Effectiveness of screening for congenital dislocation of the hip

The epidemiology and demographics of hip dysplasia

The etiology of developmental dysplasia of the hip (DDH) is unknown. There are many insights, however, from epidemiologic/demographic information. A systematic medical literature review regarding DDH was performed. There is a predominance of left-sided (64.0%) and unilateral disease (63.4%). The incidence per 1000 live births ranges from 0.06 in Africans in Africa to 76.1 in Native Americans. There is significant variability in incidence within each racial group by geographic location. The incidence of clinical neonatal hip instability at birth ranges from 0.4 in Africans to 61.7 in Polish Caucasians. Predictors of DDH are breech presentation, positive family history, and gender (female). Children born premature, with low birth weights, or to multifetal pregnancies are somewhat protected from DDH. Certain HLA A, B, and D types demonstrate an increase in DDH. Chromosome 17q21 is strongly associated with DDH. Ligamentous laxity and abnormalities in collagen metabolism, estrogen metabolism, and pregnancy-associated pelvic instability are well-described associations with DDH. Many studies demonstrate an increase of DDH in the winter, both in the northern and southern hemispheres. Swaddling is strongly associated with DDH. Amniocentesis, premature labor, and massive radiation exposure may increase the risk of DDH. Associated conditions are congenital muscular torticollis and congenital foot deformities. The opposite hip is frequently abnormal when using rigorous radiographic assessments. The role of acetabular dysplasia and adult hip osteoarthritis is complex. Archeological studies demonstrate that the epidemiology of DDH may be changing.

Screening for developmental dysplasia of the hip: a systematic literature review for the US Preventive Services Task Force

BACKGROUND

Developmental dysplasia of the hip (DDH) represents a spectrum of anatomic abnormalities that can result in permanent disability.

OBJECTIVE

We sought to gather and synthesize the published evidence regarding screening for DDH by primary care providers.

METHODS

We performed a systematic review of the literature by using a best-evidence approach as used by the US Preventive Services Task Force. The review focused on screening relevant to primary care in infants from birth to 6 months of age and on interventions used in infants before 1 year of age.

RESULTS

The literature on screening and interventions for DDH suffers from significant methodologic shortcomings. No published trials directly link screening to improved functional outcomes. Clinical examination and ultrasound identify somewhat different groups of newborns who are at risk for DDH. A significant proportion of hip abnormalities identified through clinical examination or ultrasound in the newborn period will spontaneously resolve. Very few studies examine the functional outcomes of patients who have undergone therapy for DDH. Because of the high rate and unpredictable nature of spontaneous resolution of DDH and the absence of rigorous comparative studies, the effectiveness of interventions is not known. All surgical and nonsurgical interventions have been associated with avascular necrosis of the femoral head, the most common and most severe harm associated with all treatments of DDH.

CONCLUSIONS

Screening with clinical examination or ultrasound can identify newborns at increased risk for DDH, but because of the high rate of spontaneous resolution of neonatal hip instability and dysplasia and the lack of evidence of the effectiveness of intervention on functional outcomes, the net benefits of screening are not clear.

Surgery for congenital dislocation of the hip in the UK as a measure of outcome of screening. MRC Working Party on Congenital Dislocation of the Hip. Medical Research Council

BACKGROUND

Universal clinical screening for congenital dislocation of the hip to detect hip instability in neonates was introduced in the UK as a national policy in 1969, but its effectiveness is not known. We aimed to assess the extent to which surgery for congenital dislocation of the hip is the result of a failure of detection through screening or follows non-surgical treatment after detection by screening.

METHODS

We established a national orthopaedic surveillance scheme and used routine hospital data for inpatients for 20% of births in the UK (Scotland and the Northern and Wessex regions) to ascertain the number of children aged under 5 years per 1000 livebirths who had received at least one operative procedure for congenital dislocation of the hip from April, 1993, to April, 1994. Estimates of the incidence of operative procedures were adjusted for under-ascertainment by capture-recapture techniques.

