Patellofemoral Pain Syndrome (PFPS) also known as runners knee, chondromalacia patellae, anterior knee pain and patellofemoral joint syndrome is a generic term used to describe patella pain at the front of the knee. Here we explain the symptoms, causes, and treatment including patella taping and exercises.
Patellofemoral pain syndrome symptoms
Symptoms include an aching pain in the knee joint, particularly at the front of the knee around and under the patella.
There is often tenderness along the inside border of the kneecap and swelling will sometimes occur after exercise. Patellofemoral pain is often worse when walking up and down hills or sitting for long periods of time.
Other signs a sports medical practitioner may pick up include a click or cracking sound when bending the knee, wasting of the quadriceps muscles if the injury is an old one and tight muscles around the knee joint.
Read more about symptoms and diagnosis.
What is a patellofemoral pain?
PFPS occurs when the patella (kneecap) rubs on the femur bone underneath. It is often thought that incorrect tracking or rubbing of the patella over the femur bone is a significant factor and results in damage or irritation of the articular cartilage underneath the patella.
Patellofemoral pain is common in people who do a lot of sport and in particular adolescent girls. It can have a number of causes but damage to the cartilage itself cannot directly cause pain because there are no blood vessels or nerves involved. However, it can lead to other problems which in turn result in pain. These include synovitis (inflammation of the synovial membrane or joint lining in the knee), erosion of the cartilage and bone, soft tissues injury or irritation such as to the lateral retinaculum and the infra patella fat pad.
The initial cause of patellofemoral pain syndrome is likely to be overuse. This may be from external factors, for example, a sudden increase in training, or performing high-intensity jumping and knee bending, or it can be from internal factors such as poor patella tracking. Identifying the cause is an important part of treatment.
There are a number of factors which can increase the risk of suffering patellofemoral pain including:
Incorrect running shoes for your running style can contribute to poor foot biomechanics. Some shoes are designed to resist pronation inwards by having a firmer block on the inside of the mid-sole. Looking at the wear pattern on a shoe can give an indication as to whether they are appropriate. Also the age of a running shoe is important. Most runners will replace them after 500 miles or 6 months. Some will have two or three pairs on the go at once which can extend the life of the shoe.
Increased training loads can be from increased volume for example increasing the number of miles run or days trained. This increases the overall load from repetitive strain on the patellofemoral joint. Increasing intensity such as through bounding or jumping exercises can also increase the load on the joint.
Training surfaces can increase the load through the joint. Hard surfaces such as roads or concrete floors will increase the load on the joint compared to grass or artificial 3G type training areas.
Increased internal rotation of the femur or thigh bone may contribute to the development of patellofemoral pain. The therapist will assess the patient in a standing position and will observe the patella facing inwards towards each other. This may be more prominent during running or walking or performing a single leg squat and could be due to weak hip muscles, particularly the gluteus medius.
Increase knee valgus is also known as genu valgum or an increased Q angle. Simply put, the knee bends inwards increasing the angle between the quadriceps and the patella tendon. This can be seen with the patient in a standing position or during a single leg squat exercise. A Q-angle greater than 18 to 20 degrees could indicate patella tracking problems.
Increased tibia rotation is where the tibia or shin bone rotates inwards too much. This can cause the femur to rotate inwards and the patella to track incorrectly. Rotation of the tibia is often due to an over pronated foot.
Over pronation of the foot is where the foot rolls in too much and flattening. This has a knock on effect of causing the tibia to rotate.
Poor flexibility of any of the muscles surrounding the knee joint can be a contributing factor, in particular tight muscles on the outside of the knee and hip such as the tensor fascia lata and iliotibial band.
Position of the kneecap can assessed through both active movements which the patient initiates and passive movements which are facilitated by the therapist. The patella may be rotated, tilted forwards or backwards or displaced sideways, any of which can be a contributing factor. Taping the patella back into place may also be used to determine the cause of pain.
Soft tissue surrounding the patella such as the lateral retinaculum and iliotibial band could be too tight whilst the vastus medialis muscle on the inside of the knee could be too weak. This could be obvious from assessing the patella position or through feeling or palpating the tissues.
Neuromuscular control of the vastus medialis is assessed to identify if the muscles are contracting at the right time. Just because there is plenty of muscle bulk does not mean the muscles are working properly. If the vastus medialis on the inside of the knee contracts slightly later than the rest of the quadriceps muscles then this could be a contributing factor. The therapist should assess this in a number of positions, particularly those which closely relate to the patients normal sporting activities.
Patella pain treatment and rehabilitation are based on reducing symptoms, identifying the causes and strengthening or re-training muscles which may have contributed to the injury. Apply PRICE principles of protection, rest, ice, compression and elevation after activity to help reduce pain and swelling. Rest completely from aggravating activities until there is no pain.
Wearing a patella tracking knee brace or support may help. These usually have a hole in the middle of the kneecap and straps which are pulled across the knee applying support to the patella. A patella taping technique is excellent for helping to control the position of the patella and relieve symptoms.
A professional practitioner can confirm the diagnosis and rule out other conditions which may have similar symptoms such as a synovial plica. A doctor may prescribe anti-inflammatory medication such as ibuprofen which should not be taken if you have asthma.
Sports massage can help loosen tight structures and muscles which may be contributing. Gait analysis can also be done to determine if the athlete overpronates and orthotic inserts can correct poor foot biomechanics. In chronic cases, a surgeon may operate to release the tight lateral structures of the knee although there is little evidence as to the success of the surgery.
Read more on patellofemoral pain treatment.
Patellofemoral pain syndrome exercises
Depending on what is causing the patella pain exercises to strengthen the muscles on the inside of the thigh are usually recommended. In particular, heel drop exercises can strengthen the vastus medialis muscle on the inside of the thigh. This is an important muscle for controlling patella tracking and is often weak in athletes with patellofemoral pain. Thigh stretching exercises are also important as the muscles on the outside of the thigh (vastus lateralis muscle) is often tight.
Read more on patella pain exercises.