Hip (Dunn view)

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The Dunn view is a radiographic projection of the hip that demonstrates and examines the hip joint, femoral head, acetabulum, and particularly the relationship of the femoral head and acetabulum.

Indications

The Dunn view is the preferred projection to aid in the diagnosis of femoroacetabular impingement (FAI) due to its increased sensitivity for detecting femoral head-neck asphericity.

Patient position

  • patient is supine with the pelvis in neutral rotation (anterior superior Iliac spine equidistant from the tabletop)
  • the hip joint is flexed 90° and abducted 20° while the pelvis remains in neutral rotation

Technical factors

  • AP projection
  • centering point
    • the midpoint between the anterior superior iliac spine (ASIS) and pubic symphysis
  • collimation
    • laterally to the proximal third of the femur
    • superiorly to ASIS
    • inferiorly to the crease of buttock
    • medially to midline
  • orientation
    • landscape
  • detector size
    • 24 x 30 cm
  • exposure
    • 70-80 kVp
    • 20-30 mAs
  • SID
    • 100 cm
  • grid
    • yes

Image technical evaluation

  • the bony pelvis is imaged from ASIS to the proximal shaft of the femur
  • the obturator foramina appear open
  • greater and lesser trochanter of the proximal femur is in profile
  • proximal one-third of the femur is visible
  • the anterior aspect of the femoral head should be demonstrated in profile.

Practical points

The Dunn view may be performed with 45° hip flexion in a neutral rotation if 90° hip flexion is hard to achieve, this is known as the modified Dunn view .