Clinical otosclerosis is manifested by a hearing deficit caused by restriction of the mobility of the stapes due to the development of an otospongiotic area of bone either on the footplate of the stapes or in the labyrinthine capsule in proximity to the margins of the oval window. Such restriction of the stapes in transmitting sound vibrations to the inner ear results in a conductive type hearing loss. The pathogenesis changes the character of the bone growth from a spongy type of bone to a very sclerotic dense type of bone. Needless to say, the more dense and sclerotic the focus of new bone, the more difficult the removal of the stapes becomes.Historically, stapedectomy was a procedure first introduced by Shea1, who in the late 1950s reported his success in the treatment of clinical otosclerosis by removal of the stapes and insertion of a vein graft with a beveled polyethylene strut, the latter to perform as a stapes replacement. Shortly thereafter, Schuknecht introduced the wire-fat prosthesis, which has retained considerable popularity up to the present time.2Not being satisfied with either the principles or techniques of the latter two prostheses, In 1960 I began to consider a totally different design in a stapes prosthesis that would be so standardized that it could be used in virtually every case of otosclerosis. The prosthesis was designed to engage on the lenticular process of the incus with a centrally placed shaft and a wire loop, and the final design consisted of 4 holes in the socket as well as a hole in the distal portion of the stem to allow tissue ingrowth and also to allow for vascularization of the lenticular process. After determining the average length of many stapes, it was decided that a length of 4-mm would be most suitable and most appropriate for the majority of cases. This prosthesis possesss many unique features. It is fabricated of 316 L stainless steel, a metal that is completely inert to tissue. The design allows this prosthesis to be self-centering; it maintains a physiologic attachment to the lenticular process; its holes permit tissue and vascular ingrowth; it is effective with partial or total footplate removal; the 4-mm size can be used in 98percnt; of cases; and most important, its easy insertion minimizes the risk of cochlear trauma. The prosthesis is available presterile or can be autoclaved, and it can be used with any type of connective tissue graft, vein, fat, or perichondrium. This prosthesis is radiopaque and is easily identified and localized with routine x-rays. Impedance studies by other investigators revealed this prosthesis to be closest to the normal mobile stapes. The results provide an ldquo;all or nonerdquo; effect, with a 96percnt; success rate obtained over its 20 years of use by other surgeons as well as by me.There are several modifications of the Robinson stapes prosthesis. A 4.5-mra length is available, a large well is available for the unusually large lenticular process, and a narrow stem is available for the ldquo;drillout.rdquo; One modification that has been proved to be extremely useful when there is necrosis of the long process of the incus is the Robin-son-Moon-Lippy stapes prosthesis. This modification by Moon and Lippy of having part of the wall of the socket removed to accept the foreshortened long process of the incus and an offset shaft to avoid the facial nerve has been very helpful in the rare case when this situation is encountered.
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