Patellofemoral Pain Syndrome

Lower Limb

Overview

Patellofemoral pain syndrome (PFPS) is a common anterior knee condition characterized by pain around or behind the patella, often aggravated by activities involving knee flexion such as climbing stairs, squatting, or prolonged sitting. It is typically a non-inflammatory condition resulting from altered patellar tracking and increased patellofemoral joint stress. PFPS accounts for 25-40% of all knee pain presentations in clinical practice.

Pathophysiology

PFPS results from abnormal patellar tracking within the femoral groove, causing increased pressure on articular cartilage and surrounding structures. Primary causative factors include: (1) quadriceps weakness or imbalance, particularly vastus medialis obliquus (VMO) insufficiency; (2) hip muscle weakness (gluteus medius, maximus) leading to excessive hip adduction and internal rotation; (3) tight lateral structures (vastus lateralis, iliotibial band, lateral retinaculum); (4) foot biomechanics (excessive pronation, pes planus); (5) femoral anteversion or increased Q-angle; (6) postural dysfunction and altered movement patterns. Repetitive microtrauma to patellofemoral articular surfaces and periarticular tissues causes localized inflammation, pain sensitization, and proprioceptive deficits.

Typical Presentation

Site

Retropatellar or peripatellar region, particularly around medial facet or central patella; may be diffuse across anterior knee

Quality

Dull ache, pressure sensation, or sharp localized pain; often described as 'deep' or 'inside' the knee

Intensity

Mild to moderate (3-6/10), variable throughout day, often worse by end of day; rarely severe resting pain

Aggravating

Stairs (especially descending), squatting, prolonged sitting with knees bent (cinema sign), lunges, jumping, running on hard surfaces, kneeling, activities increasing knee flexion load

Relieving

Rest, leg elevation, ice application, knee extension, activity modification, sitting with leg extended

Associated

Anterior knee swelling (mild), sense of instability or 'giving way', quadriceps weakness, hip weakness, stiffness after inactivity, clicking or crepitus with movement, tight hip flexors and lateral knee structures

Orthopaedic Tests

Quadriceps Angle (Q-angle)

Procedure

Patient supine. Measure angle formed by lines drawn from anterior superior iliac spine through midpoint of patella to tibial tuberosity. Normal values: 10–15° in males, 15–17° in females.

Positive Finding

Q-angle >20° in males or >22° in females; asymmetry >3° between limbs suggests altered lower limb biomechanics

Sensitivity / Specificity

Moderate to variable across studies; not a standalone diagnostic tool / Low to moderate; present in asymptomatic individuals

Hegedus et al., 2012, BJSM (meta-analysis on patellofemoral pain assessment)

Interpretation

Elevated Q-angle may contribute to patellofemoral malalignment and lateral patellar tracking, but poor individual diagnostic value. Most useful as part of comprehensive biomechanical assessment.

Single-Leg Squat Test

Procedure

Patient performs controlled squat on one leg to approximately 45–60° knee flexion while maintaining upright torso. Examiner observes for dynamic valgus (knee inward collapse), hip adduction, and trunk lean.

Positive Finding

Knee valgus, excessive hip adduction (>10° inward movement), contralateral hip drop, or trunk lean toward stance leg

Sensitivity / Specificity

Approximately 60–74% for identifying neuromuscular control deficits in PFPS / Approximately 56–64%

Reiman & Lorenz, 2011, PM&R (examination protocols for lower extremity functional limitations)

Interpretation

Indicates possible gluteal muscle weakness (especially hip abductors) or motor control deficit. Often correlates with pain provocation and biomechanical dysfunction in PFPS.

Step-Down Test

Procedure

Patient stands on a 20–30 cm step on one leg and slowly lowers opposite limb to tap floor while maintaining level pelvis and upright posture. Observe knee and hip mechanics over 3–5 repetitions.

Positive Finding

Knee valgus, hip adduction, ipsilateral hip drop, or pelvic rotation during descent; pain reproduction

Sensitivity / Specificity

Approximately 62–88% for identifying dynamic valgus and motor control deficits in PFPS / Approximately 62–81%

Reiman & Lorenz, 2011, PM&R; Gajdosik et al., 2011, IJSPT (lower extremity functional assessments)

Interpretation

Dynamic valgus during step-down strongly suggests hip abductor weakness and poor frontal-plane control. Commonly reproduced with actual PFPS symptoms.

