Evaluation of Interobserver Agreement in the Diagnosis of Posterior Pelvic Ring Lesions Using Plain Radiography.

 To evaluate the interobserver agreement of a radiologist, two hip specialist orthopedists with experience in the treatment of pelvic and acetabulum fractures, two general orthopedists, two orthopedics residents and two radiology residents regarding the diagnosis of posterior pelvic ring injuries using plain radiography.  A cross-sectional study conducted in September 2017. The exams of 20 patients who had been treated for traumatic lesions of the posterior pelvic ring were randomly selected.. A total of nine examiners from different medical fields evaluated the plain pelvic radiographs; those were compared with computed tomography, scans, which are considered a confirmatory diagnostic criterion. Interobserver agreement was assessed using the Kappa test ( ) and 95% confidence intervals (95%CIs).  A total of 28 lesions were found by computed tomography (23%; 95%CI: 16-32%) among all of the cases evaluated. The interobserver agreement between plain radiography and computed tomography was moderate among physicians with more experience: a radiologist ( = 0.461; 95%CI: 0.270-0.652), hip specialists 1 and 2 ( = 0.534; 95%CI: 0.348-0.721 and = 0.431; 95%CI: 0.235-0.627 respectively), and general orthopedists 1 and 2 ( = 0.497; 95%CI: 0.307-0.686 and = 0.449; 95%CI: 0.254-0.645 respectively). Among the orthopedics and radiology residents, the interobserver agreement was considered poor. High false negative values were found among all of the examiners, especially regarding posterior iliac fractures and sacrum fractures.  Professionals with greater experience in the field have a better ability to identify posterior pelvic ring lesions by plain radiography, but we emphasize that plain pelvic radiography was susceptible to false negative evaluations among all of the professionals assessed.