Possible Risks of Using Ear Cartilage in Revision Rhinoplasty ?

Anytime you are using cartilage there is potential for warping. That being said, in skilled hands the risk is markedly reduced. When cartilage is correctly placed, it is concealed well and not at risk for extrusion. 

During a primary (first-time) rhinoplasty, cartilage is typically taken from the septum to make grafts that help change the shape of the nose to improve both appearance and breathing.  When a revision rhinoplasty is needed with additional grafts, the cartilage has to be harvested from somewhere else.  This can be from your ear, your rib, or purchased as a cadaver rib.  
Among the autologous (your own cartilage) options, ear cartilage harvest results in a scar that is well concealed within the creases of your ear, is technically easier for the surgeon to harvest, is close of the nose, and has an easier recovery than rib cartilage harvest.  There are minimal donor site risks in harvesting ear cartilage other than possible contour irregularity of the ear, but that is uncommon with good surgical technique.  Despite these advantages, ear cartilage is not always the best option for revision rhinoplasty.  Ear cartilage can be used for minor revisions but is more flimsy and naturally curved.  Therefore, ear cartilage is not ideal for revisions that require major shape changes such as straightening a crooked nose following a previous rhinoplasty.  Ear cartilage is effective for revision rhinoplasty when used as minor contour grafts or when a composite graft (cartilage plus skin) is needed such as for nostril defects.
Your own rib is the most reliable source of cartilage for complex revision rhinoplasty.  There is no substitute for your own rib cartilage in terms of length, strength, straightness, and quantity.  Rib cartilage can be easily harvested through a 1 inch (2.5 - 3 cm) incision over your rib cage.  The main downside of autologous rib cartilage is the small scar on the abdomen or breast crease that is less well concealed than the ear and a more arduous recovery.  However, the advantages of rib cartilage for changing the shape of the nose in complex cases far outweighs the disadvantages compared to ear cartilage.  Due to the technical difficulty or unfamiliarity of operating in the region of the ribs, many surgeons do not offer your own rib cartilage as an option.  However, it is an important option that certainly should be considered strongly for revision rhinoplasty.
Cadaver rib cartilage is also an option that has more rigidity than ear cartilage.  The advantage of using a cadaver rib is that the product is pulled off of a shelf, so the recipient has no donor site problems/scarring.  However, cadaver rib is not as proven as your own cartilage, and it tends to be slightly curved (warped) because it is treated with radiation to remove all of the living cells.  Resorption is the main concern with cadaver rib cartilage over time, which does not typically occur with your own ear or rib cartilage.  Cadaver rib is a purchased product that also adds an additional charge.
The other risks you inquire about such as warping, visibility under the skin, and extrusion can occur with any cartilage grafts.  However, extrusion is extremely rare.  Warping is typically minimal with your own rib cartilage as the majority of shape change occurs on the operating table after it is harvested and precisely cut.  To conceal cartilage grafts under the skin, a fascia graft can be used and placed over the cartilage grafts to add a layer of thickness between the cartilage and skin that minimizes visibility.  As with any surgery, there is always the chance of bleeding, infection, and damage to surrounding structures such as nerves.  However, these risks are very uncommon.  I would recommend an in-person consultation with a surgeon well versed in revision rhinoplasty for more specific recommendations to achieve the natural look you desire.  Best of luck!
Ziyad Hammoudeh, MD