Incidence of acetabular dysplasia in breech infants following initially normal ultrasound: the effect of variable diagnostic criteria

Developmental Dysplasia of the Hip - Part 1

Developmental dysplasia of the hip (DDH) is a condition characterized by changes in joint formation within the last months of intrauterine life or the first months after birth. Developmental dysplasia of the hip presentation ranges from femoroacetabular instability to several stages of dysplasia up to complete dislocation. Early diagnosis is essential for successful treatment. Clinical screening, including appropriate maneuvers, is critical in newborns and subsequent examinations during the growth of the child. Infants with suspected DDH must undergo an ultrasound screening, especially those with a breech presentation at delivery or a family history of the condition. A hip ultrasound within the first months, followed by pelvic radiograph at 4 or 6 months, determines the diagnosis and helps follow-up. Treatment consists of concentric reduction and hip maintenance and stabilization with joint remodeling. The initial choices are flexion/abduction orthoses; older children may require a spica cast after closed reduction, with or without tenotomy. An open reduction also can be indicated. After 18 months, the choices include pelvic osteotomies with capsuloplasty and, eventually, acetabular and femoral osteotomies. The follow-up of treated children must continue throughout their growth due to the potential risk of late dysplasia.

The Significance of Isolated Hip Click as a Sign of DDH: Implications on Referral Guidelines

BACKGROUND

The clinical significance of an isolated hip click remains unclear. The rates of developmental dysplasia of the hip (DDH) in those referred for hip click vary from 0% to 28%. The purpose of this study was to evaluate the rate of DDH in patients prospectively referred for isolated hip click.

METHODS

We prospectively enrolled patients referred to a single pediatric orthopaedic center with concern for DDH secondary to isolated hip click felt by the pediatrician on examination. Patients with known sonographic abnormalities or risk factors for DDH (breech presentation or positive family history) were excluded. Ultrasounds were obtained upon initial presentation and defined as abnormal if alpha angle <60 degrees and/or femoral head coverage (FHC) <50%. Mild dysplasia, analogous to Graf IIa physiological immaturity, was defined as alpha angle 50<α<60 and/or <50% FHC in a patient <3 months age. Severe dysplasia was defined as ≤33% FHC, which has been proposed to be sonographically consistent with a hip dislocation.

RESULTS

Two hundred fifty-five children were referred for isolated hip click. One hundred eighty-nine patients (74%) had normal ultrasound whereas 66 patients (26%) had sonographic abnormalities (mean age 6.5±6.2 wk at initial ultrasound). Fifty patients (19.6%) demonstrated physiological immaturity, 3 patients (1.2%) demonstrated moderate sonographic dysplasia, and 13 patients (5.1%) had sonographic findings consistent with severe dysplasia or dislocated hip. Hips with severe dysplasia were younger than the remaining population (2.8±2.4 wk vs. 6.6±6.2 wk, P <0.001) with no difference in sex distribution ( P =0.07) or first-born birth order ( P =0.36). For those with sonographic abnormality, 18 (27%) patients were treated with Pavlik harness, 1 (2%) was treated with abduction orthosis, and the remainder (71%) were observed for resolution of physiological immaturity.

CONCLUSIONS

Infants with isolated hip click identified by their pediatrician may have higher rates of dysplasia than previously reported. We recommend screening ultrasound and/or orthopaedic referral for all infants with isolated hip click.

LEVEL OF EVIDENCE

Level II-prospective prognostic study.

Assessment for late developmental hip dysplasia in a cohort of infants with risk factors and normal hip ultrasound

Background

Developmental dysplasia of the hip (DDH) is a known orthopedic pathology of newborns that, if not diagnosed and treated, can lead to debilitating long-term consequences. Ultrasound has proven to be an effective method for the early diagnosis of this condition. Recently, reports of late DDH in populations at risk (breech presentation) and after negative ultrasound examination have emerged in the literature.

Aim

The objective of the study was to assess the possible appearance of late DDH in Italian children with risk factors but negative ultrasound screening.

