Artificial bone graft implant

Claim 1

An implant for replacing the supporting function of an intervertebral space defined between adjacent vertebrae, comprising a prosthetic implant member dimensioned for insertion within a space provided by at least partial removal of the intervertebral disc, the implant member including upper and lower surfaces for respectively engaging upper and lower vertebral portions and defining an axis extending between the upper and lower surfaces, the upper and lower surfaces defining a height therebetween along the axis sufficient to span the intervertebral space and maintain the upper and lower vertebral portions in predetermined spaced relation, the implant member defining a transverse dimension transverse to the axis, the transverse dimension greater than the height of the implant member, the implant member including a first implant portion and a second implant portion, the first implant portion comprising a microporous material formed to define a predetermined configuration and having a first relatively high average porosity to facilitate rapid bone ingrowth within the first implant portion, the first implant portion extending through the upper and lower surfaces of the implant member, the second implant portion comprising a microporous material formed to define a predetermined configuration and having a second relatively low average porosity such that the second implant portion is characterized by having sufficient strength to support and maintain the adjacent vertebrae in spaced relation during permanent fixation of the implant member within the adjacent vertebrae, the second porosity being less than about 40%. the implant portion further including a third implant portion disposed between the first and second implant portions, the third implant portion having a third average porosity ranging between the first porosity and the second porosity.