Polyetheretherketone custom-made implants for craniofacial defects: Report of 14 cases and review of the literature.

Journal of Cranio-Maxillo-Facial Surgery xxx (2015) 1e7

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Polyetheretherketone custom-made implants for craniofacial defects: Report of 14 cases and review of the literature n a, M.J. Nieto a, J.L. Del Castillo a, J. Herna ndez-Godoy b, E. Alonso-Rodriguez a, *, J.L. Cebria ~o a M. Burguen a b

Department of Oral and Maxillofacial Surgery, Hospital Universitario La Paz, Paseo de la Castellana, 261, 28046 Madrid, Spain Department of Plastic and Reconstructive Surgery and Burn Unit, Hospital Universitario La Paz, Paseo de la Castellana, 261, 28046 Madrid, Spain

a r t i c l e i n f o

a b s t r a c t

Article history: Paper received 9 February 2015 Accepted 29 April 2015 Available online xxx

Background: Craniofacial defects tend to carry functional and esthetic consequences for the patient. The complex shapes in this region make such reconstructions a challenging procedure and the most suitable material to be used remains controversial. Methods: We report a series of 14 patients whose craniofacial defects were reconstructed using a computer designed PEEK-PSI (Polyetheretherketone- Patient Specific Implant). We analyzed the complications and outcomes of PEEK custom-made implants and compared our results with those of other case series reported in the current literature. Results: Fourteen patients underwent craniofacial reconstruction using a PEEK-PSI. Three cases involved a one-step primary reconstruction and the rest of cases underwent a delayed reconstruction. Two cases (14.3 %) presented infection and only in one case was the implant definitively removed. Esthetic results were considered to be highly satisfactory. Conclusion: With CAD-CAM techniques, it is possible to prefabricate an individual implant. The ideal material for reconstructing maxillofacial defects does not exist, but PEEK has demonstrated good outcomes. When autologous bone is not available or, in selected cases with large or complex defects in the maxillofacial area, PEEK is one of the best options to reconstruct these defects. However, further studies are needed to determine the long-term results. © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Keywords: Polyetheretherketone Implant Craniofacial Reconstruction

1. Introduction Craniofacial defects tend to carry severe functional and esthetic consequences, producing a negative psychological impact on the patient. Use of autologous bone is considered the gold standard for cranial defects because it allows complete biological integration without immunogenic responses and is relatively inexpensive. Replacement of the original bone removed during the resection, such as in a craniectomy, is optimal; but this option it is not always available, especially if the reconstruction is delayed. Autologous bone graft is not without risks, such as infection, bone resorption, or fragmentation, and it can have limitations relating to shaping or the size of the area that can be covered. The maxillofacial region is a difficult area to reconstruct. The complex shape of this area with * Corresponding author. Tel.: þ34 628433295; fax: þ34 91 727 70 50. E-mail addresses: [email protected] (E. Alonso-Rodriguez), rodrigator2001@ ndez-Godoy). hotmail.com (J.L. Cebri an), [email protected] (J. Herna

different curvatures and thicknesses make these reconstructions a challenge. Synthetic materials such as titanium (Kuttenberger and Hardt, 2001), hydroxyapatite (Burstein et al., 2006), alumina ceramics (Okumura et al., 1984), methyl methacrylate (Blum et al., 1997), and porous polyethylene (Yaremchuk, 2003) among others, have been reported as alternatives to these problems. However, the most suitable material remains controversial. Polyetheretherketone (PEEK) seems to be promising. It is a semicrystalline polyaromatic linear polymer with excellent biocompatibility, good mechanical strength, and radiographic translucency (Nieminen et al., 2008). Currently, computer-aided design and manufacturing (CADCAM) systems have greatly improved craniomaxillofacial reconstruction. Based on preoperative computed tomography (CT) imaging, the implant is fashioned so as to obtain a patient-specific implant (PSI). This can reduce the need for intraoperative manipulations as well as operative time (Binder, 2008). This system allows planning not only of the reconstruction, but also that of

http://dx.doi.org/10.1016/j.jcms.2015.04.028 1010-5182/© 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Please cite this article in press as: Alonso-Rodriguez E, et al., Polyetheretherketone custom-made implants for craniofacial defects: Report of 14 cases and review of the literature, Journal of Cranio-Maxillo-Facial Surgery (2015), http://dx.doi.org/10.1016/j.jcms.2015.04.028

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E. Alonso-Rodriguez et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2015) 1e7

the resection, thus offering the possibility of one-step primary reconstruction. We report a series of 14 patients whose craniofacial defects where reconstructed in one or two steps using a computerdesigned PEEK PSI.

