Which do you think is the most technically difficult operation in plastic surgery? Limb replants? Face transplants? Maybe bodylifts? In fact, most plastic surgeons will tell you that rhinoplasties are the most difficult operation. Rhino—what? No, that’s not an operation on that one-horned African animal. But the root of the word—“rhino” means “nose” in both the rhinoceros and rhinoplasty.Rhinoplasties are operations that change the shape of the nose. They’ve been performed in one form or another for hundreds of years, but they only became popular in the 1960s. Back then, rhinoplasties were dubbed “nose-jobs”, and were really pretty radical, unsophisticated procedures. Surgeons made incisions inside the nose and performed the operation upside down and inside out. To an observer, that operation would have looked like the doc simply jiggling a series of instruments inside the nose. And, truth be told, only the surgeon knew just what he did in that nose. Even the scrub nurse couldn’t tell. Nowadays, there’s about 134,000 nose altering operations each year. Not quite as popular as liposuctions and breast implants, but still a healthy number.QUIZ: How Do You Feel About Your Face?Those 1960s nose jobs were really pretty brutal procedures. Bone and cartilage was chomped away, without a good understanding of the long-term consequences of the procedure. Plastic surgeons developed their own techniques, often performing the same procedure on everyone.  It was sort of like they placed their signature on the faces of their patients, and those schnozzolas became known as “signature noses”. You could tell which surgeon did which nose by identifying that characteristic swoop or shortened tip. Those noses often looked pretty good back in the 60s, but the surgeons didn’t count on the tissue thinning that occurred over years, and in fact, decades. So those cute noses in 1965 often looked twisted and tiny by 1985. And by the 80s, with a few decades of experience behind the cosmetic surgery profession, the operation changed.By the mid 1980s, rhinoplasties were done more conservatively. Incisions were made between the nostrils, allowing the skin to be lifted off the nose like the hood is lifted off of a car. This allowed the operation to be performed “outside in”, not “inside out”, and this added great precision to the procedure. The focus no longer was simply on making the nose smaller. It was realized that correct proportions and proper angles were as important, or even more important, than size. Surgeons began to individualize the operation, respecting ethnicity and patient desires.But even with these sweeping changes in nasal reshaping surgery, there were still problems with the procedure. Rhinoplasties involve shaving and cutting bone and contouring, moving and sculpting cartilage. But every surgeon knows that bone can regrow after surgery—after all, it just thinks it’s been broken and it tries to fix itself. And cartilage can warp and bend and droop and stitches can rip through long after the procedure has been completed.So, when the dust has settled a year after the last stitch was placed, nearly one of five people have less than a perfect result—even in the best of hands. And so rhinoplasty has the highest “redo” rate of all cosmetic surgery. Honest surgeons will tell you they have to redo 15-20 percent of rhinoplasties. Plastic surgeons know that there are only two types of doctors who don’t have to reoperate on noses:  new doctors (who haven’t done enough yet) and dishonest doctors (they won’t tell you).So, that statistic and the unpredictability of this operation make rhinoplasty the most difficult cosmetic surgical procedure. But don’t let this bother you. Even those who need a second operation usually will tell you that their nose is still better than it was before surgery.  And the vast majority of patients are thrilled with their new noses.MORE: Can Plastic Surgery Make You Happier?Rhinoplasty is an operation that can vastly improve self-esteem. Of course, surgery is not for everyone, and so there are makeup techniques and even some new minimally invasive procedures like injectables that can substitute for going under the knife. But the effects of surgery can be powerful; I’ve seen introverted teenagers become extroverted after surgery.  The change can be remarkable.With all of these considerations, rhinoplasties are my favorite surgical procedure. Every nose is different and every operation is individualized. Rhinoplasties require an artistic flare and a steady hand. And yes, it is the most difficult procedure that I perform.MORE: 12 Celebs Who Regret Having Plastic Surgery