High-resolution X-ray computed tomographic scanning of the human stapes footplate.

OBJECTIVES The mechanical behaviour of the footplate and its annular ligament depends critically on their shape and orientation in the oval window, but accurate measurements have been difficult to make owing to their small size. Our aims are to visualize the footplate at high resolution and understand its dynamics. METHODS The human cadaver stapes footplate was dissected, and very high-resolution x-ray computed tomographic (CT) scans, with voxel sizes from 4 to 8 pm, were performed. Locally developed software was used to reconstruct the images. RESULTS The data permit us to explore minor details of shape and orientation. The footplate looks like a footprint, and the annular ligament has variable thickness, with a cleft (groove) in its anterior attachment to the oval window. The CT data also permit us to create a three-dimensional finite-element model that can simulate footplate motion. CONCLUSIONS The results obtained lead to further understanding of the mechanical behaviour of the footplate and the annular ligament.