What are the technical maneuvers surgeons use to minimize the risk of warping in coastal onlay grafts for bridge augmentation?

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  It depends on your nasal anatomy.  In my practice I often perform dorsal augmentation using diced cartilage wrapped in facsia which can avoid the risk of warping.   Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most
important aspect is to find a surgeon you are comfortable with. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon

Over the past 35+ years I've rarely used rib cartilage to augment the nasal bridge. Usually there is enough septal or ear cartilage available which is much easier to harvest. I also prefer diced cartilage so I don't have to worry about possible warping with onlay grafts.