Letters to the Editor
In Reply: There are several issues regarding the repair of incudostapedial joint (ISJ) discontinuity, which warrant discussion. However, before I proceed, I wish to disclose my financial relationship with both Walter Lorenz to obtain Food and Drug Administration clearance for the use of OtoMimix for ossicular reconstruction and Gyrus ENT for distribution of OtoMimix.
A primary objective in all ossicular chain reconstructions (OCRs) is restoration of continuity while maintaining as much native ossicular chain function as possible. In the case of isolated ISJ erosion/discontinuity, it seems logical to preserve the incus and restore continuity with either a preformed (titanium or hydroxyapatite [HA]) prosthesis or a bone cement rather than to reposition the incus or to use a partial ossicular replacement prosthesis. Both the article and the Letter to the Editor have addressed the problem but differ on the primary mode of repair. When deciding on which method to use, the following issues should be considered:
- How large is the ISJ defect? In cases of fibrous union or gaps less than 2 mm, bone cement ossiculoplasty is my primary mode of reconstruction. Application of the cement in this scenario is straightforward and technically uncomplicated. However, if the gap is greater than 2 mm, I would prefer to use a preformed prosthesis to bridge the gap and then secure this prosthesis in place with cement for a more durable repair.
- What is the potential risk of using bone cement in the case of spillage? As the article and the letter state, ionomeric cements do carry a potential risk of aluminum ion toxicity, although this is minimized with the most recent ionomeric cement formulation to reduce (but not eliminate) aluminum ion release. In contrast, HA cements have no identified toxic properties and any spillage into the oval or round window region or on the facial nerve can easily be removed with suction without risk of neural injury.
- How dry is the operative field during OCR? All cements work best in a dry operative field during the initial application of the cement. This can be accomplished in most cases with use of dry Gelfoam around the ISJ to keep any blood away from the cement for at least 1 minute while it starts to harden. After that point in time, blood or irrigation fluid has minimal effect while the surgeon waits an additional few minutes before closing the ear. In cases of an excessively moist operative field, bone cement OCR might not be possible.
- What are the chances that sometime in the future the OCR might need to be disconnected due to recurrent disease (i.e., cholesteatoma)? If recurrent cholesteatoma is an issue, it is possible to remove the bone cement repair with a laser and sharp dissection. However, in my experience, it is unusual to have an isolated ISJ erosion with cholesteatoma without involvement of either the stapes superstructure or the body of the incus. In such cases, the incus and/or stapes superstructure would have been removed and a preformed prosthesis is placed. It is possible to stabilize these prostheses with cement at their interface with the manubrium, but I would discourage the use of cement at the prosthesis/capitulum or prosthesis/footplate interface. If recurrent disease is encountered at revision surgery, the prosthesis can be lifted off the stapes while remaining adherent to the drum/malleus surface, the disease removed and the prosthesis repositioned onto the stapes without necessarily removing the prosthesis and starting over.
There is a short learning curve when using bone cement for OCR-proper patient selection, mixing and placement, and securing a dry field. Because such a small amount of HA cement is used, the drying time in the ear where blood will not affect the repair is actually quite quick (about 1 minute) while still allowing the surgeon 3 to 4 minutes of working time to apply additional cement from the mixing cup if necessary. In selected cases, HA cement offers the possibility of a firm durable repair with no known toxicity and expands the surgeon's armamentarium for OCR.
Joel A. Goebel, M.D., F.A.C.S.
Department of Otolaryngology-Head and Neck Surgery
Washington University School of Medicine
St. Louis, Missouri, U.S.A.