It depends. Like any fracture, a pars defect is relatively serious and will require some form of treatment. However, it can be difficult to detect and makes things a bit trickier than when you break an arm or foot. Since pars defect is common among children who are quite active or participate in a sport of some kind, the healing rate for bones is rather quick meaning that most children recover with not much more than a bit of downtime. However, on some occasions, the symptoms of a pars defect won't show up until later in life. Overall, yes, a pars fracture is serious but not life-threatening and can be treated.