Screening of developmental dysplasia of the hip in the newborns

Received Accepted ٢٨.٣.٢٠١٠ ١٤.١١.٢٠١٠ ABSTRACT Background: Newborn babies are known to have risk for occurrence developmental dysplasia of the hip so early clinical screening test is very important to detect this problem and prevent further abnormal growth. The aim of this study is to find the rate of occurrence of developmental dysplasia of the hip (DDH) among newborn babies and establish good screening program. Patients and methods: From August ٢٠٠٦ to March ٢٠٠٩ in AL-Khansaa Maternity and Children Teaching hospitals, ٩٥٩٢ newborn babies were examined clinically using Barlows and ortolani tests for detecting DDH. Results: Only ١٦٢ newborn babies out of ٩٥٩٢ examined babies had DDH and it was found more common among female and more on left side than right side. Female sex, rural residence, first born baby breach, caesarean section positive family history, multiple pregnancy post-mature babies, high birth weight (>٣٥٠٠ g). Conclusion: The occurrence of neonatal DDH is still form a major problem among newborn babies causing a lot of morbidity need to follow up to avoid further complicating problem.


Clinical screening
The purpose of screening programs is to diagnose dislocation at early age when treatment is easy and the prognosis is excellent ٧ , also to prevent pain, limitation of function and disability due to dislocated or subluxated hips ٩ .
Ortolani/Barlow's maneuvers are the only currently acceptable nontraumatic procedures which do not unduly expose all children to routine irradiation ١٠ . The Ortolani / Barlow's tests are ١٠٠% specific but only ٦٠% sensitive in expert hands ١٠ .

Patients and methods
Nine thousand five hundred and ninety two newborn babies out of were examined clinically (in patients) for the presence of any sign of DDH in Al-Khansaa Maternity and Children Teaching Hospitals during the period from the ١st of August ٢٠٠٦ to the March ٢٠٠٩. Detailed information were taken from their mothers or any near relative including: ١.  The clinical examination consisted of the following maneuver: Ortolani (reduction) test: to detect dislocated hip, with the newborn relaxed and content on a firm surface the hips and knees are flexed to ٩٠º, the hips are examined once at a time, then grasping the newborn thigh with the middle finger over the greater trochanter and lifts the thigh to bring the femoral head from its dislocated posterior position to reducing the femoral head into the acetabulum. In a positive finding, examiner senses reduction by a palpable and nearly audible clunk ( Figure ١).
This test was also carried as the following: After placing the baby on his/her back with the leg pointing towards the examiner, the hips are flexed to a right angle and the knees are fully flexed. The finger applied to the greater trochanter and the thumb of each hand is applied to the inner side of the thigh opposite to the position of the lesser trochanter as shown in ( Figure ٢). Then the newborn thigh is adducted with a gentle downward pressure (posterior force). If the hip is dislocatable this usually readily felt as femoral head slips out of the acetabulum. After release of posterior pressure the hip will usually relocate spontaneously.
The results were analyzed statistically by using Chi-square (χ٢) test, Odd's ratio and Confidence Interval (C.I.) for the Odd's ratio. P value less than ٠.٠٥ was considered significant.

Results
One hundred and sixty two newborn babies out of the examined ٩٥٩٢ proved to have DDH in one or both hip joints during the first few hours after birth forming a rate of ١٦.٩/١٠٠٠ live births. Table ١. Sex distribution of neonatal DDH cases and control Sex Cases Control shows that the majority of the cases were female (٧٥%) with a female to male ratio of ٣:١.  Table ٢ shows that a highly significant difference between cases and control in their residence (P value ≤ ٠.٠٠١) were a good number of patients came from rural areas (OR = ٢.١).
From Table ٣, it is clear that the first born baby is affected more than the subsequent babies with a highly significant difference (P-value ≤ ٠.٠٠١ and OR = ٢.٣ for the first born baby).
Ttable ٤ shows that consanguineous marriage is a risk for the occurrence of DDH (OR = ١.١٦) although there is no significant difference between cases and control in the frequency of parental consanguinity.  Table ٥ shows that breech presentation is a risk factor with a significant difference (P-value = ٠.٠٤, OR = ٢.٢) between cases and control.  Table ٦ shows no significant difference between cases and control, while the OR seems to be operational in the causation of DDH (OR = ١.٦).  Table ٧ shows that ٢٦% of cases had a family history of DDH compared to ٦% of the control group with a highly significant difference (P ≤ ٠.٠٠١, OR = ٥.٤).  Table ٨ shows that multiple pregnancy is a risk factor for the occurrence of DDH( P = ٠.٠٠١, OR = ٣.١).
Overall χ ٢ = ٣.٨, df = ٢, P = ٠.١٤٣ (N.S) Table ٩ shows no significant difference in the gestational age of DDH cases and control, but there is additional risk for post-term newborn to have DDH than that of preterm (OR = ٢.٥).
Overall χ ٢ = ٤٠.٢, df = ٢, P ≤ ٠.٠٠١    Table ١٢ shows that Ortolani test was positive in ٤٠% of cases.   Table ١٤ shows that the left hip is more commonly involved than right hip, and bilateral involvement of the hips is also common.  Table ١٥ demonstrates that unequal skin thigh creases were more common in the cases than in the control group (P-value ≤ ٠.٠٠١). Also an evident difference is observed among those with equal and inapparent creases.  Table ١٦ shows that unequal inguinal skin folds were more common in DDH cases than in the control group (Pvalue ≤ ٠.٠٠١).
One hundred forty babies (٨٦.٤%) out of ١٦٢ came for follow-up every two weeks and at the end of one month of their age ١١٠ (٦٨%) of them, their hips were completely stabilized following our instructions of using double or triple nappies together with the avoidance of heavy wrapping and rolling bed. The other remaining ٣٠ cases (١٨.٥%) were asked to come back for other follow-up for every two weeks.

