The simultaneous traumatic rupture of the patellar tendon and the quadricipital tendon is a rare lesion entity. We report the case of a bipolar rupture of the extensor knee system in a young adult following sports traumatism. Magnetic Resonance Imaging allowed the assessment of associated lesions. The management of this "floating" kneecap was surgical associated with rehabilitation. A functional assessment at 02 years of follow-up was performed. The functional prognosis is related on the one hand to the difficulties of positioning of the patella and on the other hand to the associated lesions (meniscus-ligamentous knee injuries).