A perforation instrument and method of using same, including a shaft capable of being inserted into a joint of a patient, having a longitudinal axis, and carrying at least one piercing member, each piercing member having a tip suitable to pierce sub-chondral bone. The instrument is capable of being altered between an exposed condition wherein the tip of the at least one piercing member is exposed and a safety condition wherein the tip of the at least one piercing member is not capable of piercing tissue.