A surgical system for treating a sacro-iliac joint jointing sacrum and ilium, the system comprising: a set screw (32; 132) including a tapered leading end (34; 134), a trailing end (36; 136) with a planar surface (37; 137) and a socket (40; 140) which is configured to accommodate a driver so that the screw (32; 132) can be driven into an implant space prepared by a medical device, and an elongated shaft (38; 138) which is disposed along a longitudinal axis (a) between the leading end (34; 134) and the trailing end (36; 136), wherein the shaft (38; 138) has a cylindrical cross-section configuration and includes an outer surface having a continuous screw thread (44; 144) formed thereon, wherein the screw thread (44; 144) continuously extends between the trailing end (36; 136) and the leading end (34; 134) of the screw (32; 132) and is formed on a portion of the outer surface of the shaft (38; 138) surrounding the socket (40; 140), and wherein the screw (32; 132) is cannulated defining a cannulated portion (42; 142) configured to facilitate passage of a guide wire and/or bone graft and/or agents, and a bone graft which is configured for disposal and engagement on or about the surfaces of the screw (32; 132) and anatomical surfaces of a body and to be disposed, packed and/or layered about the surfaces of the ilium and the sacrum to facilitate a bony contact between the ilium and the sacrum, wherein the shaft (38; 138) of the screw (32; 132) has a length which varies from about 20 mm to about 60 mm so that the screw (32; 132) can be disposed for fixation with the ilium and the sacrum of the sacro-iliac joint in a cavity of a pathway formed in the body along a selected trajectory that includes a target of a posterior superior iliac spine of the body and at least a portion of the sacrum of the body in a manner such that the screw (32; 132) extends through cortical layers and cancellous bone of the ilium into the sacro-iliac joint, through the bone graft and into the first cortical layer of the sacrum with the planar surface being disposed in substantially flush alignment with an outer surface of the ilium.. a set screw (32; 132) including a tapered leading end (34; 134), a trailing end (36; 136) with a planar surface (37; 137) and a socket (40; 140) which is configured to accommodate a driver so that the screw (32; 132) can be driven into an implant space prepared by a medical device, and an elongated shaft (38; 138) which is disposed along a longitudinal axis (a) between the leading end (34; 134) and the trailing end (36; 136), wherein the shaft (38; 138) has a cylindrical cross-section configuration and includes an outer surface having a continuous screw thread (44; 144) formed thereon, wherein the screw thread (44; 144) continuously extends between the trailing end (36; 136) and the leading end (34; 134) of the screw (32; 132) and is formed on a portion of the outer surface of the shaft (38; 138) surrounding the socket (40; 140), and wherein the screw (32; 132) is cannulated defining a cannulated portion (42; 142) configured to facilitate passage of a guide wire and/or bone graft and/or agents, and a bone graft which is configured for disposal and engagement on or about the surfaces of the screw (32; 132) and anatomical surfaces of a body and to be disposed, packed and/or layered about the surfaces of the ilium and the sacrum to facilitate a bony contact between the ilium and the sacrum, wherein the shaft (38; 138) of the screw (32; 132) has a length which varies from about 20 mm to about 60 mm so that the screw (32; 132) can be disposed for fixation with the ilium and the sacrum of the sacro-iliac joint in a cavity of a pathway formed in the body along a selected trajectory that includes a target of a posterior superior iliac spine of the body and at least a portion of the sacrum of the body in a manner such that the screw (32; 132) extends through cortical layers and cancellous bone of the ilium into the sacro-iliac joint, through the bone graft and into the first cortical layer of the sacrum with the planar surface being disposed in substantially flush alignment with an outer surface of the ilium..