Sports Medicine
Sports Injury Prevention & Rehabilitation

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Patellofemoral Pain Syndrome

(Also known as PFPS, Patellofemoral Syndrome, Patellofemoral Joint Syndrome, PFJ Syndrome, Chondromalacia Patellae, Anterior Knee Pain, Patella Pain Syndrome, Runner's Knee)
What is patellofemoral pain syndrome?
Patellofemoral pain syndrome is the term given to pain originating from the patellofemoral joint (i.e. the joint between the knee cap (patella) and thigh bone (femur). Patellofemoral pain syndrome is usually associated with inflammation or damage to structures of the patellofemoral joint.
The knee comprises of the union of three bones – the long bone of the thigh (femur), the shin bone (tibia) and the knee cap (patella). The patella (knee cap) is situated at the front of the knee and lies within the tendon of the quadriceps muscle (the muscle at the front of the thigh). The quadriceps tendon envelops the patella and attaches to the top end of the tibia. Due to this relationship, the knee cap sits in front of the femur forming a joint in which the bones are almost in contact with each other. The surface of each bone, however, is lined with cartilage to allow cushioning between the bones. This joint is called the patellofemoral joint.
Normally, the patella is aligned in the middle of the patellofemoral joint so that forces applied to the knee cap during activity are evenly distributed. In patients with patellofemoral pain syndrome the patella is usually misaligned relative to the femur, which therefore places more stress through the patellofemoral joint during activity. As a result this may cause pain and inflammation to the patellofemoral joint. The misalignment of the patella may occur for various reasons. One of the main causes is an imbalance in strength between two parts of the quadriceps muscle.
The quadriceps muscle comprises of four muscle bellies, two lie centrally (rectus femoris and vastus intermedius), one lies on the inner leg (vastus medialis) and one lies on the outer leg (vastus lateralis). In the majority of patellofemoral pain syndrome cases, the outer quadriceps (vastus lateralis) is stronger than the inner quadriceps (vastus medialis), resulting in the knee cap being pulled towards the outside of the leg. This may result in abnormal movement of the knee cap when bending and straightening the knee. There are many factors which can cause this strength imbalance of the quadriceps. These need to be identified and corrected by a physical therapist.
Patellofemoral pain syndrome is a very common condition that is frequently seen in clinical practice, particularly in runners. It often affects adolescents at a time of increased growth and usually affects girls more than boys. In older patients, patellofemoral pain syndrome is often associated with degenerative joint changes. A history of knee injury may increase the likelihood of developing patellofemoral pain syndrome.

Signs and symptoms of patellofemoral pain syndrome
Patients with patellofemoral pain syndrome usually experience pain at the front of the knee and around or under the knee cap. Pain can sometimes be felt at the back of the knee or on the inner or outer aspects. Patients usually experience an ache that may increase to a sharper pain with activity. Pain is typically experienced during activities that bend or straighten the knee particularly whilst weight bearing. Activities that frequently aggravate symptoms include going up and down stairs or hills, squatting, running or jumping. Occasionally pain may be felt whilst sitting with the knee bent for prolonged periods. There may also be an associated clicking or grinding sound when bending or straightening the knee. Patients may also experience episodes of the knee giving way or collapsing due to pain. In more severe or chronic cases there may be evidence of quadriceps muscle wasting.

Diagnosis of patellofemoral pain syndrome
A thorough subjective and objective examination from a physician is usually sufficient to diagnose patellofemoral pain syndrome. Investigations such as an X-ray or MRI may be used to assist with diagnosis.

Treatment for patellofemoral pain syndrome
Most cases of patellofemoral pain syndrome settle well with an appropriate physical therapy program. This requires careful assessment by the physical therapist to determine which factors have contributed to the development of the condition, with subsequent correction of these factors.
The success rate of treatment for patients with patellofemoral pain syndrome is largely dictated by patient compliance. One of the key components of treatment is that the patient rests sufficiently from ANY activity that increases their pain until they are symptom free. Activities which place large amounts of stress through the patellofemoral joint should be minimized, these include: squatting, jumping, running and going up and down stairs. Exercising into pain must also be avoided. This allows the body to begin the healing process in the absence of further tissue damage. Ignoring symptoms or adopting a 'no pain, no gain' attitude is likely to lead to the problem becoming chronic. Immediate, appropriate treatment in patients with patellofemoral pain syndrome is essential to ensure a speedy recovery. Once the condition is chronic, healing slows significantly resulting in markedly increased recovery times.
Patients with patellofemoral pain syndrome will usually benefit from protective taping and following RICE. RICE is beneficial in the initial phase of the injury (first 72 hours) or when inflammatory signs are present (i.e. morning pain or pain with rest). This involves resting from aggravating activities, regular icing, the use of a compression bandage and keeping the leg elevated. Anti-inflammatory medication may also significantly hasten the healing process by reducing the pain and swelling associated with inflammation.
Patients with patellofemoral pain syndrome should perform pain-free flexibility and strengthening exercises as part of their rehabilitation to ensure an optimal outcome. One of the key components of rehabilitation is pain-free strengthening of the vastus medialis obliquus muscle (VMO). This is often in combination with core stability, pelvic and gluteal strengthening exercises to improve the control of the patellofemoral joint with weight-bearing activities. The treating physical therapist can advise which exercises are most appropriate for the patient.

Contributing factors to the development of patellofemoral pain syndrome

There are several factors which can predispose patients to developing patellofemoral pain syndrome. These need to be assessed and corrected with direction from a physical therapist. Some of these factors include:
  • muscle strength imbalances
  • muscle weakness (especially the VMO and gluteal muscles)
  • tightness in specific joints (hip, knee or ankle)
  • tightness in specific muscles (especially the ITB or quadriceps)
  • poor lower limb biomechanics
  • excessive or inappropriate training or activity
  • inappropriate footwear or training surfaces
  • poor foot posture
  • poor training technique

Physical therapy for patellofemoral pain syndrome
Physical therapy treatment for patellofemoral pain syndrome is vital to hasten the healing process and ensure an optimal outcome. Treatment may comprise:
  • soft tissue massage
  • electrotherapy
  • taping or bracing to correct patella position
  • mobilization
  • dry needling
  • ice or heat treatment
  • progressive exercises to improve flexibility, balance and strength (especially the VMO muscle)
  • activity modification advice
  • biomechanical correction
  • anti-inflammatory advice
  • weight loss advice where appropriate
  • the use of Ultrasound to assess and retrain the VMO muscle
  • a graduated return to activity program

Other intervention for patellofemoral pain syndrome

Despite appropriate physical therapy management, some patients with patellofemoral pain syndrome do not improve. When this occurs the treating physical therapist or doctor can advise on the best course of management. This may include pharmaceutical intervention or a referral to an orthopaedic specialist who will advise on any procedures that may be appropriate to improve the condition. A review with a podiatrist may also be indicated for the prescription of orthotics to correct any foot posture abnormalities.