Acute trauma of the extensor hood of the metacarpophalangeal joint: MR imaging evaluation.

Abstract

To assess detectability of the components of the extensor hood, especially the sagittal bands, with magnetic resonance (MR) imaging in normal and injured metacarpophalangeal (MP) joints. T2*-weighted, T1-weighted, and contrast material-enhanced T1-weighted images were obtained of 54 normal MP joints (108 sagittal bands). The ability to detect the sagittal bands with each sequence was rated for three observers. These same sequences were used for MR imaging of nine patients with acute MP injury. Seven patients underwent surgery. The sensitivity of MR imaging for the detection of normal sagittal bands was 0.89-0.92 for T2*-weighted images, 0.80-0.88 for T1-weighted images, and 0.81-0.91 for contrast-enhanced T1-weighted images. MR imaging findings in patients with extensor hood injury included irregularity, poor definition, and increased signal intensity or uptake of contrast material by structures in and around the extensor hood. All MR imaging findings correlated well with those of surgery. MR imaging is accurate for determination of the presence and severity of injury to the extensor hood.