[Correlation between sex, intrauterine position and familial predisposition and neonatal hip ultrasound results]

[Hip dysplasia]

BACKGROUND

Hip dysplasia is one of the most common malformations in childhood and has a significant impact on the further life of those affected. A distinction must be made between congenital and the much rarer acquired dysplasia. Early diagnosis and therapy are pivotal for further development of patients.

OBJECTIVES

The paper gives an overview of current radiological possibilities of diagnosis with focus on congenital hip dysplasia supplemented by insights into therapeutic options.

MATERIALS AND METHODS

Basic and review papers were analyzed.

RESULTS

Clinical examination of the newborn has low sensitivity and specificity in the diagnosis of hip dysplasia. The introduction of Graf ultrasound screening has significantly improved the early detection of dysplastic hips. With the help of sonography, but also magnetic resonance imaging (MRI), the shape of the acetabulum and the position of the femoral head in the socket can be precisely and quickly determined, while X‑ray examinations have their place especially in the context of follow-up examinations after treatment from the age of 1 year and in the diagnosis of secondary dysplasia. Therapeutic options range from spreading treatment to open reduction with fixation in the newborn as well as conversion osteotomy in older children.

CONCLUSION

Early detection of hip dysplasia is critical to the course of treatment. The right choice of examination method and correct performance are essential for further treatment.

The Impact of Hip Dysplasia on CAM Impingement

Predisposing factors for CAM-type femoroacetabular impingement (FAI) include acetabular protrusion and retroversion; however, nothing is known regarding development in dysplastic hips. The purpose of this study was to determine the correlation between CAM-type FAI and developmental dysplastic hips diagnosed using X-ray and rotational computed tomography. In this retrospective study, 52 symptomatic hips were included, with a mean age of 28.8 ± 7.6 years. The inclusion criteria consisted of consecutive patients who suffered from symptomatic dysplastic or borderline dysplastic hips and underwent a clinical examination, conventional radiographs and rotational computed tomography. Demographics, standard measurements and the rotational alignments were recorded and analyzed between the CAM and nonCAM groups. Among the 52 patients, 19 presented with CAM impingement, whereas, in 33 patients, no signs of CAM impingement were noticed. For demographics, no significant differences between the two groups were identified. On conventional radiography, the acetabular hip index as well as the CE angle for the development of CAM impingement were significantly different compared to the nonCAM group with a CE angle of 21.0° ± 5.4° vs. 23.7° ± 5.8° (p = 0.050) and an acetabular hip index of 25.6 ± 5.7 vs. 21.9 ± 7.3 (p = 0.031), respectively. Furthermore, a crossing over sign was observed to be more common in the nonCAM group, which is contradictory to the current literature. For rotational alignment, no significant differences were observed. In dysplastic hips, the CAM-type FAI correlated to a lower CE angle and a higher acetabular hip index. In contrast to the current literature, no significant correlations to the torsional alignment or to crossing over signs were observed.

Rotational abnormalities in dysplastic hips and how to predict acetabular torsion

OBJECTIVES

The aim of this study was to investigate the degree to which conventional radiography can represent the acetabular and femoral rotational alignment profile between dysplastic and borderline-dysplastic hips.

METHODS

A retrospective trial was conducted including 56 borderline-dysplastic and dysplastic hips at a mean age of 28.9 years (range from 18 to 46). Inclusion criteria consisted of symptomatic patients with hip dysplasia undergoing 2-dimensional radiography as well as computed tomography. On radiography, the lateral center edge angle, acetabular hip index, hip lateralization index, acetabular index angle, and the Sharp angle were measured, and the presence of a crossover sign was noted. In computed tomography, the full rotational profile of the lower limb was measured.

RESULTS

Significant correlations were observed in the overall analysis between the anteversion of the acetabulum and the hip lateralization index (mean 0.56, coefficient of regression (CoR) -32.35, p = 0.011) as well as the acetabular index angle with a mean of 11.50 (CoR 0.544, p = 0.018). Similar results were found in the subgroup of dysplastic hips with an acetabular index angle of 13.9 (p = 0.013, CoR 0.74). For the borderline-dysplastic group, no significant correlations between the pelvis radiography and rotational CT were seen.

