A Kerrison Rongeur 90 with Downward Cutting is a specialized bone punch used in spinal and neurosurgery to remove bone, typically lamina, during a laminectomy or other decompression procedures. The "90" designation in this context refers to the length of the instrument (90 mm) and the angle of the footplate, not the cutting direction. It is a delicate, short instrument (9 cm) designed for use in extremely confined surgical fields, such as the cervical spine.

This instrument is available in upward-cutting and downward-cutting versions, which are mirror-image designs that allow the surgeon to approach the bone from the optimal angle.