Crape Myrtles that have been continually cut back severely year to year will develop a “knuckle” at the end of each trunk. This is commonly referred to as “Crape murder”.
Although it doesn’t actually kill the tree, it weakens the structure and healthy of the tree. Once the tree is “murdered”, can you bring it back to life? I most cases, you can repair this effect of poor pruning, although the whole process can take seasons to complete.
First prune off the knuckles at the end of the stems, leaving a clean cut. When new shoots begin to emerge in spring, pick out one or two new shoots per stem to keep and prune off the remaining. These are the shoots that will develop back into healthy, strong new trunks. You will need to trim off any additional small sprouts that emerge at the base of the selected shoots. After a few growing seasons, the new shots will thicken up to the size of the original stem.