Bone boring instrument

A manually operable bone boring instrument for removing, by the hand manipulation of the user, a cylindrical section of bone for a medical purpose comprising:

• an elongated trephine having a hollow shaft, circularly-arranged saw teeth at the distal end thereof and an enlarged head portion at the proximal end thereof, and
• a handle means for engaging and causing rotation of said trephine about its longitudinal axis for cutting a cylindrical core of bone for removal,
• said handle means including
• a body having a longitudinally extending central bore,
• a drive shaft extending longitudinally within said central bore,
• means for supporting said drive shaft on said body for rotation within said central bore including
• means for providing one-way driving engagement between said body and said drive shaft so that when said body is caused to rotate in one direction relative to said drive shaft, said means for providing one-way driving engagement causes conjoint movement of said drive shaft and said body, and when said body is caused to rotate in the opposite direction relative to said drive shaft, said body is free to rotate freely relative to said drive shaft, so that the user can by an oscillating hand motion on said handle means perform a manual bone cutting operation by rotating the trephine in only one direction without letting go of said handle means,
• said drive shaft having an end portion extending from one end of said body, and
• quick-release coupling means on said extended portion of said drive shaft for releasably engaging said trephine at said enlarged head portion thereof.