Patellofemoral Pain Syndrome (PFPS) is an overuse injury of the extensor mechanism of the knee, distinguished by retropatellar or peripatellar pain1.
The etiology of PFPS is multi-factorial and commonly related to biomechanical and tissue overload which lead to increased stress in the patellofemoral joint. Predisposing factors may be classified as those related to local joint impairments, altered lower extremity biomechanics and training errors or overuse, including inadequate training load management2,3.
Epidemiology including risk factors and primary prevention
PFPS is seen in adults and adolescents and has a 22.7% prevalence in the general population3. The reported incidence in the clinical setting ranges from 21 to 40%, affecting females twice as often as males1. It constitutes nearly 25% of all knee injuries in runners. Risk factors can be divided into intrinsic and extrinsic as well as those factors that are modifiable and those that are not. Modifiable intrinsic factors include weak muscles (hip abductors, external rotators, and vastus medialis); inflexibility of the iliotibial band, quadriceps, hamstring, and gastroc-soleus tendons; foot overpronation; and increased joint reactive forces with heel strike. Non-modifiable factors include patella alta, femoral anteversion, pes planus, age, gender and race. Extrinsic factors include training errors or overtraining, such as an overly rapid increase in training progression or intensity, inappropriate running shoes, uphill training and hard playing surfaces. Preventive strategies include identification and correction of modifiable risk factors2.
The anatomy and biomechanics of the patellofemoral joint play a major role in its function, stability, and pathology. Abnormalities to bony structures, dynamic and static stabilizers affect patellar tracking along the femoral trochlea, and lead to uneven distribution of patellofemoral compressive forces and joint stress4.
Patellofemoral joint reaction forces increase with high degrees of knee flexion and this may trigger pain receptors in the subchondral bone4, associated with stimulation of free nerve endings and secretion of inflammatory mediators. Other pain generators include the synovial capsular and retinacular soft tissues, and tendon insertions on the patella.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
In the early stage of PFPS, anterior knee pain occurs with jumping, running, and stair climbing. As the clinical condition progresses, pain occurs with activity, may impair sports performance and improves after a period of inactivity. If not diagnosed and treated appropriately, patellar pain will present with less activity and even at rest and may affect activities of daily living. When exercise resumes following periods of rest, the pain may return if biomechanical, training, or footwear errors are not corrected. Over time, abnormal wear to the patella and associated femoral cartilage leads to chondromalacia and chronic pain. The pain tends to persist in many individuals with as many as 40% of patients persisting with pain 12 months after starting treatment5.
Specific secondary or associated conditions and complications
Pain, arthrogenic muscle inhibition, abnormalities in lower limb biomechanics, reduced sports performance, and ultimately degenerative changes in articular cartilage and subchondral bone will occur leading to patellofemoral osteoarthritis (PFOA). PFOA is highly prevalent affecting both lateral and medial patellar facets6.
Essentials of Assessment
Patients often describe an ill-defined ache in the anterior knee with insidious onset, pain may also be sharp. It worsens with activities involving knee flexion, such as squatting, sitting for prolonged periods (theater sign), ascending or descending stairs, or running hills. Patients may describe episodes of give-way, weakness/instability, buckling, patellar instability, clicking and knee swelling or stiffness.
Examination includes evaluation of static and dynamic factors that can alter patellofemoral mechanics as well as evaluation for other knee pathology. Assess the kinetic chain including lower extremity alignment and hip range of motion, looking for femoral anteversion or generalized hip dysplasia, increase in the dynamic Q angle, genu valgum or recurvatum, external tibial rotation, and foot over-pronation. Evaluate gait pattern and posture. Inspect the patella for abnormal tilt, rotation, superior-inferior position, and the thigh for muscle atrophy. Assess patellar tracking, evaluating for the J-sign (lateral tracking of the patella as the knee moves from flexion to extension). Assess for joint warmth or effusion and palpate the patella, patellar tendon, and peripatellar soft tissues and perform apprehension testing. Assess muscle strength of the hip, knee, and ankle musculature, and flexibility of the ITB, hamstrings, quadriceps, and gastroc-soleus tendons. Referred pain from the hip should also be evaluated for4,8. Footwear should be examined for wear patterns6. Of all maneuvers, pain with squatting is the most sensitive physical exam finding with patellar tilt test being the most specific finding6.