Materials and methods

We selected patients with risk factors for DDH and a negative hip ultrasound from the medical records of children referred to the Hip Ultrasound Clinic (Rome, Italy) from January 2018 to November 2021. To identify possible cases of late DDH, from February 2022 to July 2022, all patients who met the inclusion criteria were submitted to orthopedic follow-up clinical evaluation. In the case of a pathological objective examination, radiography was performed.

Results

Fifty-five patients (52.7% female, 52.7% with breech presentation, and 41.8% with a positive family history) met the inclusion criteria. The median age of gait onset was 13 months. The median age of orthopedic follow-up examination was 45 months. Only three patients (5.5%) had a pathological examination, but no x-ray were pathological.

Conclusion

Our study has not documented cases of late DDH. Considering the small study population and the only clinical follow-up, further studies are needed to clarify the possible late development of this condition.

Late presenting developmental dysplasia of the hip after a normal hip ultrasound at 6 weeks of age: A report of two cases

Developmental hip dysplasia (DDH) is a paediatric condition in which the 'ball and socket' hip joint fails to form properly during infancy. The increased mechanical stress on the hip joint from DDH can contribute to the development of osteoarthritis during adulthood. Therefore, careful physical examination and imaging of all infants to diagnose DDH is critical to provide the best possible functional outcome. Ultrasonography (US) is a useful diagnostic test in providing a real-time evaluation and three-dimensional view of the hip in infants less than 4 months. In infants with a normal hip ultrasound, the risk of subsequent development of hip dysplasia at an older age and the need for further follow-up is assumed to be unnecessary. In the present study, we report 2 cases of late presenting DDH in infant girls born breech with a previous normal hip exam and normal hip ultrasound at 6 weeks of age.

Risk factors and screening timing for developmental dysplasia of the hip in preterm infants

BACKGROUND

The delayed diagnosis of developmental dysplasia of the hip (DDH) requires complex treatment and sometimes progresses to hip osteoarthritis.

PURPOSE

This study aimed to evaluate the risk factors and screening time for DDH in preterm infants.

METHODS

A total of 155 preterm infants with a gestational age <32 weeks screened for DDH with ultrasonography were enrolled in this retrospective chart review.

RESULTS

The incidence of DDH was 6.45% (10 of 155). Gestational age, birth weight, sex ratio, and breech presentation did not differ significantly between infants treated for DDH (n=10) and nontreated infants (n=145) (gestational age, 29.2±1.4 weeks vs. 29.6±2.0 weeks, P=0.583; birth weight, 1,240±237 g vs. 1,295±335 g, P=0.607; female sex, 7 of 10 (70.0%) vs. 77 of 145 (53.1%), P=0.346; and breech presentation, 5 of 10 (50.0%) vs. 43 of 145 (29.7%), P=0.286, respectively). Performing the first ultrasonography earlier than 38 weeks of postmenstrual age (PMA) increased the risk of an abnormal finding by 3.76 times compared to performing it at ≥38 weeks of PMA. These abnormal findings on ultrasonography resolved spontaneously. Breech presentation increased the risk of minor abnormal findings on the first ultrasonography by 3.11 times versus nonbreech presentation and resolved spontaneously. DDH in preterm infants did not occur predominantly on the left side or in infants born with breech presentation.

CONCLUSION

Performing ultrasonography screening earlier than 38 weeks of PMA caused unnecessary subsequent ultrasonography and overtreatment. Breech presentation was not a risk factor for DDH in preterm infants. However, breech presentation could increase the risk of minor abnormal findings at the 1st ultrasonography compared to nonbreech presentation, which resolved spontaneously. The etiology and risk factors for DDH in preterm infants are somewhat different from those for DDH in term infants.

Is Radiographic Imaging Necessary for Identifying Late Developmental Dysplasia of the Hip in Breech Infants with Normal Ultrasounds?

Purpose. The goal of our study was to investigate the prevalence of late DDH cases in breech infants who had a normal screening hip ultrasound and subsequent follow-up hip x-ray imaging. Methods. Infants with a history of intrauterine breech position, normal hip ultrasound within 3-months of birth, and follow-up hip x-rays within 2-years were included. Acetabular indices were measured on a supine AP pelvis radiograph. Results. Fifty-six patients had breech presentation at birth, a normal hip ultrasound, and returned for radiographic evaluation within 2 years. Of those, 11/112 (10%) of hips had late DDH based on their radiographic images at 1 standard deviation greater than normative values from age-adjusted controls. No infants showed hip dysplasia at 2 standard deviations greater than normative values from age-adjusted controls. Conclusions. Our results support previous studies that follow up should be considered for infants with breech presentation and normal hip ultrasounds near birth. Level of evidence. II.

