Comparison of Two Different Medial Reference Points for Measurements of the Acetabular Index
Volume 4 | Issue 1 | January-June 2018 | Page: 07-11 | Sandeep Vijayan, Dhiren Ganjwala, Hitesh Shah
DOI- 10.13107/ijpo.2018.v04i01.003
Authors: Sandeep Vijayan, Dhiren Ganjwala [1], Hitesh Shah
Department of Orthopaedics, Paediatric Orthopaedic Service, Kasturba Medical College, Manipal, Karnataka,
[1] Paediatric Orthopaedic Service, Ganjwala Orthopaedic Hospital, Ahmedabad, Gujarat, India.
Address of Correspondence
Dr. Hitesh Shah,
Department of Orthopaedics, Kasturba Medical College, Manipal – 576 104, Karnataka, India.
E-mail: hiteshshah12@gmail.com
Abstract
Introduction: Acetabular index (AI) is a commonly used quantitative measurement of acetabular inclination in plain radiographs. Repeated measurements of this index are used to determine dysplasia in children and for decision making about surgical management. Persistent acetabular dysplasia may be an indication for performing an acetabuloplasty. AI is commonly measured between the Hilgenreiner’s line (line that connects both triradiate cartilages) and the line joining lateral most ossified margin of the acetabulum and triradiate cartilage. Two different methods for measurement of AI with two different medial reference points at the triradiate cartilage have appeared in the literature. Aim: The specific aim of the study was to investigate the difference between AI measurements with two different methods and report on intraobserver and interobserver reliability of both the methods. Materials and Methods: Ninety-eight children with developmental dysplasia of the hip (DDH) (treated and untreated), younger than 9 years, were included in the study. Anteroposterior radiographs of the pelvis having acceptable pelvic rotation and pelvic tilt were included in the study. AI was measured using two different reference points for the affected and normal sides. AI was measured twice at 1-month interval by two investigators. The difference between the two measurement techniques was compared by the paired “t” test. Pearson’s correlation coefficient was calculated to test associations between the two measurement techniques. Results: The reproducibility of measurements of both the techniques was found satisfactory [intraclass correlation (ICC)-0.90 and 0.87]. Statistically significant difference (P value < 0.001) (5.7° for affected and 5.3° for normal side) between the indices measured by two techniques was noted. This difference was noted for all age groups. Significant positive correlations between both the techniques were noted in normal as well as dysplastic hips. Conclusion: Acetabular indices measured with two different medial points gave significantly different values. All subsequent assessment should be consistently carried out by the same method.
Keywords: Acetabular index, Acetabuloplasty, Developmental dysplasia of hip, Medial reference point
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| How to Cite this Article: Vijayan S, Ganjwala D, Shah H | Comparison of two different medial reference points for measurements of the acetabular index| International Journal of Paediatric Orthopaedics | January-June 2018; 4(1): 07-11.
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