The step-down or single leg squat test, observational analysis of walking and running and of jumping/landing mechanics can be incorporated to evaluate dynamic lower extremity kinematics. Biomechanical assessment includes looking for excessive contralateral pelvic drop, lateral trunk deviation, hip adduction and internal rotation, knee valgus, tibial external rotation, and foot pronation.
Erythrocyte sedimentation rate (ESR) and C-reactive protein test (CRP) screen for active systemic inflammatory arthritis or connective tissue disorder and are not recommended routinely.
If knee pain continues after 6 to 8 weeks of conservative treatment9, radiographs of the knee (weight-bearing A-P, lateral with 30°of flexion, tunnel, Merchant views) are useful to rule out other sources of anterior knee pain, including bipartite patella, degenerative changes, loose bodies, and occult fractures. Abnormal knee changes in PFPS to assess on x-ray include patella alta, lateromedial subluxation, patellar tilt, patellar translation, shallow trochlear groove, and prominent lateral ridge10. There is a high radiographic prevalence of PFOA across a heterogeneous population7. If plain films are negative and the diagnosis is not clear, or surgery is being considered, then magnetic resonance imaging (MRI) or a computed tomography (CT) scan may be indicated10. CT helps assess trochlear morphology and tibial tubercle lateralization via tibial tubercle-trochlear groove distance. 10. MRI is more sensitive for evaluating soft tissues abnormalities, including patellofemoral cartilage, patellar and quadriceps tendinopathy or tears, medial patellofemoral ligament integrity, superolateral and pre-patellar fat pad edema (which is indicative of maltracking), and prepatellar or deep infrapatellar bursitis10. Musculoskeletal ultrasound can be useful in evaluating for joint effusion and soft tissue integrity around the patella, including the thickness of the lateral retinaculum, quadriceps tendon and patellar tendon. A method using real-time MRI allows measurement of patellofemoral joint kinematics during weight-bearing and non–weight- bearing dynamic tasks, however this technology is not commonly available for routine clinical use10.
Supplemental assessment tools
Instrumented biomechanical and in vivo evaluation of specific tasks such as squats, step-down maneuvers and the drop jump, using dynamic electromyography and video analysis, can be used in athletes and active individuals. Patients should have their gait evaluated in order to determine any factors that could lead to PFPS, such as excessive or prolonged pronation, tibial internal rotation, or femoral internal rotation. Runners with PFPS may exhibit greater vertical load rates and stiffness upon foot impact, particularly rearfoot strikers11.
Early predictions of outcomes
Factors that may result in slow response to treatment include the severity of symptoms on initial clinical presentation and persistent quadriceps pain and weakness. In one study, younger age at the time of presentation was predictive of success of exercise interventions12. Longer duration of pain and symptoms of PFPS is associated with a poor prognosis13. Older age has been associated with benefit from orthotic use14. Greater midfoot arch difference from non-weight bearing to weight bearing serves as a potential treatment effect modifier with a successful outcome after management with foot orthosis13.
Training surface and uphill training are important factors to consider. These surfaces may increase the stress reaction forces that are applied to the extensor mechanism during running or jumping activities. The patient should be assessed to determine if they are wearing the appropriate shoes as well. Minimalist, lightweight footwear can reduce patellofemoral joint forces compared with motion-control and high-cushioning footwear in runners with PFPS and its effect is enhanced with increased cadence14,15. Different foot and body types demand the correct type of running shoe as abnormal forces in the foot and ankle will translate to the knee.
