Retaining mechanism for an implantable medical device connector assembly

An implantable medical system comprising:

• an implantable lead;
• a sealed casing having electronic circuitry therein;
• a header assembly for interconnecting the electronic circuitry with the implantable lead, the header assembly comprising:
• a support body having a receptacle connector extending therefrom, wherein the receptacle connector receives the implantable lead therein and is electrically coupled to the electronic circuitry, and the support body having a fastener bore;
• a clamp having a clamp fastener bore, the clamp being movable with respect to the support body to receive the lead between the clamp and the support body;
• and
• a threaded fastener received in the fastener bore and the clamp fastener bore for securing the clamp to the support body, the threaded fastener having first and second sets of threads for engaging first and second threaded portions, respectively, wherein the first and second threaded portions are included in at least one of the fastener bore and the clamp fastener bore, and wherein the first and second sets of threads have different thread types;
• and
• an insert received in the support body, the insert defining the fastener bore and including the first and second threaded portions.