Results were evaluated according to patients' assessment as excellent (good patient acceptance without additional procedures required), good (good patient acceptance with additional procedures required), and poor (poor patient acceptance). 3. Results

2. Material and methods We report a retrospective review of 14 patients who underwent PEEK craniofacial reconstruction between 2008 and 2014 at the Hospital Universitario La Paz, Spain. A preoperative high-resolution CT (1.0-mm-thick slices) was obtained for each patient. The images were delivered to the manufacturer (Synthes Maxillofacial, Oberdorf, Switzerland), and, by making a semiautomatic mirroring of the healthy side on to the affected side, the implant model was designed. This method allows a precise and symmetrical reconstruction. If both resection and reconstruction are performed during the same operation, the surgeon defines the resection that is required using a virtual three-dimensional (3-D) model, and it is even possible to produce a prefabricated template or a custommade cutting guide (Fig. 1). A file with all of the information is sent to the surgeon for final approval, and the data are used to create the implant by using a rapid prototyping machine. The definitive implant is sent to the hospital and sterilized immediately prior to surgery. All procedures are performed under general anesthesia. Different approaches to the facial skeleton are used, on an individual patient basis, such as a transconjunctival or coronal approach (Fig. 2). If planned, the resection of the lesion is carried out. The PEEK PSI is then put in place and checked for fit. If necessary, the contours of the implant can be adjusted with a cutting burr. Finally, it is fixed to the surrounding bone with titanium screws and miniplates (Synthes). A postoperative CT scan is requested when the primary pathology of the patient requires follow-up imaging or when there are complications during the first year postoperatively. Intravenous amoxicillin and clavulanic acid are administered, both at induction and postoperatively for 7 days.

Over the 6 years, 14 patients (4 men and 10 women; mean age 42.7 years) underwent craniofacial reconstruction using a PEEK PSI due to defects arising from different pathologic conditions including trauma (1 patient), congenital deformities (4 craniofacial dysplasias and 1 facial cleft), and various benign and malignant tumors (8 cases). The defect was located in the zygomaticomaxillary area in 35.7% of cases, the frontal area in 28.6%, the cranial area in 21.4%, and in the orbital area in 14.3%. One of the patients had received radiotherapy previously, and another had other types of implants fitted before PEEK PSI (titanium mesh). Results are summarized in Table 1. In three patients, the resection of the lesion and the reconstruction were performed at the same time (one-step reconstruction). The rest of patients underwent a delayed reconstruction. Most of these patients had been treated for neurosurgical pathologic conditions causing cerebral edema and in whom bone reconstruction was delayed. The bone was sterilized and frozen. When reimplanted for reconstruction, it suffered unpredictable resorption and infection. The bone was therefore removed, and a secondary reconstruction was required. In numerous cases, such as in congenital deformities, patients underwent multiple attempts at reconstruction before PEEK was finally implanted. The average operative time was 238 min (range 95e500 min), and the mean duration of hospitalization was 5.7 days (range 1e18 days). The wide ranges reported were influenced by the need for subsequent procedures additional to the primary reconstruction and whether or not the resection was carried out at the same time. Adjustments to the PEEK implant were generally unnecessary. Postoperative complications were observed in five patients. One patient had a seroma, another patient had a cerebrospinal fluid

Fig. 1. Case with resection and reconstruction at the same time. (A) Virtual 3D model with the cutting guide defining the planned resection. (B) Intraoperative view with the cutting guide and the tumor resected. (C) Intraoperative view with custom-made polyetheretherketone (PEEK) patient-specific implant in the defect of the tumor.



