Translaminar facet joint screw insertion with a rapid prototyping guide template: a cadaver study

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Spinal Fusion Techniques

Background:

• Transforaminal lumbar interbody fusion (TLIF) often requires complex screw placement.
• Traditional translaminar facet screw (TFS) insertion is technically demanding and requires extensive surgical experience.
• Computer-assisted design and rapid prototyping (RP) offer potential improvements in accuracy and safety for TFS placement.

Purpose of the Study:

• To evaluate the accuracy and safety of TFS placement using a patient-matched RP drill guide template system.
• To assess the feasibility of RP-guided TFS insertion in multilevel unilateral TLIF procedures.

Main Methods:

• A custom RP drill guide template was designed for each specimen based on 3D CT scans.
• Fourteen cadaveric lumbar spine specimens were used to test the RP guide system.
• The 3D positioning of screw entry points and trajectories was compared to the preoperative plan.

Main Results:

• Sixty trajectories were assessed, with no clinically significant laminar perforations observed.
• Mean deviation for entry point on the spinous process was 1.22 mm.
• Mean angular deviations for tail and submergence were 0.68° and 1.46°, respectively, with no statistical significance.

Conclusions:

• The RP drill guide template system demonstrates high accuracy and safety for TFS placement.
• This technology facilitates precise screw insertion, potentially reducing surgical risks in TLIF procedures.