The Expansile Properties of Kryptonite Relating to Cranioplasty Gaby D. Doumit, MD, MSc, Eileen Meisler, RNFA, Joseph Sidaoui, MD, James E. Zins, MD, and Frank A. Papay, MD Background and Purpose: Since 2009, a synthetic material known as kryptonite has become increasingly utilized during cranioplasty to repair bony defects. It provides bone-like strength and adhesive properties that make it a suitable replacement for bone. However, applications have been observed in the immediate postoperative period that demonstrates an increase in its original volume, giving rise to irregularities in the cranial surface. Methods: Ten kryptonite samples were reconstituted and allowed to polymerize according to the manufacturer’s directions. The kryptonite samples were molded into a cylindrical shape, and they were immersed in 10 graduated cylinders filled with normal saline. Measurements of the rise in saline relative to baseline were taken at 0, 10, 20, 30, 40, 50, and 60 minutes, and then hourly through 5 hours, with the final measurement recorded at 24 hours. Results: The mean expansion of kryptonite was approximately 49% with an SD of 22%. The bulk of the expansion occurred within the first 2 hours, after which the rate tended to plateau for the remaining 22 hours. Conclusions: Kryptonite has been touted as an excellent alternative for repairing contour abnormalities manifested in cranioplasty. Given the unpredictability of its expansile properties, the surgeon must take this variability into careful consideration when planning the desired surgical outcome. The results of the current study were communicated with the man- ufacture. Immediately thereafter, the manufacturer withdrew the product from the US market and is no longer Food and Drug Ad- ministration approved for cranioplasty. Key Words: Expansile properties, expansion, cranioplasty, kryptonite (J Craniofac Surg 2014;25: 880Y883) C ranioplasty is defined as the surgical repair of skull defects. It was first performed in the 16th century, initially in the form of gold plates. 1 Bone grafting was first introduced in the late 19th century, 2 and the use of autografts (cranium and rib primarily) be- came popular in the 20th century. 1 Because of the advent of warfare during this time, the search began for different metals and plastics that could be substituted for bone in the cases of more frequent complex and large instances of cranial trauma. Autografts, although beneficial in avoiding an immune re- sponse, have the disadvantages of lacking enough material for large cranial defects, propensity for reabsorption, and causing donor-site morbidity. There are avariety of allografts used today. Titanium is the most widely recognized metal material. It is biocompatible, light, strong, and radiolucent. The major drawback to titanium, however, is that it is difficult to shape and does not often mold to accommodate the contour abnormality. 3 Calcium phosphate cement is an inorganic compound composed of calcium, phosphate, and hydroxide that offers strength and is able to be easily molded, although it is too brittle to support the stress load in many cases. 4 Methylmethacrylate is strong and offers the advantage of being able to be easily contoured. However, it is also brittle and demonstrates increasing exothermic qualities, often raising the temperature of surrounding tissues significantly. 5,6 As of November 2009, a new material has emerged on the scene. Kryptonite bone cement, which has been Food and Drug Administration approved for cranioplasty applications, is a nontoxic, low-exotherm, porous material composed of fatty acids and calcium carbonate, which provides bone-like strength and adhesive proper- ties. 7 It has the capability to be used alone or in combination with other allografts and has been proven to promote tissue in-growth. In addition, kryptonite is suitable for application in either a more liquid or more putty-like form, depending on the size and shape of the defect in consideration. Postoperatively, it has been observed that the kryptonite has expanded in volume unpredictably, therefore modi- fying the intended surgical result. This article discusses the expan- sive properties of kryptonite based on a series of experiments. METHODS To quantitate the amount of kryptonite’s expansion, the following experiment was performed: 10 graduated cylinders (Graduated Bomex CLINICAL STUDY 880 The Journal of Craniofacial Surgery & Volume 25, Number 3, May 2014 From the Department of Plastic Surgery, Institute of Dermatology and Plastic Surgery, Cleveland Clinic, Cleveland, Ohio. Received September 3, 2013. Accepted for publication October 28, 2013. Address correspondence and reprint requests to Gaby D. Doumit, MD, MSc, Department of Plastic Surgery, Institute of Dermatology and Plastic Surgery, Cleveland Clinic, 9500 Euclid Ave, Suite A60, Cleveland, OH; E-mail: doumitg@ccf.org The minimal material support needed was contributed from the personal funds of the authors. The authors report no conflicts of interest. Authors’ roles/participation in the authorship of the manuscript: G.D.D.: primary author with significant participation in study design, study execution, data analysis, and manuscript preparation; E.M.: assistant author with significant participation in study execution and manuscript preparation; J.S.: assistant author with significant participation in data analysis and manuscript preparation; J.E.Z.: assistant author with significant participation in survey design and manuscript preparation; F.A.P.: senior author with significant participation in survey design and manuscript preparation. Statement declaring adherence to the Helsinki Declaration: G.D.D., William Abouhassan, MD, and Michael J. Yaremchuk, MD, declare that thework ‘‘Aesthetic Refinements in the Treatment of Graves’Ophthalmopathy’’ conforms to the Helsinki Declaration. Copyright * 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000508 Copyright © 2014 Mutaz B. Habal, MD. 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