Abstract

In a prospective screening of 2222 consecutive live hospital births over a ten-month period in Abha, there was an incidence of 3.6% for congenital hip instability by examination within 48 hours of delivery. This is a higher incidence than that reported from most parts of the world and is comparable to earlier Japanese figures. This suggests a regional variation in the incidence of hip instability within the Kingdom of Saudi Arabia. Bilateral instability was found in 32% and there was a left lateral dominance. There was a significantly higher incidence in female babies, in the local Saudi population and in first degree relatives of affected babies. Hip instability was noted in 8% of breech deliveries. No association was demonstrable with maternal age, birth order, size of the baby or gestation. Our findings are compared with other published data from Saudi Arabia and the West. The need for continued appropriate neonatal screening for early diagnosis of congenital hip instability is emphasized.

Patients and Methods

During the first ten months of the year 1407H, 2222 consecutive liveborn babies delivered at Abha General Hospital were examined by the authors within 48 hours of birth. The history was obtained from the mother and the obstetrical case notes The hips were examined using Ortolani am Barlow maneuvers. The hip was graded as being unstable if it was dislocatable or dislocated Babies with “clicks” and those with tight adductors but without clinical dislocation were no included in this group. Routine x-rays ant ultrasound examination were not used for screening.

All babies with hip instability were splinted using the von Rosen splint or the Pavlik harness. The babies were reviewed at one, six, and twelve weeks of age to ensure compliance with the treatment and to assess the progress. Initial hip x-ray were taken at four months and splinting continued until the capital femoral epiphysis appeared con centrically in the acetabulum. The babies were further followed until walking age.

The neonatal data were analyzed using the Chi square and Student’s t tests. The chosen level of significance was 5%.

Results

Incidence and Laterality

There were 81 babies with hip instability giving an overall incidence of 3.6%. Bilateral instability (N = 26) was noted in 32% of this group of neonates. In babies with unilateral instability (N = 55), the left hip was more commonly involved than the right with a ratio of 5.8:1.

Sex and Nationality

The distribution by sex and nationality is shown in Table 1. Hip instability was twice as common in Saudi babies as those born to non-Saudi mothers There was no instance of unstable hip among the 53 babies born to non-Arab mothers. A significantly higher incidence was noted among female neonates.

Table 1. Nationality and sex distribution.

The association of hip instability with birth weight and maternal age is shown in Table 2 and the distribution among various “weight for age” categories [6] in Table 3. No significant association was demonstrable with any of these parameters. There was one unstable hip among 81 preterm neonates and none among 24 twin births.

Hip instability was noted in 4.1% of firstborn babies (N = 363), and in 3.6% of babies of a higher birth order (N = 1859). This did not indicate a significant difference (P > 0.05).

There was a higher proportion of babies with unstable hips born by cesarean section (5.5%), vacuum extraction (4.2%) or breech delivery (7.9%) than among those born by spontaneous vertex delivery (3.2%). However, this difference was statistically significant only for breech births (Table 4).

A positive family history of hip dislocation in first degree relatives was obtained in six of 81 babies (7.4%) with hip instability and in four of the 2141 babies (0.2%) with stable hips. This difference was significant (P < 0.05).

Table 2. Association with birth weight and maternal age.

Table 3. Association with “weight for age” categories.

Table 4. Association with mode of delivery.

*Versus spontaneous vertex delivery.

Hip instability was noted in three of eight babies with congenital talipes equinovarus (P < 0.05). One baby each had dysmorphic features and bilateral undescended testes in association with hip instability. Planovalgus, metatarsus varus and spinal anomalies were not noted among the neonates with unstable hips in this cohort.

Limitation of hip abduction in flexion to > 30 degrees above the examination table was noted in 104 (4.7%) and palpable “clicks” in 322 (14.5%) babies of the population. Repeated examination and follow-up of these groups of babies failed to reveal any hip dislocations.

