Can custom 3D printed implants successfully reconstruct massive acetabular defects? A 3D‐CT assessment

We report on the accuracy, measured with three‐dimensional (3D) computed tomography (CT) postoperatively, in positioning custom 3D printed titanium components in patients with large acetabular defects. Twenty patients (13 females and 7 males) received custom‐made acetabular implants between 2016 and 2018; the mean age was 66 years (SD = 11.6) and their mean body mass index was 28 (SD = 6.1). The median time to follow up was 25.5 months, range: 12 to 40 months. We describe a comparison method that uses the 3D models of CT‐generated preoperative plans and the postoperative CT scans to quantify the discrepancy between planned and achieved component positions. Our primary outcome measures were the 3D‐CT‐measured difference between planned and achieved a component position in six degrees of freedom: center of rotation (CoR), component rotation, inclination (INC), and version (VER) of the cup. Our secondary outcome measures were: Oxford hip score, walking status, and complication rate. All components (100%) were positioned within 10 mm of planned CoR (in the three planes). Eighteen (95%) components were not rotated by more than 10° compared to the plan. Eleven (58%) components were positioned within 5° of planned cup angle (INC and VER). To date one complication has occurred, a periprosthetic fracture. This is the largest study in which postoperative 3D‐CT measurements and clinical outcomes of custom‐made acetabular components have been assessed. Accurate pre‐op planning and the adoption of custom 3D printed implants show promising results in complex hip revision surgery.