Protocol and validity testing of femoroacetabular posterior translation with dynamic hip ultrasonography.

ABSTRACT

OBJECTIVE: To describe femoroacetabular posterior translation (FAPT) using dynamic hip ultrasonography (DHUS), and to determine the inter- and intra-rater reliability of hip ultrasound measurements of FAPT. MATERIALS AND METHODS: The study design was a feasibility study of 13 healthy young adults (26 hips) using test-retest analysis. The data was collected prospectively over a 2-week time period. Three DHUS measurements (posterior neutral (PN), flexion, adduction, and internal rotation (PFADIR), and stand and load (PStand) were measured by four independent raters (2 senior who divided the cohort, 1 intermediate, 1 junior) at two time points for bilateral hips of each participant. Reliability was assessed by calculating the intraclass correlation coefficient (ICC) along with 95% confidence intervals (CIs) for each rater and across all raters. RESULTS: A total of 468 US scans were completed. The mean age of the cohort was 25.7 years (SD 5.1 years) and 54% were female. The inter-rater reliability was excellent for PFADIR (ICC 0.85 95% CI 0.76-0.91), good for PN (ICC 0.69 95% CI 0.5-0.81), and good for PStand (ICC 0.72 95% CI 0.55-0.83). The intra-rater reliability for all raters was good for PFADIR (ICC 0.60 95% CI 0.44-0.73), fair for PN (ICC 0.42 95% CI 0.21-0.59), and fair for PStand (ICC 0.42 95% CI 0.22-0.59). CONCLUSION: This is the first study to present a protocol using dynamic ultrasonography to measure FAPT. DHUS measure for FAPT was shown to be reliable across raters with varying levels of ultrasound experience.