Improved Identification of Adolescent Hip Dysplasia Using a Screening Method Based on Lateral Center Edge Angle Measurements

Abstract

Background: In addition to the clinical exam, several quantitative measurement tools are performed on pelvic radiographs in the assessment of adolescent hip dysplasia at most dedicated pediatric hip preservation clinics, with the most commonly used measurement called the lateral center edge angle (LCEA). However, most pediatric radiologists do not use these quantitative measuring tools and instead make the diagnosis of adolescent hip dysplasia based on subjective review.

Objective: The purpose of this study is to determine the additive value of a measurement-based diagnosis of adolescent hip dysplasia using LCEA versus subjective radiographic interpretation by pediatric radiologists.

Methods: A review of pelvic radiographs for the binomial diagnosis of hip dysplasia was performed by four pediatric radiologists (two general, two musculoskeletal). The review included 97 pelvic AP radiographs (mean age 14.4 years [range 10-20 years], 81% female) for a total of 194 hips (58 cases of adolescent hip dysplasia and 136 normal) all of whom were evaluated in a tertiary care pediatric subspecialty hip preservation clinic. Subjective radiographic interpretation of each hip for a binomial diagnosis of hip dysplasia was performed. 2 weeks later and without knowledge of the subjective radiographic interpretation results, the same review was performed with LCEA measurement and a diagnosis of hip dysplasia made when LCEA angles were under 18 degrees. A comparison of sensitivity/specificity between methods per reader was conducted. A comparison of accuracy between methods for all readers combined was performed.

Results: For all four reviewers, the sensitivity of subjective versus LCEA measurement-based diagnosis of hip dysplasia was 54-67% (average 58%) versus 64-72% (average 67%), respectively, and specificity was 87-95% (average 90%) versus 89-94% (average 92%), respectively. All four readers demonstrated an intra-reader trend for improvement in the diagnosis of adolescent hip dysplasia after the addition of LCEA measurements but was only statistically significant in one of the four readers. The combined accuracy of all four readers for subjective and LCEA measurement-based interpretation was 81% and 85%, respectively with p = 0.006.

Conclusion: Compared with subjective interpretation, LCEA measurements demonstrate increased diagnostic accuracy amongst pediatric radiologists for the correct diagnosis of adolescent hip dysplasia.