Purpose: This study evaluated variability in the clinical parameters commonly used to characterize mandible fractures.
Patients and methods: Inter-rater reliability of 18 oral and maxillofacial surgeons was assessed using radiographs of 22 cases of mandible fractures. Raters were asked to evaluate each case based on several parameters including number, location, and displacement of the individual fractures and severity of the composite injury. To evaluate intra-rater reliability, selected cases were reviewed at a second session by a subgroup of these surgeons. Tests of concordance used to quantify measurement reliability included the interclass correlation coefficient and multiple-rater kappa statistics.
Results: Inter-rater agreement on the number of constituent fractures ranged from excellent for simpler fractures to poor for complex gunshot injuries. Even within raters, the range of interclass correlation for complex injuries was only 0.33 to 0.42 between the 2 assessments. Clinicians appeared to be better at delineating coronoid, condyle, ramus, and angle fractures; symphyseal and canine region fractures had lower inter- and intrarater agreement. Tests of concordance showed moderate to excellent reliability when fracture displacements were expressed in millimeters, but only fair reliability when displacements were expressed as categories. Even when the clinicians concurred on displacement measurements, a large overlap was observed in their categorization of these displacements. Despite the differences in the assessment of individual parameters, the high intrarater reliability coefficient (0.78) indicated that the individual clinicians had a high internal consistency in their assignment of summary severity scores. Multiple regression analysis revealed the number of constituent fractures, the type of fracture, and amount of fracture displacement (millimeters) to be significant predictors of clinician ratings of injury severity.
Conclusions: The clinician variability underscores the difficulties involved in trauma description and scoring. The study identifies some sources of clinician variability and emphasizes the need to standardize the characterization of mandible fractures by using explicit guidelines.