Late Hip Dysplasia After Normal Ultrasound in Breech Babies: Implications on Surveillance Recommendations

BACKGROUND

There is significant controversy in the literature over rates of late-developing dysplasia following normal screening ultrasound in breech babies, with reported rates varying from 7% to 29%. The purpose of this study is to investigate the rates of radiographic dysplasia in breech babies after a normal ultrasound with a minimum of 1 year of radiographic follow-up.

METHODS

This study was an institutional review board-approved prospective study of all patients referred by their pediatrician for concern for developmental dysplasia of the hip between July 2008 and August 2014. We identified all subjects with breech presentation and excluded those with an abnormal initial examination/ultrasound or with <12 months of radiographic follow-up. Anterior-posterior pelvis films were obtained after >12 months and acetabular indices (AIs) were measured and compared with contemporary normative data. Dysplasia was diagnosed as >2 SDs above the mean.

RESULTS

A total of 654 patients were referred with a history of a breech presentation, and 150 (22.9%) were found to have clinical instability or sonographic evidence of dysplasia on initial presentation and were observed with serial imaging or treated. Of the remaining 504 subjects with a normal clinical examination and screening ultrasound, 133 (26.4%; 74.4% females, 25.6% males) were followed until at least 12 months of age. Of those presenting at age 12 to 14 months, the mean AI was 0.42±0.83 SD above the mean with a skew towards elevated AIs. At the final follow-up (mean: 20.7±6.7 mo), the mean AI was 0.05±0.92 SD above the mean, and only 3/133 (2.2%) patients had a dysplastic hip. No patients underwent treatment other than an observation during the study period.

CONCLUSIONS

One in 5 breech babies have dysplasia at presentation, but late dysplasia following normal screening ultrasound may be less common than previously reported and may be due to our prolonged follow-up period. We recommend surveillance of breech babies with follow-up visits after 12 months of age since earlier visits may offer limited benefits.

LEVEL OF EVIDENCE

Level II-prospective prognostic study.

Part-time Abduction Bracing in Infants With Residual Acetabular Dysplasia: Does Compliance Monitoring Support a Dose-dependent Relationship?

INTRODUCTION

Residual acetabular dysplasia is often seen after successful Pavlik treatment or during follow-up for infants with risk factors for developmental dysplasia of the hip. A previous study supported the effectiveness of part-time abduction bracing for treating this residual dysplasia. However, the relationship between time in the brace and acetabular improvement was not established given the lack of compliance data. The purpose of this prospective study was to validate the effect of part-time bracing on acetabular dysplasia and determine if a dose-dependent relationship exists.

METHODS

Eligibility criteria included infants ~6 months of age with an AP pelvic radiograph demonstrating acetabular dysplasia, defined as an acetabular index (AI) ≥30 degrees. After obtaining informed consent, a rigid abduction orthosis was prescribed with a thermal compliance sensor. Patients were instructed to wear the brace for nights/naps and follow-up at 1 year of age for repeat radiograph. AIs were measured by the senior author who was blinded to the compliance data. Hours of wear were compared with changes in AI over the study period using descriptive statistics and a generalized estimating equation model.

RESULTS

Our series consisted of 26 infants (36 hips) with a mean age at enrollment of 5.9 months (range, 4.9 to 7.9); 84.6% were female individuals. At a mean follow-up of 6 months (range, 5.1 to 8.2), average wear time/day was 11.5 hours (range, 1.3 to 21.7), and total time in brace averaged 1698 hours (range, 218 to 3244 hours). The mean improvement in AI over the study period was 4.8 degrees (95% confidence interval, 3.9-5.5 degrees). The authors found a significant correlation between average hours of brace wear per day and improvement in AI (r=0.36, P<0.05), a relationship that remained significant in our multivariate model after adjusting for confounders.

