Associations Between Slower Walking Speed and T1ρ Magnetic Resonance Imaging of Femoral Cartilage Following Anterior Cruciate Ligament Reconstruction

Abstract

Objective: To determine whether walking speed, collected at 6 and 12 months following anterior cruciate ligament reconstruction (ACLR), is associated with inter-extremity differences in proteoglycan density, measured via T1ρ magnetic resonance imaging, in tibiofemoral articular cartilage 12 months following ACLR.

Methods: Twenty-one individuals with a unilateral patellar-tendon autograft ACLR (10 women and 11 men, mean ± SD age 23.9 ± 2.7 years, mean ± SD body mass index 23.9 ± 2.7 kg/m2 ) were recruited for participation in this study. Walking speed was collected using 3-dimensional motion capture at 6 and 12 months following ACLR. The articular cartilage of the medial femoral condyle (MFC) and lateral femoral condyle and medial and lateral tibial condyles was manually segmented and subsectioned into 3 regions of interest (anterior, central, and posterior) based on the location of the meniscus in the sagittal plane. Inter-extremity mean T1ρ relaxation time ratios (T1ρ ACLR extremity / T1ρ contralateral extremity) were calculated and used for analysis. Pearson product-moment correlations were used to determine associations between walking speed and inter-extremity differences in T1ρ relaxation time ratios.

Results: Slower walking speed 6 months post-ACLR was significantly associated with higher T1ρ relaxation time ratios in the MFC of the ACLR extremity 12 months following ACLR (posterior MFC, r = -0.51, P = 0.02; central MFC, r = -0.47, P = 0.04). Similarly, slower walking speed at 12 months post-ACLR was significantly associated with higher T1ρ relaxation time ratios in the posterior MFC ACLR extremity (r = -0.47, P = 0.04) 12 months following ACLR.

Conclusion: Slower walking speed at 6 and 12 months following ACLR may be associated with early proteoglycan density changes in medial femoral compartment cartilage health in the first 12 months following ACLR.

© 2017, American College of Rheumatology.

Figures

Figure 1

The weight-bearing articular cartilage of the femur and tibia were segmented and sub-sectioned into three different sections (Posterior, Central, and Anterior) that corresponded to the area articulating with the meniscus in the sagittal plane.

Figure 2

Represents a sample map of T1ρ relaxation times of an anterior cruciate ligament reconstructed (ACLR) knee (1A) and contralateral knee (1B). Figure 1A depicts the articular cartilage from an ACLR knee with greater T1ρ relaxation times compared to the contralateral uninjured knee (1B). The color of the cartilage corresponds with a specific T1ρ relaxation time value (ms) that is outlined in the color scale.

Figure 3

Scatter-plots depicting significant associations between 6 (2A & 2B) and 12 (2C) month walking speed (x-axis) and 12 month inter-limb T1ρ relaxation time ratios (y-axis). Slower walking speed at 6 months following ACLR significantly associated with higher 12 month inter-limb mean T1ρ relaxation time ratios of regions of interest in the articular cartilage of the posterior medial femoral condyle (MFC; r=−0.448, P=0.027; 2A) and central MFC (r=−0.448, P=0.042; 2B). Those who walked slower at 12 months following ACLR significantly associated with 12 month inter-limb mean T1ρ relaxation time ratio for posterior MFC (r=−0.471, P=0.036, 2C).