The objective is to develop an understanding of the biomechanical mechanisms that result in basilar skull fractures when the head is subject to a mandibular impact. Two experimental studies were performed. The first study evaluated the tolerance of the mandible subject to midsymphysis loading on the mental protuberance (chin). Five dynamic impacts using a vertical drop track and one quasi-static test in a servo-hydraulic test frame were performed. The mean mandibular fracture tolerance among the six tests was 5270 about 930 N and appears insensitive to loading rate. In each test, clinically relevant mandibular fractures were produced. No basilar skull fractures were observed. The second study assessed the fracture The second study assessed the fracture tolerance of the base of the skull subject to direct loading on the temporo-mandibular joint in conjunction with tensile loading imposed locally around the foramen magnum to simulate the effect of the neck. Among four specimens that sustained either complete or incomplete basilar skull ring fractures remote from the sites of load application, the mean load at fracture was 4300 about 350 N. Energy to fracture was computed in three of those tests and averaged 13.0 about 1.7 joules. Injuries produced were consistent with clinical observations that have attributed basilar skull ring fractures to mandibular impacts.
Abstract