Frontal plane knee mechanics and medial cartilage MR relaxation times in individuals with ACL reconstruction: A pilot study

Background: The objective of this pilot study was to evaluate cartilage T-1 rho and T-2 relaxation times and knee mechanics during walking and drop-landing for individuals With anterior cruciate ligament reconstruction (ACL-R). Methods: Nine patients (6 men and 3 women, age 35.8 +/- 5.4 years, BMI 23.5 +/- 2.5 kg/m(2)) participated 1.5 +/- 0.8 years after single-bundle two-tunnel ACL reconstruction. Peak knee adduction moment (KAM), flexion moment (KFM), extension moment (KEM), and peak varus were calculated from kinematic and kinetic data obtained during walking and drop-landing tasks. T-1 rho and T-2 times were calculated for medial femur (MF), and medial tibia (MT) cartilage and compared between subjects with low KAM and high KAM. Biomechanical variables were compared between limbs. Results: The high KAM group had higher Tip for MT (p = 0.01), central MT (p = 0.05), posterior MF (p = 0.04), posterior MT (p = 0.01); and higher T-2 for MT (p = 0.02), MF (p = 0.05), posterior MF (p = 0.002) and posterior MT (p = 0.01). During walking, ACL-R knees had greater flexion at initial contact (p = 0.04), and lower KEM (p = 0.02). During drop-landing, the ACL-R knees had lower KAM (p = 0.03) and KFM (p = 0.002). Conclusion: Patients with ACL-R who have higher KAM during walking had elevated MR relaxation times in the medial knee compartments. These data suggest that those individuals who have undergone ACL-R and have higher frontal plane loading, may be at a greater risk of knee osteoarthritis. (C) 2014 Elsevier B.V. All rights reserved.