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Evaluation of the measurement methods for protrusio acetabuli in normal children
S E Gusis1, J C Babini, S M Garay
1Instituto Nacional de Rehabilitación, Sección Reumatologia, Buenos Aires, Argentina.
Insights
This study establishes normal radiological line values for diagnosing acetabular protrusion in children. The ilioischial line method is most reliable, aiding early detection of pediatric hip conditions.
Area of Science:
- Pediatric Orthopedics
- Radiology
- Hip Dysplasia
Background:
- Protrusio acetabuli (PA) diagnosis in adults relies on specific radiological lines.
- Establishing normal reference values in children is crucial for accurate diagnosis.
- Previous studies have not prospectively determined these values in a pediatric cohort.
Purpose of the Study:
- To prospectively determine normal values for key radiological lines used in diagnosing protrusio acetabuli.
- To identify the most reliable radiological method for evaluating PA in children aged 2-15 years.
- To establish age- and sex-specific reference ranges for these measurements.
Main Methods:
- Prospective study of 150 children (300 hips) aged 2-15 years without femoral pathology.
- Radiological assessment using teardrop shape, centre edge (CE) angle, and acetabular ilioischial line.
- Analysis of how these measurements vary with age and sex.
Main Results:
- Teardrop shape classification showed a "crossed" type predominance (48.7%) in children.
- Mean CE angle was 31.2° ± 6.2°, increasing with age and slightly higher in females.
- Acetabular ilioischial line values ranged from +7 to -5 mm (mean +1.8 ± 2 mm), unaffected by X-ray incidence.
Conclusions:
- The acetabular ilioischial line is the most suitable method for diagnosing PA in children.
- PA in children is diagnosed when the acetabular line is medial and the ilioischial line is ≥1 mm (boys) or ≥3 mm (girls).
- The "line crossing" method is recommended as the most trustworthy for evaluating pediatric protrusio acetabuli.
Abstract:
The normal values of the radiological lines most frequently used as references in the diagnosis of adult protrusio acetabuli were prospectively determined in 150 children (300 hips) without femoral pathology and aged between 2 and 15 years, mean age 8 years. The teardrop shape was modified according to the child's age, the "crossed" type predominating (48.7%). The mean centre edge (CE) angle fluctuated, with a median value of 31.2 degrees +/- 6.2 degrees, increasing with age and with slightly greater values in females; a large spread of CE angle values was observed within age groups. Acetabular ilioischial line values ranged from +7 to -5 mm, with a mean of +1.8 +/- 2 mm. This last method was the most suitable because it was not modified by changes in incidence of X-rays in radiological studies. With this method protrusio is diagnosed in children when the acetabular line is projected medially, provided that the ilioischial line is 1 or 3 mm or more for boys and girls, respectively. We conclude that the most trustworthy method available to evaluate PA in children should be "line crossing".