A stabilization device significantly improves measurement reliability and efficiency of Graf ultrasonography for developmental dysplasia of the hip: a retrospective cohort study.

OBJECTIVES: To compare the measurement reliability, procedural efficiency, and infant stress responses between device-assisted and manual restraint approaches in Graf hip ultrasonography for developmental dysplasia of the hip (DDH) screening. METHODS: In this retrospective cohort study, 238 infants (aged 0-6 months) underwent consecutive hip ultrasound examinations using both a Graf stabilization device and manual restraint during the same visit. Each examination included triple measurements of α and β angles by a single experienced sonographer. Primary outcomes included angle measurements and Graf classification. Examination time and infant crying incidence were also recorded. Intra-observer reliability for repeated measurements within each technique and inter-technique agreement between the two methods were evaluated separately using intraclass correlation coefficients (ICC) and Cohen's kappa. RESULTS: No significant differences were observed in α angle (67.00° vs. 67.50°, P = 0.313), β angle (71.00° vs. 69.00°, P = 0.179), or Graf classification distribution (P = 0.832) between device-assisted and manual methods. However, the device-assisted approach showed significantly shorter examination time (P < 0.001) and a 13.5-fold reduction in crying incidence (0.84% vs. 11.34%, P < 0.001). Intra-observer reliability was excellent with device assistance (α angle: ICC = 0.95, β angle: ICC = 0.90) but poor with manual restraint (α angle: ICC = 0.49, β angle: ICC = 0.23). Inter-technique agreement was moderate for α angle (ICC = 0.71) and substantial for Graf classification (κ = 0.66), but poor with β angle (ICC = 0.36). CONCLUSION: The use of a stabilization device in Graf hip ultrasonography significantly improves measurement reliability and may enhance examination efficiency and infant comfort without altering diagnostic outcomes, supporting its integration into high-volume DDH screening programs.