Social role and social support system
Because of the multifactorial nature of PFPS, psycho-social factors may play an important role in the treatment planning and education of the patient, family members, and coaching staff. Objective tools that assess physical domains of PFPS can provide more accurate psychological assessment of quality of life16. A linear association between PFPS and pain catastrophization, fear avoidance of pain, anxiety and depression has been reported, especially in younger populations17. Individuals with PFPS have worse knee and health-associated quality of life than healthy controls with similar or greater impairments than patients with ACL tears. Athletes with PFPS have impaired quality of life, but better compared to non-athletes16. Understanding the nature of the disease process and treatment interventions may lead to better outcomes and function.
PFPS is a condition best treated via a multidisciplinary team approach. The team includes the primary and consulting physicians, athletic trainer, physical therapist, and other sports health specialists (psychology, exercise physiology). Adherence to treatment by the patient is directly influenced by the proper coordination of treatment care and communication within the treating team. It is important to address the athlete’s return to sport criteria. Athletes should have normal motion, strength and lower extremity biomechanics. They should be free of pain at rest and with activity prior to returning to full exercise and participation.
Rehabilitation Management and Treatments
Available or current treatment guidelines
There are no standard treatment guidelines for PFPS. Rehabilitation should follow a comprehensive, criteria-based, multimodal approach that targets individual risk factors and integrates assessment findings, patient preferences and clinical expertise18,19. Early therapeutic interventions include relative rest, physical modalities, and/or oral medications. Exercise, particularly combined hip and knee strength training, with open (OKC) and closed kinetic chain (CKC) exercises has been shown to lead to long-term improvement in pain and function. Strength training focused on trunk muscle control and ankle muscles may also be effective in long-term management20. Activity modification and load management has resulted in successful outcomes in hip and knee pain, function and torque and return to play in a 12-month period in adolescents with PFPS21.
At different disease stages
Acute management includes modified rest, ice, and NSAIDs to control symptoms and allow participation in a treatment program. Foot orthoses, patellar taping, and pulsed electromagnetic field therapy may be effective as an adjunctive therapy for short-term improvement of symptoms, treatment tolerance, and adherence to training regimen18,19,22. Patellar taping and braces to reduce abnormal patellar tracking can be beneficial if it enables pain-free exercise20,23. Foot orthoses can be most beneficial in patients with greater changes in midfoot arch from non-weight bearing to weight bearing13.
Exercise therapy should be task-oriented, and target speed, power, and multiplanar neuromuscular control24. The goal is to improve biomechanical abnormalities, reduce joint overload and achieve kinetic chain control during complex movements24. Strength training with OKC and CKC exercises is proven to be effective for long-term treatment of PFPS in the sub-acute phase. In the early stages, OKC quadriceps exercises should be performed between 45 and 90 degrees of knee flexion while CKC quadriceps exercises should be performed between 0 and 45 degrees of knee flexion to minimize patellofemoral joint stress19,20,22,25. Hip strengthening exercises, particularly abductors and extensors, should also be emphasized early on. Combined strengthening of the hip abductors, hip external rotators, VMO, and lumbo-pelvic core muscles improves pelvic, hip, and knee dynamic stabilization during functional activities. Strengthening the quadriceps and hip muscles and stretching the iliotibial band reduces patellar lateralization. Overall, the goal is to gradually progress to functional stages of rehabilitation as tolerated.
Neuromuscular electrical stimulation can be helpful for arthrogenic muscle inhibition. Joint and soft tissue mobilization across the kinetic chain and stretching of tight retinacular structures may improve patellar mobility19,20,22,26. However, they provide uncertain benefits as an adjunctive therapy for patellofemoral pain19,26,27. ITB, hamstring, and quadriceps stretching improves patellar tracking. Foot pronation correction with Achilles tendon stretching and ankle strengthening is also beneficial28,29.
