Patellofemoral Pain Syndrome

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 9 min read
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Article Summary

Patellofemoral pain syndrome is pain at the front of your knee, around your kneecap (patella). Sometimes called "runner's knee," it's more common in people who participate in sports that involve running and jumping. Patellofemoral syndrome can cause symptoms that range from uncomfortable to very painful, the condition can usually be treated at home. You may be able to reduce your pain with rest and conservative...

Key Takeaways

  • This article explains Pathophysiology in simple medical language.
  • This article explains Causes in simple medical language.
  • This article explains Diagnosis in simple medical language.
  • This article explains Treatment in simple medical language.
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Definition

Patellofemoral is pain at the front of your knee, around your (). Sometimes called “runner’s knee,” it’s more common in people who participate in sports that involve running and jumping. Patellofemoral syndrome can cause symptoms that range from uncomfortable to very painful, the condition can usually be treated at home. You may be able to reduce your pain with rest and measures.

Other Names
  • Patellofemoral Pain Syndrome (PFPS)
  • Patellofemoral Pain (PFP)
  • Anterior knee pain
  • knee pain

Pathophysiology

  • General
    • PFPS is a common cause of anterior knee pain
    • It is most commonly seen in young women without any structural or pathological changes to the articular
    • The underlying etiology is often considered to be
  • Patellar Tracking/ Malalignment
    • Patella maltracking has long been implicated as a cause
    • Witvrou et al: hypermobile patella had a significant correlation with the incidence of PFPS[9]
    • Draper et al: patients with PFPS squat with increased lateralization, the increased lateral tilt of patella[10]
  • Vastus Lateralis and Vastus Medialis (VMO)
    • Cowan et al demonstrated by delayed the of VMO activation relative to vastus lateralis[11]
    • Patients with PFP tend to exhibit of the VMO as well[12]
  • Quadriceps Dysfunction
    • Several studies have shown that quadriceps muscle size, strength, and force are impaired in patients with patellofemoral [13]
  • Dynamic Valgus/ Q angle
    • The role of the Q-angle as a cause or predictor of PFPS is controversial
    • Some authors have demonstrated a relationship between the Q-angle and the development of PFPS[14]
    • Other authors have not recreated that relationship[15]
    • Likely related to dynamic or functional malalignment than a structural problem
    • Multiple studies have demonstrated increased knee abduction, and dynamic valgus stressors on the knee joint in PFPS among athletes[16]
  • Hip Stability, abductor strength
    • Multiple studies have shown the of hip external rotators, abductors lead to functional malalignment at the patellofemoral joint
    • Prins et al systematic review: strong evidence that females with PFPS have a decreased hip abduction, external rotation and extension strength[17]
    • Note that this is in female athletes, the evidence for male athletes is not strong
  • Disorders of the foot
    • Barton et al: PFPS associated with delayed timing of peak rear-foot eversion, increased rear-foot eversion at heel strike and reduced rear-foot eversion range[18]
    • Early rear-foot eversion appears to increase risk of developing PFPS[19]
    • Abnormalties with navicular bone, such as increased navicular drop, navicular drift and dorsiflexion also seem to contribute[20]
  • Hamstring imbalance, tightness
    • Several studies have identified a significant association between PFPS, hamstring tightness[21]
    • Besier et al: patients with PFPS have greater co-contraction of the quadriceps and hamstrings compared to controls[22]
  • Iliotibial Band
    • The IT band may have an influence on patellar tracking[23]
    • Kaplans fibers connect the IT band to the patella
  • “Knee-Spine Syndrome”
    • Significant difference in sacral inclination between subjects with and without anterior knee pain[24]
    • Otherwise not well described or understood
  • Psychological factors
    • Jensen et al: patients with PFPS have higher level of mental distress compared to healthy controls[25]
    • Coping mechanism of patients with PFPS similar to other groups of patients with pain, PFPS more likely to catastrophize their pain[26]
    • Fear avoidance belief about physical activity associated with pain, function in PFPS patients[27]
    • Domenech et al: high incidence of psychological distress such as anxiety and depression[28]
  • Triggers for PFPS
    • Overload of the patellofemoral joint (e.g. highintensity training)
    • Dynamic valgus and functional lateralization of the patella may lead to overuse
  • Neurological etiology of pain in patients with PFPS
    • Most pain probably develops in the insertions of the extensor mechanism or within the subchondral bone
    • Increased expression of neurofilament protein, S-100 protein, neural growth factor and substance P in the lateral retinacula of PFPS[29]
    • Draper demonstrated increased metabolic bone activity in patients with PFPS using PET/[10]
  • Implicated pain sources
    • The medial retinaculum and MPFL[30]
    • Patellar compression of subchondral bone[31]
    • Fat pad

Causes

  • Overuse
    • Including , insertional tendonosis
  • Patellar instability
  • Osteochondral damage

Associated Conditions

of the patellofemoral mechanism[32]
  • Chondromalacia Patellae
  • Osteochondral Defect Knee
  • Patellofemoral
  • Extensor
  • Patellar Instability
  • Plica Syndrome
  • Infrapatellar Fat Pad Impingement

