Low/no water pressure after replacing stem valve in shower?

Several months ago the hot water stem in our shower broke and we could not shut the water off. The shower has separate hot and cold knobs. Only the hot went out so we only replaced the hot. Since then we have no water pressure. There is no change in pressure when you turn the knobs and the water seems to just trickle out. It does the same with the cold water side. Regardless if one or both is turned on just a little or completely open the pressure is the same. We have checked the main shut off to make sure it is completely open and we have checked the shower head for any clogs. The valve itself also appears to have no clogs.