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Fig. 2. (A) File showing a frontal defect due to a meningioma and the planned implant (blue). (B and C) Intraoperative view; the defect is exposed through a coronal approach and the implant is placed. (D and E) Clinical preoperative photographs of the patient. (F and G) Clinical postoperative photographs.

(CSF) leak that was treated conservatively, and two other patients presented with infection. In one of the patients with infection, the implant had to be removed, sterilized, and replaced during a single intervention. In this particular case, after some infective episodes that did not resolve with conservative treatment, we decided to review the surgical bed. Using a subciliary approach, we were able

to access the implant placed in the orbital floor. The implant was sterilized in an autoclave and replaced, as active infection was absent at the time. The surgical bed was washed with rifampicin and clorhexidine, and antibiotics (amoxicillin and clavulanic acid) were prescribed for 1 week based on the antibiogram. With a follow-up of 27 months, this patient has not had any further episodes.

Table 1 Patient data from case series of polyetheretherketone (PEEK) patient-specific implant reconstruction. Sex

Age (y)

Etiology

Location

Time of reconstruction

Surgery duration (min)

Hospital stay (days)

Complications

Follow-up (mo)

1 2

F M

45 27

Frontal bone Zygomaticomaxillary complex

Delayed Delayed

265 300

2 5

None None

48 43

3

F

21

Craniofacial dysplasia Nasopharyngeal angiofibroma Craniofacial dysplasia

Orbital floor

Delayed

240

9

27

4 5

F F

26 53

Facial cleft Intraosseous angioma

Zygomaticomaxillary complex Frontal bone

210 95

9 3

6 7 8

F M F

45 37 55

Brain cavernoma Odontogenic myxoma Meningioma

Frontal bone Zygomaticomaxillary complex Zygomatic and temporal bones

120 125 500

2 1 18

9

F

73

Craniofacial dysplasia

Zygomaticomaxillary complex

275

11

10

F

41

Trauma

200

5

11 12 13

M F F

36 44 53

Craniofacial dysplasia Meningioma Meningioma

Orbital bone (floor and medial wall) Cranial (temporoparietal) Cranial (frontoparietal) Cranial (temporoparietal)

Delayed Immediate (1-step reconstruction) Delayed Delayed Immediate (1-step reconstruction) Immediate (1-step reconstruction) Delayed

Infection; implant removed and replaced None CSF leak

Delayed Delayed Delayed

320 200 180

4 2 2

14

M

42

Esthesioneuroblastoma

Frontal bone

Delayed

300

7

28 20

None None Implant infection; not removed None

19 9 5

None; asymptomatic sinus inflammation Seroma None Exposure; implant removed None

38

8

35 72 36 13

CSF, cerebrospinal fluid; F, female; M, male.


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In the second infective case, the patient was treated with a 4 week course of antibiotics according to the antibiogram (vancomycin) leading to a full resolution of the symptoms. As this single infective episode resolved with conservative treatment, we decided not to remove the implant, which was placed as the zygomatic arch and temporal bone. After 5 months of follow-up, the patient remains asymptomatic. In this particular case, the infection occurred after a traumatic episode in which there was no contact with the paranasal sinuses. In a single case, inflammation of the frontal sinus was observed in follow-up imaging, but the patient was asymptomatic, and no treatment was deemed necessary. One wound dehiscence with implant exposure due to cutaneous necrosis was observed; this was the only case requiring removal of the implant. No complications relating to breakdown or displacement of the implant were noted. Results were excellent in nine patients (64.3%), good in five patients (35.7%), and poor in no patients. Additional procedures such as autologous fat transfer for facial recontouring were necessary in the five patients with good results, and other procedures such as canthopexy were performed in three patients in this group. The mean follow-up period was 28.6 months (range 5e72 months). 4. Discussion Craniofacial deformities have important consequences, not only from a functional point of view but also from esthetic and psychological ones. Due to the anatomically complex structures of this region, maxillofacial reconstruction remains a challenging procedure.

