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Updated: May 27, 2026
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A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique
Published on: January 6, 2023
The lateral sacral triangle--a decision support for secure transverse sacroiliac screw insertion
1Department of Trauma Surgery, Employers' Liability Insurance Association Hospital Bergmannstrost, Merseburger Straße 165, D-06112 Halle (Saale), Germany. thomasmendel@hotmail.com
Injury
|November 15, 2011
Summary
This study identifies key sacral measurements for safe sacroiliac (SI) screw fixation in pelvic injuries. A lateral sacral triangle ratio of 1.5 or less reliably predicts sufficient bone for SI screw placement.
Area of Science:
- Orthopedic Surgery
- Radiology
- Anatomy
Background:
- Sacroiliac (SI) screw fixation is crucial for pelvic injury stabilization.
- Reliable radiological landmarks and anatomical classifications for the sacrum are currently lacking.
- Variability in sacral shape impacts the security of transverse SI screw positioning.
Purpose of the Study:
- To investigate how sacral shape variability influences secure transverse SI screw positioning.
- To analyze correlations between anatomical conditions and standard pelvic radiographic views.
- To identify reliable radiological parameters for predicting successful SI screw insertion.
Main Methods:
- 3D reconstructions from 80 human CT datasets using Amira 4.2 software.
- Identification of anatomical conditions (ACs) affecting the bony screw pathway.
- Spatial alignment of pelves to create standard Matta projections for analysis.
Main Results:
- The height of the pedicular isthmus (PH) was identified as the limiting variable for screw insertion.
- A lateral sacral triangle ratio (S1 body height/width) correlated highly with PH (p=0.0001).
- A ratio of 1.5 reliably predicted sufficient bone stock (97% PPV); EJ distance of 0 mm in outlet view ensured 100% insertion possibility.
Conclusions:
- SI screw insertion demands meticulous planning, with sacral pedicle orientation being critical.
- Narrow sacroiliac channels and high sacral shape variability pose challenges for secure screw placement.
- The lateral sacral triangle ratio offers a simple, accurate preoperative method to assess SI screw feasibility, with outlet view evaluation aiding safety.
