Mullins et al: Accuracy of pin placement in the canine thoracolumbar spine using a free-hand probing technique versus 3D-printed patient-specific drill guides: An ex-vivo study
Veterinary Surgery 5, 2023

🔍 Key Findings

• Both free-hand probing (FHP) and 3D-printed guides (3DPG) enabled accurate spinal pin placement, with 87.5% vs 96.4% of pins graded as optimal (Grade I).
• 3DPGs had fewer intraoperative deviations (0/56 pins) compared to 6/56 with the FHP technique.
• No pins using either method fully breached the medial vertebral canal (Grade IIb) — a critical safety outcome.
• Pins placed using 3DPGs required less time overall (mean 2.6 min) than FHP (mean 4.5 min).
• FHP required specific experience and has a learning curve, whereas 3DPG use requires CAD software and 3D printing access.
• FHP had more lateral canal violations (Grade IIIa: 4/56 vs 0/56 for 3DPG), suggesting slightly less precision.
• Both techniques were safe, and all deviations were recognized and corrected intraoperatively.
• 3DPGs may offer practical advantages in clinical settings lacking surgical expertise, while FHP allows immediate intervention without 3D printing delay.