Rib carving is a tedious procedure, says Dr. Paul Nassif in this video. He soaks the rib graft in normal saline solution to soften it up and gives you the curve of where the cartilage is going to go. The inner cortex of rib has less chance of warping, so its left intact. For rim grafts you need to carve the cartilage which is very delicate process, since you have to make sure the graft doesn't end up splintering.
Symmetric carving of the costal cartilage graft will minimize the chance of the graft warping over time.
Dr.Jack Gunter, has devised a technique in which the larger grafts, the dorsal onlay graft and the columellar strut, are reinforced with a centrally placed Kirschner (K)- wire to decrease warping and provide a more stable and predictable result.
"Graft warping can occur in autogenous rib cartilage and lead to long-term postoperative distortions of nasal shape. The use of stabilizing K-wires placed through the center of these grafts has been a successful technique to counterbalance the tendency of the grafts to warp. To avoid warping of smaller grafts, we follow the principle of carving balanced cross-sections originally described by Gibson and later substantiated by Kim et al"
Control of grafted rib cartilage warping using K wire by Dr. A. Nakamura
Controversies in Otolaryngology: By Myles L Pensak
Revision Rhinoplasty: By Daniel G. Becker, Stephen S. Park