If the reconstruction is poorly performed, it may result in a high rate of recurrent cholesteatoma. Preservation of the ear canal wall. If poorly performed, it may result in a high rate of both residual and recurrent cholesteatoma. Reconstruction of the chain of hearing bones using a passive middle ear implant.Clearly, preservation and restoration of ear function at the same time as total removal of cholesteatoma requires a high level of surgical expertise. Endoscopic surgery
Traditionally, ear surgery has been performed using the surgical microscope. The direct line of view dictated by that approach necessitates using the  mastoid as the access port to the middle ear. It has long been recognized that failure in cholesteatoma surgery occurs in some of the out of view spaces of the tympanic cavity like the sinus tympani and facial recess that are out of view using the traditional microscopic technique. More recently, the endoscope has been increasingly utilized in the surgical management of cholesteatoma in one of two ways:

Using the endoscope as an ancillary instrument to the microscope when trying to visualize areas that are hidden from the microscope such as the sinus tympani. This work was pioneered by Professor Thomassin. Using the endoscope as the main surgical instrument through the ear canal, or whats called:  Endoscopic Ear Surgery, pioneered by Professor Tarabichi.There are multiple advantages for the use of the endoscope in cholesteatoma surgery:

The endoscope wide angle of view and the ability to "see around the corner".
The removal of the ear canal wall results in: 

a space, the "mastoid cavity", which is less likely than the original ear canal to resist infection;
exposure of the ossicles, which may allow the subsequent formation of a new cholesteatoma deep to the ossicles. To prevent this, these ossicles must be removed, which may diminish the patients hearing.The formation of a mastoid cavity by removal of the canal wall is the simplest and most effective procedure for facilitating the removal of cholesteatoma, but may bestow the most lasting infirmity due to loss of ear function upon the patient treated in this way. The following strategies are employed to mitigate the effects of canal wall removal:

Careful design and construction of the mastoid cavity. This is essential for the health and integrity of the protective sheet of migrating, keratising epithelium which lines the distorted ear canal. This requires the surgeon to saucerise the cavity. A high facial ridge and an inappropriately small cartilaginous meatus are obstructions to epithelial migration and are particularly high risk factors for failure of the self-cleaning mechanism of the external ear. Partial obliteration of the mastoid cavity. This can be performed using a wide range of materials. Many of these resorb in time, which means that the long-term results of such surgery are poorer than the short-term results. Reconstruction of the ear canal wall. Canal wall reconstruction has been performed using ear canal skin alone, fascia, cartilage, titanium as well as by replacing the original intact wall.