Pathoanatomy

  • Knee Extensor Mechanism
    • Quadriceps  inserts into Patella, Patella Tendon in turn attaches to Tibial Tubercle
  • Patellofemoral Joint
    • Characterized by the articulation of the patella within the condylar groove of the
    • Stabilized by the medial and lateral retinaculae
  • Patella
    • Functions as a lever, increasing the moment arm of the extensor mechanism[33]
    • Acts as a pulley, controlling the direction of the quadriceps
    • Articular cartilage, which is the thickest in the body, provides a smooth sliding surface with the femoral trochlea[34]
    • Acts as a absorber
  • Non-modifiable
    • Female gender
    • Poor shock absorption (i.e. footwear, surface, muscles)
  • Sports
    • Running, Jumping sports
    • Endurance athletes
    • Basketball
    • Soccer
    • Lacrosse
  • Training
    • Training errors or overuse
    • Increased running mileage
    • Increased jumping
  • Muscular
    • Weak knee extension strength, especially VMO[35]
    • Weak hip abduction strength[36]
    • Weak hip external rotation strength
    • Poor flexibility of quadriceps, hamstring, iliotibial band
    • Poor core muscle endurance[37]
    • Foot pronation
  • Biomechanical/ Anatomic
    • Larger Q-angle[38]
    • Sulcus angle
    • Patellar tilt angle, typically lateral
    • Hypoplasia of the medial patellar facet
    • Patella Alta, Patella Infera
    • Patellar Hypermobility
    • Previous surgery
    • Excessive foot pronation[39]
    • Limb Length Discrepency[40]
    • Hyperlaxity[41]
    • Genu Varum or Genu Valgum
    • Gait Dysfunction[42]
    • Positive J sign
  • Other
    • Trauma
  • Not associated
    • Foot arch height index[38]

  • Fractures
    • Distal Femur
    • Patellar Fracture
    • Tibial Plateau Fracture
  • Dislocations & Subluxations
    • Patellar  (and subluxation)
    • Knee Dislocation
    • Proximal Tibiofibular
  • Muscle and Tendon Injuries
    • Quadriceps Contusion
    • Iliotibial Band Syndrome
    • Quadriceps
    • Patellar Tendonitis
    • Popliteus Tendinopathy
    • Extensor Mechanism Injury
      • Patellar Tendon Rupture
      • Quadriceps Tendon Rupture
      • Patellar Fracture
  • Ligament Pathology
    • ACL Injury
    • PCL Injury
    • MCL Injury
    • LCL Injury
    • Meniscal Pathology
    • Posterolateral Corner Injury
    • Multiligament Injury
  • Arthropathies
    • Knee Osteoarthritis
    • Septic Arthritis
    • Gout
  • Bursopathies
    • Prepatellar Bursitis
    • Pes Anserine Bursitis
    • MCL Bursitis
    • Infrapatellar Bursitis
  • Patellofemoral Pain Syndrome (PFPS)/ Anterior Knee Pain)
    • Chondromalacia Patellae
    • Patellofemoral Osteoarthritis
    • Osteochondral Defect Knee
    • Plica Syndrome
    • Infrapatellar Fat Pad Impingement
    • Patellar Instability
  • Neuropathies
    • Saphenous Nerve Entrapment
  • Other
    • Bakers Cyst
    • Patellar Contusion
  • Pediatric Considerations
    • Patellar Apophysitis (Sinding-Larsen-Johnansson Disease)
    • Patellar Pole Avulsion Fracture
    • Tibial Tubercle Avulsion Fracture
    • Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)

Diagnosis

Clinical demonstration of the patellar grind test
  • History
    • Pain is universally anterior
    • They may describe it as “behind,” “underneath,” or “around” the patella
    • Usually insidious, but can be acute in nature
    • Pain is typically worse after prolonged sitting, squatting, kneeling, and stair climbing[43]
    • Patients often report clicking, popping, snapping and cracking
    • May report buckling, which is typically transient inhibition of quadriceps due to pain or deconditioning[44]
    • Theatre sign: Pain in the patellofemoral joint after a prolonged period of sitting with the knee flexed
    • Pain is often bilateral
  • Physical Exam: Physical Exam Knee
    • Absence of joint effusion; if present consider other etiology
    • Patellar J Sign: lateral tracking of patella shifts medially as knee brought into flexion
    • Compare quadriceps muscle tone and the bulk of VMO to the contralateral limb
    • On palpation, crepitus may be present
    • Palpate medial/lateral and superior/inferior patellar poles
    • Maybe ttp to the medial or lateral retinaculum
    • Maybe ttp medial or lateral facets
  • Special Tests
    • Patellar Grind Test: move patella in all planes to assess cartilage
    • Patellar Compression Test: apply caudal force to the patella while the patient actively contracts quadriceps muscle
    • Patellar Apprehension Test: apply medial/lateral pressure while flexing/extending the knee
    • Passive Patellar Glide: patella is moved medial/lateral with the knee fixed at 30° flexion
    • Patella Alta Test
    • Patellar Tilt Test: Attempt to lift lateral aspect of the patella with thumb
    • Squat Test: The patient is asked to perform repetitive squats
    • Vastus Medialis Coordination Test
    • Waldrens Test: Palpate patella while patient performs squats
    • Step Down Test: Eccentric step down from an approx. 20 cm box
    • Resisted Isometric Quadriceps Contraction
    • Lateral Step Down Test
  • Note: Diagnosis is primarily clinical and imaging is not generally required to make the diagnosis

