2015 ISAKOS Biennial Congress ePoster #907

Unacceptable Reliability of Femoroacetabular Impingement Radiographic Parameters - Renewed Emphasis for Physical Exam Diagnosis and Three-Dimensional Advanced Imaging

Joshua D. Harris, MD, Houston, TX UNITED STATES
Jonathan M. Frank, MD, Beverly Hills, CA UNITED STATES
Andrew Riff, MD, Chicago, IL UNITED STATES
Shane Nho, MD, Chicago, IL UNITED STATES

Rush University Medical Center, Chicago, IL, USA

FDA Status Not Applicable

Summary: Inter- and intra-observer reliability for measurement of all measured quantitative femoroacetabular impingement radiographic parameters was unacceptable, except for lateral and anterior center edge angles.

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Abstract:

Purpose

To determine the inter- and intra-observer reliability of all radiographic parameters used to evaluate femoroacetabular impingement (FAI). Methods Institutional review board (IRB) approval was obtained prior to study commencement. Adult subjects with symptomatic cam and/or pincer FAI that had failed conservative treatment underwent hip arthroscopy for indicated procedures related to impingement, the labrum, and capsule. Fifty consecutive subjects with a complete pre-operative radiographic evaluation were selected for analysis. Five subjects' radiographs were inadequate due to either rotational or tilted positioning, leaving 45 sets of radiographs to be reviewed by two reviewers, one board-eligible Orthopaedic Surgeon fellowship-trained in Sports Medicine and hip arthroscopy (Reviewer #1), and a fourth-year Orthopaedic Surgery resident (Reviewer #2). The following parameters were measured on anteroposterior (AP) pelvis, false profile, and Dunn 90 degree lateral radiographs: Lateral and anterior center-edge angle (CEA), alpha angle, anterior and posterior head-neck offset, femoral head maximum diameter, head-neck offset ratio, anterior-posterior head neck offset ratio. Continuous data was reported as mean +/- standard deviation. Inter- and intra-observer reliability was calculated using two-way mixed intraclass correlation coefficient (ICC) for single measures. For intra-observer reliability, the second reading session was completed two weeks after the first session to reduce recall bias. Acceptable reliability was defined as ICC >/= 0.60. Statistical analysis was performed using PASW Statistics Student Version 18. Results Acceptable inter-observer reliability was measured for lateral (ICC 0.892) and anterior (ICC 0.933) CEA. Inter-observer reliability for all other measurements was unacceptable (ICC < 0.60). Intra-observer reliability was acceptable for both reviewers for lateral and anterior CEA (ICC 0.824 - 0.981) and Dunn posterior head-neck offset (ICC 0.725, 0.736). Intra-observer reliability was acceptable for only one reviewer for Dunn alpha angle (ICC 0.909), false-profile head-neck ratio (ICC 0.642), Dunn and false profile anterior-posterior head-neck offset ratio (0.644, 0.683), Dunn anterior head-neck offset (ICC 0.709), and false-profile posterior head-neck offset (ICC 0.832). Conclusion This study underscores the necessity of a thorough physical examination to diagnose symptomatic FAI, and not just radiographs. Advanced imaging, including three-dimensional CT or MRI, may more reliably characterize FAI versus radiographs due to the lack of acceptable reliability of most parameters commonly assessed.