A 'saphenous vein cutdown' is a procedure used to locate the great saphenous vein at the ankle. To find this vein, the skin would be incised:

At the ankle, the great saphenous vein travels anterior to the medial malleolus. At the knee, it travels posterior to the medial condyle of the femur. However, saphenous cut-downs are done at the ankle, not the knee, so anterior to the medial malleolus is the correct answer. The other impoant relationship to remember is that the lesser saphenous vein travels posterior to the lateral malleolus.