3D printed custom-made titanium cranioplasty after repeatedly failed cranial reconstructions and surgical site infections

Dear editor,

Even though it counts among frequently performed procedures and is often considered a routine one, cranial reconstruction can turn into a challenging issue, especially after repeated failures of previous cranioplasties. We would like to report a case of successful cranioplasty utilizing a custom-made 3D printed titanium alloy implant in an environment of a long-term surgical site infection.

Our male patient underwent evacuation of a traumatic intracerebral hematoma in the right temporal lobe through an insufficiently sized craniectomy at another neurosurgical department in April 2011. A synthetic dural substitute was used for duraplasty. Despite the insufficient size (Fig. 1), the therapeutic effect of the operation was adequate, most likely due to the effect of internal decompression and patient’s young age (19 years old at the time of injury). He was surviving with no apparent neurological deficit. In May 2011, he underwent cranioplasty with an autologous bone flap, which, however, was unsuccessful due to surgical site infection with Methicillin resistant Staphylococcus aureus (MRSA) involving the bone flap and requiring its removal as well as removal of the original synthetic dural substitute. A new synthetic dural substitute was introduced. After prolonged antibiotic treatment, cranioplasty using a 3D custom-made hydroxyapatite implant CustomeBone® (Finceramica, Italy) was performed in November 2011. After almost 6 uneventful years, the patient developed purulent meningitis in July 2017. CT examination was performed, verifying an epidural abscess under the cranial implant. Evacuation of the abscess and extraction of the hydroxyapatite implant were performed urgently and no further reconstruction was attempted in the following months. In May 2018, the patient turned to our hospital for further care, presenting with two defects of the skin flap with purulent secretion and visible duraplasty. CT examination did not confirm any intracerebral or extracerebral abscess/empyema (Fig. 1).

Microbiological examination of samples from the defects confirmed Staphylococcus epidermidis and Enterobacter cloacae. We proceeded with antibiotic treatment using clindamycin and local debridement. After regression of the purulent secretion and satisfactory MRI and CT findings, we proceeded with definitive operative treatment. We excised both skin defects (Fig. 2A) and removed the synthetic dural substitute using autologous fascia lata as a dural graft. There were no collections in the subdural space. Cranioplasty was performed using a 3D custom-made titanium alloy implant (Biomedical Engineering, Slovakia, Fig. 2B).

The used custom-made cranial titanium alloy implant was developed and produced by the company Biomedical Engineering (Košice, Slovakia). It is designed to anatomically fit the relief of the skull and provides satisfactory aesthetic results. After digital creation of 3D models of the skull defect and a corresponding implant based on the sub-millimetre CT scan, the cranial implant was produced utilizing 3D printing technology. An alloy of titanium, aluminium and vanadium – Ti64ELI (Fig. 4A, Fig. 4B) was used in the process. The applied porous structure of the implant mimics the real bone architecture and secures fusion with the adjacent bone. A unique butterfly fixation mechanism is designed to promote rigidity of the human-implant interface (Fig. 4B, Fig. 5). Likewise, the titanium fixing screws are custom-made according to the patient’s skull thickness. During the operation of our patient, after successful fixation of the titanium flap, the patient’s scalp was reconstructed by a plastic surgeon using local skin flaps. Subsequently, another defect in the operative wound occurred in December 2020, requiring its excision and skin flap reconstruction. The aesthetic effect of this reconstructive surgery was then considered satisfactory and the surgical wounds healed well (Fig. 3).

Advantages of titanium cranioplasty include mechanical resistance and a low profile of the implant, better aesthetic results, possibility of re-use after repeated sterilization and a lower incidence of surgical site infections [1−5]. Disadvantages of titanium cranioplasty include CT and MRI artifacts and low osteoconductive properties. Since titanium cranial implants have a low tendency to form a biofilm, they are a safe choice for cranioplasty in patients at a high risk for infectious complications or after chronic surgical site infection, as illustrated in this case report.

René Opšenák, M.D.

Clinic of Neurosurgery

Jessenius Faculty of Medicine in Martin

Comenius University in Bratislava

University Hospital Martin

Kollárova 2

 036 01 Martin

Slovakia

e-mail: opsenak@gmail.com