An implant system for use in orthopaedic surgery for fixation of bone includes an intramedullary nail, a bone fastener and a coupling member. The intramedullary nail includes a proximal portion defining a longitudinal axis. The proximal portion includes an axial bore defining an axis substantially parallel to the longitudinal axis of the proximal portion and a transverse bore configured to receive the bone fastener. The bone fastener is configured to be received in the transverse bore of the intramedullary nail. The coupling member includes a through hole and is configured to be movably arranged within the axial bore of the proximal portion of the intramedullary nail. Further, the coupling member includes a drive portion and a bone fastener engagement portion. The drive portion is movably towards the distal portion of the intramedullary nail within the proximal portion axial bore so as to urge the bone fastener engagement portion toward the distal portion of the intramedullary nail within the proximal portion axial bore and into engagement with a bone fastener penetrating the transvers bore. The bone fastener engagement portion includes an extended contact region configured to engage a complementarily shaped contact region of a bone fastener penetrating the transverse bore.
