CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY J Oral Maxillofac Surg 70:e169-e176, 2012 Cranioplasty With Custom-Made Implants: Analyzing the Cases of 10 Patients Horatiu Rotaru, MD, DDS, PhD,* Horatiu Stan, MD, PhD,† Ioan Stefan Florian, MD, PhD,‡ Ralf Schumacher, MSc, PhD, BSc,§ Yong-Tae Park, DDS,储 Seong-Gon Kim, DDS, PhD,¶ Horea Chezan, Eng,# Nicolae Balc, MSc, PhD, BEng,†† and Mihaela Baciut, MD, DDS, PhD** Purpose: The aim of this study was to assess quantitatively whether a symmetric reconstruction of the calvaria could be achieved using 3-dimensional (3D) custom-made implants and to examine any complications caused by the cranioplasty. Patients and Methods: Custom-made cranial implants were produced using data obtained from computed tomographic scanning of the defect using computer-aided design and rapid prototyping techniques. Polymethylmethacrylate was used as the reconstruction material and the implant was cast from a silicone rubber mold. These implants were used in 10 patients (9 men and 1 woman) who previously received a craniectomy. The symmetry gained after cranioplasty was quantified by volumetric analysis using 3D reconstructed postoperative computed tomographic imaging. Any complications after cranioplasty also were recorded. Results: The average follow-up was 42.5 months (range, 7 to 85 mo). The esthetic appearance of all patients was much improved. When the volume of the reconstructed right calvaria was compared with the left calvaria, the difference was not statistically significant (P ⬎ .05). There were 2 cases of complications. One exhibited a transient seroma collection. Another had a wrinkle formation in the forehead. No infectious episodes or signs of plate rejection were encountered. Conclusions: The custom-made implants for cranioplasty showed a significant improvement in morphology. The implants may be very useful for repairing large and complex-shaped cranial defects. The technique may be useful for the bone reconstruction of other sites. © 2012 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 70:e169-e176, 2012 Received from the “Iuliu Hatieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania. *Assistant Professor, Department of Craniomaxillofacial Surgery. †Assistant Professor, Department of Neurosurgery. ‡Professor and Chairman, Department of Neurosurgery. §Head, Medical Additive Manufacturing Group, University of Applied Sciences, Muttenz, Switzerland. 储Resident, Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea. ¶Associate Professor and Chairman, Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea. #PhD student, National Rapid Prototyping Laboratory, Cluj-Napoca, Romania. **Professor and Chairman, Department of Implantology and Maxillofacial Surgery. ††Professor and Chairman, Department of Manufacturing Engineering, Technical University, Cluj-Napoca, Romania. This study was supported by grant 5/2010 from the project New Biocompatible Materials for Personalised Implants made by SLS and SLM (BIOMAPIM) PN I-PCCE-ID 101, financed by the Romanian Government, and grant PJ007170201006 from the BioGreen21 Program, Rural Development Administration, Suwon, Republic of Korea. Address correspondence and reprint requests to Dr Kim: Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea; e-mail: epker@chol.com © 2012 American Association of Oral and Maxillofacial Surgeons 0278-2391/12/7002-0$36.00/0 doi:10.1016/j.joms.2011.09.036 e169 e170 CRANIOPLASTY WITH CUSTOM-MADE IMPLANTS Table 1. SUMMARY OF PATIENTS Case Age (yr) Gender Cause of Defect Site of Defect Postoperative Complication Follow-Up (mo) 1 2 3 4 5 6 7 8 9 10 24 53 33 31 21 25 49 30 51 27 male male male male female male male male male male trauma stroke trauma trauma trauma trauma Pott puffy tumor trauma trauma trauma unilateral unilateral unilateral bifrontal unilateral bifrontal bifrontal bifrontal bifrontal bifrontal no no serous collection no no wrinkle formation no no no no 62 85 11 11 42 67 51 7 29 60 Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. A cranial bone defect can occur owing to trauma, infection of the calvarial bone, and craniectomy for cerebral decompression procedures. Cranial defects result in esthetic and functional deficiencies.1-3 Symmetry of the calvaria is achieved by correcting the depressed appearance of the skull, and an esthetic appearance is important for a patient’s psyche and social relationships. Functional deficiencies also have been observed in patients with cranial defects. A trephination syndrome can be encountered in such patients. The main symptoms are dizziness, irritability, anxiety, and intolerance to noise or vibrations.2,3 The cranioplasty procedure has been found effective in the resolution of the trephination syndrome.4 Some investigators have observed a significant improvement in major neurologic functions after cranioplasty.5,6 For these reasons, reconstruction of the cranial bone and the achievement of symmetry are of the utmost importance, not only for cosmetic repair but also for improving neurologic functions. Many kinds of materials have been used for cranioplasty, such