Functional data for the diagnosis of patellofemoral laxity obtained by MRI during quadriceps isometric contraction.

Patellofemoral instability is related to anatomy. Magnetic resonance imaging (MRI) provides anatomic detail, but spoiled gradient echo (SPGR) imaging during isometric quadriceps contraction provides objective functional data for diagnosing patellofemoral laxity. Knee MRI studies and medical charts of 398 patients were retrospectively reviewed.