Age- and Sex-Specific Morphologic Variations of Capital Femoral Epiphysis Growth in Children and Adolescents Without Hip Disorders

Abstract

Background:Understanding the development of the capital femoral epiphysis is essential to identify pathologic variations that may lead to cam morphology.Purpose/Hypothesis:The purpose of this study was to investigate the development of the capital femoral epiphysis during childhood and adolescence, with specific morphologic analysis of the peripheral growth and the metaphyseal surface of the growth plate. We hypothesized that age- and sex-dependent morphologic variations of the peripheral growth (cupping) and surface anatomy (epiphyseal tubercle) of the epiphysis would be evident with increasing age.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Pelvic computed tomography scans of 80 children and adolescents (range, 8-15 years; n = 10 per age group; 50% male), imaged because of suspected appendicitis, were used to reformat the proximal femur. All patients had asymptomatic hips with no signs or history of hip disorder. We measured the peripheral cupping of the epiphysis and the epiphyseal tubercle dimensions from 3-dimensional models. All measurements were normalized to the epiphyseal diameter. The effect of age on these parameters was evaluated by use of linear regression analysis. A 2-way analysis of variance (ANOVA) was used to compare these parameters between males and females.Results:The mean epiphyseal cupping increased with increasing age (R2 = 0.54; P < .001). The mean normalized epiphyseal cupping was consistently higher in the anterior and posterior directions compared with the inferior and superior locations. Male patients aged 10 and 11 years had lower (P = .002) mean epiphyseal cupping compared with female patients of the same age. We observed no difference between male and female participants after 12 years of age (P > .3). The normalized epiphyseal tubercle height (R2 = 0.08; P = .009), width (R2 = 0.13; P = .001), and length (R2 = 0.45; P < .001) decreased with increasing age, with no differences between male and female patients. On average, a 2.6-fold increase was found in epiphyseal cupping from 8 to 15 years of age, whereas normalized tubercle height decreased by 0.4-fold.Conclusion:Peripheral cupping of the epiphysis over the metaphysis increases with age, while the relative epiphyseal tubercle dimensions decrease. Females have an earlier onset of rapid increase in the peripheral cupping compared with males; however, no differences in epiphyseal tubercle dimensions were found between male and female patients. These findings may guide future studies investigating the development of cam morphology, which should consider the surface morphologic characteristics of the capital femoral epiphysis, the growth plate, and the differences in morphologic characteristics according to age and sex.

Relative contribution of epiphyseal tubercle and peripheral cupping to capital femoral epiphysis stability during daily activities

“…We found that the stabilizing role of the tubercle is primarily at early stages of adolescence when the tubercle is prominent, and the peripheral cupping is absent or underdeveloped . The age‐related changes in epiphyseal surface morphology shifts the loading dynamics of the epiphysis in a way that the epiphyseal cupping will become a more important stabilizer of the epiphysis in later stages of adolescence.…”

“…Previous investigations about morphologic variations of the capital femoral epiphysis have described that the epiphyseal tubercle reduces while the peripheral cupping increases during the period of rapid adolescent growth . The epiphyseal tubercle has been suggested to act as a keystone stabilizer of the capital femoral epiphysis.…”

“…A total of 80 subjects (age: 8–15 years; 10 per age group; 50% females) with normal hips were selected, Hip normality was verified radiographically by measuring alpha angle, epiphyseal tilt angle, and the acetabular index angle . Details of patients selection process and their baseline characteristics are previously reported in a study focused on age‐ and sex‐related changes in development of capital femoral epiphysis morphology . This previous study showed that the epiphyseal tubercle is located eccentrically in the posterior and superior quadrant of the capital femoral epiphysis.…”

“…The CT scans were segmented in three anatomical planes and then converted in 3D models using Mimics (v17.0, Materialise, Belgium) . Reconstructed geometries were then imported to 3‐Matics (v9.0, Materialise, Belgium) to measure multiple morphological features of the capital femoral epiphysis including the size and location of the tubercle as well as the peripheral cupping height.…”

“…Recent studies have shown that the epiphyseal tubercle reduces in all dimensions and moves to the more inferior position during skeletal growth and maturation . Those studies also indicated a concomitant peripheral growth of the epiphysis around the metaphysis, described as epiphyseal cupping.…”