from The Century Dictionary and Cyclopedia
- n. The knee-cap of a sheep: so named because it was considered a charm against cramp.
Sorry, no etymologies found.
Another and very common charm resorted to for the cure of this painful disorder, consists in the wearing about the person the patella of a sheep or lamb, here known as the "cramp-bone."
The cramp-bone is a delicacy, and is obtained by cutting down to the bone at 4, and running the knife under it in a semicircular direction to 3.
The knee-cap bone, or patella, of a sheep, known locally as the "cramp-bone," is worn in Northamptonshire for a like purpose; also the application of a gold wedding ring (first wetted with saliva, an ingredient in the holy salve of the Saxons), to a stye threatened in an eyelid is often found to disperse the swelling; but in this case  it may be, that a sulphocyanide of gold is formed with the spittle, which promotes the cure by absorption.