CONCLUSION

Although the femoral and acetabular torsion cannot be predicted from x-rays, the anteversion of the acetabulum correlates with the acetabular index angle, the hip lateralization index, and eventually the beta angle in dysplastic hips. For borderline-dysplastic hips, such results did not show up, which strongly illustrates the need for computed tomography in these cases.

KEY POINTS

• Much of the current literature focuses on rotational alignment especially with respect to the femur and tibia in healthy patients, although little is known about the acetabular, femoral, and tibial torsion in dysplastic hips. • This is the first study showing significant correlations between the anteversion of the acetabulum and the hip lateralization index as well as the acetabular inclination angle. Also, it is the first study to provide a mechanism for estimation of the torsion of the acetabulum with plain radiography in dysplastic hips. • In borderline-dysplastic hips, no significant correlation was found, which raises the question if a simple x-ray has enough validity to address the acetabular deformity with surgery.

Clinical examination and patients' history are not suitable for neonatal hip screening

Purpose

To assess the percentage of missed developmental dysplasia of the hip, which escape the German criteria for newborn hip high-risk screening, we analyzed our data gained from the general neonatal sonographic hip screening performed at our department. The aim of the study was to determine the number of potentially belatedly treated developmental dysplasia of the hip.

Methods

The data from 1145 standardized newborn hip ultrasound examinations according to the Graf technique were analyzed retrospectively comparing findings for general neonatal sonographic hip screening and high-risk screening subgroups.

Results

We diagnosed developmental dysplasia of the hip in 18 of the 1145 newborns via ultrasound. A total of 10 out of 18 developmental dysplasia of the hip would have been missed by high-risk screening, which corresponds to a proportion of 55.6% false-negative results. The sensitivity of high-risk screening was only 44.4% and specificity, 78.3%. The positive predictive value was 3.2%. Family history as a screening criterion yielded false-negative results in 77.8% and false-positive results in 16.8%. In all, 83.3% of the children who were born with developmental dysplasia of the hip but not from breech position as a risk factor were false negative. The clinical examination was false negative in 88.9% and false positive in 0.6%.

Conclusion

High-risk screening detected less than every second developmental dysplasia of the hip, rendering the first month as the most effective treatment window unavailable for inapparent dysplastic hips, potentially resulting in the need for more invasive treatment. Due to the high sensitivity of ultrasound in the detection of developmental dysplasia of the hip, we recommend to replace the current German high-risk screening guidelines with a general newborn screening for all neonates using Graf ultrasound in the first week of life.

Level of evidence

Level II.

Population-based study of the incidence of congenital hip dysplasia in preterm infants from the Survey of Neonates in Pomerania (SNiP)

Background

Some etiological factors involved in developmental dysplasia of the hip (DDH) occur in the last trimester of pregnancy, which could result in a decreased incidence of DDH in preterm infants. The aim of this study was to compare the incidence of DDH between preterm and term infants.

Methods

Ultrasound of the hip joint was performed in 2,534 term infants and 376 preterm infants within the population-based Survey of Neonates in Pomerania (SNiP) study.

Results

A total of 42 (1.66%) term infants had DDH (Graf type II c, 0.8%; type D, 0.3% left and 0.4% right; type III a, 0.2% left). Eighteen infants had bilateral findings. Hip dysplasia occurred more frequently in female neonates (32/1,182 vs. 10/1,302, p < 0.023; 95% CI 0.012–0.022, χ² test). A familial disposition for DDH was found in 169 (6.7%) term infants and 181 (7.1%) infants in the overall population. In preterm infants, dysplasia of the hip was found in only three late preterm infants with gestational age between 36 and 37 weeks (n = 97) and not in preterm infants <36 weeks gestational age (n = 279). Regression analysis revealed a narrowly significant association between gestational week of birth and DDH (relative risk = 1.17; 95% confidence interval 0.99–1.37; p = 0.065).

Conclusion

Our study suggests that preterm infants <36 weeks gestational age have a decreased risk of DDH.

[Incidence and duration of therapy of pathological hip findings in U2 and U3 examinations (SNiP study)]

INTRODUCTION AND OBJECTIVES

Determination of the efficacy of an early ultrasound examination followed by immediate treatment of hip joint dysplasia as well as measuring the therapeutic success in a population-based cohort study of neonates.

