Cranioplasty with Customized Titanium and PEEK Implants in a Mechanical Stress Model

Abstract

Large skull defects as a result of craniectomies due to cerebral insults, trauma, or tumors create functional and aesthetic disturbances for the patient. Cranioplasty with implants in these cases are an alternative to autogenous bone transplantation. In our clinic, customized titanium or optima poly-ether-ether ketone (PEEK) implants are used to reconstruct craniectomy defects. To compare the two materials we investigated the structural changes of the implants fixed to a sintered polyamide skull model under mechanical stress in four simplified models. In a standard testing machine, the models were subjected to a load under a quasi-static loading rate of 1.925 mm/min. Fractures of the PEEK implants occurred at a force of 24.2 and 24.5 kN with a displacement of 8.4 and 8 mm. The titanium implants showed no deformation, but extensive damage was seen in the polyamide skull models. The highest pressures achieved were 45.8 and 50.9 kN. In a simplified model with quasi-static loading, both implants withstood forces that were higher than those capable of causing skull fractures. It seems that the mechanical properties of PEEK could provide better protection when used for cranioplasty in patients after craniectomy if reconstruction with autogenous bone is not possible.

Cranioplasty after decompressive craniectomy: is there a rationale for an initial artificial bone-substitute implant? A single-center experience after 631 procedures

“…The results of some studies suggested that PEEK may be better than titanium. 17 In our cohort, the groups were too small to make valid comparisons.…”

“…17,[19][20][21] However, because of their high costs compared with autologous flaps and a suspected higher complication rate for allogenic materials, these materials are not widely used for initial cranioplasty.…”

Materials used in cranioplasty: a history and analysis

“…18 These implants have strength, thickness, and elasticity comparable to cortical bone and can be incorporated accurately within the defect without the use of miniplates. 18 Newer technologies such as PEEK implants are commonly used today because they can be designed specific to a patient's craniotomy defect with 3D printing technologies (Figs. 7 and 8).…”

“…Computer-assisted 3D modeling can be used to design these synthetic implants. 18 The PEEK implants offer 3 main advantages (Table 1). First, they do not create artifacts on CT or MRI because they are translucent to x-rays and are nonmagnetic.…”

“…Lastly, they do not conduct temperature unlike metallic implants, which can have negative ramifications on the brain. 18 Despite these advantages, PEEK implants are expensive and lack osteointegrative properties. Despite the paucity of literature on the risks of infection with PEEK implants, in our personal experience, PEEK, like other foreign implants, may have a higher than expected infection rate as seen in military personnel who served in the Iraq and the Afghanistan Wars.…”