Use of autologous bone graft is considered the gold standard for craniomaxillofacial defects by many surgeons; however, it has some disadvantages, including limited bone availability, shaping difficulty, donor site morbidity, a time-consuming harvest leading to a longer operative time, infection, fragmentation, and an unpredictable bone resorption rate that can result in a poor long-term esthetic result. Autologous bone grafts can work well if the defect is small and the contours are simple; however, in the presence of larger and more complex shape defects, we prefer to use alloplastic materials. The ideal material must be biocompatible, strong, light, malleable, temperature resistant, inert, radiolucent, and with low infection and fracture rates. Methyl methacrylate is strong and inexpensive but undergoes an exothermic reaction that can cause burn injuries (Shah et al., 2014). Titanium mesh is easy to adapt to fit the defect and is associated with a low infection rate (Matsuno et al., 2006), but produces artifacts during imaging techniques. Esthetic outcomes are good in cranial defects but in facial ones it is more difficult to achieve a good cosmesis. Titanium mesh can be used either alone or in conjunction with other synthetic materials, nsuch as porous polyethylene, to strengthen the prosthesis (Cebria Carretero et al., 2004). Porous polyethylene is inert and biocompatible, and is usually used for facial augmentation. Many other materials are also used, depending on individual patient characteristics such as age, comorbidities, and type of defect. The ideal material has yet to be discovered, but PEEK is achieving good results. PEEK is a semicrystalline thermoplastic polymer that is chemically inert, can be sterilized by steam or gamma irradiation, and has a thickness and elasticity comparable to

Fig. 3. (A and B) File showing the patient defect (red), due to craniofacial dysplasia, and the planned implant (blue). (C) Polyetheretherketone (PEEK) patient-specific implant. (DeF) Intraoperative views in which the defect is exposed, showing the relationship with the frontal sinus (D), a pericraneal flap is carried out to isolate the sinus (E), and the implant is fitted (F).



that of cortical bone (Lethaus et al., 2012). Furthermore, it is biocompatible, has strength and stiffness, and is radiolucent and nonmagnetic. Given these characteristics, PEEK is considered a good alternative to other alloplastic materials. With CAD-CAM techniques, we have operated on 14 defects arising from a number of causes. In three cases, reconstruction was done at the same time that extirpation was carried out (one-step primary reconstruction), this being the ideal scenario in benign lesions for which a preoperative virtual planning of the resection can be carried out. On the other hand, when the defect has evolved over many years or is a congenital defect, the healthy side is used as a template. The implant is shaped preoperatively, which avoids excessive intraoperative manipulations and thus reduces operative time. In our experience, intraoperative adjustments to the PEEK implants were generally unnecessary, but, if required, modifications of PEEK implants can be made during surgery. Our operative time range (95e500 min) is quite extensive, but that can be explained by the need to carry out some additional procedures and by the fact that different approaches were used by various members of the multidisciplinary team. As we know, one of the main disadvantages of PEEK implants, together with other alloplastic materials, is that of postoperative complications, namely infection. Within a follow-up range of 5e72 months, 14.3% of the patients had an infective episode. Although the infection rate may be deemed to be high, only in one case was it necessary to remove the implant, which was subsequently sterilized

5

before being replaced. The other case resolved with conservative treatment. In these two cases, we have been unable to find anything in common, which may help to explain the source of the infection. However, in the case of the orbital floor implant, it is thought that communication with the maxillary sinus may possibly be involved. When the clinical picture is indicative of infection, we first administer empirical antibiotic therapy, continuing the treatment according to antibiogram results of bacterial cultures. In the event of recurrent infections, removal of the implant must be considered. If, at the time of the surgery, there is no active infection, in special cases like our reported one, it may even be possible to re-sterilize and replace the prosthesis; however, in the presence of active infection, the best course of action is to remove it. Only one of the patients needed a definitive removal of the implant, following wound dehiscence. The remaining complications (one seroma and one CSF leak) resolved with conservative treatment. It is important to isolate the sinuses by performing a cranialization or a sinus closure with a pericraneal flap (Figs. 3 and 4), although the current literature does not describe the relationship between PEEK and the sinuses. If there is any communication between the implant and the facial sinuses, the risk of infection is increased. Our complication rate is comparable to that in other series reported (Table 2). Hanasono et al. (Hanasono et al., 2009) reported the first case series with PEEK for delayed calvarial reconstruction. Almost all patients had previously undergone radiotherapy. One of

Fig. 4. Clinical preoperative (A and B) and postoperative (C and D) photographs of the same patient as in Fig. 3.


