Bone, pinner's bone

Pinners bone. Bovine metatarsal right side, fused. Lateral and medial sides of the distal articular end sawn off, revealing cancellous structure of exposed bone. The posterior side of the medial condyle has been largely removed. Four flat facets have been cut into proximal end of the shaft, with ten grooves in the longitudinal axis made by a saw. Small foramen. There are file marks on every side, and the medullary cavity has been enlarged considerably at the proximal end. This hole probably fitted over a spike, serving perhaps to secure the bone onto the work surface.