Excessive lateral pressure syndrome (ELPS) is the abnormal lateral tilt of the patella without lateral translation and considered one of the relatively common causes of anterior knee pain.
It can affect both adolescents or adults.
Patients usually present with insidious onset anterior knee pain aggravated by physical activity.
ELPS is due to an imbalance between medial and lateral dynamic stabilizers, either secondary to more common abnormally tight lateral retinaculum/vastus lateralis or lax medial retinaculum/vastus medialis. This results in a lateral tilt of the patella without obvious subluxation or dislocation. In fact, in some cases, even slight medial translation can be present. Over time, chronic impaction of the lateral patellar facet to the lateral femoral trochlea ensues chondral damage and osteoarthritis.
Abnormal tilt can be measured by patellofemoral angle with a medial opening of the angle or an angle less than 8° is diagnostic of ELPS in an appropriate clinical setting.
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