Patellofemoral Pain Syndrome (PPS)
Patellofemoral Pain Syndrome (PPS)
Christopher D. Meyering
Basics
Description
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Overuse injury with pain located around or behind the patella
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Multifactorial in origin resulting in biomechanical changes in normal alignment of the patella
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Synonym(s):
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Chondromalacia patella (term frequently used synonymously in older literature; a subset of anterior knee pain related to softening and damage to the articular cartilage)
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“Runner's knee”
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Epidemiology
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Anterior knee pain represents 20–40% of all knee problems.
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Most common running injury presenting to a sports medicine clinic
Risk Factors
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Recent increase or change in training/activity
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Deviations of normal rollover pattern of foot (ie, excessive or insufficient pronation)
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Patellar hyper- or hypomobility
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“Miserable malalignment syndrome” (ie, increased femoral anteversion, inward-looking patella, external tibial torsion, pronated feet, and bayonet sign)
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Valgus deformity of the leg
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Vastus medialis oblique (VMO) muscle strength deficit relative to vastus lateralis
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Varus position of the subtalar joint
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Gluteus medius inhibition or dysfunction; leads to decreased hip control and greater femoral adduction and/or internal rotation
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Family history of patellofemoral or anterior knee pain
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Q-angle formerly felt to be a significant risk factor, but multiple studies have not seen any significant correlation when comparing symptomatic and asymptomatic individuals
Commonly Associated Conditions
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Chondral injury, especially with history of blunt trauma
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Increased residual laxity or tearing of the medial patellar stabilizers with lateral dislocation of the patella
Diagnosis
History
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Recent changes in activity frequency, type, and intensity
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Duration of wearing and changes to current exercise footwear
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Past effusion, if knee currently not swollen. Effusion is not a typical finding of patellofemoral pain syndrome (PFPS). Its presence is likely related to other pathology, although PFPS cannot be excluded.
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Subluxation vs dislocation episodes and/or history of direct trauma
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Prior treatments, including NSAIDs, taping, physical therapy, orthotics, injections, or surgery
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The presence of crepitus is not helpful to make a diagnosis, as most healthy women and almost half of healthy men also have crepitus on exam.
Physical Exam
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Insidious onset of anterior knee pain with activity
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Pain around or behind the patella with one or more of the following activities: prolonged sitting, squatting, stair climbing, running, kneeling, hopping/jumping
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In-line “giving way” of the knee secondary to pain and not ligamentous or tendinous deficiency
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Physical examination tests have been reported to have sensitivities <50%, although specificity for some tests have ranged from 72–100% (1)[B].
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Evaluate gait and overall limb alignment, as mentioned in “Risk Factors.”
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Note any atrophy of the lower extremity, especially VMO.
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Assess strength of gluteus medius using Trendelenburg test or side-lying hip abduction test.
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Examine flexibility of quadriceps (Thomas' test), iliotibial band (Ober's test), hamstring (popliteal angle test), hip (Thomas' test), and gastrosoleus (ankle range of motion).
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Assess for presence of crepitus or J-sign (abrupt lateral motion of patella with full extension) during active flexion and extension of the knee.
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Assess for patella alta, patella baja, squinting patella, or grasshopper eyes (proximal and lateral patellar rotation).
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Rule out patellar and quadriceps tendinopathy, ligamentous instability, and meniscal pathology.
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Evaluate the prepatellar, infrapatellar, and pes anserine bursae and presence of joint effusion.
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Examine for patellar facet and retinaculi tenderness. Tenderness over lateral retinaculum present in 90% of patients.
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Evaluate patellar glide and apprehension:
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Divide patella into quadrants.
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If moves 1 quadrant or less laterally or medially, a tight medial or lateral retinaculum is present.
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If able to translate >3 quadrants medially or laterally, the patella is hypermobile. Hypermobility usually results in apprehension as the patient senses impending patellar dislocation.
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Perform patellar tilt test: With knee in full or 30 degrees of flexion, if examiner cannot get the lateral border of patella to horizontal with posterior pressure on medial edge, a tight lateral retinaculum is present.
Diagnostic Tests & Interpretation
Imaging
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Imaging studies are not required for an accurate diagnosis of patellofemoral pain syndrome. Multiple studies have evaluated sulcus angle, patellar height (determined by Insall-Salvati index), patellar tilt (determined by Laurin angle), and patellar displacement (determined by Merchant angle) and have found no significant difference between symptomatic and asymptomatic patients (1)[A].
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Imaging studies are recommended if there is clinical suspicion of another diagnosis or if a patient has failed initial conservative management. Most radiographs will appear normal. Any structural abnormalities may need to be addressed when determining the appropriate care plan for an individual patient.
