Patellofemoral Pain Syndrome (PFPS)

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Patellofemoral pain syndrome (PFPS) is characterized by knee pain caused by lateral displacement of the patella producing wear on the inferior patella surface. Onset can either be acute or chronic. Pain occurs when overloading the joint under knee extension torque as in descending stairs, squatting or running. Stiffness or pain typically occurs during prolonged sitting with knees flexed, also known as “theater sign” or “movie sign”.

Risk factors include:

  • overuse (increased frequency, duration, or intensity)
  • trauma or previous surgery
  • muscle dysfunction (Vastus Medialis Weakness, Improper Firing Pattern)
  • tight lateral restraints (ie: Lateral Retinaculum, Iliotibial band)
  • poor quadriceps, hamstring, or iliotibial band flexibility
  • lower extremity malaligned or altered biomechanics
  • patellar hypermobility

Those with PFPS symptoms range from limited patellar mobility to patella hypermobile. PFPS can be compounded by excessively worn or inappropriate foot wear.

Diagnostic imaging is typically not needed before beginning treatment. However, radiography is recommended for patients with a history of trauma or surgery, those with an effusion, those older than 50 years (to rule out osteoarthritis), and those whose pain does not improve with treatment.

PFPS is one of several conditions collectively known as runner's knee. Other conditions include Chondromalacia patellae, Iliotibial band syndrome, and Plica syndrome. Chondromalacia patellae is sometimes used synonymously with PFPS, however Chondromalacia patellae also includes cartilage damage, which is rarely actually determined since diagnosis typically does not include imaging and does not significantly effect the therapeutic modalities.

Treatment

The first steps in reducing pain involves addressing the underlying cause of PFPS and reducing the loading of the patellofemoral joint and surrounding soft tissues. The patella initates contact with the femur at 20º flexion and increases up to 90º flexion. Forces on the patella are between 1/3 to ½ body weight during walking and cycling, up to 3 times body weight during stair climbing, up to 7 times body weight during jogging and squatting, and 20 times bodyweight during deep squatting.

Physical Therapy has shown to be an effective treatment of PFPS. No one program that will be effective for all patients. The rehabilitation program should be customized to address findings identified on the physical examination. Some may require strengthening of the vastus medius whereas others may need to focus on soft tissue techniques and flexibility exercises.

Both open kinetic chain and closed kinetic chain programs lead to an equal long-term good functional outcome. In closed kinetic chain exercises, Maximal VMO/VL ratio can be obtained at 60 degrees knee flexion.

Dynamic Valgus Alignment may be linked to PDFPS in young female athletes. Females with PFPS tend to have decreased hip abduction, external rotation and extension strength as compared to healthy controls. This evidence does not exist for males with PFPS.

Other factors such as Rear-foot and forefoot abnormalities, hamstring imbalance and tightness, and iliotibial tract tightness may also influence patellar tracking.

Strengthening Exercises

Stretching Exercises

There is little evidence to support the routine use of knee braces or non-steroidal anti-inflammatory drugs. There is conflicting evidence on the efficacy of glycosaminoglycan polysulphate. The anabolic steroid nandrolone phenylpropionate (25 mg weekly for 6 weeks) has shown to be effective in treating patellofemoral pain syndrome (significantly improved both pain and function compared to placebo injections) but but its use remains controversial, particularly in athletes.

References

Darracott J. Darracott, J (1973). Treatment of the painful knee fulfilling diagnostic criteria for 'chondromalacia patellae'. Current Medical Research & Opinion;1:412-22.

Dixit S, Difiori JP (2007). Management of Patellofemoral Pain Syndrome. Am Fam Physician. 75(2):194-202.

Heintjes E, Berger MY, Bierma-Zeinstra SM, Bernsen RM, Verhaar JA, Koes BW (2004). Pharmacotherapy for Patellofemoral Pain Syndrome. Cochrane Database Syst Rev. (3):CD003470.

Peterson W, Elleermann A, Gösele-Koppenburg A, Best, R, Rembitzki IV, Brüggemann G, Liebau C (2014). Patellofemoral pain syndrome. Knee Surg Sports Traumatol Arthrosc. 22(10): 2264–2274.

Tang SF, Chen CK, Hsu R, Chou SW, Hong WH, Lew HL (2001). Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study. Arch Phys Med Rehabil. 82(10):1441-5.

Witvrouw E, Danneels L, Tiggelen DV, Willems TM, Cambier D (2014). Open Versus Closed Kinetic Chain Exercises in Patellofemoral Pain: A 5-Year Prospective Randomized Study. Am J Sports Med, 32(5), 1122-1130.


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