Use of Hausdorff Distance and Computer Modelling to Evaluate Virtual Surgical Plans with Three-Dimensional Printed Guides against Freehand Techniques for Navicular Bone Repair in Equine Orthopaedics
Authors: A. Biedrzycki, H. Kistler, Erik E Perez-Jimenez, A. Morton
Journal: Veterinary and Comparative Orthopaedics and Traumatology
Summary
# Editorial Summary Navicular bone fracture repair requires precise screw placement to avoid complications, yet freehand surgical techniques offer limited control over positioning and trajectory. Researchers compared virtual surgical planning (VSP) with 3D-printed guides against conventional aiming devices using eight cadaveric equine forelimbs, with computer-modelled analysis (Hausdorff distance measurement) quantifying deviation between planned and executed screw placement. The VSP group achieved significantly superior accuracy with mean deviations of just 1.19 mm compared to 3.53 mm with the aiming device approach—roughly three times more precise—and was five times more likely to achieve sub-1 mm accuracy. The study also established critical angular tolerances: a standard 3.5 mm cortical screw can deviate up to approximately 3.2 degrees proximally, 2.7 degrees dorsally, or 2.4 degrees palmarly before breaching the navicular cortex. For equine practitioners, these findings suggest that virtual surgical planning with 3D printing represents a meaningful advancement for complex fracture cases where millimetre-level precision directly influences healing outcomes and complication rates, though adoption will depend on access to appropriate imaging and manufacturing resources.
Read the full abstract on PubMed
Practical Takeaways
- •3D-printed surgical guides for navicular screw placement offer substantially better accuracy (3× smaller deviation) than conventional aiming devices, potentially reducing complications from malplacement
- •Virtual surgical planning allows surgeons to identify safe margins and maximum tolerance angles before surgery, improving confidence in execution and case planning
- •This technology may be particularly valuable for complex navicular repairs where precision is critical to avoiding articular surface violation or implant loosening
Key Findings
- •3D-printed surgical guides achieved mean deviation of 1.19 ± 0.42 mm from planned screw position, significantly superior to freehand aiming device (3.53 ± 1.24 mm, p = 0.0018)
- •Virtual surgical plan group was 5.0 times more likely to achieve aberration <1.0 mm compared to conventional technique
- •Cortical screw with optimal entry point can tolerate maximum deviation angles of 3.23° proximally, 2.70° dorsally, and 2.37° palmarly before violating cortical surfaces
- •Computer-modelled Hausdorff distance analysis provides objective, automated evaluation of surgical accuracy