Risk factors and diagnosis of developmental dysplasia of hip in children

Abstract

Developmental dysplasia of hip (DDH) is one entity one occasionally comes across while in a busy orthopaedic or paediatric outpatient department. The knowledge of risk factors and awareness of the condition is must for every orthopaedic surgeon and paediatrician as well lest the diagnosis will be missed. An early diagnosis can alter the prognosis of the disease and prevent late disabilities.

Keywords: Congenital dislocation of hip; Developmental dysplasia of hip; Diagnosis; Risk factors.

Fig. 1

Ortolani manoeuvre.

Fig. 2

Barlow manoeuvre.

Fig. 3

Galeazzi manoeuvre. Note that skin creases may look similar on both sides. The right hip is dislocated.

Fig. 4

Ultrasound interpretation of DDH. The alpha and beta angle measurements are used to indicate the degree of acetabular development. A line is drawn parallel to the ossified lateral wall of the ilium (baseline). A second line is drawn along the roof of the cartilaginous acetabulum (from the lateral bony edge of the acetabulum to the labrum) to give the beta angle; this denotes the slope of the cartilaginous acetabulum. A third line is drawn from the inferior edge of the bony acetabulum, at the triradiate cartilage, to the distal part of the ilium, tangential to the slope of the bony acetabulum (roof line). The angle between the 1st and 3rd line is the alpha angle. The alpha angle denotes the slope of the bony acetabulum. Normally, the alpha angle is greater than 60° and an angle less than 55° is considered abnormal.

Fig. 5

Radiographic findings in DDH. The triradiate cartilage lies between the ilium, the ischium, and the pubis. Hilgenreiner's line passes through the triradiate cartilages. Perkin's line, drawn at the lateral margin of the acetabulum, is perpendicular to the Hilgenreiner's line. Shenton's line is a curved line that begins at the lesser trochanter, goes up the femoral neck, and connects to a line along the inner margin of the pubis. Acetabular index is an angle formed by the juncture of Hilgenreiner's line and a line drawn along the acetabular surface. Centre edge (CE) angle (used in older children) is formed at the juncture of Perkin's line and a line connecting the lateral margin of acetabulum to the centre of the femoral head. In normal hip, the medial beak of the femoral physis lies in the lower inner quadrant formed by the juncture of Perkin's and Hilgenreiner's line, the Shenton's line is not broken, acetabular index is less than 30°, the CE angle is more than 19° (6–13 years).

Fig. 6

Same patient as Figs. 1–3 above. The plain radiographs show the dislocated right hip.