Femoral avulsion of the medial patellofemoral ligament after primary traumatic patellar dislocation predicts subsequent instability in men: a mean 7-year nonoperative follow-up study - Sillanpää, P J; Peltola, E; Mattila, V M; Kiuru, M; Visuri, T; Pihlajamäki, H (Am J Sports Med, 2009)