In later stages of the syndrome, gait and running retraining is essential for a complete rehabilitation and prevention of subsequent symptomatic episodes. Barefoot or forefoot running may be beneficial in decreasing anterior knee stress. Areas of focus include keeping the pelvis level, knees facing forward, softer landing technique, non-rear foot strike pattern, and increasing the step rate19,20. In runners, gait retraining focuses on reducing hip adduction, increasing forward lean, transitioning to a forefoot strike pattern, and increasing cadence30. Furthermore, training errors should be identified, such as excessive training load, increasing intensity too fast, inadequate time to recover, and excessive hill work.
Surgical intervention should be reserved after failed rehabilitation trials and evidence of lateral patellar compression or patellar instability. Lateral retinacular release or lengthening should be considered in PFPS patients with excessive lateral patellar tilt without instability. Joint realignment procedures such as Fulkerson osteotomy should be considered in patients with PFPS and patellar instability20.
Coordination of care
Patient coordination of care will depend on response to initial treatment. Early intervention may lead to return to activity, however patients that do not respond to treatment may require further evaluation with advanced imaging, interventional procedures, and in some instances, surgical evaluation. In patients with kinesiophobia and fear of reinjury, psychological evaluation may be warranted.
Patient and family education
Education about the condition, diagnostic approach, and treatment plan is essential in all medical issues. Advice about load management, self-management of pain and the nature and possible causes of PFPS should be consistently used in this population. Health professional-derived education should be combined with exercise therapy to enhance patient response31. This is especially true in the young athletic population since the parents play a leading role in the health-related decision-making process. An important consideration in the long-term management of PFPS is to strongly encourage the patient to maintain their home exercise program even after symptoms have resolved. If the PFPS was related to strength or flexibility deficit, those issues will likely return if the patient does not continue their home program.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
PFPS is a multifactorial problem; therefore, an increased understanding of the pathoanatomy and etiology of the condition will improve treatment outcomes. Implementing exercise protocols that establish triplanar neuromuscular control in the lower kinetic chain and proximal musculature will help limit contralateral pelvic drop, femoral adduction and internal rotation, and reduce patellofemoral joint stress24. Clinicians should consider foot orthoses for older patients and those with greater forefoot valgus, exercise for younger patients, and patellar taping for pain relief12.
Cutting Edge/ Emerging and Unique Concepts and Practice
The use of dynamic assessment of lower extremity alignment and biomechanics aids the clinician in further defining the etiology of PFPS and planning treatment. Dynamic MRI, instrumented biomechanical testing and gait analysis, including evaluation of running technique, should be considered in the management of athletes or patients not responding to treatment.
Use of ‘minimalist’ footwear has been well studied in reducing patellofemoral joint stresses in healthy subjects. The literature remains limited in PFPS patients, but emerging evidence also supports use of ‘minimalist’ footwear as more beneficial in reducing patellofemoral joint stresses in the symptomatic individual.
Emerging therapeutic interventions for musculoskeletal injuries include the use of prolotherapy, platelet rich plasma (PRP), and mesenchymal stem cell therapy. Botulinum toxin use has been evaluated in small studies in PFPS patients with short-term improvement in pain and functional activities requiring knee flexion32. PRP and autologous stem cell therapies are being used in the knee for cartilage lesions and PFOA with reported functional improvements33. As for steroid injections, there are no clear, well-designed studies showing benefits in PFPS32. Otherwise, there are currently no published studies about these therapies for PFPS.
Gaps in the Evidence- Based Knowledge
There is no common agreement on the definition of PFPS, objective diagnostic criteria, specific treatment protocols, or objective return to play criteria that addresses all patients with PFPS. Specific objective maneuvers, such as single-leg squat versus double-leg squat or step down, should be assessed in future studies. Return to play criteria in patellar disorders are mostly focused on post-surgical cases of patellar dislocations or instability. Determining optimal exercise prescription for PFPS, including frequency, intensity, load and contraction type will help determine the most suitable dose-response relationship between exercise frequency and recovery18. Most exercise regimens focus on limited-angled OKC exercises. Thus, implementing triplanar CKC protocols can help compare better the effects on pain and function in PFPS patients25. General uncertainty remains with the long-term benefits of combined therapy with adjunctive interventions such as patellar taping, bracing, manual therapy, acupuncture and patellar immobilization19. Future studies should also focus on the impact of different training surfaces and evidence-based recommendations for the use of pharmacological interventions, injectables19, footwear, alternative modalities such as shockwave therapy, and lifestyle and ergonomic changes as treatment for the condition.
