What is the Accuracy of PEEK Implants for Cranioplasty in Comparison to Their Patient Specific Surgical Plan?

Abstract

Patient specific virtual surgical planning is a useful tool in craniofacial reconstruction. The aim of this paper is to quantify the surgical accuracy of polyetheretherketone (PEEK) cranial implant placement by comparing a computer tomography (CT)-based plan with the measured postoperative position. This is a retrospective case series. All patients who presented for evaluation and management of cranial defects at the University Health Sciences Center at San Antonio from June 2018 to July 2021 were eligible for the study. For each patient, we assessed accuracy by comparing the planned PEEK implant position, defined by a 3-dimensional mesh, to the measured postoperative position at multiple mesh vertices. The primary outcome variable in our study is the root mean square error (RMSE) between the planned position and the actual position of the implant. Twelve patients (7 men, 5 women, mean age: 25.6, median age: 30.5, range 6-74) were identified who underwent cranioplasty procedures with custom-made PEEK implants to reconstruct cranial defects. The RMSE of the vertex positions ranged between 0.66 and 3.1millimeters (mm). Eleven of the twelve patients had an RMSE less than 2mm. The Spearman rank-order correlation between the average error and the length and area of the implant were 0.59 (P=.04, significant) and 0.42 (P=.17, nonsignificant), respectively. The Pearson correlation between age and RMSE was -0.18 (P=.57), and not significant. Patient specific implant planning can design and guide the implant placement with a typical accuracy within 2mm. This level of accuracy suggests that we can place implants accurately enough to achieve good patient aesthetics. The quantitative analysis suggests that the key to accurate placement is understanding the number and spatial distribution of plates and fixation.