Early age-related changes to articular cartilage T1ρ in hips with Legg–Calvé–Perthes disease deformity

Abstract

Objective

To determine whether the relationship between cartilage T_1ρ relaxation time and age during adolescence and young adulthood is different in hips with Legg–Calvé–Perthes disease (LCPD) deformity compared to hips without LCPD deformity.

Design

We recruited 17 participants with LCPD deformity and 15 control participants aged 10–25 years in this frequency-matched cohort study. Quantitative magnetic resonance images were obtained for both hips in LCPD participants and one hip from each control using a T_1ρ MAPSS sequence. The average T_1ρ relaxation time in the weight-bearing articular cartilage was calculated, and we tested the interacting effects of age and participant group (LCPD vs non-LCPD) or subgroup (control, contralateral LCPD, spherical LCPD, and aspherical LCPD) on T_1ρ using mixed effects models.

Results

The main effect of age on T_1ρ relaxation time in hips without LCPD deformity was −0.63 ​ms/year (95 ​% confidence interval [−0.94, −0.32]). The age-adjusted main effect of LCPD deformity was +2.93 ​ms [0.65, 3.42] and the interaction effect of age and LCPD deformity was +0.46 ​ms/year [0.16, 0.76]. Moderate differences were observed between control and contralateral LCPD subgroups, and between spherical LCPD and aspherical LCPD subgroups.

Conclusions

Age-related changes in T_1ρ relaxation time differ between hips with and without LCPD deformity, suggesting that cartilage degradation in LCPD is progressive and begins early in the healed stage of LCPD. By young adulthood, the difference in T_1ρ between LCPD and non-LCPD hips is clinically important when considering osteoarthritis progression and outcomes.