My son lost his finger due to wrong bandaging with a rigid splint...

My son, 9 months old, had a burn accident on his left hand. Three fingers burned second degree. We went to the emergency room and stayed 2 nights at the hospital. 3 days after the accident the fingers looked already much better. The physical therapist decided to bandage the hand with a rigid splint, so that the skin on the three fingers would not grow back tight. She told me to come back in a week for bandage removal. When we went back, she removed the bandage and we saw that the little finger (that was a healthy finger before) was badly injured. The blood-supply was cut off, gangrene already developed. The finger-tip looked black. After three months the finger (2 digits) self amputated. It does not make sense to me that the physical therapist did not check earlier, nor did she tell me to check the fingers frequently.
My question is, if applying a splint on a baby's hand is a common practise?
Does this happen more often? Should rigid splints generally not used? Does anyone have experience with that?