Prevention and management of complications associated with the hydroxyapatite implant.

The hydroxyapatite orbital implant offers many advantages compared to conventional implants; however, its use is not entirely free of complications. The objectives of this study are to review the complications encountered with the hydroxyapatite orbital implant, suggest mechanisms contributing to the development of these complications, and emphasize aspects of surgical technique that will minimize the risk of the most frequent complication, implant exposure. Preoperative, operative, and postoperative records of 154 patients receiving primary and secondary hydroxyapatite implants were studied retrospectively. Three clinical types of exposure defects were observed; dehiscences along the horizontal suture line, defects over holes in the hydroxyapatite, and a defect adjacent to the site of radiation plaque therapy. Most small exposures healed spontaneously. Medium and large defects were associated with anteriorly malpositioned implants, most often required surgical intervention, and were successfully managed with one or a combination of techniques including flaps, mucous membrane grafts, or repositioning of the implant more posteriorly. Placing the hydroxyapatite implant as far posteriorly as possible and advancing the extraocular muscles 3-5 mm from the apex of the implant will prevent most exposures. Unlike other types of implants, the hydroxyapatite implant does not migrate or extrude, and when exposed, usually does not require removal.