FINDINGS

The ascertainment-adjusted incidence of a first operative procedure for congenital dislocation of the hip in the UK was 0.78 per 1000 livebirths (95% CI 0.72-0-84). Congenital dislocation of the hip had not been detected by routine screening in 222 (70%) of 318 children reported to the national orthopaedic surveillance scheme. In 112 (35%) children the diagnosis was made primarily as a result of parental concern. 67 (21%) children had previously received non-surgical treatment. In Scotland and the Northern and Wessex regions, 81 cases were notified to the national orthopaedic surveillance scheme, 62 cases were identified only through routine hospital data on inpatients, and an estimated 20 cases were not identified by either source, making a total of 163 cases. Thus, 81 (50%) of these 163 cases were identified by surveillance, 125 (77%) by routine data, and 143 (88%) by both sources.

INTERPRETATION

The incidence of a first operative procedure for congenital dislocation of the hip in the UK was similar to that reported before screening was introduced. In most children who received surgery, congenital dislocation of the hip was not detected by screening. Formal evaluation of current and alternative screening policies, including universal primary ultrasound imaging, is needed.

A national survey of screening for congenital dislocation of the hip

OBJECTIVE

To identify current screening and management practices for congenital dislocation of the hip (CDH), and determine the extent to which ultrasound imaging of the hips is practised throughout the United Kingdom and the Irish Republic.

METHODS

Postal questionnaire to paediatricians responsible for the routine neonatal care of infants in all maternity units in the UK and the Irish Republic.

RESULTS

Questionnaires were returned for 254 maternity units (92% response rate). By 1994, 69% of maternity units had access to ultrasound imaging of the hips, compared to 14% in 1984. Ultrasound imaging of the hip was not used for universal primary screening, but in 93% of units was undertaken for further assessment of infants with clinically detected hip instability or those identified as being at high risk of CDH, or both. Clinical screening of newborn infants was performed by junior paediatricians, but training with a 'Baby Hippy' hip simulator model was provided in only 37% of units. Treatment of clinically detected hip instability, initiated by an orthopaedic surgeon in 93% of units, varied widely in type and duration.

CONCLUSIONS

Ultrasound imaging of the hip is increasingly used in the UK for secondary, rather than primary, screening. Current recommendations are implemented to a variable extent nationally, and the existing wide variation in screening and management for CDH reflects a lack of research evidence to support current screening practices. The effectiveness of screening for CDH needs to be established.

McKeown, Record, and the epidemiology of malformations

Thomas McKeown and RG Record were colleagues in Birmingham, England, from 1947 to 1977. During their first decade together, they laid the foundations of epidemiological research on malformations with a series of case-control studies of the commoner major defects. They found evidence of numerous trends of birth prevalence with variables such as season and year of birth, maternal age, birth rank, and socioeconomic status, suggesting that environmental factors played an important part in causation. The work that has led recently to the use of folate to reduce the risk of neural tube defects is among the lines of research that can be traced back to these case-control studies. McKeown and Record also initiated, in Birmingham, the first population-based register of malformations to be set up as an on-going activity. As well as paving the way for the international networks of registers that now exist, the Birmingham register has been used in a variety of cohort studies. This work has confirmed many of the case-control study findings and continues to yield new observations, including evidence that enteroviruses are involved in aetiology.

High incidence of congenital dislocation of the hip in Northern Ireland

To determine the incidence of congenital hip dislocation (CDH) a retrospective study was carried out of cases occurring in a defined population using multiple information sources. Of 138,600 children born in the period 1983-1987, a total of 243 were diagnosed with CDH, defined as those requiring splintage or surgery whose treatment extended beyond 6 months of age. Incidence and estimates of relative risks for pre-disposing factors were determined. The rate was 1.75 cases per 1000 livebirths. Major risk factors were female gender and breech presentation. The proportions of cases identified before 1, 3 and 6 months of age were 8, 14 and 35%, respectively. Despite using a restrictive definition, we have obtained an incidence rate among the highest reported in any United Kingdom population. Early detection is widely accepted as desirable, but neonatal screening has proved ineffective.

A case-control study of congenital hip dislocation

In this study we have investigated various epidemiological factors which may be related to congenital dislocation of the hip (CDH). Eighty-one cases born during the period 1st January 1988 to 31st August 1990, with four matched controls per case, were identified from consultants' records held at the Queen's Medical Centre and City Hospital, Nottingham. One hundred and twenty-four subjects who were referred to a new Hip Instability Clinic with suspected CDH, but not diagnosed or treated for CDH, were also included as a third group. Information about the mother's pregnancy, previous medical history and family history was collected from obstetric records kept at the two hospitals. Multigravidae and similarly multiparous women had a statistically significantly reduced risk of having a baby with CDH. The relative risks were 0.55 (95% confidence interval 0.33, 0.93) and 0.53 (95% confidence interval 0.31, 0.91) respectively. The method of delivery was also of importance. Babies born by Caesarean section or in breech position had an increased risk of CDH which was statistically significant. Using addition clinical information obtained from subjects attending the Hip Instability Clinic we also found that cases were more likely to have a family history of CDH than subjects who were screened for CDH but found to be normal.

