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Association between early sonographic findings and acetabular index at the age of 6 months: a prospective
Wen-Chieh Chang1,2, Kuei-Hsiang Hsu1,2, Yu-Ping Su3,4
1Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, Taipei, Taiwan.
Insights
Early ultrasound measurements of femoral head coverage (FHC) and Graf classification can help predict acetabular index (AI) in developmental dysplasia of the hip (DDH) screening. Measurements at three months show superior accuracy compared to those taken at two weeks.
Area of Science:
- Pediatric Orthopedics
- Diagnostic Imaging
- Developmental Dysplasia of the Hip (DDH)
Background:
- Developmental Dysplasia of the Hip (DDH) is a condition affecting hip joint development in infants.
- Early detection and accurate assessment are crucial for effective treatment and preventing long-term complications.
- The acetabular index (AI) is a key measurement for diagnosing DDH, but its reliability in early screening is debated.
Purpose of the Study:
- To investigate the association between early ultrasound findings and the acetabular index (AI) at six months of age.
- To evaluate the predictive value of Graf classification and femoral head coverage (FHC) for abnormal AI in newborns.
- To determine the optimal timing for ultrasound screening in DDH.
Main Methods:
- A prospective observational study enrolled 169 newborns, excluding those with specific hip conditions.
- Ultrasound examinations were performed at two time points: mean age 12.3 days and 3.2 months.
- The acetabular index (AI) was measured at a mean age of 6.6 months, alongside Graf classification and femoral head coverage (FHC).
Main Results:
- At the first ultrasound (around two weeks), only FHC showed a significant negative correlation with AI (P=.02).
- At the second ultrasound (around 3.2 months), both alpha angle (P<.01) and FHC (P<.01) significantly correlated negatively with AI.
- Second ultrasound FHC measurements demonstrated high sensitivity (95%) and specificity (97%) for detecting abnormal AI.
Conclusions:
- Femoral head coverage (FHC) and alpha angle measurements at three months show potential for predicting AI in DDH screening.
- Ultrasound at three months, using Graf and FHC, offers superior sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) compared to two-week-old measurements.
- Further research is needed to establish the optimal timing for ultrasound examinations in DDH screening.
Background:
This study investigated the association between early Graf classification and femoral head coverage (FHC) with the acetabular index (AI) at the age of 6 months.
Methods:
A prospective observational study was conducted between 2017-2018. Patients requiring Pavlik harness treatment and patients with syndromic dislocation or neurogenic dislocation were excluded. In total, 169 newborns with the first ultrasound performed at the mean age of 12.3 (0-15) days, the second ultrasound performed at the mean age of 3.2 (2.5-4.1) months, and the AI measured at the age of 6.6 (4.3-7.1) months were enrolled. The correlation between the AI and first and second alpha angles and FHC measurements, and the correlation of dysplasia in early ultrasound with dysplasia in the AI were analyzed.
Results:
At the first ultrasound, only the FHC (P = .02) demonstrated a significant negative correlation with the AI. At the second ultrasound, both the alpha angle (P < .01) and FHC (P < .01) demonstrated a significant negative correlation with the AI. With the AI as a reference, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were found to be 77%, 7%, 5%, and 81%, respectively, for the first Graf; 91%, 37%, 9%, and 98%, respectively, for the first FHC measurement; 82%, 90%, 35%, and 99%, respectively, for the second Graf; and 95%, 97%, 68% and 99%, respectively, for the second FHC measurement.
Conclusions:
FHC and alpha angle exhibited significant negative correlations with the AI at six months, both ultrasound parameters may have the potential to predict AI in DDH screening. Compared to the ultrasound measurements taken at 2 weeks, Graf and FHC at 3 months demonstrated superior sensitivity, specificity, PPV, and NPV to detect abnormal AI. The best timing to perform ultrasound examination may need further research.
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