Otosclerosis Otosclerosis is when abnormal bone remodeling occurs in your middle ear. Bone remodeling is a normal lifelong process in which existing bone tissue replaces itself with new bone tissue. When this process doesn’t go as expected, however, it can cause health problems. With otosclerosis, the tiny bones inside of your middle ear (the malleus, incus and stapes) become hardened and stop vibrating. As a result, sound doesn’t travel properly. Surgery is usually necessary to treat otosclerosis.