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Table 2 Comparison of case series of polyetheretherketone (PEEK) craniofacial implants. Case series

No. of patients

Location

Average surgery duration (min)

Average follow-up (mo)

Complications

Hanasono et al. (12) Kim et al. (16) Lethaus et al. (13)

6 4 4

? ? 97

9 ? ?

1 CSF leaka 1 Dehiscence 1 Epidural hematomaa

Ng et al. (14) Jalbert et al. (15)

12 5

Cranial Maxillofacial Cranial (temporoparietal) Cranial (temporoparietal) Orbito-frontal Craniofacial

174 ?

10 ?

Rosenthal et al. (17)

65 (3-center experience)

?

24

3 CSF leak 2 Diplopia (transitory) 1 Seroma 2 Cerebral edema (all resolved) 5 Infection (all implants removed); 1 dehiscence (implant removed); 2 epidural hematomas; 1 hematoma; 7 hydrocephalus; 3 seizures; 1 CSF leak

Calvarial

CSF, cerebrospinal fluid. a Implant removed and replaced.

the six patients presented with a CSF leak requiring removal of the implant; however, it was able to be replaced. No infections were observed. Lethaus et al. (Lethaus et al., 2011) reported a series of 12 patients of whom four underwent a calvarial reconstruction with PEEK; only one epidural hematoma in an anticoagulated patient was observed. Ng and Nawaz (Ng and Nawaz, 2014) reconstructed 12 cranial defects with good results, and they recommended PEEK implants for cranioplasties as a viable alternative when autologous bone grafts are unavailable or unsuitable. Jalbert et al. (Jalbert et al., 2014) operated on five patients with fronto-orbital defects in a single-step procedure for resection and reconstruction with a navigation device and PEEK PSI, with very good results and no

major complications; this was similar to the experience of Kim et al. (Kim et al., 2009), who reported four cases of maxillofacial defects. Rosenthal et al. (Rosenthal et al., 2014) describe their experience with PEEK PSI in 66 cranioplasties at three different institutions. These authors reported a complication rate comparable to that of other implants or autologous bone, with an infection rate of 7.6% and a surgical removal rate of 9.1%, with overall satisfactory esthetic results. They recommended PEEK implants as a viable option for large cranial defects. We describe one of the largest case series reported in the current literature, with different craniofacial defects, together with good esthetic and functional outcomes.

Fig. 5. (A and B) Files showing a defect arising from a venous malformation, and the planned implant (blue). (C) Polyetheretherketone (PEEK) patient-specific implant. (D) Clinical preoperative photographs. (E) Clinical postoperative photograph. Asymmetry of soft tissues can still be observed due to a deficit of the temporal muscles. Patient underwent an autologous fat transfer 1 year after surgery.



PEEK PSI allows an accurate and effective reconstruction of bony defects, but the asymmetry of soft tissues is not always solved with the implant alone. For this reason, in some cases with soft tissue defects, additional procedures may be needed to achieve optimal esthetic outcomes, such as the use of autologous fat transfers or soft tissue procedures (Fig. 5). Some authors, however, use computeraided design to build a combined soft tissue and boneeskull model (Marbacher et al., 2011), but outcome prediction is difficult. In general, esthetic outcomes in our case series were excellent in most patients. Costs of the PEEK implants range between 2,000 V and 8,000 V, depending on their size and complexity; however, we believe that the benefits outweigh the costs in certain cases. 5. Conclusion With CAD-CAM techniques, it is possible to prefabricate a specific and individual implant allowing an accurate reconstruction. The perfect material for maxillofacial defects does not yet exist, but PEEK has demonstrated good outcomes both esthetically and functionally, with a complication rate similar to that of other alloplastic materials. We believe that when autologous bone is not available, or in selected cases with large or complex defects in the maxillofacial area, PEEK is one of the best options for reconstruction of these types of defects. However, further studies are needed, because some questions remain unanswered and the long-term results need to be evaluated. References Binder WJ: Custom-designed facial implants. Facial Plast Surg Clin North Am 16: 133e146, 2008 Blum KS, Schneider SJ, Rosenthal AD: Methyl methacrylate cranioplasty in children: long-term results. Pediatr Neurosurg 26: 33e35, 1997

