Incidence of Developmental Hip Dysplasia by Ultrasonographic Screening of Asymptomatic Infants Less Than 6 Months Old at Assiut University Hospital Outpatient Clinics

The origin and pathogenesis of DDH are multifactorial. Abnormal laxity of the ligaments and hip capsule is seen in patients with DDH. The maternal hormone relaxin may also be a factor. Extreme hip flexion with knee extension, as in the breech position, tends to promote femoral head dislocation and leads to the shortening and contracture of the iliopsoas muscle.

It was previously reported that DDH was the underlying aetiology in about 25 % of the performed hip replacements under the age of 40 years and the initial diagnosis age ranged from 0 to 39 years, with a mean of 8 years in these patients.

The main purpose of a newborn hip screening program is to detect DDH as early as possible, so that early treatment can be given and the need for surgical treatment as well as the development of residual hip dysplasia can be avoided.

Ultrasonography offers distinct advantages compared with other imaging techniques: unlike plain radiography, it can distinguish the cartilaginous components of the acetabulum and the femoral head from other soft tissue structures, real-time US permits multiplanar examinations that can early determine the position of the femoral head in respect to the acetabulum; thus it provides the same type of information that can be obtained with arthrography, computerized tomography, or magnetic resonance imaging, but at lower cost, although ultrasonography is more expensive than plain radiography, it doesn't require sedation and doesn't involve ionizing radiation, unlike other techniques and it allows observation of changes in hip position with movement.