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CT, MRI, and bone scintigraphy are recommended to determine presence of additional pathology causing anterior knee pain or to assist with surgical options when conservative management has failed.
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Plain films:
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Anteroposterior bilateral standing: May show varus or valgus orientation of femur, knee, or tibia
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Lateral view of affected knee: Evaluate for patella alta (patella length to patellar tendon length <0.8) or patella baja (patella length to patellar tendon length >1.2) with Insall method.
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Merchant view of bilateral patellofemoral joints, as this view does not distort the trochlea/patella appearance. Evaluate for a shallow sulcus angle, subluxation degree, and femoral condyle appearance.
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Tunnel view if osteochondral deficit lesion suspected
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CT:
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Useful to evaluate patellofemoral relationships (eg, tilt and subluxation), especially in patients with suspected subluxation at <30–45 degrees of flexion that cannot be visualized well on plain film
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Useful to evaluate intraosseous lesions
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Useful to plan selective surgical realignment procedures
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MRI:
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Provides information similar to CT
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May add evaluation of articular cartilage (stage III and IV chondromalacia can be evaluated reliably with accuracy of 89%), presence of loose bodies, and integrity of surrounding soft tissue structures such as the medial and lateral patellar retinacula
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Bone scintigraphy:
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Increased uptake at patella and distal femur believed to indicate poor prognosis with prolonged pain (average 6–9 mos)
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Positive bone scan correlates with chondromalacia, with positive predictive value of 72%.
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Differential Diagnosis
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Patellar or quadriceps tendinopathy
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Patellofemoral osteoarthritis
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Patellar instability with subluxation or dislocation
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Osteochondral defect of the trochlear or patellar surface
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Osteochondritis dissecans
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Iliotibial band syndrome
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Anterior fat pad inflammation
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Synovial plica
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Retinacular strain
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Osgood-Schlatter disease
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Sinding-Larsen-Johansson disease
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Referred pain from the hip, often affecting the anterior distal thigh and knee
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Multiple other sources of knee pain and arthritis (eg, gout, infection, reflex sympathetic dystrophy, neuroma, or sickle cell disease)
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Pigmented villonodular synovitis
Treatment
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Because patellofemoral pain syndrome is typically multifactorial in origin, adequate treatment should address multiple facets of care:
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80% of patients respond to conservative management.
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Reduce activities that may have led to onset of symptoms, such as resistance training (lunges or full squats), increased mileage with running, or plyometric exercises.
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Encourage relative rest using alternate exercises (ie, pool running, bicycling, swimming, or using an elliptical trainer).
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Evaluate footwear with focus on excessive deterioration, inadequate support, or excessive support.
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Ice application after activity can help with pain symptoms, but will not treat any underlying cause of the pain.
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Effective therapy must focus on the physical findings or deficits seen for each individual patient (ie, strength training for those with muscle weakness and flexibility training for those with decreased range of motion. Physical therapy program should be individualized for maximal results:
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Strength training consists of closed chain (end of limb is in contact with a surface) or open chain (limb end is not in contact). Typical muscle strength deficits will be in the quadriceps muscle group, but can also be in the gluteus medius or core muscle groups.
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Witvrouw et al. evaluated the long-term effects of an open vs a closed kinetic chain training program and concluded that both training programs lead to good functional outcome. On initial evaluation and 3 mos later, the closed chain exercises produced less pain, better functional improvement, and less subjective clicking. At the 5-yr follow-up, however, 3 of 18 evaluations by visual analog scales revealed the open chain group showed fewer complaints than the closed group (2).
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Flexibility training should address the hamstrings, quadriceps, hip flexors, iliotibial band, and gastrocsoleus.
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Hazneci et al. determined that isokinetic exercise (variable resistance applied so movement remains at a constant speed) has positive effects on knee joint position sense, which in turn increases strength and work capacity (3).
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Medication
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Medication management should focus on pain, not inflammation control.
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Acetaminophen or NSAIDs may be used initially to provide relief of pain symptoms during daily activities.
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Steroid injections are of limited value.
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Additional Treatment
Additional Therapies
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Bracing:
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Lun et al. randomly assigned patients diagnosed with PFPS to 1 of 4 treatment groups consisting of a home exercise program, patellar bracing alone, home exercise program with patellar bracing, and home exercise program with knee sleeve, and found no significance in the pain or function between the groups (4).
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Finestone et al. evaluated the subjective pain of military recruits using a simple knee sleeve, a brace with a patellar ring, or no treatment, and found no significant differences (5).
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Miller et al. compared a dynamic patellar brace, a counterforce knee strap, and no brace in patients receiving medication and physical therapy, but found no significant difference with the groups (6).
