercises to strengthen the thigh muscles, hip stabilization, stretching of the thigh muscles and improvement of movement patterns / coordination. The exercises should ideally be performed three to four times a week . Ask your doctor in advance if the exercises are suitable for you.

Patellofemoral Pain Syndrome
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