Lateral Step-Up Test

Procedure

Patient stands sideways on a 20–25 cm step, steps up onto it with leading leg, then steps down. Observe knee and hip mechanics during ascent and descent. Can be performed with or without upper extremity support.

Positive Finding

Knee valgus, ipsilateral hip drop (>5° below horizontal), lateral trunk lean, or pain reproduction

Sensitivity / Specificity

Approximately 65–75% for detecting hip abductor weakness and kinetic chain dysfunction in PFPS / Approximately 60–70%

Bolgla & Malone, 2005, JOSPT; Reiman & Lorenz, 2011, PM&R

Interpretation

Poor performance indicates hip abductor insufficiency and lack of frontal-plane stability. Often provokes anterolateral knee pain in PFPS patients.

Y-Balance Test (Lower Quarter)

Procedure

Patient stands on one leg at center of balance mat, reaches with opposite leg in three directions (forward, posterolateral, posteromedial) as far as possible while maintaining single-leg stance. Measure reach distance in each direction.

Positive Finding

Asymmetry of >4 cm between limbs; score >90% of leg length may be normal; reduced reach distance in any direction or loss of balance indicates compromise

Sensitivity / Specificity

Approximately 70–72% for identifying dynamic balance deficits in lower extremity injuries including PFPS / Approximately 76–82%

Plisky et al., 2009, Journal of Athletic Training; Kinzey & Armstrong, 1998, JOSPT (original Y-Balance development)

Interpretation

Reduced anterior reach may correlate with quadriceps weakness; reduced posterolateral/posteromedial reach may indicate hip abductor/external rotator deficiency. Useful for functional assessment.

Patellar Tilt Test (Ober Modification / Hip Abductor Strength)

Procedure

Patient supine. Clinician palpates medial and lateral patella facets while passively flexing/extending knee to assess patellar tracking. Alternatively, perform manual hip abductor strength test (patient sidelying, examiner resists hip abduction).

Positive Finding

Palpable lateral shift or tilt during knee motion; weakness or pain during resisted hip abduction; asymmetrical strength compared to contralateral side

Sensitivity / Specificity

See current literature / See current literature

See current literature (patellar tilt assessment is descriptive; few high-quality diagnostic accuracy studies available)

Interpretation

Suggests lateral patellar tracking dysfunction (tilt test) or hip abductor insufficiency (strength test). Both findings commonly associated with PFPS biomechanics. Should be combined with other tests.

⚠ Red Flags

  • •Acute severe trauma with significant swelling and inability to bear weight (rule out fracture, ligamentous injury)
  • •Knee locked in flexion or extension (meniscal pathology)
  • •Severe effusion with systemic symptoms (septic arthritis, inflammatory arthropathy)
  • •Unilateral calf swelling with calf pain and warmth (DVT)
  • •Signs of acute ACL or MCL rupture (acute instability, hemarthrosis)
  • •Swelling, warmth, and erythema suggesting infection or acute inflammatory process

⚡ Yellow Flags

  • •High pain catastrophizing or fear-avoidance beliefs related to knee pain
  • •Significant psychological distress or depression affecting rehabilitation engagement
  • •Excessive reliance on passive treatments without active participation
  • •Inconsistent reporting of pain severity versus functional limitation
  • •Social or occupational stressors limiting rehabilitation compliance
  • •Secondary gain factors or litigation involvement
  • •Poor sleep quality exacerbating pain perception

Osteopathic Techniques

Region

Hip musculature (gluteus medius, gluteus maximus, hip rotators)

Technique

Soft Tissue

Rationale

Myofascial release and friction techniques to address hip abductor and external rotator tightness, improving hip stability and reducing compensatory femoral adduction and internal rotation that drives abnormal patellar tracking

Region

Vastus lateralis and iliotibial band

Technique

Soft Tissue

Rationale

Targeted soft tissue manipulation to reduce lateral knee tension and myofascial restrictions that contribute to lateral patellar tracking and increased patellofemoral compression forces

