Preparing the Lumbar Intervertebral Disk Space for Interbody Procedures: a Comparison Between the Traditional Method and a New Automated Method

Study Design: Cadaveric laboratory study.

Objective: To quantify and compare automated disk-space preparation with traditional methods.

Summary Of Background Data: Removal of nucleus pulposus to prepare a disk space for interbody fusion is performed with various techniques. Our aim was to determine the safety and effectiveness of an automated technique in comparison to traditional methods and gauge its expected clinical application.

Methods: This study was conducted in 2 phases. In the phase 1 safety trial, ''maximal'' force was applied to an automated shaver against cadaveric annulus and endplates until flexion of the shaft caused the blades to bind. This simulated the risk of creating an incidental cortical or annular defect. In phase 2, 27 cadaveric lumbar disk spaces were randomized to traditional or automated preparation techniques through a standard transforaminal lumbar interbody fusion approach. Traditional method comprised the use of paddle shavers, pituitary rongeurs, and curettes. Automated technique involved insertion of an 8-mm paddle shaver, followed by straight and angled hand pieces to remove nucleus pulposus and endplate cartilage. Unintended cortical and annular breaches, preparation time, instrument insertions, percentage area of exposed endplate underlying the nucleus pulposus, and percentage volume of nuclear space cleared were measured and compared.

Results: In phase 1, ''maximal'' force applied for 10 seconds produced no full-thickness annular or cortical defects. In phase 2, automated technique produced fewer endplate cortical defects (3 vs. 7) and full-thickness annular breaches (0 vs. 1), required fewer instrument insertions (29 vs. 6; P<0.001), exposed more endplate (65% vs. 52%; P=0.037), and removed more nucleus pulposus volume (83% vs. 59%; P=0.01).

Conclusions: Automated shaving decreased instrument insertions and prepared the disk space more effectively, with fewer cortical or annular defects. This technique holds promise for improved outcomes in spinal fusion surgery.