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Studies evaluating the change in patellar tracking patterns using kinematic MRI have not supported the proposed mechanisms of action in the patellofemoral braces (7).
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Regardless of the reason for benefit, patellar bracing can potentially improve the symptoms of patellofemoral pain syndrome and can be tried, as not all patients may be willing or able to complete an adequate trial of physical therapy.
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Orthotics:
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Collins et al. compared patients treated with off-the-shelf foot orthoses, flat inserts, physical therapy, or foot orthoses plus physical therapy. Foot orthoses were found to be better than the flat inserts, but no significant improvement was found compared to therapy with or without orthoses (8). The overall recommendation is that an orthotic may improve pain symptoms for patients who cannot complete therapy.
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Taping:
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Multiple studies have evaluated the effects of patellar taping and found decreased pain, increased exercise tolerance, and improvement in timing of quadriceps contraction (9).
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Whittingham, Palmer, and Macmillan performed a randomized controlled trial and found that a combination of daily patella taping and exercise was superior to exercise alone (10).
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Surgery/Other Procedures
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After at least 6–12 mos of adequate conservative therapy has been tried, surgery may be considered.
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Isolated lateral retinacular release of the patella has not been shown to provide long-term benefit for treatment of patellar instability, but may be used along with proximal or distal realignment of the extensor mechanism.
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Patients with Q-angles >20 degrees plus abnormal congruence angles may undergo distal realignment procedures such as an anterior medial tibial tubercle transfer.
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Dislocators are operated on if symptoms of patellofemoral instability were present before their dislocation.
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Patellectomy and derotational osteotomies are last resorts.
References
1. Haim A, Yaniv M, Dekel S, et al. Patellofemoral pain syndrome: validity of clinical and radiological features. Clin Orthop Relat Res. 2006.
2. Witvrouw E, Danneels L, Van Tiggelen D, et al. Open versus closed kinetic chain exercises in patellofemoral pain: a 5-year prospective randomized study. Am J Sports Med. 2004;32:1122–1130.
3. Hazneci B, Yildiz Y, Sekir U, et al. Efficacy of isokinetic exercise on joint position sense and muscle strength in patellofemoral pain syndrome. Am J Phys Med Rehabil. 2005;84:521–527.
4. Lun VM, Wiley JP, Meeuwisse WH, et al. Effectiveness of patellar bracing for treatment of patellofemoral pain syndrome. Clin J Sport Med. 2005;15:235–240.
5. Finestone A, Radin EL, Lev B, et al. Treatment of overuse patellofemoral pain. Prospective randomized controlled clinical trial in a military setting. Clin Orthop Relat Res. 1993:208–210.
6. Miller MD, Hinkin DT, Wisnowski JW. The efficacy of orthotics for anterior knee pain in military trainees. A preliminary report. Am J Knee Surg. 1997;10:10–13.
7. Chew KT, Lew HL, Date E, et al. Current evidence and clinical applications of therapeutic knee braces. Am J Phys Med Rehabil. 2007;86:678–686.
8. Collins N, Crossley K, Beller E, et al. Foot orthoses and physiotherapy in the treatment of patellofemoral pain syndrome: randomised clinical trial. Br J Sports Med. 2009;43:163–168.
9. Post WR. Patellofemoral pain: results of nonoperative treatment. Clin Orthop Relat Res. 2005:55–59.
10. Whittingham M, Palmer S, Macmillan F. Effects of taping on pain and function in patellofemoral pain syndrome: a randomized controlled trial. J Orthop Sports Phys Ther. 2004;34:504–510.
Additional Reading
Arroll B, Ellis-Pegler E, Edwards A, et al. Patellofemoral pain syndrome. A critical review of the clinical trials on nonoperative therapy. Am J Sports Med. 1997;25:207–212.
Bellemans J, Cauwenberghs F, Witvrouw E, et al. Anteromedial tibial tubercle transfer in patients with chronic anterior knee pain and a subluxation-type patellar malalignment. Am J Sports Med. 1997;25:375–381.
Blond L, Hansen L. Patellofemoral pain syndrome in athletes: a 5.7-year retrospective follow-up study of 250 athletes. Acta Orthop Belg. 1998;64:393–400.
Brushoj C, Albrecht-Beste E, Bachmann M, et al. Acute Patellofemoral pain: Aggravating activities, clinical examination, MRI and US findings. Br J Sports Med. 2007.
Cowan SM, Crossley KM, Bennell KL. Altered hip and trunk muscle function in individuals with patellofemoral pain. Br J Sports Med. 2008.
Davis W, Fulkerson J. Initial evaluation of the athlete with anterior knee pain. Op Tech Sports Med. 1999;7:55–58.