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Burstein FD, Williams JK, Hudgins R, Boydston W, Reisner A, Stevenson K, et al: Hydroxyapatite cement in craniofacial reconstruction: experience in 150 patients. Plast Reconstr Surg 118: 484e489, 2006 rez-Lo pez C, Alvarez F, Sarmiento MA, del Castillo JL, Cebri an-Carretero JL, Pe ~ oz-Caro JM: Cranial reconsctruction with titanium mesh and hydroxyapMun atite cement. Neurocirugia 15: 571e577, 2004 Hanasono MM, Goel N, DeMonte F: Calvarial reconstruction with polyetheretherketone implants. Ann Plast Surg 62: 653e655, 2009 Jalbert F, Boetto S, Nadon F, Lauwers F, Schmidt E, Lopez R: One-step primary reconstruction for complex craniofacial resection with PEEK custom-made implants. J Craniomaxillofac Surg 42: 141e148, 2014 Kim MM, Boahene KDO, Byrne PJ: Use of customized polyetheretherketone (PEEK) implants in the reconstruction of complex maxillofacial defects. Arch Facial Plast Surg 11: 53e57, 2009 Kuttenberger JJ, Hardt N: Long-term results following reconstruction of craniofacial defects with titanium micro-mesh systems. J Maxillofac Surg 29: 75e81, 2001 Lethaus B, Ter Laak MP, Laeven P, Beerens M, Koper D, Poukens J, et al: A treatment algorithm for patients with large skull bone defects and first results. J Craniomaxillofac Surg 39: 435e440, 2011 Lethaus B, Safi Y, ter Laak-Poort M, Kloss-Brandst€ atter A, Banki F, Robbenmenke C, et al: Cranioplasty with customized titanium and PEEK implants in a mechanical stress model. J Neurotrauma 29: 1077e1083, 2012 Marbacher S, Andereggen L, Fandino J, Lukes A: Combined bone and soft-tissue augmentation surgery in temporo-orbital contour reconstruction. J Craniofac Surg 22: 266e268, 2011 Matsuno A, Tanaka H, Iwamuro H, Takanashi S, Miyawaki S, Nakashima M, et al: Analyses of the factors influencing bone graft infection after delayed cranioplasty. Acta Neurochir 148: 535e540, 2006 Ng ZY, Nawaz I: Computer-designed PEEK implants: a peek into the future of cranioplasty? J Craniofac Surg 25: 55e58, 2014 Nieminen T, Kallela I, Wuolijoki E, Kainulainen H, Hiidenheimo I: Amorphous and crystalline polyetheretherketone: mechanical properties and tissue reactions during a 3-year follow-up. J Biomed Mater Res A 84: 377e383, 2008 Okumura T, Oda Y, Mori K, Uchida Y, Morimoto M, Kamimura Y, et al: Alumina ceramic (Bioceram) as the cranioplastic materialdexperimental study and application in cranioplasty. No Shinkei Geka 12: 246e252, 1984 Rosenthal G, Ng I, Moscovici S, Lee KK, Lay T, Martin C, et al: Polyetheretherketone (PEEK) implants for the repair of large cranial defectsda 3-center experience. Neurosurgery 75: 523e529, 2014 Shah AM, Jung H, Skirboll S: Materials used in cranioplasty: a history and analysis. Neurosurg Focus 36: E19, 2014 Yaremchuk MJ: Facial skeletal reconstruction using porous polyethylene implants. Plast Reconstr Surg 111: 1818e1827, 2003


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