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
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
- 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
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.
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.
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.
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.
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