Integrating Biomechanics and Psychological Factors in Patellofemoral Pain

Defining the Right Profile: Gradual-Onset PFP (Non-Traumatic)

Target population: patients with anterior knee pain that developed progressively, without prior patellar dislocation or traumatic event.

Key Characteristics

• Location: around or behind the patella.
• Load-related pain: aggravated by running, stair climbing (up or down), squatting, ramps.
• Description: diffuse pain “around the patella,” often indicated with an open hand.
• Pain at rest (exception): occurs mainly with prolonged sitting (cinema, plane, bus), especially with crossed legs in some women.

(Present or Absent) Non-Essential Signs

• Crepitation: can strongly affect patient perception and concerns, but not a defining feature.
• Palpation pain: often absent, despite movement-related pain.
• Apprehension with touch: discomfort does not necessarily equal pain.
• Mild effusion: may appear after exercise, but not a primary feature.

The Main Trigger: Joint Overload

Core idea: “too much, too soon”—when load exceeds the tissue’s adaptive capacity.

Practical takeaway: “altered” movement patterns only become problematic in the presence of overload. Gradual progression and recovery time are essential.

Biomechanics: What Matters and What Doesn’t

Consistent Alterations Observed

• Hip: excessive adduction.
• Knee: reduced flexion (e.g., on stairs), often a protective strategy linked to pain-related fear.
• Foot: excessive rearfoot eversion (pronation).
• Runner’s marker: hip adduction about +4° higher than in healthy runners.

Performance Deficits

• Reduced strength / power: knee extensors and hip abductors.
• Present in isometric, concentric, and eccentric contractions.
• Patients typically show ≥ 2 alterations (hip / knee / ankle); the more present, the higher the pain and the lower the function.
• Foot-knee-hip chain: pronation → tibial internal rotation → hip internal rotation → ↑ patellofemoral stress.

Myth to Discard

• Delayed activation of vastus medialis vs. lateralis: hypothesis rejected (EMG shows no significant difference). Do not base interventions on this outdated concept.

Psychological Factors (Yellow Flags)

Common profile: anxiety, fear of movement, avoidance behaviors, catastrophizing, depressive symptoms.

In practice

• Avoidance ≠ phobia: patients avoid stairs to limit anticipated pain, not because of true movement phobia.
• Physio’s role: address avoidance and re-expose patients to movement gradually. Temporary aids: taping, bracing.
• Assessment: TSK (Tampa Scale for Kinesiophobia), pain catastrophizing scales.
• Scope limits: anxiety or depressive symptoms → refer to psychology and initiate multidisciplinary care.

Core Message: Integrating Biomechanics and Psychology

• Higher fear of movement = less knee flexion (e.g., going down stairs).
• Some patients can physically perform the task… but do not due to anticipated pain.
• Strength training alone is not enough if psychological factors remain unaddressed.
• In one sample, self-reported pain correlated strongly with fear of movement, but weakly with patellofemoral stress: here, psychological factors outweighed biomechanics in the pain experience.

Clinical Application: Quick Guide

Assess

1. Confirm PFP profile and key characteristics.
2. Quantify recent load: volume, intensity, variation (“too fast”).
3. Biomechanical screen: hip adduction, knee flexion in functional tasks, rearfoot pronation; quadriceps/abductor strength and power tests.
4. Psychosocial screen: TSK, catastrophizing; identify concrete avoidance behaviors (stairs, squats, running).
5. List combined alterations (≥ 2 frequent) to set priorities.

Address

• Load management: reduce just enough to calm symptoms, then progress gradually (week by week).
• Targeted strengthening:
  • Quadriceps (included eccentric, concentric, and isometric work).
  • Hip abductors (strength and power).
• Motor retraining: restore knee flexion in stairs / squats within pain tolerance.
• Foot-knee chain: address excessive pronation if contributing (exercise choices, technical advice, short-term aids).
• Graded exposure to avoided activities: stairs, squats, running (structured progressions).
• Adjuncts: taping / bracing short-term to support exposure and confidence.
• Education: explain the capacity ↔ load principle, the role of fear in movement patterns, and the rejection of the VMO myth.

Avoid

• Focusing treatment on a single factor (e.g., “activating the VMO”): PFP is multifactorial.
• Skipping load progressions: increases risk of relapse.
• Overlooking psychological factors when avoidance is obvious.

Key Takeaways

• Overload = main driver: modulate load and allow adaptation.
• Relevant biomechanics: hip adduction, reduced knee flexion, rearfoot pronation, quadriceps / abductor deficits.
• Psychological impact: fear / avoidance drive pain and movement patterns; must be measured and addressed.
• VMO myth: exclude from treatment strategies.
• Integrated approach: strength training + graded exposure + education + load management ± adjuncts.

Conclusion

PFP is rarely explained by a single factor. Skilled physical therapists assess and address the whole picture: load, movement patterns, strength / power, and psychological variables. This integration—anchored in controlled load progression and graded exposure—maximizes functional recovery and long-term outcomes.

For more information and detailed explanations, as well as video demonstrations, we invite you to check out the complete Masterclass on Fullphysio. This content is only a summary of the original video.