Dear Sac, The technique of placing the residual rib graft cartilage in the scalp has been used for many years. This is used both in rhinoplasty and when rebuilding an ear from rib cartilage in microtia. If you have gone to the trouble of having the rib harvested, then the most inconspicuous place to place your own potential future cartilage graft is in the scalp.
The use of rib cartilage for rhinoplasty can be an excellent choice in certain circumstances. If a person has undergone a previous septoplasty, then that cartilage source is not available for any necessary revision. If the cartilage in the scalp bothered you in several years, it can be removed in a simple in-office procedure.