Children treated for developmental dysplasia of the hip at birth and with normal acetabular index at 1 year: How many had residual dysplasia at 5 years?

Residual Acetabular Dysplasia at Walking Age: A Study of 470 Hips Treated With Pavlik Harness

BACKGROUND

This study aims to report on the acetabular indices of walking age children following successful DDH treatment with Pavlik harness and investigate risk factors for residual acetabular dysplasia (RAD).

METHODS

We retrospectively reviewed the data for children treated for DDH at a single centre between 2015 and 2020. Acetabular indices (AI) measured on pelvic radiographs taken at 2- and 4-year follow-up visits were referenced against age-matched and sex-matched normal data. Values ≥90th percentile were considered to represent RAD.

RESULTS

A total of 305 children with 470 hips were suitable for inclusion. The mean age at treatment initiation was 7.0±4.5 weeks and mean treatment duration was 15.9±4.3 weeks. Overall, 27% and 19% of hips were found to have RAD at 2- (n=448) and 4-year (n=206) follow-up, respectively. The χ 2 test for independence demonstrated that the difference in the proportion of hips with RAD at both time points was significant ( P =0.032). Patients with RAD at 2 years were found to have been treated for longer ( P =0.028) and had lower alpha angles on final ultrasound assessment ( P <0.001). Patients with RAD at 4 years were older at initiation of treatment ( P =0.041), had lower alpha angles on final ultrasound assessment ( P <0.001) and were more likely to have had RAD at 2 years ( P <0.001). Multivariate analysis identified lower alpha angles on final ultrasound to be predictive for RAD at 2 years ( P =0.011), and presence of RAD at 2 years to be predictive for RAD at 4 years ( P <0.001).

CONCLUSIONS

The risk of RAD beyond walking age in children successfully treated with Pavlik harness is not negligible. However, we observed that a significant proportion of children with RAD at 2-year follow-up had spontaneously improved without any intervention. This data suggests that routine long-term radiologic follow-up of children treated with Pavlik harness is necessary, and surgical intervention to address RAD should be delayed until at least 4 years of age.

LEVEL OF EVIDENCE

Level III-case-control study.

Resolving residual acetabular dysplasia following successful brace treatment for developmental dysplasia of the hip in infants

Aims

Radiological residual acetabular dysplasia (RAD) has been reported in up to 30% of children who had successful brace treatment of infant developmental dysplasia of the hip (DDH). Predicting those who will resolve and those who may need corrective surgery is important to optimize follow-up protocols. In this study we have aimed to identify the prevalence and predictors of RAD at two years and five years post-bracing.

Methods

This was a single-centre, prospective longitudinal cohort study of infants with DDH managed using a published, standardized Pavlik harness protocol between January 2012 and December 2016. RAD was measured at two years' mean follow-up using acetabular index-lateral edge (AI-L) and acetabular index-sourcil (AI-S), and at five years using AI-L, AI-S, centre-edge angle (CEA), and acetabular depth ratio (ADR). Each hip was classified based on published normative values for normal, borderline (1 to 2 standard deviations (SDs)), or dysplastic (> 2 SDs) based on sex, age, and laterality.

Results

Of 202 infants who completed the protocol, 181 (90%) had two and five years' follow-up radiographs. At two years, in 304 initially pathological hips, the prevalence of RAD (dysplastic) was 10% and RAD (borderline) was 30%. At five years, RAD (dysplastic) decreased to 1% to 3% and RAD (borderline) decreased to < 1% to 2%. On logistic regression, no variables were predictive of RAD at two years. Only AI-L at two years was predictive of RAD at five years (p < 0.001). If both hips were normal at two years' follow-up (n = 96), all remained normal at five years. In those with bilateral borderline hips at two years (n = 21), only two were borderline at five years, none were dysplastic. In those with either borderline-dysplastic or bilateral dysplasia at two years (n = 26), three (12%) were dysplastic at five years.

Conclusion

The majority of patients with RAD at two years post-brace treatment, spontaneously resolved by five years. Therefore, children with normal radiographs at two years post-brace treatment can be discharged. Targeted follow-up for those with abnormal AI-L at two years will identify the few who may benefit from surgical correction at five years' follow-up.

The incidence of late-detected developmental dysplasia of the hip and its functional outcomes: a 17-year cohort study using selective ultrasound screening

BACKGROUND AND PURPOSE

We aimed to establish the incidence of late-detected developmental dysplasia of the hip (DDH) with a selective ultrasound (US) examination over 17 years using the femoral head coverage (FHC) as a US measurement. The secondary aim was to establish the everyday function using patient-reported outcome measures (PROMs).

