Pelvic Tumor Near the Sciatic Notch: Fixing the Sacroiliac Joint Before It Moves
- Isabelle Têcheur
- 3 days ago
- 2 min read
When a pelvic tumor invades the sacroiliac joint, resecting it leaves that joint without the stability it had before the cut. Placing the reconstruction implants afterward becomes difficult, since the joint can no longer be trusted to sit exactly as planned.
The solution is to prepare those trajectories before the resection, while the joint is still intact.
Dr. Vincent Crenn, at CHU Nantes, referred a pelvic tumor resection near the sciatic notch, invading the sacroiliac joint. The plan combined six cutting planes, a reinforced safety margin near the S1 foramen, and a postero-lateral approach. The procedure ends with a reconstruction of the sacroiliac joint.
Fixing the Joint Before It Moves
Two patient-specific guides were used, in a deliberate order. The first, the fixation guide, sits on the intact iliac bone, away from the tumor. It prepares the trajectories for the reconstruction implants while the joint still holds its original shape and those paths match the plan exactly.
This same guide also carries a cutting plane of its own: it opens the sacroiliac ring, giving access to the endopelvic region and making it easier to remove the resected bone once it is freed.
Once this step is complete, the guide is removed, leaving pins in the bone that will later guide the reconstruction implants into position.
Room for the Laminectomy, Without Losing the Plan
The resection guide then takes over. It seats on the bone in its own single position, through the same postero-lateral approach, and guides the six cutting planes of the resection.
A feature of the guide allows, if needed, a laminectomy to reach the sacral canal without losing its position: the guide can be lifted off temporarily, the laminectomy performed freehand, and the guide put back exactly in place using two wires kept in the bone. The procedure then continues normally through to full resection of the specimen.
Closing the Case
With the specimen removed, the pins placed in the very first step were still there, guiding the reconstruction implants straight into position and rebuilding the sacroiliac joint without having to relocate its original geometry.
We thank Dr. Vincent Crenn for his trust and for the precision of his feedback throughout the design process.
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