Radiographic evaluation provides essential information regarding the diagnosis and treatment of musculoskeletal disorders. We evaluated the ability of hip specialists to reliably identify important radiographic features and to make a diagnosis based on plain radiographs alone. Five hip specialists and one fellow performed a blinded radiographic review of 25 control hips, 25 hips with developmental dysplasia (DDH), and 27 with femoroacetabular impingement (FAI). On two separate occasions, readers assessed acetabular version, inclination and depth, position of the femoral head center, head sphericity, head-neck offset, Tönnis grade, and joint congruency. Observers made a diagnosis categorizing each hip as normal, dysplastic, FAI, or combined DDH and FAI (features of both). Reliability was determined using Cohen's kappa coefficient. Intraobserver values were highest for acetabular inclination (κ = 0.72) and determination of femoral head center position (κ = 0.77). Interobserver reliability values were highest for acetabular inclination (κ = 0.61) and Tönnis osteoarthritis grade (κ = 0.59). All other measurements, including diagnosis, had kappa values less than 0.55. We concluded many of the standard radiographic parameters used to diagnose DDH and/or FAI are not reproducible. Accordingly, a more clear set of definitions and measurements must be developed to allow for more reliable diagnosis of early hip disease. Level of Evidence: Level III, diagnostic study. See the guidelines for authors for a complete description of the levels of evidence.
Bibliographical noteFunding Information:
This work was supported in part by Award Number UL1RR024992 from the National Center for Research Resources (JCC). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health. This work was also supported in part by the Curing Hip Disease Fund (JCC). Each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.