Region

Quadriceps musculature (all quadriceps components)

Technique

MET

Rationale

Muscle energy techniques to normalize quadriceps tone, address VMO inhibition, and improve neuromuscular control of patellar positioning during functional movements

Region

Patellofemoral joint and surrounding structures

Technique

Articulation

Rationale

Gentle patellofemoral joint mobilization to improve synovial fluid distribution, reduce cartilage stress concentration, and normalize joint mechanics without excessive compression

Region

Hip joint and lumbar spine

Technique

Articulation

Rationale

Mobilization of hip capsule and lumbar segments to address postural dysfunction, correct lower limb mechanical alignment, and improve kinetic chain function from proximal to distal

Region

Foot and ankle (talus, subtalar joint, plantar fascia)

Technique

Soft Tissue

Rationale

Treatment of foot pronation and ankle stiffness through myofascial release and joint mobilization, correcting biomechanical foot posture that contributes to altered knee mechanics and patellar tracking

Add-On Approaches

Chinese Medicine

TCM diagnosis typically focuses on Liver Qi stagnation or Kidney Yang deficiency affecting the knee. Acupuncture points such as ST34 (Xiyan), ST35 (Dubi), GB34 (Yanglingquan), and UB40 (Weizhong) may be used to regulate Qi flow, reduce pain, and support local healing. Herbs supporting Qi movement and local circulation (such as formulas containing dried rehmannia or eucommia) may be indicated.

Chiropractic

Chiropractic approach includes foot orthotics assessment for pronation control, patellar taping or bracing for tracking improvement, and lower extremity adjustments. Particular attention to ankle-foot complex and subtalar joint to correct biomechanical foot faults and reduce compensatory knee stress.

Physiotherapy

Progressive resistance exercise program emphasizing VMO strengthening, hip abductor and external rotator strengthening, core stability, proprioceptive training, and lower limb kinetic chain optimization. Gait retraining to reduce dynamic knee valgus and improve shock absorption.

Remedial Massage

Deep tissue massage focusing on releasing trigger points in vastus lateralis, iliotibial band, gluteus medius, and hip rotators; cross-friction techniques to reduce myofascial tension; soft tissue mobilization to improve local circulation and tissue extensibility

Rehabilitation Exercises

Quadriceps and Hip Flexor Stretching

Range of MotionBeginner

Iliotibial Band and Lateral Knee Stretching (Modified Ober Position)

Range of MotionBeginner

Gastrocnemius and Soleus Calf Stretching

StretchingBeginner

Vastus Medialis Obliquus Strengthening (Terminal Knee Extension with Band)

StrengtheningBeginner

Gluteus Medius Strengthening (Side-Lying Hip Abduction)

StrengtheningBeginner

Gluteus Maximus Strengthening (Bridging with Single-Leg Progression)

StrengtheningIntermediate

Hip External Rotation Strengthening (Clamshells)

StrengtheningBeginner

Wall Squats with Attention to Knee Alignment

PosturalBeginner

Step-Up and Step-Down with Proper Femoral Alignment

PosturalIntermediate

Single-Leg Stance with Hip Stability Focus

BalanceIntermediate

Lateral Stepping with Resistance Band

BalanceIntermediate

Low-Impact Aerobic Activity (Swimming, Cycling with Proper Bike Fit, Elliptical)

CardiovascularBeginner

Referral Criteria

  • •Persistent pain unresponsive to conservative treatment over 6-8 weeks of structured rehabilitation
  • •Suspected structural damage (meniscal pathology, cartilage defect) indicated by locking, catching, or positive McMurray test
  • •Signs of patellofemoral osteoarthritis with imaging confirmation and progressive functional decline
  • •Suspected patellar instability or dislocation history requiring orthopedic surgical evaluation
  • •Concurrent knee ligamentous injury (ACL, MCL, PCL) with positive special tests and imaging confirmation
  • •Severe knee swelling, effusion, warmth, or systemic symptoms suggesting inflammatory or septic arthritis
  • •Significant functional limitation preventing ADLs or work duties unresponsive to conservative care
  • •Complex cases with multiple comorbidities or psychosocial factors limiting conservative management success