Pathophysiology The most common site of involvement is the anterior oval window near the fistula ante fenestrum When both the anterior and posterior ends of the footplate are involved it is termed"bipolar"involvement or fixation(if the footplate is immobile) f only the footplate is involved, it is sometimes referred to as a " stapedial otosclerosis When the entire footplate and annular ligament are involved it is known as an obliterated footplate or obliterative otosclerosis The round window is involved in approximately 30% to 50% of casesPathophysiology ◼ The most common site of involvement is the anterior oval window near the fistula ante fenestrum. ◼ When both the anterior and posterior ends of the footplate are involved it is termed “bipolar” involvement or fixation (if the footplate is immobile). ◼ If only the footplate is involved, it is sometimes referred to as a “stapedial otosclerosis”. ◼ When the entire footplate and annular ligament are involved it is known as an obliterated footplate or obliterative otosclerosis. ◼ The round window is involved in approximately 30% to 50% of cases