Related Experiment Video
Updated: Jun 16, 2026
3D Printing Model of a Patient's Specific Lumbar Vertebra
Published on: April 14, 2023
Patient-Specific 3D-Printed Reference Rod for "Smiley Face Rod" Repair of Lumbar Spondylolysis in a Patient with High
Takayuki Kitahara1, Masatoshi Morimoto1, Naoto Ono1
1Department of Orthopedics, Tokushima University Graduate School, Institute of Biomedical Sciences, Tokushima, Japan.
Introduction:
The "Smiley Face Rod" (SFR) method is an effective direct repair technique for lumbar spondylolysis. However, three-dimensional rod contouring is technically demanding, particularly in patients with a high body mass index (BMI), where deep soft tissue obscures anatomical landmarks.
Technical Note:
We report a technique using a patient-specific three-dimensional (3D)-printed model to create a sterilized "Reference Rod" template. A 27-year-old male with bilateral L5 spondylolysis and severe obesity (BMI 39.8 kg/m2) underwent SFR repair. A 3D model was printed from preoperative computed tomography data. A malleable template rod was contoured on this model to perfectly fit the lamina and spinous process and then sterilized. Intraoperatively, the final titanium rod was bent to match this sterile Reference Rod. This allowed for a "one-pass" insertion through the interspinous ligament with optimal bony contact, eliminating intraoperative trial-and-error.
Conclusions:
The 3D-printed Reference Rod technique is a feasible approach that may facilitate rod contouring for SFR in challenging high-BMI cases by providing a tangible template to address the visualization and geometric limitations of conventional fluoroscopy.
