Patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common knee conditions presenting to general practice and sports medicine, accounting for 25–40% of knee problems in primary care. It is characterised by anterior knee pain arising from the patellofemoral joint, aggravated by activities that load the joint such as squatting, stair climbing, running, and prolonged sitting. PFPS predominantly affects active adolescents and young adults, with a higher prevalence in females. The underlying mechanism involves abnormal patellar tracking, altered biomechanics of the lower limb kinetic chain, and sensitisation of peripatellar soft tissues rather than structural cartilage damage. Management is primarily non-operative and focuses on physiotherapy-led rehabilitation targeting the hip, quadriceps, and lower limb biomechanics. The long-term prognosis is variable — many patients improve significantly, though a subset develop persistent symptoms.

PFPS arises from a complex interaction between structural, biomechanical, and neurosensory factors that increase patellofemoral joint stress and sensitise peripatellar tissues. Articular cartilage damage is not required for pain — the subchondral bone, synovium, and peripatellar soft tissues are the primary pain generators.

Biomechanical Factors

• Patellar maltracking — lateral displacement and tilt of the patella during dynamic activities is the central biomechanical abnormality; reduced vastus medialis oblique (VMO) activity relative to vastus lateralis causes lateral patellar tilt; tight lateral retinaculum and iliotibial band contribute to lateral compression
• Proximal contributors — hip abductor and external rotator weakness allows dynamic knee valgus during single-leg loading; increased femoral internal rotation increases Q angle and lateral patellar stress; gluteal dysfunction is a primary modifiable driver
• Distal contributors — excessive foot pronation and pes planus increase tibial internal rotation and valgus knee position; leg length discrepancy; altered ankle dorsiflexion range
• Training load errors — rapid increase in running volume, frequency, or intensity; insufficient recovery; change of surface or footwear; overuse in adolescent athletes during growth spurts

Risk Factors

• Female sex — females have 2–3 times higher risk than males; wider pelvis increases Q angle; lower VMO activation ratios; hormonal effects on ligament laxity
• Activity level — runners, cyclists, military recruits, ballet dancers; high-volume impact loading; repeated deep knee flexion activities
• Anatomical factors — patella alta; trochlear dysplasia; increased tibial tubercle-trochlear groove (TT-TG) distance; generalised joint hypermobility
• Muscle weakness — hip abductor, external rotator, and quadriceps weakness are both risk factors and consequences of PFPS

PFPS presents with anterior knee pain exacerbated by activities loading the patellofemoral joint. The diagnosis is clinical, based on characteristic history and examination findings after exclusion of other causes of anterior knee pain.

History

• Pain characteristics — diffuse anterior knee pain; typically described as aching or dull; peripatellar or retropatellar; bilateral in up to 30% of cases; onset often insidious or associated with training load increase
• Aggravating activities — squatting, running (especially downhill), stair descent, prolonged sitting with knee flexed (theatre sign or movie sign); cycling with low saddle height; kneeling
• Theatre sign — pain or discomfort after prolonged sitting with knee bent (e.g., in a cinema); relieved by extending the knee; highly characteristic of PFPS
• Crepitus — grinding or crunching sensation with knee flexion and extension; common and not necessarily indicative of structural damage
• Giving way — occasional giving way due to pain inhibition of the quadriceps; not true ligamentous instability

Examination Findings

• Patellar grind test — compression of the patella into the trochlear groove with knee extended, followed by quadriceps contraction; pain or crepitus is positive; moderate sensitivity and specificity
• Clarke test — examiner resists patellar movement while patient contracts quadriceps; pain is positive; poor specificity but widely used
• Patellar tilt and glide — assess patellar mobility; lateral tilt and restricted medial glide indicates tight lateral retinaculum; excessive medial glide indicates VMO weakness
• Functional assessment — single-leg squat: assess dynamic knee valgus, contralateral pelvic drop (Trendelenburg), trunk lean; these indicate hip abductor weakness; single-leg squat reproduces pain in PFPS
• Hip abductor and external rotator strength — assess with side-lying hip abduction against resistance; hip external rotation; weakness is a modifiable driver of PFPS

PFPS is primarily a clinical diagnosis. Imaging is used to exclude structural pathology and confirm the diagnosis in atypical presentations. Routine imaging is not required for typical PFPS presentations in young active patients.

