Traction MRI examination useful for evaluating cartilage lesions at the knee joint

Lesions of the articular cartilage of the knee, especially early grades, are not always accurately detected by magnetic resonance imaging (MRI) because of contact between the articular cartilage surfaces of the femur and the tibia.

Naoya Kikuchi et al conducted a study to assess the effects of axial leg traction during knee MRI examination on joint space widening and articular cartilage visualization and evaluate the ideal weight for traction. They found that - traction MRI examination may be useful in evaluating articular cartilage lesions at the medial tibiofemoral joint. A traction weight of 5 kg may be sufficient with minimum pain and discomfort. The study has been published in 'Skeletal Radiology' journal.

MRI was performed on ten healthy volunteers using a 3-T MRI unit with a 3D dual-echo steady-state gradientrecalled echo sequence. Conventional MRI was performed first, followed by traction MRI. The traction weight increased in the order of 5 kg, 10 kg, and 15 kg. Joint space widths were measured, and articular cartilage visualization was assessed at the medial and lateral tibiofemoral joints. Volunteers were asked to evaluate pain and discomfort using a visual analog scale during each procedure with axial traction to assess the safety of traction MRI.

The observations in the study were :

• The medial tibiofemoral joint space width significantly increased, and the visualization of the articular cartilage significantly improved by applying traction.

• The joint space width and the articular cartilage visualization showed no significant differences among traction weights of 5 kg, 10 kg, and 15 kg.

{The joint space width at the medial tibiofemoral joint MRI and traction MRI with weights of 5 kg, 10 kg, and 15 kg was 0.5 ± 0.5 mm and 1.8 ± 0.7 mm, 2.1 ± 0.8 mm, and 2.1 ± 0.6 mm respectively (p< 0.00009). Post hoc analysis showed significant differences between MRI and traction MRI with each traction weight (traction weights of 5 kg, 10 kg, and 15 kg; p = 0.028, 0.028, and 0.028, respectively). There were no significant differences between traction weights of 5 kg and 10 kg (p = 0.83), 5 kg and 15 kg (p=0.44), and 10 kg and 15 kg (p=1.00). }

• In contrast, the joint space width at the lateral tibiofemoral joint did not increase significantly with traction (p=0.86)

• Pain and discomfort during traction MRI examination were lowest with a traction weight of 5 kg.

The authors concluded that – their study suggests that traction MRI with a traction weight of 5 kg is possibly effective enough to investigate articular cartilage lesions at the medial tibiofemoral joint.

Further reading:

Improving visualization of the articular cartilage of the knee with magnetic resonance imaging under axial traction: a comparative study of different traction weights

Naoya Kikuchi, Sho Kohyama et al

Skeletal Radiology (2022) 51:1483–1491

https://doi.org/10.1007/s00256-021-03971-w