as autografts, xenografts, and allografts.1 Since the development of tissue engineering, many kinds of new materials, such as a combination of various scaffold materials and autologous adipose-derived stem cells7 or a combination of a silk scaffold and platelet-rich plasma, have been developed as bone graft material.8 However, there have been no reports of a long-term follow-up for those recently introduced materials. Long-term results for cranioplasty have been available mainly for autografts, polymethylmethacrylate (PMMA) grafts, or titanium caps. The novel technique of rapid prototyping (RP) has been developed in the past few decades and it offers the possibility of preoperatively forming various materials into custom-made implants to fit precisely each individual’s cranial defect.9 Compared with intraoperative cranioplasty surgery, custom-made cranioplasty implantation has many advantages, such as a shorter operative time, its positive effects on the healing process, less invasive surgery, no donor site morbidity from the use of alloplasts, improved cosmetic results, faster recuperation, and lower costs owing to a shorter operative time10,11 Using 3-dimensional (3D) models derived from computed tomographic (CT) images, cranial defects have been successfully reconstructed symmetrically.12 To the best of the authors’ knowledge, there has been no article discussing the quantitative analysis of the symmetry gained by 3D reconstruction. Only some case reports have been published. The purpose of this study was to investigate quantitatively whether symmetrical reconstruction of the calvaria is possible by 3D reconstruction using CT analysis and RP technology. Any complications from the new technique were also recorded. Patients and Methods From 2003 through 2010, 10 calvarial defects were repaired using custom-made alloplastic cranial implants in the Department of Craniomaxillofacial Surgery, “Iuliu Hatieganu” University of Medicine and Pharmacy (Cluj-Napoca, Romania). This study was approved by the institutional review board of “Iuliu Hatieganu” University of Medicine and Pharmacy, and it followed the guidelines of the Declaration of Helsinki. This study was granted an exemption by the institutional review board of Gangneung-Wonju National University (Gangneung, Republic of Korea). The patients were 9 men and 1 woman 21 to 53 years old (mean age, 34.4 yrs; Table 1). The inclusion criteria were 1) patients undergoing a craniectomy, 2) patients with neurologic symptoms related to cranial defects, and 3) patients with an asymmetric calvarium caused by a cranial defect. The exclusion criteria were 1) patients with an abnormal cranial pressure, 2) patients with any sign of infection, and 3) patients allergic to PMMA. ROTARU ET AL To produce the custom-made cranioplasty implants, a spiral CT scan of the head (Siemens Somatom, Erlangen, Germany) was performed as the first step. A virtual 3D model of the skull was obtained using a 3D reconstruction program (MIMICS, Materialise NV, Leuven, Belgium; Fig 1). The virtual 3D model of the patient-specific implant was designed using FreeForm Modeling Plus 9.0 (Sensable, Wilmington, MA; Fig 2). Using selective laser sintering (Sinter Station 2000, 3D System, Darmstadt, Germany) or 3D printing (Eden 330, Objet Geometries, Rehovot, Israel), the virtual models (of the calvarial defect and the custom-made implant) were transformed into physical models (Fig 3). The designed implant was well suited for the defect, which was not needed for further manual processing. The pattern of the implant was used to make a silicone rubber mold. Radiopaque bone cement (Surgical Simplex, Stryker Howmedica Osteonics, Limerick, Ireland) made of PMMA was poured into the silicone rubber mold and pressed into the form. After unmolding, the margins of the final custom-made implant were slightly and manually processed to eliminate any excess. On the surface of the plate, holes were made to prevent the development of an epidural hematoma. The plates were sterilized using ethylene oxide. Under general anesthesia of the patient, the bone defect was exposed and the custom-made implants were applied. The plates were fixed with 1-0 silk sutures to the bony margins of the defect to provide e171 FIGURE 2. A reconstructed virtual 3D model of the skull depicts the preoperative damaged skull (gray) and the imagined reconstructed area (apricot). Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. stability (Fig 4). To investigate the symmetry restored by the reconstruction, additional CT scans of the patients were taken postoperatively. The neurocranium is defined as the cover of brain and it is divided into 2 parts: the calvaria, the roof of the neurocranium, and the cranial base.13 The calvaria is composed of frontal, parietal, and occipital bone.13 In the FIGURE 1. A virtual 3D reconstruction model of a patient’s skull. FIGURE 3. Real model of a skull and a custom-made implant. Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. e172 FIGURE 4. Intraoperative view. Note that the plate is exactly positioned into the defect. Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. present study, the volume of the neurocranium (calvaria) was measured. For each patient, the reconstructed cranial volume was measured using Xelis (INFINITT Healthcare, Seoul, Korea) from the postoperative CT images. The reference plane was the midsagittal plane on the postoperatively reconstructed cranium (Fig 5). The midsagittal plane was defined as the plane that included 3 landmarks of the skull. The landmarks were the prosthion (the point of the maxillary alveolar process that projects most anteriorly in the midline of the maxilla), the glabella (the most prominent point in the midsagittal plane of forehead), and the bregma (the junction of the sagittal and coronal sutures at the top of the skull).14 The volume of the postoperatively reconstructed calvaria was measured. The bisected volume was compared with the reference plane. An intravenous antibiotic course was started at the induction of anesthesia and was continued for 10 days after the operation. Routine postoperative dressings were changed and the sutures were removed 7 days after the operation. Postoperative complications were recorded. Some possible complications were sudden death after cranioplasty, infection, scar contraction, and wound dehiscence. CRANIOPLASTY WITH CUSTOM-MADE IMPLANTS appearance of all patients was significantly improved (Fig 6A,B). The ratio of the right cranium to the entire cranium was 0.497 ⫾ 0.010 and to the left was 0.503 ⫾ 0.010. The difference between the right and the left was not statistically significant (P ⫽ .340). The 3D reconstructed CT examination showed that symmetry was achieved in all 10 cases and there were no secondary effects on the cerebral mass or soft tissues (Fig 7A–F). There were no problems when covering the implant plates with skin. During the recovery period, there were no signs of infection, plate rejection, or wound dehiscence (Table 1). Case 3 showed a transient extradural seroma collection at 3 days postoperatively. It was resolved after drainage at 7 days postoperatively. Case 6 had a wrinkle that was evident on the skin covering the graft at 1.5 years postoperatively (Fig 8A). This was caused by isolated bone loss on the frontal sinus wall near the graft (Fig 8B) that projected into the thin skin. However, further treatment was not required. The average postoperative follow-up was 42.5 months (7 to 85 mo). Clinically, no longterm complications occurred. Discussion In this study, 10 cases of cranial defects were successfully reconstructed by custom-made im- STATISTICAL ANALYSIS The significant differences between the right and left postoperative cranium were estimated by pairedsamples t test and were considered statistically significant when the probability was less than .05. Results In all 10 patients included in this study, the cranial bone defects rehabilitated well. The esthetic FIGURE 5. The reference plane was set as the midsagittal plane (central line) in the postoperative 3D reconstruction of the cranium. Note the symmetric shape between the reconstructed hemisphere (right) and the undamaged hemisphere (left). Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. ROTARU ET AL FIGURE 6. After surgery, the esthetical aspect of the patient improved significantly. A, Preoperative clinical photograph. B, Postoperative clinical photograph. Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. plants. Although there were 2 cases of postoperative complications, there were no serious long-term complications. An esthetic reconstruction was evident by the volumetric comparison of the postoperatively reconstructed skull. The volume of the right e173 postoperative calvaria was 99.8% of the volume of the left postoperative calvaria. The difference between the right and left was not statistically significant (P ⬎ .05). Considering the many advantages of custommade implants, such as the shorter operative time, no donor site morbidity, and improved cosmetic results, custom-made implants should be considered for cranioplasty. For cranioplasty, many kinds of grafts can be considered. Among them, the autograft has been the most prominent. The autograft can be produced during craniectomy. The bone flap is stored in the refrigerator. When a patient’s status becomes stable, the stored bone flap is repositioned into the defect. However, some common complications are resorption of the graft and infection. In 1 study on the use of a bone flap, 17% of patients showed signs of bone flap resorption, and this resorption was related to postural headaches and vertigo.15 The incidence of bone flap resorption has been reported as 3% to 12%.16-18 If the graft shows some degree of resorption, further surgery is necessary for adjustment.19,20 Autografting for cranioplasty also can be performed using the adjacent calvarial bone. Although it produces better results than PMMA or titanium mesh, it can be applied into a moderately large cranial defect.21 Because the custom implant in this study was made of PMMA, it was not resorbed. In addition to resorption, 11.6% of patients have developed infection