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

Does Screening Ultrasound Timing in Developmental Dysplasia of the Hip Need to be Adjusted for Moderate Preterm and Near-term Infants: A Prospective Study

INTRODUCTION

An initial screening ultrasound is essential for patients at higher risk of developmental dysplasia of the hip (DDH) due to breech presentation or a family history of DDH. The American Academy of Pediatrics recommends screening ultrasounds to be performed after 6 weeks of age to reduce the rate of false positives. However, there is limited evidence regarding whether these screening ultrasounds need to be adjusted for gestational age in prematurity. The purpose of this study was to evaluate the influence of moderate preterm and near-term births on screening hip ultrasounds for high-risk DDH populations.

METHODS

We identified all prospectively enrolled patients in a single-center database referred for screening hip ultrasound for DDH. We included those hips referred for risk factors of DDH, including breech presentation, family history of DDH, or hip click, and excluded those with known dysplasia or referral for hip instability. Each ultrasound was measured by a pediatric radiologist to determine the alpha angle and femoral head coverage. Patients were classified as "premature" if born at <37 weeks gestation or "full term" if born at ≥37 weeks gestation. All patients underwent screening hip ultrasound between 5 and 8 weeks of age. Sonographic markers of dysplasia and the incidences of abnormal ultrasound and Pavlik harness treatment were compared between cohorts. Significance was set at P <0.05.

RESULTS

A total of 244 hips in 122 patients were included, 58 hips in the premature cohort and 186 hips in the full-term cohort. The premature cohort had a significantly decreased gestational age compared with the full-term cohort (35.4 ± 1.1 vs 38.5 ± 1.1 wk, respectively, P < 0.001). However, there was no difference between premature and full-term cohorts in sex distribution (69% vs 75%, females, P = 0.39), unadjusted age at the time of ultrasound (6.6 ± 0.7 vs 6.8±0.7 wk, respectively, P = 0.07), or referral reason ( P = 0.14). On hip ultrasound, there was no difference between premature and full-term cohorts with respect to alpha angle (62.6 ± 3.3 vs 62.2 ± 5.3 degrees, P = 0.41), femoral head coverage (54.9 ± 6.3 vs 55.1 ± 10.6, P = 0.19), rate of abnormal ultrasound (18.3% vs 20.7%, respectively, P = 0.68), or the rate of Pavlik harness treatment (0% vs 5.3%, respectively, P = 0.12).

DISCUSSION

There was no significant difference in alpha angle or femoral head coverage between premature and full-term patients at 5 to 8 weeks of unadjusted age. This preliminary data suggests that screening ultrasounds can be performed without adjusting for prematurity.

LEVEL OF EVIDENCE

Level II, prognostic study.

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.

The Diagnosis of Developmental Dysplasia of the Hip From Hip Ultrasonography Images With Deep Learning Methods

BACKGROUND

Hip ultrasonography is very important in the early diagnosis of developmental dysplasia of the hip. The application of deep learning-based medical image analysis to computer-aided diagnosis has the potential to provide decision-making support to clinicians and improve the accuracy and efficiency of various diagnostic and treatment processes. This has encouraged new research and development efforts in computer-aided diagnosis. The aim of this study was to evaluate hip sonograms using computer-assisted deep-learning methods.

METHODS

The study included 376 sonograms evaluated as normal according to the Graf method, 541 images with dysplasia and 365 images with incorrect probe position. To classify the developmental hip dysplasia ultrasound images, transfer learning was applied with pretrained VGG-16, ResNet-101, MobileNetV2 and GoogLeNet networks. The performances of the networks were evaluated with the performance parameters of accuracy, sensitivity, specificity, precision, F1 score, and AUC (area under the ROC curve).

RESULTS

The accuracy, sensitivity, specificity, precision, F1 score, and AUC results obtained by testing the VGG-16, ResNet-101, MobileNetV2, and GoogLeNet models showed performance >80%. With the pretrained VGG-19 model, 93%, 93.5%, 96.7%, 92.3%, 92.6%, and 0.99 accuracy, sensitivity, specificity, precision, F1 score, and AUC results were obtained, respectively.

CONCLUSION

In this study, in addition to the ultrasonography images of dysplastic and healthy hips, images were also included of probe malpositioning, and these images were able to be successfully evaluated with deep learning methods. On the sonograms, which provided criteria appropriate for evaluation, successful differentiation could be made of healthy hips and dysplastic hips.

LEVEL OF EVIDENCE

Level-IV; diagnostic studies.

Prediction of Late Dysplasia Based on Ultrasound and Plain X-Ray at 6 Months

BACKGROUND

Developmental dysplasia of the hip represents a spectrum of deformity. Residual dysplasia at 2 years of age is associated with an increased risk for osteoarthritis and functional limitations. We compared the prognostic value of 6-month imaging modalities and aimed to identify optimal diagnostic metrics for the prediction of residual dysplasia.

METHODS

After IRB approval, patients who underwent Pavlik treatment between 2009 and 2018 with 2-year follow-up were identified. Sonographs [ultrasound (US)] and radiographs (x-ray) were obtained at 6-month and 2-year-old visits. Dysplasia at 2 years was defined as an acetabular index (AI) >24 degrees. Receiver operating characteristic curves were constructed to quantitatively compare the prognostic ability of US and x-ray-based measures at 6 months. Youden's index [(YI) (values range from 0 (poor test) to 1 (perfect test)] was used to evaluate existing cutoffs at 6 months of age (normal measurements: alpha angle (AA) ≥60 degrees, femoral head coverage (FHC) ≥50%, and AI <30 degrees) relative to newly proposed limits.

RESULTS

Fifty-nine patients were included, of which 28.8% of patients (95% CI: 17.3 to 40.4%) had acetabular dysplasia at 2 years. After adjusting for sex, AA [Area under the Curve (AUC): 80] and AI (AUC: 79) at 6 months of age were better tests than FHC (AUC: 0.77). Current diagnostic cutoffs for AA (YI: 0.08), AI (YI: 0.0), and FHC (YI: 0.06) at 6 months had poor ability to predict dysplasia at 2 years. A composite test of all measures based on proposed cutoffs (AA ≥73 degrees, FHC > 62% and AI ≤24 degrees) was a better predictor of dysplasia at 2 years (Youden's index (YI): 0.63) than any single metric.

CONCLUSIONS

The rate of residual dysplasia remains concerning. The 6-month x-ray and US both play a role in the ongoing management of the developmental dysplasia of the hip. The prediction of dysplasia is maximized when all metrics are considered collectively. Existing parameters were not accurate; We recommend the following cutoffs: AA ≥73 degrees, FHC > 62%, and AI ≤24 degrees. These cutoffs must be validated.

LEVEL OF EVIDENCE

Prognostic Level II.

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.