CONCLUSIONS

Part-time abduction bracing is effective for treating residual dysplasia, with the degree of improvement in AI correlating with hours of brace wear per day. Given this dose-dependent relationship, the optimal hours of wear may depend on the severity of residual dysplasia and the tolerance of the child and family to bracing.

Predictors of Hip Dysplasia at 4 Years in Children with Perinatal Risk Factors

While perinatal risk factors are widely used to help identify those at risk for developmental dysplasia of the hip (DDH) within the first 6 to 8 weeks of life, limited data exist about their association with radiographic evidence of dysplasia in childhood. The purpose of this study was to determine which perinatal risk factors are associated with acetabular dysplasia in children who are ≥2 years of age.

Coronal Flexion Versus Coronal Neutral Sonographic Views in Infantile DDH: An Important Source of Variability

BACKGROUND

Ultrasound (US) is the preferred imaging modality for the diagnosis and treatment of infantile developmental dysplasia of the hip (DDH). Currently accepted indices that distinguish normal from dysplastic hips in the coronal plane include percent femoral head coverage (FHC), α angle, and β angle. Recent data suggests that significant user and interscan variability may exist for these metrics. Less studied, however, is potential variability because of patient positioning, specifically coronal flexion versus coronal neutral views. The purpose of this study was to compare standard DDH indices between coronal US views with hips in flexion versus neutral positions, for hips of varying DDH severity.

METHODS

This retrospective study included normal infants and those treated for different severities of DDH. Coronal flexion and coronal neutral US images from the same study were evaluated at diagnosis, early treatment, start of weaning, and treatment resolution. FHC, α, and β angles were measured on both views at each time point and compared. Inter-rater and intra-rater reliability assessments were performed for all metrics.

RESULTS

Among the 168 hips in this study (45 normals, 45 Ortolani positive, 17 Barlow positive, and 61 stable dysplasia), median FHC was significantly lower in coronal flexion compared with coronal neutral for normals and all 3 severities of DDH at each time point (mean decrease 8.4%; range 5.5% to 10.9%; P<0.01). Alpha angle also decreased on coronal flexion views, observed for all hip types, but only at certain time points (mean decrease 3.3 degrees; range 0 to 7.5 degrees; P<0.01 to 0.35). β angles demonstrated less variability between views, but also had poor reliability.

CONCLUSIONS

Coronal flexion and coronal neutral views demonstrated significant differences in FHC and α angle across a spectrum of DDH severities and treatment time points. Flexion views may represent a "baby Barlow" test, revealing subtle instability as evidenced by the significant and consistent decrease in FHC across all hips. Indices measured in flexion, therefore, may represent more stringent criteria for defining normal hips.

LEVEL OF EVIDENCE

Level III-diagnostic study.

Investigating the need for routine ultrasound screening to detect developmental dysplasia of the hip in infants born with breech presentation

Objectives

Breech presentation is a recognized risk factor for developmental dysplasia of the hip (DDH). Within North America, there is a lack of consensus on screening guidelines for DDH in infants with a negative physical examination of the hips. This study evaluates the need for ultrasound screening in all breech born infants to detect DDH and whether this is influenced by gender, gestational age and mode of delivery.

Methods

A retrospective chart review was conducted to identify breech born infants who underwent routine hip ultrasound to detect DDH between 2010 and 2015. Patients were grouped by physical exam and ultrasound findings and compared based on gender, gestational age and mode of delivery.

Results

Three hundred and eighteen patients were identified (191 female, 127 male; 26 preterm, 57 late preterm, 235 term; 263 caesarean section delivery, 55 vaginal delivery). Three hundred and eight patients had a negative physical exam of which 27 were diagnosed with DDH based on screening ultrasound with females predominant (P<0.05). 12.50% of females with a negative physical exam had DDH compared to 3.23% of males (P<0.05). There was no difference in the rate of DDH detected by screening ultrasound based on gestational age (P=0.94) or mode of delivery (P=0.59).

Conclusions

The diagnosis of DDH in breech born infants by screening ultrasound in those with a negative physical exam of the hips is more predominant in females, with no apparent association with gestational age or mode of delivery. Future analyses with larger sample sizes are needed before conclusions can be made on screening protocols.