• Essential
  X-ray knee (AP, lateral, skyline/sunrise view)

  First-line when imaging is required. Lateral view assesses patella alta or baja (Caton-Deschamps index). Skyline (merchant or sunrise) view at 30–45 degrees flexion shows patellofemoral joint, lateral tilt, trochlear morphology. AP standing view excludes tibiofemoral OA and loose bodies. Not required for typical PFPS in young active patients without history of trauma or mechanical symptoms. Arrange if diagnosis uncertain, prior trauma, or older patient (>40 years).
• Recommended
  MRI knee

  Not required for typical PFPS. Arrange when: diagnosis uncertain; mechanical symptoms (locking, giving way); prior trauma; suspected osteochondral lesion; failed conservative management without clear diagnosis. MRI can assess cartilage, patellar tracking, soft tissue structures. Bone marrow oedema in subchondral bone of patella may be seen in PFPS. Item 63560.
• Specialised
  CT scan (TT-TG distance)

  Specialised assessment of tibial tubercle-trochlear groove (TT-TG) distance when surgical realignment is being considered. TT-TG >20 mm suggests anatomical lateral patellar maltracking amenable to tibial tubercle osteotomy. Arranged by orthopaedic surgeon — not indicated in primary care.

PFPS is stratified by symptom severity, impact on function, and response to initial management to guide treatment intensity and referral decisions.

Pharmacological management in PFPS is purely symptomatic and plays a secondary role to physiotherapy rehabilitation. Analgesics are used to facilitate participation in rehabilitation rather than as primary treatment.

Physiotherapy-led exercise rehabilitation is the primary treatment for PFPS. A comprehensive program addresses hip abductor and external rotator strengthening, quadriceps strengthening, and patellar tracking. Adjuncts including patellar taping, foot orthoses, and activity modification support the rehabilitation program.

Physiotherapy Exercise Program

• Hip strengthening — hip abductor and external rotator strengthening is the most evidence-based component; reduces dynamic knee valgus and medial patellar drift; exercises include clamshells, side-lying hip abduction, lateral band walks, and single-leg bridges; targets a 20% improvement in hip abductor strength
• Quadriceps strengthening — VMO-targeted exercises (terminal knee extension, short-arc quads, mini-squats); closed-chain exercises preferred (leg press, step-ups at 0–45 degrees flexion); avoid deep flexion activities during acute phase; isometric quadriceps exercises for acute pain
• Neuromuscular and proprioceptive training — single-leg stance; perturbation training; step-down exercises with emphasis on frontal plane control; address dynamic knee valgus during functional tasks; gait retraining if indicated
• Program duration and evidence — combined hip and knee strengthening programs provide superior outcomes to knee-only programs (Ferber 2015, Dolak 2011); 6–12 weeks of supervised physiotherapy; 12+ sessions; home exercise maintenance critical for sustained benefit

Patellar Taping

• McConnell taping — medial glide taping of the patella to correct lateral displacement; significantly reduces pain during exercise in acute phase; useful to facilitate pain-free physiotherapy participation; evidence supports short-term pain reduction; should be combined with exercise rehabilitation, not used alone
• Patellar bracing — patellar stabilisation brace with lateral buttress; moderate evidence for pain reduction; useful when taping is impractical; some patients prefer brace to tape; does not replace rehabilitation

Foot Orthoses

• Prefabricated orthoses — prefabricated foot orthoses show equivalent benefit to custom orthoses for most PFPS patients; reduce tibial internal rotation and knee valgus; evidence supports short-term benefit particularly when pes planus is present; Cochrane review (Calllaghan 2012) supports adjunctive use
• Custom orthoses — indicated when prefabricated orthoses are inadequate; significant pes planus or cavus; referral to podiatrist for assessment and custom orthotic prescription

Activity Modification and Load Management

• Training modification — reduce running volume by 20–30% during acute phase; avoid deep squatting and stair running initially; cycling (with raised saddle) and swimming are pain-free alternatives; gradual return to full activity as strength improves
• Biomechanics advice — increase step rate (cadence) by 5–10% reduces patellofemoral joint stress during running; forefoot or midfoot landing pattern preferred; address footwear if inadequate shock absorption or worn

Surgical Options (Rare)

• Lateral retinacular release — rarely indicated; reserved for documented tight lateral retinaculum with lateral patellar tilt on imaging; poor outcomes when performed for pain alone without structural abnormality; risk of medial instability if overcorrected; requires specialist assessment
• Tibial tubercle osteotomy (Fulkerson procedure) — for elevated TT-TG distance (>20 mm) or patella alta; anteromedialization of the tibial tubercle reduces lateral and proximal patellar contact pressure; reserved for anatomical contributors after failed extensive conservative management

Non-pharmacological management underpins PFPS treatment. Patient education, activity modification, and rehabilitation are the core components. PFPS is a condition that responds well to informed self-management when patients understand the biomechanical contributors and engage with rehabilitation.

