The incidence of DDH requiring treatment in the world literature varies from less than 1/1000 to 34/1000 [4]. There is no data available on the incidence of DDH in our country. A large proportion (90%) of late presenting DDH in our practice combined with very few referrals in early infancy have been the stimulus for this study to assess the incidence of ultrasonological abnormalities and the true hip dislocation rate in Indian children.

This study aimed to determine the incidence of DDH and ultrasonological hip abnormality in our population. An average of the highest and the lowest incidence of DDH reported in the literature is 1.7% (<0.1% to 3.4%), while the average incidence of sonographic abnormality in infants from the studies across the world was 17.1% [2,3]. Based on this a pilot study with 1000 infants was planned. The ethical clearance from Institutional Review Board was obtained.

After informed consent, 1000 consecutive infants, presenting for their first DPT vaccination at the well baby immunization clinic of our institution were selected for screening using Graf’s technique [5]. Clinical examination of the hip, other congenital abnormalities, and family history was documented.

LOGIC e ultrasound machine (General Electric Medical Systems, Chalfont St. Giles, United Kingdom) with a linear probe (8-12 MHz) was used. The training in performing and reading ultrasounds according to Graf’s technique was obtained by the authors in a 3-day workshop conducted by Dr Graf and practised in the department. Children were screened in lateral position in a specialized cradle. Ultrasonologically, abnormal but centered hips were followed till they became mature. Decentered hips (type D, III and IV) were given treatment.

One thousand infants, 563 boy and 437 girls, mean age 47.8 days (40 to 67 days) were screened and their ultrasonological distribution of the hip types according to Graf is shown in Table I. Seventy five infants showed ultrasonological abnormalities of which seventy four had dysplastic hips (7 of these were bilateral) while one infant had a dislocated hip (Graf III) and required treatment. Seventy out of the 74 infants with Graf type II hips were followed up sonographically till maturity while 4 were lost to follow up. The ultrasonological incidence of abnormal hips was 7.5% with a relative precision of 22% at 5% level and the incidence of true dislocation at examination was 1 in 1000.

Table I



Distribution of Hip Type (Graf’s) in the Population

Fifty one (11.67%) out of the 437 girls and 24 (4.26%) of the 563 boys were affected which was statistically significant (P<0.01). No infant had a family history of DDH.

A positive Ortolani test was noted in the one child with a dislocated hip after the screening. Associated foot deformities included bilateral calcaneovalgus in two, bilateral clubfoot in one and metatarsus adductus in one infant. One of the infants with clubfoot and one with bilateral calcaneovalgus had an immature hip (IIa) on one side.

In our country, the only screening is clinical and is carried out by pediatricians or obstetrician. There is no national screening protocol or national registry and no data exists on incidence of DDH estimated clinically or ultrasonologically.

The ultrasound screening was chosen by us because it is the gold standard and is highly sensitive. The disadvantage is that further follow up of all abnormal hips is required. While Graf IIa and IIb only require observation many authors choose to treat Graf IIc hips, which are severely dysplastic but not unstable [2]. In our study, we observed all abnormal hips except the one with dislocation. All type II hips returned to normal by 3 months of age. The ultrasonological follow up thus allowed us to decrease the number needed to be treated to just one in thousand.

Contributors: CB and VM planned, carried out the study and wrote the manuscript.

Funding: None.

Competing interests: None stated.

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