Are your ninebarks in full sun or part shade? I had one that when it was in full sun did great. But, when a neighboring tree grew, the canopy shaded the ninebark. When that happened, it had problems with dead branches. With your shrubs, aphids certainly weakened the plants. With mine, I cut the entire shrub back close to the ground in mid-spring. The new branches and leaves are quite pretty. I also climbed up the tree to give it a little more sunlight. So far, so good. I would recommend rejuvenating your shrubs the same way next spring.