Design of minimally invasive extraforaminal lumbar interbody fusion (ELIF) based on 3D printing technology

Abstract

Objective To design a new operation, extraforaminal lumbar interbody fusion (ELIF), with the help of 3D printing technology and to discuss the efficiency of using 3D printing technology in the clinical research. Methods A healthy male volunteer recruited for this study underwent CT scan of his lumbar vertebrae. He was 26 years old, 172 cm in height and 67 kg in weight. Software Mimics V14.0 was used to read and reconstruct his CT scan data into 3D images. We observed the anatomical bone structures and nerve roots of the intervertebral foramen on 3D reconstruction images in Mimics to analyze the anatomic features of this area. The self-designed ELIF, pedicle screw insertion and cage placement were simulated via digital technology in Mimics. 3D printing technology was then used to manufacture a real object to test ELIF on it. The feasibility of this new approach was further tested in a cadaveric specimen. Results In our designed ELIF, an incision of 6 cm lateral from the central line and 45° from the sagittal plane was made to fully expose the foraminal area. ELIF made it simple and visualized to fully expose the target intervertebral disk and nerve roots, and posteriorly the superior and inferior articular processes and joint capsules as well. ELIF also made it feasible to remove only the superior facet but save the inferior facet. There was enough room to fully reveal and excise the intervertebral disc, and place the cage after distraction of nerve roots through the intervertebral foramen. The test results on the 3D printing object and the cadaveric specimen were consistent. Conclusions 3D printing technology is an effective, reliable and economic method to design an operation. Our results suggest that ELIF is a safe, more minimally invasive and efficient operation to treat degenerative lumbar diseases. Key words: Lumbar vertebrae; Spinal fusion; Surgical procedures, minimally invasive; 3D printing technology