髕股骨疼痛症候群為膝關節前側及周圍疼痛的症狀，在上下樓梯、蹲、跪、跳躍等動作時會感到膝蓋疼痛，好發在下肢活動頻繁的運動項目中。一般認為發生原因是髕骨與股骨間的滑動出現異常，使得髕股骨關節磨損而出現疼痛。本文統整相關文獻研究，發現Q_angle的增加，以及股內斜肌收縮反應延緩的肌電特性，與髕股骨疼痛症候群有密切相關。另外，距下關節過度旋前、髂脛束過緊以及髖關節外展肌群與外轉肌群無力，易導致Q_angle增加。瞭解髕股骨疼痛症候群的相關影響因子與肌電特性，可以提供教練、運動傷害防護員與物理治療師作為復健訓練和傷害防護的參考。

Patellofemoral pain syndrome is a syndrome in which pain occurs at anterior knee and periarticular area. People with patellofemoral pain syndrome usually have anterior knee pain during upstairs, downstairs, squatting, kneeling or jumping. The abnormal gliding between patella and femur results in wear on articular surface and pain. We reviewed previous literatures and found that the increased Q_angle and delayed electromyographic onset time of vastus medialis obliquus are associated with the patellofemoral pain syndrome. In addition, excessive subtalar pronation, iliotibial band tightness and hip abductor / external rotator weakness can lead to the increase of Q_angle. Understanding the electromyographic characteristics and the risk factors of patellofemoral pain syndrome is important for the coaches, athletic trainers and physical therapists to provide the guideline in rehabilitation and athletic training.