Fallout: New Vegas implants

General
Implants are available in Fallout: New Vegas from Doctor Usanagi, a Followers of the Apocalypse doctor who heads the New Vegas Medical Clinic. Other special implants are available in Big MT in the Fallout: New Vegas add-on Old World Blues.

The physical implants behave in the same manner as the Intense Training perk, permanently raising a single statistic by one, except the implants in the Old World Blues (add-on), many of which strengthen the player in various ways. The total number of implants you can receive is equal to your Endurance statistic (again, except in Old World Blues, in which you can get all of the implants offered by the Auto-Doc, so long as you have the caps to spend. Temporary boosts to Endurance from apparel or drugs are ignored by the game, as is the Endurance implant. Although implants can be bought when a statistic is at 10, it will confer no benefit.

The number of implants that can be installed by Dr. Usanagi depends on the player's Endurance. The only way to increase the amount of implant "slots" is boosting the statistic through Intense Training. A single point of SPECIAL will be added upon completion of Lonesome Road in form of one of four Perks; if Endurance is chosen, this will add a "slot." However, none of the implants added by the Old World Blues add-on count against a character's Endurance total.

Since the effects of implants bought from Dr. Usanagi are counted as a permanent increase to your SPECIAL, they will affect the perks available to the player.

Fallout: New Vegas
Dr. Usanagi sells implants to augment your physical abilities, and two special implants to augment the player's combat performance. Only one of each type can be installed.

Old World Blues
These implants can be obtained from the Sink Auto-Doc in the Big MT.

Bugs
If you are offered the low-intelligence discount but do not purchase the intelligence implant and then you leave the hospital, when you return and speak to Usanagi next time she will no longer offer this implant - discounted or otherwise.