Two peculiar cases of cranial fractures running through craniotomy burr holes: may this be a kind of “exception” to the Puppe rule

A correct assessment on the position, path, and direction of fracture lines is crucial when the sequence of different injuries on the skull has to be ascertained. In this context, the so-called Puppe’s rule on intersecting fracture lines has always been considered a cornerstone of such an investigation. However, there is one factor that has never been previously considered: how do fracture lines behave when they reach the edges of an old and remodeled hole from a previous craniotomy? Two peculiar cases are presented of subjects undergoing cranial fractures due to blunt force trauma (case 1) and gunshot (case 2). Both previously underwent neurosurgical operations with persistence of the burr holes produced by the craniotomy drill (15 and 20 years before death). What was arguable, according to Puppe’s rule, was that the fracture lines, when at the edge of the craniotomy hole, stopped. However, what has been detected was different than what expected: fracture lines continued exactly in the opposite direction, as though they were “skipping” the hole, following the same direction and the same axis and stopping a few centimeters over on the opposite side of the craniotomy hole. Puppe’s rule has never been refuted, but these cases are the closest to an exception ever seen in forensic anthropology.