An alpha angle below which value indicates dislocation of the hip?

An alpha angle below which value indicates dislocation of the hip?

• A. 39 degrees
• B. 41 degrees
• C. 43 degrees
• D. 45 degrees

Answer: (C)

An alpha angle on neonatal hip ultrasound reflects the slope of the acetabular roof. A smaller angle means a shallower socket and a higher likelihood of dislocation. In many ultrasound criteria, a cutoff around 43 degrees is used to signal dislocation: if the alpha angle falls below this value, the hip is considered dislocated. Normal hips show a much larger angle (well above 50°), and as dysplasia progresses the angle decreases, but dislocation is most consistently indicated when the angle is in the low 40s or below. Therefore, an alpha angle below 43 degrees is the threshold that best indicates dislocation in this context.

An alpha angle on neonatal hip ultrasound reflects the slope of the acetabular roof. A smaller angle means a shallower socket and a higher likelihood of dislocation. In many ultrasound criteria, a cutoff around 43 degrees is used to signal dislocation: if the alpha angle falls below this value, the hip is considered dislocated. Normal hips show a much larger angle (well above 50°), and as dysplasia progresses the angle decreases, but dislocation is most consistently indicated when the angle is in the low 40s or below. Therefore, an alpha angle below 43 degrees is the threshold that best indicates dislocation in this context.