Relationship between knee kinetics during jumping tasks and knee articular cartilage MRI T1rho and T2 relaxation times

BackgroundArticular cartilage of young healthy individuals is dynamic and responsive to loading behaviors. The purpose of this study was to evaluate the relationship of cartilage T1ρ and T2 relaxation times with loading kinetics during jumping tasks in healthy young individuals.MethodsFourteen healthy subjects underwent: 1) motion analysis while performing a unilateral hopping task and bilateral drop jumping task; and 2) quantitative imaging using a 3 Tesla MRI for T1ρ and T2 relaxation time analysis. Three dimensional net joint moments and angular impulse was calculated using standard inverse dynamics equations. Average T1ρ and T2 relaxation times and medial-lateral ratios for each were calculated. Multiple regression was used to identify predictors of cartilage relaxation times.FindingsAverage knee flexion moment during hopping was observed to best predict overall T1ρ (R2 = .185) and T2 (R2 = .154) values. Peak knee adduction moment during a drop jump was the best predictor of the T1ρ medial-lateral ratio (R2 = .220). The T2 medial-lateral ratio was best predicted by average internal rotation moment during the drop jump (R2 = .174).InterpretationThese data suggest that loads across the knee may affect the biochemistry of the cartilage. In young healthy individuals, higher flexion moments were associated with decreased T1ρ and T2 values, suggesting a potentially beneficial effect. The medial-to-lateral ratio of T1ρ and T2 times appears to be related to the frontal and transverse plane joint mechanics. These data offer promising findings of potentially modifiable parameters associated with cartilage composition.