Patellofemoral Pain Syndrome

Also known as: Runner's knee (patellofemoral), PFPS (patellofemoral pain syndrome), Patellofemoral pain syndrome, Patellofemoral disorder

Last updated: December 18, 2024

Patellofemoral pain syndrome is a common cause of anterior knee pain, marked by dull aching pain around or behind the kneecap that often worsens when the joint is loaded. Often called runner’s knee, it may be linked to overuse, muscle imbalance, or abnormal kneecap tracking. Pain can flare with squatting, running, stairs, prolonged sitting, and after sitting with knees bent. Many improve with conservative care over weeks to months.

Key Facts

  • •Patellofemoral pain syndrome is a common condition characterized by pain around or behind the kneecap (patella) that worsens with activities loading the patellofemoral joint
  • •Dull, aching pain around or behind the kneecap
  • •Diagnosed through history, physical exam, and imaging
  • •First-line treatment includes exercise, weight management, and activity modification

What It Is

Patellofemoral pain syndrome is a common condition characterized by pain around or behind the kneecap (patella) that typically worsens with activities loading the patellofemoral joint. Often called runner's knee, it may result from overuse, muscle imbalances, or abnormal tracking of the patella within the femoral groove. The condition is one of the most common causes of anterior knee pain.

Affected Anatomy

This condition affects several structures in and around the joint:

  • •Patella (kneecap)
  • •Trochlear groove of the femur
  • •Articular cartilage of the patella and femur
  • •Quadriceps muscles (particularly vastus medialis obliquus)
  • •Patellar retinaculum (medial and lateral)
  • •Synovium of the patellofemoral joint

Common Symptoms

Symptoms can vary in intensity and may change over time. Common experiences include:

  • •Dull, aching pain around or behind the kneecap
  • •Pain that worsens with activities such as squatting, running, climbing stairs, or prolonged sitting
  • •Pain may increase after sitting with knees bent for extended periods (theater sign)
  • •Grinding, clicking, or popping sensation with knee movement
  • •Swelling around the kneecap may occur in some cases
  • •Stiffness after prolonged inactivity
  • •Pain with kneeling or direct pressure on the kneecap
  • •Symptoms often bilateral but may be asymmetric

Causes and Risk Factors

Multiple factors can contribute to the development of this condition:

Causes

  • •Overuse or sudden increase in physical activity, particularly running or jumping
  • •Muscle imbalances, particularly weak or improperly firing quadriceps
  • •Abnormal patellar tracking due to anatomical or biomechanical factors
  • •Tight quadriceps, hamstrings, or iliotibial band
  • •Flat feet or abnormal foot mechanics
  • •Malalignment of the lower extremity
  • •Direct trauma to the kneecap

Risk Factors

  • •Participation in running, jumping, or cycling activities
  • •Female sex, with higher prevalence in adolescent and young adult females
  • •Recent increase in training intensity or volume
  • •Weak quadriceps or hip abductor muscles
  • •Tight lower extremity muscles or connective tissues
  • •Excessive pronation of the feet
  • •Previous knee injury or surgery
  • •Anatomical factors such as patella alta or trochlear dysplasia

How It's Diagnosed

Diagnosis typically involves a combination of clinical assessment and imaging studies:

  • •Medical history focusing on activity patterns, symptom characteristics, and aggravating factors
  • •Physical examination assessing patellar tracking, alignment, and tenderness
  • •Assessment of quadriceps and hip muscle strength and flexibility
  • •Evaluation of lower extremity alignment and foot mechanics
  • •X-rays may be obtained to assess patellar alignment and rule out other conditions
  • •MRI is not routinely required but may be used if diagnosis is unclear or structural abnormality is suspected
  • •Diagnosis is primarily clinical based on history and examination

Treatment Options

Treatment approaches range from conservative measures to surgical interventions, often starting with the least invasive options:

Self-Care and Activity Modification

  • •Activity modification to reduce pain-provoking activities temporarily
  • •Patellar taping or bracing may provide symptomatic relief for some individuals
  • •Foot orthotics may help if abnormal foot mechanics are contributing
  • •Ice application after activity
  • •Gradual return to activity with attention to training load and technique

Physical Therapy and Exercise

  • •Physical therapy focusing on quadriceps strengthening, particularly vastus medialis
  • •Hip strengthening exercises, especially gluteal muscles
  • •Stretching tight muscles including quadriceps, hamstrings, and iliotibial band

Medications

  • •NSAIDs may be used for short-term pain relief

Surgery

  • •Surgery is rarely needed but may be considered for refractory cases with identifiable structural problems

Prognosis and Recovery

The course of this condition varies between individuals:

  • •Most individuals improve with conservative treatment, though recovery may require weeks to months
  • •Consistent adherence to rehabilitation exercises is important for long-term improvement
  • •Recurrence is common, particularly with return to aggravating activities without adequate preparation
  • •Some individuals may have persistent symptoms despite treatment
  • •Early intervention and addressing underlying biomechanical factors may improve outcomes

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