There have not been many failures yet, but what is failure. Options are still available. The beauty of this procedure is that if tethering does not arrest the curve, the patient can still undergo a spinal fusion. The hope is, at this stage, the spine has grown enough that the patient will not have a short trunk which typically happens when a fusion is done at a younger age.
There is heaps of discussion (March 2017) on boards around the world on failure. VBT is still in it's infancy, and failure isnt really a word to be used as each person and each family are so very different. We know of tethers that have broken, and a second operation has been offered to replace the tether, and we know of overcorrection in some instances which have come right over time.