Complex Frontal Bone Reconstruction Using Computer-designed Polyetheretherketone Implant: Case Report and Literature Review

Summary:

Calvarial reconstruction of complex frontal bone defects after head trauma surgery is challenging, especially when it coexists with an absence of eyebrow arch and supraorbital wall. Due to various reasons, the patient’s bone flap could not be used. Common alternative materials include polyetheretherketone (PEEK) and titanium. Careful and detailed planning is required to maximize functional and aesthetic reconstruction, thereby benefiting the patient. We present a case of a 36-year-old man who had multiple frontal bone defects after multiple operations for craniofacial fractures performed with reconstruction surgery using a PEEK implant successfully. With a follow-up for 2 years, the patient was satisfied with the long-term aesthetic effect without any consequences such as surrounding tissue infection or implant displacement. The authors believe that the PEEK implant has great potential for calvarial reconstruction due to its incredible strength, durability, and inertness.

Reconstruction of skull defects in patients operated on for traumatic brain injury, tumors, and vascular brain diseases is a challenging issue of reconstructive neurosurgery. Frontal bone deformities as a sequel to trauma may be high.¹ The other causes are congenital malformations, ablative tumor resection, and osteomyelitis. Cranioplasty aims to restore the integrity and shape of the skull.² The surgeon’s priority is to achieve a stable functional and aesthetic outcome of surgery that eliminates the psychological problems of patients, increases the quality of life, and improves social adaptation.

Cranioplasty per se and repair of frontal bone defects remain a difficult procedure for all facial surgeons, particularly when concerning the reconstruction of large lacunae in the skull. Considering the significant clinical and economic impact of the procedure, the search for materials and strategies to provide more comfortable and reliable surgical procedures is one of the most important challenges faced by modern craniofacial surgery.

Although assessing the reconstructive options in a patient with a frontal bone deformity, the timing of the reconstruction, location of the defect, biomaterial, medical history, and surgical technique must be considered. Various materials and methods are available which include autologous bone, biomaterials such as bioceramics, hydroxyapatite, polyether ketone, polymethylmethacrylate, polyetheretherketone (PEEK), and titanium.¹

PEEK implants as a new material are gaining popularity for craniofacial reconstruction today because they have proven to have advantages in several settings, such as radiolucency, chemical inertness, stiffness, and various methods of sterilization. Additionally, PEEK implants could be designed specifically for patients’ cranial defects with computer-assisted three-dimensional (3D) printing technology and could also be used in complex craniofacial reconstruction.^3,4 Here, we present a case of a 36-year-old man who underwent reconstruction surgery of the eyebrow arch and supraorbital wall using a PEEK implant successfully.

CASE PRESENTATION

The patient underwent emergency craniotomy and intracerebral hematoma removal in the local hospital due to a traffic accident in May 2019. During the operation, there were multiple facial fractures and frontal bone fractures, including the absence of a left eyebrow arch and supraorbital wall. Two months later, the patient underwent a ventriculoperitoneal shunt for hydrocephalus, followed by reduction and fixation of the maxillary fracture, mandibular fracture, and zygomatic arch fracture. In the following 3 months, the patient’s left eyeball became more and more enophthalmic, and his vision gradually decreased. Meanwhile, the strange appearance not only made it difficult for him and his family to accept him psychologically but also seriously affected his social life. [See figure, Supplemental Digital Content 1, which displays (A) preoperative frontal and lateral view of patient with left frontal defect; (B) after 2 months, the patient’s frontal appearance recovered satisfactorily. http://links.lww.com/PRSGO/D375.] According to the clinical manifestations and demands of the patient, it was decided to perform corrective surgery.

After the informed consent of the patient and the tripartite confidentiality agreement, the 3D computed tomography (CT) image data of the patient’s brain and the intraoperational pictures of the eyebrow arch and supraorbital wall of another patient in our previous craniotomy were sent to the outsourcing company, and they used the computer to carry out 3D reconstruction of the brain and outlined the shape and size of the bone defect, established a 3D model, modified and optimized it with the features of bone, and then printed it out with PEEK material 3D. The surgery was performed in the winter of 2019. After an initial incision was made along the previous incision site, the scalp flap was raised anteriorly to the supraorbital margin, where we found the defect of the left eyebrow arch supraorbital wall and intraocular fat. The gap was obtained after separation, between fat and dura mater, where the PEEK implant was later placed with four sets of titanium plates and screws. The operation was successful, and the patient’s shape improved significantly. The postoperative 3D CT of the skull showed that PEEK material was well aligned with the surrounding skull. Our patient had an uneventful recovery, had an excellent cosmetic outcome as seen by postoperative imaging, and was discharged from the hospital. After 2 months, the patient’s frontal appearance recovered satisfactorily [Supplemental Digital Content 2, which displays (A) the operation pictures of eyebrow arch and supraorbital wall of another patient in our previous craniotomy; (B) the company made the artificial bone model using peek material based on the structure of the other patient in Fig. 1A. http://links.lww.com/PRSGO/D376].

Fig. 1.

Intraoperative and postoperative images. A, PEEK implant was placed with four sets of titanium plates and screws after the scalp flap was raised anteriorly to the supraorbital margin. B, Three-dimensional reconstruction of CT front view at 7 days after the operation.

DISCUSSION

With a high-resolution CT scan of the patient’s head and computer-assisted techniques, the virtual 3D model of the skull was generated, and the titanium mesh and PEEK cranioplasties were both designed individually for our patient, which could restore structural integrity and achieve bone symmetry.⁵ Titanium meshes were generated by compression into a mold, cutting to shape with a thickness from 0.6 to 1.0 mm, whereas the PEEK implants were fabricated using 3D print technology in line with the model. Therefore, the range of titanium mesh is usually a bit larger than that of the cranial defect, and the PEEK implant could be perfectly matched to the cranial defect.

PEEK is one of the most interesting materials used in the medical field, such as in spine surgery, orthopedic surgery, prosthodontics surgery, maxillofacial surgery, and cardiac surgery, and more recently in cranioplasty.^2,6,7 It is a semicrystalline thermoplastic aromatic polymer, chemically inert, and can be easily modeled with a smooth surface and accurately incorporated during cranioplasty with the aid of 3D printing technology.⁸ The advantages of using PEEK implants are that their physical properties closely resemble that of bone and they are radiolucent, which facilitates postoperative imaging. PEEK implants have been shown to provide excellent symmetrical contour for craniosynostosis patients.⁹

Recent advances in 3D printing technology have allowed PEEK implants to be designed before the operation, which could cut down on operating time. The advancement in technology has also limited the risk of implant extrusion by allowing for the design to match the actual cranial defect more carefully. The ideal fit PEEK implants are well known to have minimal tissue irritation.¹⁰ In addition to PEEK bioactivity, the biomechanical strength of 3D-printed implants is crucial to their performance.⁹ PEEK has stiffness and strength like bones, so it can provide sufficient brain protection and be handled similarly to bones.

CONCLUSIONS

A PEEK implant was ideal for correcting facial asymmetry and providing symptomatic relief. The patient was highly satisfied with the result. By utilizing advanced presurgical planning technology, the ideal PEEK implant was readily adapted for the defect, which allowed successful placement with minimal countering on no sites of extrusion.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.