T1ρ and T2 MRI show hip cartilage damage in adolescents with healed Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease (LCPD) is a juvenile hip disorder associated with residual femoral head deformity, cartilage degeneration and a high risk of early onset hip osteoarthritis. Assessing management of LCPD in the healed phase requires an understanding of when and where hip cartilage damage happens. While it has been shown that cartilage is degenerated in healed LCPD hips in adults, it is not clear when this degeneration begins. Our research question was: Are the MR markers of cartilage degeneration T1ρ and T2 increased in healed LCPD hips in adolescents? Twelve adolescents [10-17 years old (mean 14); 3 female 9 male] with healed LCPD (Stulberg 2-5; 8 unilateral and 4 bilateral) and 15 age- and sex-matched controls were imaged in a 3T MRI using a T1ρ and a T2 sequence. We applied a mixed-effects model adjusted for age and nested by subject to determine the effect of Stulberg grade on overall and regional mean T1ρ and T2 values. T1ρ was significantly higher overall and in the medial region of Stulberg ≥3 hips, and in the medial region of Stulberg 2 hips than in the control group. T2 was significantly higher in the medial region of Stulberg ≥3 hips than in the control group. Our results suggest that cartilage damage in LCPD has begun by adolescence and that T1ρ can detect early changes in cartilage associated with LCPD.