- Crossley K, Stefanik J, Selfe J, Collins J, Davis I, Powers C, McConnell J, Vicenzino, Bazett-Jones D, Esculier J, Morrissey, Callaghan. Patellofemoral pain consensus statement from the 4th International Patellofemoral in Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. Professor Michael J Callaghan, Faculty of Health, Psychology and Social Care, School of Health Professions. Manchester Metropolitan University, Manchester, UKReceived 26 April 2016 Accepted 1 May 2016
- Fredericson M, Khadavi M, Dutton R. Update on rehabilitation on patellofemoral pain. Curr Sports Med Reports. 2014;13(3): 172-178.
- Neal B, Lack S,Lankhorst N, Raye A, Morrissey D,Middelkoop M. Risk factors for patellofemoral pain: A systematic review and meta-analysis. Neal BS, et al. Br J Sports Med 2019;53:270–281. doi:10.1136/bjsports-2017-098890.
- Collado H, Fredericson M. Patellofemoral pain syndrome. Clin Sports Med. 2010;29: 370-398.
- Collins NJ, Bierma-Zeinstra SM, Crossley KM, van Linschoten RL, Vicenzino B, van Middelkoop M. Prognostic factors for patellofemoral pain: a multicentre observational analysis. Br J Sports Med. 2013 Mar;47(4):227-33. doi: 10.1136/bjsports-2012-091696. Epub 2012 Dec 13. PMID: 23242955.
- Witvrouw E, Callaghan M, Stefanik J, et al. Patellofemoral pain: consensus statement from the 3rd International Patellofemoral Pain Research. Br J Sports Med 2014;48: 411-414
- Hart HF, Stefanik JJ, Wyndow N, Machotka Z, Crossley KM. The prevalence of radiographic and MRI-defined patellofemoral osteoarthritis and structural pathology: a systematic review and meta-analysis. Br J Sports Med. 2017 Aug;51(16):1195-1208. doi: 10.1136/bjsports-2017-097515. Epub 2017 Apr 29. PMID: 28456764.
- Fredericson M, Yoon K: Physical examination and patellofemoral pain syndrome. Am J Phys Med Rehabil. 2006;85: 234–243.
- Gaitonde D, MD; Ericksen A, MD; and Robbins R, MD. Patellofemoral Pain Syndrome. Dwight D. Eisenhower Army Medical Center, Fort Gordon, Georgia. American Family Physician www.aafp.org/afp Volume 99, Number 2 January 15, 2019).
- Gulati A, McElrath C, Wadhwa V, Shah JP, Chhabra A. Current clinical, radiological and treatment perspectives of patellofemoral pain syndrome. Br J Radiol. 2018 Jun;91(1086):20170456. doi: 10.1259/bjr.20170456. Epub 2018 Jan 22. PMID: 29303366; PMCID: PMC6223269.
- Johnson CD, Tenforde AS, Outerleys J, Reilly J, Davis IS. Impact-Related Ground Reaction Forces Are More Strongly Associated With Some Running Injuries Than Others. Am J Sports Med. 2020 Oct;48(12):3072-3080. doi: 10.1177/0363546520950731. Epub 2020 Sep 11. PMID: 32915664.
- Lack S, Barton C, Vicenzino B. Outcome predictors for conservative patellofemoral pain management: A systematic review and meta analysis. Sports Med 2014;44: 1703-1716.
- Matthews M, Rathleff MS, Claus A, McPoil T, Nee R, Crossley K, Vicenzino B. Can we predict the outcome for people with patellofemoral pain? A systematic review on prognostic factors and treatment effect modifiers. Br J Sports Med. 2017 Dec;51(23):1650-1660. doi: 10.1136/bjsports-2016-096545. Epub 2016 Dec 13. PMID: 27965435.