after autografting.22 This may be caused by improper handling of the graft, contamination during storage, or decreased host immunity.23-25 Even if the autograft is suspected of being contaminated, it cannot be autoclaved. For an infected autograft, the treatment is to remove the graft. In that case, an additional subsequent cranioplasty is unavoidable. There were no postoperative infections in the present study. Since antiquity, different types of alloplastic materials have been used to cover cranial defects.1,26 The most frequently used current alloplastic materials are hydroxyapatite cements, acrylics, titanium, and carbon fiber-reinforced plastics.11,27 The main disadvantage of alloplastic materials is their high susceptibility to infection.20,28,29 In addition, precise shaping of the preformed graft in the operating theater is very difficult. If the applied graft fails to gain symmetry with the normal side, it is inharmonious and unesthetic. There have been several reports on custom-made implants manufactured by RP techniques.30,31 The present method used a silicone rubber mold. During the impression, the silicone rubber allows for the preservation of the surface morphology and the marginal details of the plate because of the fluidity of the silicone rubber. The precision of the marginal reproductions has improved the stability of the implant. If the PMMA graft is allowed to polymerize in the bone e174 CRANIOPLASTY WITH CUSTOM-MADE IMPLANTS FIGURE 7. Three-dimensional computed tomographic images A-C, before versus D–F, after surgery show that the defect was successfully reconstructed. Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. e175 ROTARU ET AL who had an ill-fitting margin at the time of graft application in this study. If the graft is unstable, rigid fixation with an additional graft should be considered. Considering the small sample, this study should be considered a preliminary report. However, it is a promising technique in some aspects. The mean follow-up was 52 months and there were no serious long-term complications. The CT-based 3D RP technique could produce the cranial implant precisely and it was well suited for the defect. A cranioplasty technique similar to the present technique was performed for 3 craniectomies at an independent institute, and these investigators reported good results with no complications.33 Although the technique was used only for cranioplasty in the present study, it can be used for the bone reconstruction of other sites. Because this study was performed with a limited number of patients, a large-scale, multicenter study with a longer follow-up should be encouraged. Another limitation of the present study is that all patients enrolled were adults. In hydroxyapatite bone cement cranioplasty, secondary head asymmetry has been frequently observed in pediatric patients.34 Because the PMMA graft would not be replaced by new bone, it should be used with caution in pediatric patients. The custom-made cranial implants produced by 3D modeling, RP, and additive manufacturing were particularly useful for repairing large defects. A significant improvement in morphology and function was achieved. There were no signs of infection, plate rejection, or serious long-term complications. This technique may be useful for the bone reconstruction of other sites. FIGURE 8. A, Skin wrinkle formed on the graft at 1.5 years postoperatively (arrows). B, Postoperative 3D computed tomographic image shows isolated bone loss (arrow). Rotaru et al. Cranioplasty with Custom-made Implants. J Oral Maxillofac Surg 2012. defect, the graft can be made precisely. However, the temperature increases during the polymerization of PMMA,32 which will damage the adjacent vital structure. However, there were some limitations of the present technique. Because this technique required 3D reconstruction of the images, impression, and casting, the reconstruction of a detailed margin was strongly dependent on 1) the reproducibility of the impression material, 2) the fluidity of the casting material, and 3) the quality of the 3D image. Many impression and casting materials have shown dimensional change during setting (expansion or constriction). The quality of the image depends on the thickness of the slice cut and the resolution. However, there was no patient References 1. Durand JL, Renier D, Marchac D: [The history of cranioplasty]. Ann Chir Plast Esthet 42:75, 1997 2. Dujovny M, Aviles A, Agner C, et al: Cranioplasty: Cosmetic or therapeutic? Surg Neurol 47:238, 1997 3. Dujovny M, Agner C, Aviles A: Syndrome of the trephined: Theory and facts. Crit Rev Neurosurg 24:271, 1999 4. Mokri B: Orthostatic headaches in the syndrome of the trephined: Resolution following cranioplasty. Headache 50:1206, 2010 5. Agner C, Dujovny M, Gaviria M: Neurocognitive assessment before and after cranioplasty. Acta Neurochir (Wien) 144:1033, 2002 6. Kuo JR, Wang CC, Chio CC, et al: Neurological improvement after cranioplasty—Analysis by transcranial Doppler ultrasonography. J Clin Neurosci 11:486, 2004 7. 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