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

Abstract

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. This study aimed 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. MRI was performed on ten healthy volunteers using a 3-T MRI unit with a 3D dual-echo steady-state gradient-recalled echo sequence. Conventional MRI was performed first, followed by traction MRI. The traction weight increased in the order of 5kg, 10kg, and 15kg. 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 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 5kg, 10kg, and 15kg. Pain and discomfort during traction MRI examination were lowest with a traction weight of 5kg. Traction MRI examination may be useful in evaluating articular cartilage lesions at the medial tibiofemoral joint. A traction weight of 5kg may be sufficient with minimum pain and discomfort.