Cuisses came in much later than greaves and there was also a piece to protect the kneecap called the poleyn. Once firearms came in, armour started to disappear but the breastplate and cuisses stayed around for a while. You can see so called threequarter suits of armour that were worn in the English Civil War. The place of the greaves had been taken by heavy riding boots, but the cuisses were still useful in protecting a rider from a downward sword blow from another rider.