Use of hydroxyapatite bone cement for difficult ossicular reconstruction

Abstract

Objectives: Conventional ossiculoplasty relies on favorable anatomy, surface tension, and packing to hold the reconstruction in its desired position. This can be frustrating when faced with difficult ossicular chain abnormalities that need a more stable fixation. We describe the use of Mimix™, a rapidly setting, nontoxic hydroxyapatite bone cement for the repair of complex ossicular problems in patients undergoing tympanomastoidectomy or stapedotomy. Methods: Mimix™ was used to cement partial ossicular replacement prostheses into position, repair incudostapedial joint separation and incus necrosis, repair incus necrosis during revision stapedotomy, augment the tapered incus during primary stapedotomy, and rebuild a total tympanic membrane perforation with a tympanic membrane/malleus head homograft. Preoperative and serial postoperative audiograms were examined for 4-tone pure tone average (PTA), speech reception thresholds (SRT), and word recognition scores (WRS) in 14 patients with up to 18 months follow-up. Results: The average improvement for PTA, SRT, and WRS approximated 22dB, 23dB, and +6%. Most patients demonstrated a significant closure of their air-bone gap. There was 1 case of unexplained delayed mixed hearing loss 7 months after surgery following successful air-bone gap closure. Conclusions: Even experienced otologists have desired some way to better fixate an ossicular repair into place during difficult cases. Our experience with Mimix™ hydroxyapatite bone cement suggests that such rigid fixation may now be available. Its paste-like consistency, rapid setting time, osteoconductivity, and lack of neurotoxicity make it ideal for middle ear reconstruction. Prolonged stable fixation may translate into long term improvements in hearing.