The Mandible Injury Severity Score: Development and Validity

PurposeTo develop and validate a clinical method for characterizing and scoring mandible injury severity.Materials and MethodsConstituent fracture variables (fracture type, location, occlusion, soft tissue involvement, infection, and interfragmentary displacement [FLOSID]) were used to develop the FLOSID taxonomy for characterizing injury. Each component was assigned an empirical weight to help derive a summary measure of injury severity called the UCLA Mandible Injury Severity Score (MISS). Subsequently, MISS values were calculated for a group of 336 patients treated for mandible fractures. The validity of the summary score was evaluated by relating the MISS measure to the treatment modality used and to various variables, related as well as unrelated to injury outcomes.ResultsEach of the FLOSID components correlated significantly with the MISS (P < .001). Unrelated variables, including ethnicity, education, and gender, had no correlation to the MISS. On average, patients treated with rigid internal fixation had a higher MISS than patients treated with maxillomandibular fixation (P < .001). The MISS had a statistically significant association with surrogate markers of injury severity such as sensory nerve deficit, need for hospitalization, and pain at 1-month follow-up (P < .001). However, there was no significant association between MISS and indicators of postoperative complications (infection, nonunion, malunion, malocclusion).ConclusionsThe FLOSID taxonomy offers a useful alternative to narrative summarization of mandible injury. The MISS is readily derived from clinical parameters obtained at the initial patient encounter and appears to be a valid index of mandible injury severity across important clinical domains.