The options in improving the appearance in Poland's Syndrome where the bottom half of the muscle is missing can include a custom shaped pectoral implant, fat grafting or both. The choice of which method would work best will depend on his exam. Pictures certainly would help. It is important to see the amount of discepancy between the right and left side as well as how much deficiency is apparent on the one side as well. I also use Strattice in cases of Poland's syndrome. It is an acellular dermal graft i use to cover the portion of the implant not under muscle. Implants placed in a subcutaneous plane only have a high rate of a shrink wrap effect around the implants making it very visable. Strattice, and sometimes fat, allow for better cover, transition and results.
I think you are on the right track with researching pec implant for correction of Poland syndrome. I have found this to be the best choice for this deformity. Unfortunately, even with the diagnosis, it can be difficult to have the insurance pay for this. Good Luck!