Developmental dysplasia of the hip — formative SAQs

SAQ 1 (10)

A six-week-old girl born in the breech position at thirty-seven weeks is referred after her general practitioner felt a clunk on the left Ortolani test at the six-week check. She is otherwise well, with a normal developmental history. A coronal hip ultrasound reports a left Graf type III hip with an alpha angle of forty degrees. [1] [2]

a) Describe how to perform the Ortolani and Barlow tests on a newborn, naming the hand positions and the movement that each test provokes. (4 marks) [2]

b) State the Graf alpha-angle thresholds that separate a normal hip, an immature hip, a critical hip, and a dislocated hip. (4 marks) [1]

c) Outline the immediate management of this infant, naming the device, its target position, and the investigation that confirms reduction at three weeks. (2 marks) [3]

SAQ 2 (10)

A two-year-old girl is brought in by her parents because she has been limping on the left leg for two months. She is afebrile, walks with a painless antalgic gait, and has a left leg that is shorter than the right. She had normal newborn checks. An anteroposterior pelvis radiograph shows the left femoral head displaced upward and lateral to Perkins's line above a shallow acetabulum. [4] [2]

a) Explain why the newborn Ortolani and Barlow tests may have been negative in this child despite an established dislocation, and name the bedside sign that is most reliable in the older infant. (3 marks) [1]

b) Name the radiographic reference lines used to grade the dislocation, and state the acetabular index value that defines a dysplastic socket. (3 marks) [1]

c) Outline the surgical management of a child presenting at this age, naming the procedure and one reason the outcome is guarded compared with an infant treated in a Pavlik harness. (2 marks) [4]

d) The parents ask why a hip problem was missed if the newborn checks were normal. Explain the limitations of clinical screening and name the two infant groups for whom selective ultrasound is recommended. (2 marks) [2]