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Fredericson M, Yoon K. Physical examination and patellofemoral pain syndrome. Am J Phys Med Rehabil. 2006;85:234–243.
Gerbino PG, Zurakowski D, Soto R, et al. Long-term functional outcome after lateral patellar retinacular release in adolescents: an observational cohort study with minimum 5-year follow-up. J Pediatr Orthop. 2008;28:118–123.
Hartig DE, Henderson JM. Increasing hamstring flexibility decreases lower extremity overuse injuries in military basic trainees. Am J Sports Med. 1999;27:173–176.
20. Kannus P, et al. An outcome study of chronic patellofemoral pain syndrome: seven-year follow-up of patients in a randomized, controlled trial. J Bone Joint Surg. 1999;81:355–363.
21. Kaufman KR, Brodine SK, Shaffer RA, et al. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med. 1999;27:585–593.
22. Kelly M. Proximal realignment and medial tibial tubercle transfer. Op Tech Sports Med. 1999;7:76–80.
23. Laprade J, Culham E. Radiographic measures in subjects who are asymptomatic and subjects with patellofemoral pain syndrome. Clin Orthop Relat Res. 2003:172–182.
24. Lattermann C, Toth J, Bach BR. The role of lateral retinacular release in the treatment of patellar instability. Sports Med Arthrosc. 2007;15:57–60.
25. Macintyre JG, Taunton JE, Clement DB, et al. Running injuries: a clinical study of 4,173 cases. Clin J Sport Med. 1991;1(2):81–87.
26. Merchant A. Radiography of the patellofemoral joint. Op Tech Sports Med. 1999;7:59–64.
27. Natri A, Kannus P, Järvinen M. Which factors predict the long-term outcome in chronic patellofemoral pain syndrome? A 7-yr prospective follow-up study. Med Sci Sports Exerc. 1998;30:1572–1577.
28. Nigg BM, Nurse MA, Stefanyshyn DJ. Shoe inserts and orthotics for sport and physical activities. Med Sci Sports Exerc. 1999;31:S421–S428.
29. Papagelopoulos PJ, Sim FH. Patellofemoral pain syndrome: diagnosis and management. Orthopedics. 1997;20:148–157; quiz 158–159.
30. Powers CM, Landel R, Sosnick T, et al. The effects of patellar taping on stride characteristics and joint motion in subjects with patellofemoral pain. J Orthop Sports Phys Ther. 1997;26:286–291.
31. Presswood L, Cronin J, Keogh JWL, et al. Gluteus medius: applied anatomy, dysfunction, assessment, and progressive strengthening. Strength Cond J. 2008;30:41–53.
32. Schreiber S. Arthroscopic surgery and the lateral release for patellofemoral disorders. Op Tech Sports Med. 1999;7:69–75.
33. Stiene HA, Brosky T, Reinking MF, et al. A comparison of closed kinetic chain and isokinetic joint isolation exercise in patients with patellofemoral dysfunction. J Orthop Sports Phys Ther. 1996;24:136–141.
34. Thijs Y, Tiggelen DV, Roosen P, et al. A prospective study on gait-related intrinsic risk factors for patellofemoral pain. Clin J Sport Med. 2007;17:437–445.
35. Timm KE. Randomized controlled trial of protonics on patellar pain, position, and function. Med Sci Sports Exerc. 1998;30:665–670.
36. Witvrouw E, Sneyers C, Lysens R, et al. Reflex response times of vastus medialis oblique and vastus lateralis in normal subjects and in subjects with patellofemoral pain syndrome. J Orthop Sports Phys Ther. 1996;24:160–165.
Codes
ICD9
719.46 Pain in joint involving lower leg
Clinical Pearls
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Return to activity:
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If patient has patellofemoral pain during, immediately following, or the day after exercising:
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Decrease activity. Avoid strength training exercises such as full squats and lunges.
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Consider alternate activities, such as an elliptical trainer, bicycling, or swimming.
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Runners who need to maintain running-specific conditioning, utilize a floatation belt for pool running.
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80% of patients respond to a nonoperative therapy, most within 4 wks
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Complete resolution of symptoms may take longer.
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In athletes with patellofemoral pain followed for 5–7 yrs, 27–75% were pain-free at 6–8 mos, and ∼50% had a significant decrease in pain at 6–8 mos; 70% of patients remained pain-free at 7 yrs in 1 study.
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Correlates of improvement at 7 yrs include maintenance of quadriceps strength and function, young age, short stature, negative findings of patellar pain and crepitation, and absence of bilateral symptoms during the follow-up period.
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Most patients (65%) with patellofemoral pain do not get patellofemoral osteoarthritis.