Will the cochlea grow with age and require a new implant?

No, the cochlea doesn't grow with age and a cochlear implant is never replaced because the child grows. This is one of the most frequently stated concerns parents have, so it is important to make it clear: When a baby is born, their cochlea is nearly the same size as it is when they are an adult. It is fully developed at birth so there is no growth to take into consideration later and the internal implant remains in the same position as in surgery.

Here it's important to understand that there are two parts to the implant. The inner body is to be left in the cochlea once the surgery is completed, and will not be replaced as the child grows. The external processor, attached to an external part of the ear, is a different story. It may be upgraded every so often, but that's to take advantage of newer technology and improved sound processing, not because the child has outgrown it.

That said, a device may occasionally need replacement for reasons unrelated to growth, such as accidental damage to the external processor or, very rarely, a technical fault in the internal implant. Both situations are very, very rare and are not a normal part of having a cochlear implant. Most children use the same implant for many years without any issues, and if replacement is ever needed, it's simply due to one of these uncommon circumstances, never because the child has grown.