What is the Interobserver Reliability of an Ultrasound-enhanced Physical Examination of the Hip in Infants? A Prospective Study on the Ease of Acquiring Skills to Diagnose Hip Dysplasia

Abstract

Background: Developmental dysplasia of the hip (DDH) is the most common disorder found in newborns. The consequences of DDH can be mitigated with early diagnosis and nonoperative treatment, but existing approaches do not address the current training deficit in making an early diagnosis.

Question/purpose: Can ultrasound be taught to and used reliably by different providers to identify DDH in neonates?

Methods: This was a prospective observational study of a series of neonates referred for an evaluation of their hips. An experienced clinician trained three second examiners (a pediatric orthopaedic surgeon, an orthopaedic resident, and a pediatrician) in performing an ultrasound-enhanced physical examination. The 2-hour training process included video and clinical didactic sessions aimed to teach examiners to differentiate between stable and unstable hips in newborns using ultrasound. The experienced clinician was a pediatric orthopaedic surgeon who uses ultrasound regularly in clinical practice. Materials required for training include one ultrasound device. A total of 227 infants (454 hips) were examined by one of the three second examiners and the experienced clinician (gold standard) to assess reliability. Of the 454 hips reviewed, there were 18 dislocations, 24 unstable hips, and 63 dysplastic hips, and the remainder had normal findings. The cohort was composed of a series of patients younger than 6 months referred to a specialty pediatric orthopaedic practice.

Results: Ultrasound-enhanced physical examination of the hip was easily taught, and the results were reliable among different levels of providers. The intraclass correlation coefficient between the gold-standard examiner and the other examiners for all hips was 0.915 (p = 0.001). When adjusting for only the binary outcome of normal versus abnormal hips, the intraclass correlation coefficient was 0.97 (p = 0.001). Thus, the agreement between learners and the experienced examiner was very high after learners completed the course.

Conclusion: After a 2-hour course, physicians were able to understand and reliably examine neonatal children using ultrasound to assess for DDH. The success of the didactic approach outlined in this study supports the need for ultrasound-enhanced examination training for the diagnosis of DDH in orthopaedic surgery and pediatric residency core curriculums. Training programs would best be supported through established residency programs. Expansion of training more residents in the use of ultrasound-enhanced physical examinations would require a study to determine its efficacy. This finding highlights the need for further research in implementing ultrasound-enhanced physical examinations on a broader scale.

Level of evidence: Level II, diagnostic study.