膝關節鏡手術後是否需要靜脈栓塞的預防，目前仍是具爭議性的問題。我們報告一位34歲男性，因左膝前十字韌帶撕裂傷而接受膝關節鏡手術修補。一個月後因左膝微腫，於門診接受關節液穿刺檢查。病人發生突然性昏厥。急診檢查發現有心肌酵素（心肌旋轉蛋白I）上升併右側胸前心電圖有V4R ST節段上升。心導管檢查發現冠狀動脈左前降枝有75%的心肌間橋。心導管檢查後病人仍有氣促及低動脈血氧的情況。心臟超音波顯示有左心室於心舒期呈現＂D＂字型。電腦斷層檢查發現兩側肺動脈均有嚴重的栓塞，周邊血管超音波顯示左側膕靜脈嚴重栓塞。病人在接受抗凝血劑治療後氣促改善。我們將討論膝關節鏡手術後的病人是否需要靜脈血栓預防。

Thromboprophylaxis of post knee arthroscopy is a matter of debate. Herein, we report the case of a young man who developed a sub-massive pulmonary embolism following knee arthroscopic anterior cruciate ligament repair, with an initial presentation of syncope. Right sided electrocardiography revealed ST-segment elevation and mild elevation of troponin I. Emergent cardiac catheterization reveal a myocardial bridge at the left anterior descending artery, however no occlusion or thrombus was found. Echocardiography showed a D shaped left ventricle in the apical four chamber view. Computed tomography pulmonary angiography confirmed a pulmonary embolism at bilateral distal pulmonary arteries with involvement of the distal branches. We further discuss the need of thromboprophylaxis after knee arthroscopy.