- Bonacci J, Hall M, Fox A, Saunders N, Shipsides T, Vicenzino B. The influence of cadence and shoes on patellofemoral joint kinetics in runners with patellofemoral pain. J Sci Med Sport. 2018 Jun;21(6):574-578. doi: 10.1016/j.jsams.2017.09.593. Epub 2017 Oct 6. PMID: 29054746.
- Esculier JF, Dubois B, Bouyer LJ, McFadyen BJ, Roy JS. Footwear characteristics are related to running mechanics in runners with patellofemoral pain. Gait Posture. 2017 May;54:144-147. doi: 10.1016/j.gaitpost.2017.03.010. Epub 2017 Mar 6. PMID: 28292715.
- Coburn SL, Barton CJ, Filbay SR, Hart HF, Rathleff MS, Crossley KM. Quality of life in individuals with patellofemoral pain: A systematic review including meta-analysis. Phys Ther Sport. 2018 Sep;33:96-108. doi: 10.1016/j.ptsp.2018.06.006. Epub 2018 Jun 28. PMID: 30059951.
- Maclachlan LR, Collins NJ, Matthews MLG, Hodges PW, Vicenzino B. The psychological features of patellofemoral pain: a systematic review. Br J Sports Med. 2017 May;51(9):732-742. doi: 10.1136/bjsports-2016-096705. Epub 2017 Mar 20. PMID: 28320733.
- Saltychev M, Dutton RA, Laimi K, Beaupré GS, Virolainen P, Fredericson M. Effectiveness of conservative treatment for patellofemoral pain syndrome: A systematic review and meta-analysis. J Rehabil Med. 2018 May 8;50(5):393-401. doi: 10.2340/16501977-2295. PMID: 29392329.
- Collins NJ, Barton CJ, van Middelkoop M, Callaghan MJ, Rathleff MS, Vicenzino BT, Davis IS, Powers CM, Macri EM, Hart HF, de Oliveira Silva D, Crossley KM. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. Br J Sports Med. 2018 Sep;52(18):1170-1178. doi: 10.1136/bjsports-2018-099397. Epub 2018 Jun 20. PMID: 29925502.
- Bolgla LA, Boling MC, Mace KL, DiStefano MJ, Fithian DC, Powers CM. National Athletic Trainers’ Association Position Statement: Management of Individuals With Patellofemoral Pain. J Athl Train. 2018 Sep;53(9):820-836. doi: 10.4085/1062-6050-231-15. PMID: 30372640; PMCID: PMC6208300.
- Rathleff MS, Graven-Nielsen T, Hölmich P, Winiarski L, Krommes K, Holden S, Thorborg K. Activity Modification and Load Management of Adolescents With Patellofemoral Pain: A Prospective Intervention Study Including 151 Adolescents. Am J Sports Med. 2019 Jun;47(7):1629-1637. doi: 10.1177/0363546519843915. Epub 2019 May 16. PMID: 31095417.
- Espí-López GV, Arnal-Gómez A, Balasch-Bernat M, Inglés M. Effectiveness of Manual Therapy Combined With Physical Therapy in Treatment of Patellofemoral Pain Syndrome: Systematic Review. J Chiropr Med. 2017 Jun;16(2):139-146. doi: 10.1016/j.jcm.2016.10.003. Epub 2016 Nov 22. PMID: 28559754; PMCID: PMC5440631.
- Logan CA, Bhashyam AR, Tisosky AJ, Haber DB, Jorgensen A, Roy A, Provencher MT. Systematic Review of the Effect of Taping Techniques on Patellofemoral Pain Syndrome. Sports Health. 2017 Sep/Oct;9(5):456-461. doi: 10.1177/1941738117710938. Epub 2017 Jun 15. PMID: 28617653; PMCID: PMC5582697.