Discussion
In this study, the rate of occurrence of neonatal DDH was ١٦.٩ /١٠٠٠ live birth, and this number are nearly similar to that reported by other studies ١٣-١٥ . Female sex was more affected than male sex as evident by the high OR = ٣.٣, which means that a female sex is an effective risk factor. Female to male ratio, in this study, was ٣:١ similar to that found by other studies ١٦-١٨ , but Apley's ١٩ found a higher ratio of ٧:١. DDH was more common in cases who came from rural areas than in the control group, a difference of highly significant value (P ≤ ٠.٠٠١) with additional risk for rural residence among DDH cases OR = ٢.١, and this is because the incidence of DDH is influenced by geographic and ethnic factors as stated by other studies ١٨-٢٢ , however Al-Kattan ١٧ found no additional risk for rural residence among DDH cases.
First order baby is more prone to have DDH where the OR=٢.٣ in contrast to the third or more orders in the family where the OR is ٠.٤. These findings are consistent with other studies

١٩-٢٢
Parental consanguinity was not significant between the cases and control although OR of ١.١ which means that probably consanguineous marriage is a risk factor similar to that found by Al-Kattan ١٧ .
Breech presentation was a risk factor in the causation of DDH (OR=٢.٢). These result are in agreement with other studies ١٨-٢٣ also found that breech presentation and positive family history were the two most common risk factors associated with DDH. Caesarean section seems to be a risk factor for DDH where OR is ١.٦ similar to that found by Al-Kattan ١٧ .
Family history was positive in ٤٣ cases and OR was ٥.٤ which means a high risk factor and this is probably explained by the presence of genetic factor this in agreement with other studies showed strong family history in their studies.

١٧,١٨,٢٣
Multiple pregnancy was a risk factor for DDH where OR was ٣.١, probably due to the effect of crowding phenomenon within the intrauterine cavity, A similar association was found by Al-Kattan ١٧ . Post-maturity was a risk factor to have DDH (OR=٢.٥) while preterm delivery does not appear to predispose to DDH (OR=٠.٤) as Apley's ١٣ claimed that high level of maternal hormones in the last few weeks of pregnancy might aggravate ligamentous laxity in the infant, and this could account for the rarity of hip instability in premature babies born before the hormones reach their peak. All these findings are consistent with those previously reported ٢١,٢٢ .
High birth weight > ٣٥٠٠ g seems to be effective in the causation of DDH where OR=٤.٢, while babies with low birth weigh < ٢٥٠٠ g were protected from having DDH (OR=٠.٧). Left-sided and bilateral hip involvement were found in ٤١.٤% and ٣٦.٤% of patients respectively, and right hip involvement in ٢٢.٢% of patients, similar to that reported by other studies ٢٠,٢٤ . On the other hand Bower C, ٢٢ found that bilateral involvement was twice as common in the neonatal cases and left hip involvement more than right hip involvement in the post-neonatal cases.
Unequal skin thigh creases (٣٠%) were more common in the cases than in the control group (١١.٧%), a difference of a highly significant value (P≤٠.٠٠١). Asymmetry of the skin folds is a common clinical finding of DDH ٢٣ .
Unequal inguinal folds was found in ٣٢.٨% of the cases compared to ٩.٣% of the control group (P value ≤ ٠.٠٠١). Beaty, ٢٠ noticed that most of his DDH patients had abnormal inguinal folds and recommended that inguinal fold assessment is useful in screening methods and suggested that babies with asymmetrical inguinal folds need further evaluation. One hundred ten babies (٦٨%) had clinical stabilization of the hip joint at the age of four weeks, and this is consistent with other results ٢٤ .

Conclusions
Developmental dysplasia of the hip is still a major problem among newborn babies causing a lot of morbidity to them. Female sex, rural residence, first born baby, parental consanguinity, breech presentation, caesarean section, positive family history, multiple pregnancy, post-mature babies, high birth weight (>٣٥٠٠ g) and other associated congenital anomalies are all risk factors for DDH. Left hip dysplasia was more common than bilateral hip dysplasia which was more common than right hip dysplasia.The majority of the babies (٦٨%) improved nicely at the age of one month by adoption of double or triple nappies and following our instructions.