PATIENTS AND METHODS

The incidence of late-detected DDH was based on 60,844 children. Patients diagnosed for the first time after 3 months and before the age of 8 years were included. In the second part of the study, consent to participate was mandatory. PROMIS-25 Pediatric, PROMIS-25 Parent, and EQ-5D-5L were used according to the patient's age to assess everyday function.

RESULTS

The incidence of late-detected DDH was 0.48/1,000. The median age at diagnosis was 8 months (range 4-41 months), with a tendency to require repeated treatment with open surgery if DDH was diagnosed later. Most children reported no or minor health problems with a mean of 18 years' follow-up.

CONCLUSION

We found that selective US examination of the hips by measuring the FHC is a reliable method to examine newborns for DDH resulting in a low incidence of late-detected DDH amounting to 0.48/1,000 newborn children.

Defining the Incidence of Residual Acetabular Dysplasia After Successful Reduction With a Harness

BACKGROUND

The purpose of this study was to evaluate the rate of residual acetabular dysplasia (RAD), defined as an acetabular index (AI) of >90th percentile of age and sex-matched controls, in a cohort of infants successfully treated with the Pavlik harness (PH).

METHODS

We retrospectively studied typically developing infants at a single center, with at least 1 dislocated hip, that was successfully treated with a PH and had a minimum of 48 months follow-up. Hip dislocation was defined as <30% femoral head coverage at rest on pretreatment ultrasound or IHDI grade 3 or 4 on the pretreatment radiograph.

RESULTS

Forty-six dislocated hips (41 infants) were studied (4 males and 37 females). Brace treatment was initiated at an average age of 1.8 months (range: 2 d to 9.3 mo) and was maintained for an average of 10.2 months (range: 2.3 to 24.9 mo). All hips achieved IHDI grade 1 reduction. Five of 46 hips (11%) had an AI >90th percentile at the conclusion of bracing. Average follow-up was 6.5 years (range: 4.0 to 15.2 y). We found a 30% incidence of RAD (14/46 hips) on final follow-up radiographs. Of these hips, 13/14 (93%) had AI <90th percentile at the end of brace treatment. Comparing children with and without RAD, there were no differences in age at the initial visit or brace initiation, total follow-up, femoral head coverage at the initial visit, alpha angle at the initial visit, or total time in the brace (P > 0.09).

CONCLUSION

In a single-center cohort of infants with dislocated hips treated successfully with a PH, we observed a 30% incidence of RAD at a minimum 4.0-year follow-up. Normal acetabular morphology at the end of brace treatment did not result in normal acetabular morphology at the final follow-up in 13/41 hips (32%). We recommend that surgeons should pay close attention to the year-over-year change in both the AI and AI percentile.

LEVEL OF EVIDENCE

Level IV: case series.

Intra- and interobserver variability of novel magnetic resonance imaging parameters for hip screening and treatment outcomes at age 5 years

BACKGROUND

The outcome measure of neonatal hip screening is usually the radiographic acetabular index.

OBJECTIVE

To assess the feasibility of magnetic resonance imaging (MRI) without sedation and compare the utility of outcome parameters measured from MRI images.

MATERIALS AND METHODS

The invitation for MRI scanning at 5 years of age was incorporated into follow-up for babies who had more than one ultrasound examination during treatment or surveillance.

RESULTS

Diagnostic images were obtained in 132 of 134 children. The mean osseous acetabular index (standard deviation [SD]) was 16.6 (3.3) degrees for the right hip and 17.8 (3.2) for the left; the values for the cartilaginous acetabular index were 3.1 (3) and 3.4 (3.2). The mean downslope of a tangent to the lateral bony acetabular roof was 10.4 (4.5) and 9.0 (4.3) with respect to Hilgenreiner's line and that of a line drawn through the apex to the margin of the acetabulum was 3.7 (4.6) and 3.9 (4.7). Intra- and interobserver variation was greater for measures specific to the lateral acetabular roof than for ossific and cartilaginous indices. There was significant negative correlation between the downslope of the tangent to the lateral roof index and the age at onset of treatment on both sides, but no significant correlation for ossific or cartilaginous acetabular indices or apex-marginal index.

CONCLUSION

MRI without sedation at 5 years of age is feasible as an outcome measure for hip screening programmes. Parameters specific to the lateral acetabulum may better reflect acetabular sufficiency, despite having greater observer variation than cartilaginous and ossific acetabular indices.