- Dischiavi SL, Wright AA, Tarara DT, Bleakley CM. Do exercises for patellofemoral pain reflect common injury mechanisms? A systematic review. J Sci Med Sport. 2020 Sep 10:S1440-2440(20)30745-3. doi: 10.1016/j.jsams.2020.09.001. Epub ahead of print. PMID: 32978070.
- Rogan S, Haehni M, Luijckx E, Dealer J, Reuteler S, Taeymans J. Effects of Hip Abductor Muscles Exercises on Pain and Function in Patients With Patellofemoral Pain: A Systematic Review and Meta-Analysis. J Strength Cond Res. 2019 Nov;33(11):3174-3187. doi: 10.1519/JSC.0000000000002658. PMID: 30074970.
- Jayaseelan DJ, Scalzitti DA, Palmer G, Immerman A, Courtney CA. The effects of joint mobilization on individuals with patellofemoral pain: a systematic review. Clin Rehabil. 2018 Jun;32(6):722-733. doi: 10.1177/0269215517753971. Epub 2018 Jan 12. PMID: 29327606.
- Martimbianco ALC, Torloni MR, Andriolo BN, Porfírio GJ, Riera R. Neuromuscular electrical stimulation (NMES) for patellofemoral pain syndrome. Cochrane Database Syst Rev. 2017 Dec 12;12(12):CD011289. doi: 10.1002/14651858.CD011289.pub2. PMID: 29231243; PMCID: PMC6486051.
- Finnoff JT, Hall MM, Kyle K, et al. Hip strength and knee pain in high school runners: a prospective study. PM&R. 2011;3(9): 792-801.
- Earl JE, Hoch AZ. A proximal strengthening program improves pain, function, and biomechanics in women with patellofemoral pain syndrome. Am J Sports Med. 2011;39(1): 154-63.
- Davis IS, Tenforde AS, Neal BS, Roper JL, Willy RW. Gait Retraining as an Intervention for Patellofemoral Pain. Curr Rev Musculoskelet Med. 2020 Feb;13(1):103-114. doi: 10.1007/s12178-020-09605-3. PMID: 32170556; PMCID: PMC7083994.
- De Oliveira Silva D, Pazzinatto MF, Rathleff MS, Holden S, Bell E, Azevedo F, Barton C. Patient Education for Patellofemoral Pain: A Systematic Review. J Orthop Sports Phys Ther. 2020 Jul;50(7):388-396. doi: 10.2519/jospt.2020.9400. Epub 2020 Apr 29. PMID: 32349640.
- Sisk D, Fredericson M. Taping, Bracing, and Injection Treatment for Patellofemoral Pain and Patellar Tendinopathy. Curr Rev Musculoskelet Med. 2020 Aug;13(4):537-544. doi: 10.1007/s12178-020-09646-8. PMID: 32500350; PMCID: PMC7340692.
- Pintat J, Silvestre A, Magalon G, Gadeau AP, Pesquer L, Perozziello A, Peuchant A, Mounayer C, Dallaudière B. Intra-articular Injection of Mesenchymal Stem Cells and Platelet-Rich Plasma to Treat Patellofemoral Osteoarthritis: Preliminary Results of a Long-Term Pilot Study. J Vasc Interv Radiol. 2017 Dec;28(12):1708-1713. doi: 10.1016/j.jvir.2017.08.004. Epub 2017 Oct 12. PMID: 29031987.
- Nielsen T, Miller L, Mygind-Klavsen B, Lind M.A simple rehabilitation regime improves functional outcome in patients with patellofemoral pain after 12 month. Journal of Experimental Orthopaedics, 2020.
Previous Version(s) of the Topic
William F. Micheo, MD, Gerardo Miranda, MD, Juan Carlos Perez, MD. Patellofemoral syndrome. Published 8/17/2016
William F. Micheo, MD
Nothing to Disclose
Jose L. Rios Russo, MD, ATC
Nothing to Disclose
Richard Fontanez, MD
Nothing to Disclose
Gerardo Miranda-Comas, MD
Nothing to Disclose