The new treatment tested by this study is an implant that will partially replace the voicebox or upper windpipe in order to cure the narrowing. The implant is based on a human donor voicebox or windpipe that has been processed with detergents and enzymes in order to remove all the cells from the donor, leaving a 'scaffold' of connective tissue. The patient's own stem cells are removed from the bone marrow, then are grown on the scaffold in the laboratory. These cells will form the cartilage in the wall of the scaffold. A split skin graft from the patient may be needed to line the inside of the implant. The implant can be considered 'living' due to the cells grown on it, and this type of treatment is referred to as 'tissue engineering' or 'regenerative medicine'.