Standard radiographic values for the acetabulum in Japanese adolescents: a cross-sectional study

Abstract

Background Most previous reports of normal acetabular radiographic values focused on adults or elderly people. Recent reports have described premature hip osteoarthritis in adolescents not caused by acetabular dysplasia. In addition, there is a certain failure rate of surgical treatment for young patients with borderline acetabular dysplasia. Accurate indices for treatment of adolescent hips are unclear because standard measurement values of the adolescent acetabulum have not been reported. Methods This cross-sectional study involved 552 Japanese adolescents aged 12–18 years who had scoliosis or suspected scoliosis and asymptomatic hips. All persons underwent plain standing anteroposterior whole-spine radiography, and measurements were obtained using the pelvic part of the radiograph. We excluded persons who were unable to correctly perform measurements because of conditions such as pelvic rotation or lateral inclination and persons in whom closure of the triradiate cartilage or closure of the secondary ossification centers of the acetabulum had not yet occurred. In 1101 hips, we measured the lateral center–edge angle (LCEA), Tönnis angle, Sharp angle, acetabular head index (AHI), lateral subluxation (LS), vertical subluxation (VS), and peak-to-edge distance (PED). We evaluated the correlation coefficient and coefficient of determination between each parameter and age, height, body weight, and body mass index (BMI) and assessed the intra- and inter-rater reliability of each radiographic parameter. Results Among all hips, the mean of each parameter was as follows: LCEA, 27.9° ± 4.8°; Tönnis angle, 5.0° ± 3.7°; Sharp angle, 44.1° ± 3.1°; AHI, 82.1% ± 5.5%; LS, 5.4 ± 1.4 mm; VS, 0.3 ± 1.2 mm; and PED, 14.0 ± 2.3 mm. The correlation between each parameter and age, height, body weight, and BMI was considerably low. Intra- and inter-rater reliability was moderate or good for almost all parameters. Conclusions The values for each radiographic parameter of the acetabulum in this study are considered standard for the adolescent acetabulum without age-related changes. Some parameters differ slightly from the normal values for adults or elderly people in previous reports; thus, we suggest careful evaluation of these parameters for adolescents.

Prevalence of Acetabular Dysplasia at a Mean age of 18 Years After Treatment for Neonatal hip Instability

“…Also, Japanese adolescents had slightly lower mean values of LCEA (27.5°) than in the present study. 29 Consequently, the present results of the low prevalence of acetabular dysplasia after NHI apply to Europe. Previous studies have suggested a tendency in patients treated for DDH to develop dysplasia during growth.…”

“…Two recent Japanese studies reported a similar mean value for the AHI compared with that found in the present study. 18,29 Nishimura et al reported an even higher mean SA and speculated whether the propensity for dysplastic values was caused by the young age (12 to 18 years) of the participants in their cohort. 29 The clinical significance of these findings is unknown as the most important measurement for acetabular dysplasia, LCEA, did not indicate a higher rate of dysplasia.…”

“…Moreover, several studies have already demonstrated the reproducibility of LCEA, SA, and AHI. 17,18,29 We did not control for femoro-acetabular impingement or other hip pathology in the analysis or lifestyle factors, such as smoking, which leaves the possibility of residual confounding. Finally, as acetabular dysplasia was uncommon, the sample size for evaluating the association between hip-related QOL and radiographic parameters was too small to draw definite conclusions.…”

The Proportion of Normalized Hips with Growth in Japanese Adolescents Aged > 10 years with Acetabular Dysplasia who Presented with Suspected Scoliosis

“…Furthermore, the center of focus changed slightly depending on the growth in height. However, we reported previously that there is no significant effect of height of body on the problems of using whole-spine radiographs for evaluating the acetabular parameters [ 30 ]. Regarding the fact that one investigator performed the measurements, in the same previous study, we reported intra-rater reliability of more than moderate for LCEA, Sharp angle, Tönnis angle, and AHI [ 30 ].…”