MATERIAL AND METHODS

The Survey of Neonates in Pomerania (SNiP) study included 4,093 neonates which represents 95.1 % of the total neonatal population. Of these children 2,534 (61.9 %) underwent ultrasound examination of the hip joint during the U2 stage (3-10 days after birth). The mean gestational age was 38.9 weeks. The sonographic classification was performed according to Graf.

RESULTS

Initially (U2 stage) 42 (1.66 %) children were reported to be in need of therapy (stage IIc or higher according to Graf). The analysis showed a significantly higher incidence in girls (32 girls vs. 10 boys, p < 0.023, χ(2) test) and in children who had a breech birth (116, 4.6 %). A genetic predisposition was ascertained in 180 (7.1 %) children. The children could be subdivided into two groups: 1) children who underwent hip joint ultrasound during both U2 and U3 and 2) children who were first screened at the U3 stage. Of the 49 out of 54 neonates where the ultrasound findings were positive at the U2 examination the hip joint was matured in 32 children at U3 (4-8 weeks), 11 children had to be treated for 8-12 weeks 5 children were treated for over 3 months and1 child needed surgical correction.

CONCLUSION

The early diagnosis of hip maturation disorders and joint dysplasia facilitates early implementation of effective treatment. At our clinic over 60 % of the infants underwent the U2 check up and, given a pathological finding, could undergo early treatment. It was possible to successfully treat 78 % of these children with a Tübingen hip flexion splint in just 4-8 weeks. In contrast, infants who were first examined at the U3 stage needed treatment for 4-12 months. In our opinion, early diagnosis at the age of 3-10 days should be carried out for all newborns.

Is prematurity a risk factor for developmental dysplasia of the hip? : a prospective study

The aim of this prospective study was to investigate prematurity as a risk factor for developmental dysplasia of the hip (DDH). The hips of 221 infants (88 female, 133 male, mean age 31.11 weeks; standard deviation (sd) 2.51) who were born in the 34th week of gestation or earlier, and those of 246 infants (118 female, 128 male, mean age 40.22 weeks; sd 0.36) who were born in the 40th week of gestation, none of whom had risk factors for DDH, were compared using physical examination and ultrasound according to the technique of Graf, within one week, after the correction of gestational age to the 40th week after birth or one week since birth, respectively. Both hips of all infants were included in the study. Ortolani's and Barlow's tests and restricted abduction were accepted as positive findings on examination. There was a statistically significant difference between pre- and full-term infants, according to the incidence of mature and immature hips (p < 0.001). The difference in the proportion of infants with an α angle < 60° between the two groups was statistically significant (p < 0.001). The incidence of pathological dysplasia (α angle < 50 º) was not significantly different in the two groups (p = 1.000). The Barlow sign was present in two (0.5%) pre-term infants and in 14 (2.8%) full-term infants. These results suggests that prematurity is not a predisposing factor for DDH.

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.

Survey of Neonates in Pomerania (SNiP): a population-based birth study--objectives, design and population coverage

Neonatal health is of major concern to parents, midwives, physicians and society as a whole, yet a prospective population-based birth cohort to collect comprehensive data on multiple issues including medical, social, environmental and genetic aspects remains to be established in Germany. The survey of newborns in Pomerania (SNiP) described in this paper attempts to take up this goal. The objectives of SNiP are to establish (a) a population-based birth cohort providing detailed information about neonatal health, morbidity and mortality, (b) a biobank with newborn DNA and serum from cord blood, placenta tissue samples and DNA obtained from oral mucosal swabs of the mothers, (c) a prospective study design by re-examination of the SNiP population prior to attendance at primary school. From March 2003 until November 2008 all childbearing mothers in a well-defined region in North-Eastern Germany were asked to participate with their newborns. Detailed data on health status of the newborn, pregnancy, medical and family history, socio-economic status and maternal life style were obtained via face-to-face interview, standardised questionnaires and medical records. Placental tissue samples, cord blood plasma and DNA were continuously collected; sampling of maternal DNA from mouth swabs started in 2007. As a result, during the study period n = 6747 births and n = 6828 babies were enrolled. A population coverage of 95% was achieved. The active participation rate was 75%. A non-responder analysis revealed no meaningful selection bias. Thus, SNiP is a population-based, representative study in Germany that is able to describe the health and living conditions of newborns and their families comprehensively. It can contribute to existing knowledge and to similar cohort studies since data are accessible by researchers.