A typical hardwood armpit crutch has a 20-inch length of 1"x1" wood at the bottom to which are attached 2 other lengths of about 4 feet or longer that taper upward and outward, like the letter "Y," to a maximum width of about 5 inches at the top. Across the top is a padded or unpadded horizontal piece 6 to 8 inches wide that fits under the armpit to support the body. In the middle of the crutch, between the tapering shafts, is a crosspiece used as a handgrip. Holes, bolts and wing nuts in the sides of the bottom shaft and the two tapering top shafts allow the user to adjust the length of the crutch and the position of the handgrip. A typical aluminum armpit crutch has a similar design and may have push buttons to allow for easy adjustment. Arm crutches typically are metal and have a single shaft with a projecting handgrip and a cuff that closes around the arm. Crutches usually have a nonskid rubber tip on the bottom.
"Crutch" is derived from the Middle English words "crutche" and "crucche."