Discussion

The incidence of congenital hip instability shows a variation in different communities and races [2]. At a symposium on clinical neonatology in Tabuk in 1986, Fysh raised the question about the frequency and severity of the problem in the Asir region of Saudi Arabia. The current prospective study confirms this impression by showing an unusually high incidence of the problem in this part of the Kingdom. This is comparable to the incidence found in some communities such as the Lapps, American Indians, and the Japanese in the early sixties [2,7]. Al-Umranet al [3] reported a lower incidence (0.49%) with congenital hip instability in a hospital born cohort over a five-year period from the Eastern Province of Saudi Arabia. This suggests a true regional variation in the incidence of hip instability within the country.

Examination of the hips within the first few days after birth has been known to give a higher yield of positive findings than later examination [8]. In addition, Palmen [1] emphasized the importance of experienced personnel and good organization of the hip screening program in order to maximize the yield. We believe that these factors were operative in the present prospective study and contributed to the recording of a high incidence.

Familial factors such as joint laxity are known to predispose to congenital dislocation of the hip [9]. The finding of a significantly higher incidence of the problem in family members, as in this study, has been previously reported [10]. The custom of consanguineous marriages in the Kingdom [11] and the higher frequency of hip instability in the indigenous Saudi population suggests that hereditary factors may also be contributory to the local high incidence of the problem.

Various factors associated with congenital hip instability reported locally and internationally are compared in the present report. The female predominance is in keeping with other reports from the Middle East and the West [3,10]. The proportion of bilateral instability and left laterality are similar to Western figures [12] and at variance with Mufti’s [13] data from Riyadh as shown in Table 5.

The association of hip instability with breech position in utero, whether delivered vaginally or by cesarean section, has been recognized [14]. Congenital hip dislocation has been reported to be present in 11% to 22% of breech presentations [1,15]. Our finding of a relatively lower proportion (8%) of hip instability in breech births could possibly be explained by the fact that babies in breech position who were delivered by cesarean section were not taken into consideration.

There have been conflicting reports of the association of birth weight and gestational age with hip instability. Both large and small baby sizes have been implicated as risk factors [1,10]. Khouryet al [16] noted that congenital dislocation of the hip, unlike most other malformations, was not associated with intrauterine growth retardation. Within the Kingdom, Al-Umran found an association with large for gestational age babies, and Mufti with preterm babies [3,13]. The present study failed to demonstrate any significant association of hip instability with the size of the baby or gestational age. The finding of congenital hip dislocation being uncommon in twins, as in the present study, has been previously reported [17].

Lower maternal age and first birth rank are thought to predispose to hip dislocation owing to the extrinsic pressure of a tight uterus on the fetal hips in these circumstances [10,13,18]. Neither of these variables was shown to be a significant risk factor for hip instability in this study.

Table 5. Comparison of laterality in CDH.

Postnatal cultural practices such as swaddling, that maintain the infant’s hips in extension and adduction, are known to cause progression of an unstable hip to established dislocation [7]. We have noted this practice to be prevalent in Abha. as has been reported from other parts of Saudi Arabia [19]. This cannot, however, explain the high incidence of hip instability noted at birth on screening, but has implications for health education about the postnatal care of babies [20].

The role of ultrasound in screening for congenital hip instability is under investigation and remains a matter of controversy with advocates for and against this method [21,22]. Used selectively, ultrasound may be helpful in confirming hip instability in clinically equivocal cases or in following up high risk cases [22]. However, it would be impractical to use as a routine screening method in areas with high birth rates or inadequate facilities for the procedure. Despite questions about its accuracy [2], neonatal physical examination remains the most practical routine screening method available for early diagnosis of congenital hip instability [23].

This study highlights congenital instability as an important problem in the Asir region of the Kingdom. It underlines the need to ensure that the practice of screening for hip instability is implemented throughout the region and that the program is adequately supervised. Follow-up studies are indicated to assess the impact of such a program in reducing the incidence of later morbidity. Further regional studies are needed to determine the extent of the problem in different areas of the country.

Acknowledgment

This study was supported by the College of Medicine Research Committee, King Saud University, Abha.

References