Patient Education

• Reassurance — PFPS does not indicate cartilage damage in most cases; reassure patients that pain does not mean structural harm; catastrophising and fear-avoidance behaviours worsen outcomes; encourage continued activity within pain limits (pain <3–4/10 on a numeric rating scale is acceptable during rehabilitation)
• Prognosis — highly variable; approximately 50% of patients have persistent symptoms at 1 year despite treatment; adolescents have better outcomes than adults; adherence to hip and quadriceps strengthening programs significantly improves long-term outcomes; recurrence common if rehabilitation is discontinued
• Activity guidance — modify training load rather than complete rest; complete rest is counterproductive and leads to muscle deconditioning; exercise within a pain threshold that does not cause significant post-activity pain flare

Dry Needling and Soft Tissue Therapy

• Evidence for dry needling and massage therapy in PFPS is limited; may provide short-term pain relief as adjunct to exercise therapy; should not replace rehabilitation; physiotherapist-administered techniques within a comprehensive program

Return to Sport

• Criteria-based return — return to running when: pain during single-leg squat <3/10; hip abductor strength >90% of contralateral; single-leg hop test >90% symmetry; no pain with step-down exercise
• Graduated return — return to running programs (walk-run); weekly volume increase no more than 10%; avoid rapid escalation; sport-specific training before return to competition

Monitoring in PFPS focuses on symptom trajectory, functional improvement with physiotherapy, and identification of structural diagnoses requiring escalation.

Indications for Specialist Referral

• Sports medicine — complex rehabilitation; return-to-sport planning; biomechanical assessment; consideration of dry needling or soft tissue therapies; failure to progress with GP-directed management
• Orthopaedic surgery — failed 3–6 months of supervised physiotherapy; suspected structural abnormality (elevated TT-TG, patella alta, trochlear dysplasia); mechanical symptoms suggesting intra-articular pathology; MRI-confirmed osteochondral lesion
• Podiatry — significant pes planus or cavus contributing to biomechanical loading; custom orthotic prescription; gait assessment

Special considerations apply to adolescents, female athletes, and runners with PFPS.

Adolescents

• Adolescent-specific causes — differentiate PFPS from Sinding-Larsen-Johansson syndrome (inferior patellar pole apophysitis) and Osgood-Schlatter disease (tibial tuberosity apophysitis); both are self-limiting with skeletal maturity; management is conservative with activity modification and analgesia; X-ray confirms diagnosis
• Prognosis in adolescents — generally better than adults; symptoms often resolve by late adolescence; rehabilitation during adolescence prevents recurrence in adult sporting life; early physiotherapy referral recommended

Female Athletes

• Higher prevalence and recurrence — due to anatomical (wider pelvis, Q angle) and neuromuscular (delayed VMO activation, hip abductor weakness) factors; hip-focused rehabilitation is particularly important in female athletes; running biomechanics assessment should specifically assess contralateral pelvic drop and dynamic knee valgus
• Relative Energy Deficiency in Sport (RED-S) — consider in female endurance athletes with PFPS; inadequate caloric intake relative to training load impairs bone health and increases soft tissue injury risk; screen with LEAF questionnaire; dietitian and sports medicine referral if RED-S suspected

Runners

• Gait retraining — increasing step rate (cadence) by 5–10% reduces patellofemoral joint load by reducing peak knee flexion moment; forefoot or midfoot strike pattern preferred; gait retraining is an evidence-based adjunct to strengthening in runners with PFPS
• Training load management — follow 10% rule for weekly mileage increases; incorporate cross-training (cycling, swimming) during high-volume training phases; adequate recovery between sessions

Stewardship in PFPS focuses on avoiding unnecessary imaging, minimising prolonged analgesic use, and ensuring physiotherapy is the primary treatment rather than surgery or injection therapies.

GP Role

• Diagnose clinically — PFPS is a clinical diagnosis in typical presentations; avoid unnecessary imaging; initiate physiotherapy referral promptly
• Refer to physiotherapy — hip and knee combined strengthening program; emphasise that physiotherapy is the primary treatment, not a bridge to surgery
• Provide activity modification advice — modify training loads; address footwear; prescribe patellar taping technique or refer for taping instruction
• Set realistic expectations — PFPS can take 3–12 months to significantly improve; encourage adherence; warn patients about high recurrence risk if rehabilitation is not maintained

Follow-up in PFPS is milestone-based and focuses on functional recovery and prevention of recurrence. Long-term rehabilitation maintenance is critical given the high recurrence rate.

• Crossley KM et al. — 2016 Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat; Br J Sports Med 2016
• Ferber R et al. — Strengthening of the hip and core versus knee muscles for the treatment of patellofemoral pain; Am J Sports Med 2015
• Dolak KL et al. — Hip strengthening prior to functional exercises reduces pain sooner than quadriceps strengthening in females with patellofemoral pain syndrome; J Orthop Sports Phys Ther 2011
• Callaghan MJ, Selfe J — Patellar taping for patellofemoral pain syndrome in adults; Cochrane Database of Systematic Reviews 2012
• Willy RW, Davis IS — The effect of a hip-strengthening program on mechanics during running and during a single-leg squat; J Orthop Sports Phys Ther 2011
• Therapeutic Guidelines: Musculoskeletal — Patellofemoral pain; available via eTG complete
• Australian Physiotherapy Association — Clinical guidelines for patellofemoral pain management
• Sports Medicine Australia — Patellofemoral pain position statement