Region-, zone-, and layer-specific knee cartilage T2 relaxation patterns in sports-active adolescents

This study aimed to investigate region-, zone-, and layer-specific differences in knee cartilage T2 relaxation times between sports-active adolescents and age- and sex-matched controls and to explore associations with training-related variables.

A color-coded T2 map was automatically produced from a sagittal multi-slice multi-echo T2 sequence obtained at 1.5-T MRI in 42 sports-active adolescents participating in football, basketball, or volleyball and in 42 matched controls. Cartilage was segmented manually in six regions, and each region was automatically subdivided into anterior, central, and posterior zones as well as superficial, intermediate, and deep layers (54 subregions per knee). T2 relaxation times were compared between groups, and multivariable regression analyses were performed to assess associations with training-related variables. Intraobserver reliability was evaluated using intraclass correlation coefficients (ICC).

Sports-active adolescents showed significantly higher T2 values in the patellofemoral joint, lateral tibiofemoral compartment, and medial femoral condyle compared with controls (all p < 0.05). The physiological superficial-to-deep T2 gradient observed in controls appeared partially altered in sports-active adolescents. Zone-specific analysis revealed more frequent T2 elevations in posterior zones. Daily training duration and years of participation were independently associated with compartment-specific T2 alterations. Intraobserver agreement was good to excellent (ICC range: 0.80-0.97).

Cartilage T2 alterations were mainly observed between sports-active adolescents and controls, with additional differences among sports disciplines, indicating sport-specific cartilage adaptations to repetitive mechanical loading.

Question Do sports-active adolescents show region-, zone-, and layer-specific differences in knee cartilage T2 relaxation times compared with non-sports-active controls? Findings Sports-active adolescents exhibited higher T2 values predominantly in the patellofemoral joint, lateral tibiofemoral compartment, and medial femoral condyle, with posterior and depth-dependent changes associated with training exposure. Clinical relevance T2 mapping is an important imaging biomarker for detecting cartilage at risk in physically active adolescents before visible structural damage occurs.