Long term effects of periconceptional multivitamin supplements for prevention of neural tube defects: a seven to 10 year follow up

Periconceptional supplementation with Pregnavite Forte F was offered to women who presented consecutively to the Oxford genetic counselling service in the early 1980s who had previously had one or more pregnancies complicated by a neural tube defect. The first 100 children born alive to these women are the subject of this study. Birth weight, gestation, and congenital abnormalities were recorded. At age 2-5 years all 96 children remaining in the United Kingdom were assessed clinically and developmentally and behavioural information was obtained by questionnaire. At age 7-10 years, follow up of 91 children by telephone and postal questionnaire yielded further information about growth, general health, vision, hearing, and educational and behavioural status. Entry criteria excluded single mothers but the social class distribution of the sample was otherwise representative of the Oxfordshire population. There were no recurrences of neural tube defects. One child had radiological evidence of spina bifida occulta affecting only the fifth lumbar vertebra. One had an autosomal recessive disorder. Eight had random minor congenital anomalies. Birth weight for gestational age was significantly greater than for the local population and at age 7-10 years the girls were considerably taller than expected. Health, auditory, visual, and developmental status were no different from the general population. None of the children had special educational needs. None showed a major behaviour disorder but worries, fussiness, and fearfulness were highly significantly over represented.

Late presentation of congenital dislocation of the hip: an audit

Despite the widespread introduction of neonatal screening programmes, the late presentation of congenital dislocation of the hip remains a considerable problem. Important gaps in our understanding of the natural history of this condition make it difficult to assess the effectiveness of screening. An audit of late presenting cases of congenital dislocation of the hip in south Bedfordshire between 1980 and 1988 suggests that improved liaison between hospital doctors and general practitioners and closer scrutiny as children start walking could make screening more effective.

Importance of the clicking hip in screening for congenital dislocation of the hip

A birth cohort of 3289 babies was investigated prospectively for one year to assess the importance of risk factors for congenital dislocation of the hip (CDH). 426 (13%) babies had an identifiable risk factor when examined by paediatric senior house officers. On further examination in the first week of life at a screening clinic, 51 proved to have CDH, an incidence of 15.5 per 1000 births. The results confirmed the importance of established factors such as family history, caesarean section, and the breech position, and demonstrated the clinical significance of the presence of clicking hips on initial examination. After up to 4.1 years of follow-up there have been no late presentations. By taking into account the clinical examination by senior house officers, secondary screening of babies at high risk of CDH can be very effective. This extended high risk group may contain all potentially abnormal hips. All such babies should be examined by ultrasonography in hospitals where it is available.

Screening for congenital dislocation of the hip by child-health nurses in Western Australia

The child-health nurse screening programme for the presence of congenital dislocation of the hip in Western Australia was evaluated by the use of data that were collected as a routine from the Congenital Malformations Registry, the records of child-health nurses and the Hospital Morbidity System. The programme performed well operationally, with a sensitivity of 68.5%, a specificity of 98.8%, and a positive predictive value of 15.1%. Of the children who were born in the study period (1981-1983), 450 children were diagnosed with congenital dislocation of the hip, and 46 (10.2%) of these children required 104 hospital admissions for the treatment of their dislocation. Of the children whose hips were found to be dislocated in screening (those who were screened as "true-positive" cases), 10.1% were hospitalized, whereas 16.1% of those children who were missed by screening (who screened as "false negative") required hospitalization (95% confidence interval [CI] for the difference in proportions, -7.8% to 19.9%). A comparison of the measures of hospitalization was made between the children who were found to be "true positive" on screening and the children whose dislocation was diagnosed in the hospitals of their birth--a group that generally is considered to show the best outcome. A somewhat-higher proportion of children who were screened as "true positive" required an open surgical procedure (5.0% of children compared with 2.8% of children; 95% CI for the difference, -2.1% to 6.5%). The differences in the other measures of hospitalization between the two groups were small.