Measuring hip development using magnetic resonance imaging

BACKGROUND: Abnormal hip development can have severe consequences if not detected and treated early. Previous studies have shown that if the abnormality is detected early, the outcome is good. Much is known about embryological hip development (weeks 1-10 after conception) from postmortem examination. For ethical reasons, information about hip development in the fetal stage of pregnancy (10 weeks to term) is less certain as it is largely gained from animal studies and from early radiograph studies. A few autopsy-based studies have been reported looking at hip development, but no one has shown, to our knowledge, that postmortem magnetic resonance is able to provide the same and possibly more information. The aim of this study was to assess the value of magnetic resonance imaging in providing information on fetal hip development. METHODS: Measurements of 30 patients (gestation, 17-42 weeks) were made regarding the width and depth of the acetabulum and the radius and diameter of the femoral head; volume and area were calculated. RESULTS: With the exception of the acetabular width, each dimension showed little development until week 20 when growth rose exponentially. The acetabular width showed a slow rate of growth, despite changes in the femoral head. Levels of observer agreement were high for all but depth (intraclass correlation coefficients, 0.90). CONCLUSIONS: The measurements were in line with previous postmortem studies. Magnetic resonance imaging is a valid alternative to postmortem in the assessment of hip development. Magnetic resonance imaging has the potential to alert clinicians to the possible abnormal development, allowing early intervention. STUDY DESIGN: Cross-sectional study with purposive sampling.