An implant for a tightly fitting prostehsis, said implant comprising an externally threaded implant body intended to be screwed into bone using an insertion tool, the body being provided with an internal open ended axial bore and an indexing region at the open end of the bore, the indexing region being provided with a connection to support a spacer element and having means for co-operating with the spacer element to prevent twisting between the spacer element, the implant body and the insertion tool, the implant comprising a deformation zone.
