Patellofemoral Pain Syndrome

The defining symptom is diffuse anterior or retropatellar knee pain provoked by loading a flexed knee. Stairs (especially descending), squatting, lunging, running (worse downhill), and jumping aggravate symptoms. Prolonged sitting with the knee bent typically produces the cinema sign, eased by extending the knee. Bilateral symptoms are present in up to 40%. Crepitus is common, benign, and a major driver of fear-avoidance. Giving way is usually quadriceps inhibition rather than true mechanical instability.

On examination, pain is reproduced during squatting, and a single-leg squat or step-down test typically demonstrates dynamic knee valgus, contralateral pelvic drop, and trunk lean. Peripatellar tenderness is common, but point tenderness at the inferior pole or tibial tubercle suggests an alternative diagnosis. The patellar apprehension test is positive in patellar instability, not PFP. Always assess quadriceps strength, hip abductor and external rotator strength, weight-bearing ankle dorsiflexion, foot posture, and the contralateral hip and lumbar spine for referred pain.

PFP is a clinical diagnosis and routine imaging is not required. Plain radiographs are reserved for atypical presentations, suspected patellofemoral OA, patellar instability (skyline view), or bony pathology. MRI is not first-line and may demonstrate chondromalacia that does not alter management. Ultrasound has a limited role and is mainly useful when patellar tendinopathy is suspected. Bloods are unnecessary unless inflammatory arthritis is being considered. Functional testing, including single-leg squat quality, step-down, hop testing, and isolated quadriceps and hip strength assessment, is more clinically useful than imaging.

Management is primarily conservative, anchored in the 2018 BJSM PFP consensus statement and the 2024 BJSM best-practice guide. Education is the foundation: explain the multifactorial nature, reassure that PFP is not driven by structural damage in most cases, frame crepitus as noise rather than damage, address fear-avoidance, and emphasise that exercise is safe.

Exercise therapy is the primary treatment. Quadriceps strengthening targets the muscle as a whole group rather than isolated VMO retraining, using both open and closed kinetic chain work. Hip-targeted exercise (gluteus medius and external rotators) reduces dynamic knee valgus and is well supported, particularly when proximal deficits are present. Blood flow restriction training is an emerging adjunct allowing strengthening at lower loads when heavy loading is poorly tolerated.

Adjuncts include patellar taping (short-term pain relief during exercise), prefabricated foot orthoses for patients with excessive pronation, running or movement retraining where cadence increase or landing-mechanics work is indicated, and manual therapy alongside exercise. Oral NSAIDs are useful for short-term symptomatic relief but are not the primary treatment.

Surgery is rarely indicated for isolated PFP. Lateral retinacular release has very limited indications without objective instability and is increasingly restricted in UK practice; MPFL reconstruction is a separate entity for objective patellar instability. Refer if symptoms persist despite 3 to 6 months of structured multimodal rehabilitation.

Phase 1 (pain-dominant, 0 to 4 weeks): education and load modification, isometric quadriceps work (quad sets, wall sits, straight leg raise), and early hip exercises (side-lying abduction, clamshells, standing hip external rotation with band). Address ankle dorsiflexion if restricted. Maintain cardiovascular fitness through low-resistance cycling or swimming. Pain up to 3 to 4 out of 10 during exercise is acceptable provided it settles within 24 hours.

Phase 2 (loading, 4 to 12 weeks): the core rehabilitation phase. Progressive resistance training for quadriceps using both open chain (leg extension, starting in inner range) and closed chain (mini squats, leg press, step-ups, split squats). Progressive gluteus medius and external rotator strengthening (lateral band walks, single-leg bridges, hip hitches). Single-leg squat quality without dynamic valgus is the key functional outcome.

Phase 3 (functional and sport-specific, 12 weeks plus): graduated running reintroduction with attention to cadence and stride length. Jumping and landing mechanics work. Sport-specific drills and plyometric progression for jumping athletes.

Return to sport is criteria-based: pain-free or minimal-pain sport-specific activity, quadriceps and hip strength 90% or more of the contralateral side, and good single-leg squat quality. PFP has a high recurrence rate, so ongoing maintenance exercise two to three times weekly is essential. Address fear-avoidance and catastrophising throughout with graded exposure.

• •2018 BJSM PFP Consensus Statement (Collins et al.): International consensus on diagnosis and management; supports exercise therapy combined with education as primary treatment.
• •2024 BJSM Best-Practice Guide for PFP: UK-aligned current best-practice framework emphasising knee and hip-targeted exercise, education, and addressing psychosocial factors.
• •Dye (2005), Envelope of Function: Foundational framework characterising PFP as tissue homeostasis overload rather than fixed structural lesion.
• •van der Heijden et al. (Cochrane review, 2015): Exercise therapy reduces pain and improves function in PFP compared with no exercise.
• •Lack et al. (BJSM, 2015): Combined hip- and knee-targeted exercise produces superior outcomes versus knee-only training in patients with proximal deficits.

• •PFP is a clinical diagnosis of diffuse retropatellar pain provoked by loading a flexed knee. Reproduction of pain on squatting is one of the most useful examination findings.
• •Dynamic knee valgus on single-leg squat or step-down reflects proximal weakness and is a key rehabilitation target. Combined hip and knee exercise outperforms knee-only training when proximal deficits are present.
• •The patellar apprehension test indicates patellar instability, not PFP. An effusion in a young patient with anterior knee pain points away from PFP.
• •Chondromalacia patellae is a pathological finding, commonly incidental on MRI, and does not change management.
• •Crepitus is noise, not damage. Addressing crepitus-related fear is a specific therapeutic intervention.
• •PFP is a recognised risk factor for patellofemoral OA. Recurrence is common, so maintenance exercise is essential.