Radiographs

  • Standard Radiographs Knee
    • Lateral, and sunrise or Merchant views most helpful
    • Frequently normal
  • Potential findings
    • Can show patellofemoral OA
    • Osteochondral Defect
    • Lateral patellar tilt
    • Bipartite Patella

Ultrasound

  • Can be used to evaluate extensor mechanism

MRI

  • Not routinely indicated in the diagnosis of PFPS
  • May be helpful to evaluate for:
    • Malalignment
    • Trochlear dysplasia
    • Patella tilt
    • Articular chondral injuries
  • Potential findings
    • Enlarged fat pad
    • Subchondral bone edema

Classification

  • Proposed clinical classification[45]
    • Patellofemoral instability, ie., subluxation or dislocation
    • Patellofemoral pain with malalignment but no episodes of instability
    • Patellofemoral pain without malalignment

Treatment

Nonoperative

  • Indications
    • Vast majority of cases
  • General goals
    • Reduce total patellofemoral compressive forces
    • Alter the distribution of stress forces on the patella
  • Relative rest and activity modification
    • Patients may need to temporarily discontinue the offending activity
    • They may need to alter their sport or training habits
    • This could include avoiding/ limiting stairs, running, jumping, squats
  • Physical Therapy
    • Quadriceps strengthening is the gold standard treatment[46]
    • Increased quadriceps strength has been shown to reduce PFPS pain[47]
    • Bolga et al systematic review: Targeting hip abductors, external rotators generated a modest reduction in pain[48]
    • Harvie et al: 2008 meta-analysis showed positive effects on pain reduction[49]
    • Exercises should address hip muscles, trunk stability, quadriceps, hamstrings, and the iliotibial tract

Pharmacotherapy

  • NSAIDS
    • A Cochrane review found limited evidence for the effectiveness of short term pain reduction in PFPS[50]
  • Topical NSAIDS
    • Cochrane review found topical NSAIDS are as effective as oral NSAIDS for chronic musculoskeletal pain[51]
  • Vitamin D
    • Anecdotal evidence that patients with PFPS have low vitamin D and osteopenia by DEXA[52]
    • It is unknown whether supplementation with vitamin D is beneficial

Bracing and Taping

  • Patellar Taping or McConnel Taping
    • Goal: modify patella tracking with adhesive tape, typically a medially directed force
    • When combined with physical therapy and daily home exercises, patellar taping was superior to the control group[53]
    • Warden et al: 2008 meta-analysis showed functional improvement, decreaesed pain when combined with exercise[54]
  • Patellar Brace
    • Goal: apply an external, medially directed force to counteract patella maltracking
    • Lun et al found patellar bracing non-superior to a home exercise program with or without a patellar brace or knee sleeve[55]
    • D’hondt et al: 2002 meta-analysis showed patellar brace had positive effects on pain, function, patellofemoral congruence angle[56]
    • Overall, the literature is weak and better-designed studies are needed.
  • Knee Brace
    • Standard hinged knee brace
  • Foot Orthosis
    • Goal: insoles could improve rear-foot eversion or pes pronates
    • Collins et al reported moderate improvement in pain in patients who used a corrective orthosis and participated in physical therapy[57]
    • Other studies have shown mixed results
    • Overall, literature is weak for PFPS and better-designed studies are needed

Other Modalities

  • Acupuncture
    • Compared to no treatment, acupuncture showed a reduction in symptoms[58]
  • Overall, evidence is lacking to support[59]
    • Therapeutic ultrasound
    • Phonophoresis
    • Iontophoresis
    • Transcutaneous Electrical Nerve Stimulation (TENS)
    • Medium-frequency neuromuscular electrical stimulation[60]
    • Low-Level Laser Therapy
    • Extracorporeal Shock Wave Therapy
    • Electromyographic Biofeedback
    • Massage Therapy

Operative

  • Indications
    • Unknown
    • Likely reserved for refractory cases
  • Technique
    • Arthroscopy
    • Percutaneous
    • Lateral reticular release
    • MPFL repair or reconstruction
    • Anteromedialization of the tibial tubercle
  • Research
    • Kettunen compared arthroscopy plus exercise to exercise alone in patients with chronic PFPS and found no difference[61]

 

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Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
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Questions to ask

  • What is the most likely cause of my symptoms?
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Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
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Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
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Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
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Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
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Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Doctor / qualified healthcare provider
Tests to discuss with doctor
  • Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
  • Relevant blood, urine, imaging, or specialist tests only after clinical assessment
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Patellofemoral Pain Syndrome

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.