Towards a Y-Shaped Pelvic Osteotomy To Address Loss of Lumbar Lordosis

4 pages•Published: January 5, 2026

Emmy Ezendam, Chien Nguyen, Edsko Hekman, Moyo Kruyt and Gabriëlle Tuijthof

Abstract

Introduction. In severe cases with lumbar lordosis loss > 25°, pedicle subtraction osteotomy is performed surgically to restore the sagittal malalignment. But it has severe limitations. So, we are developing a new Y-shaped pelvic osteotomy that targets the pelvis rather than the spine. This work presents a fixation system tailored to the Y-shaped pelvic osteotomy.
Methodology. Criteria for the fixation system were set: Offer compressed fixation on the posterior side (closed wedge), maintain a 15° wedge opening on the anterior side and use conventional fixation components. This resulted in combining a lag-screw posteriorly and a patient-specific osteosynthesis plate anteriorly. To assess feasibility, a basic finite element analysis (FEA) was performed using loads derived from a static free body analysis, and a preliminary test was performed on a Sawbones model to assess surgical usability and osteotomy accuracy.
Results. The load input to the FEA was determined to be 397 N in x-direction, 832 N in z-direction, and 18 Nm moment. The FEA showed that the width of the T-shape of the plate crossing the osteotomy should be at least 15 mm to remain below allowable material stress level.
The usability gave a score of 3.9 out of 7 for the fixation system. The Sawbone test showed obtained osteotomy angles of 16.6° and 19.5°, respectively compared to the set 15°. The bone contact area was 62% compared to the planned 61%.
Conclusion. The preliminary results indicate the feasibility of the Y-shaped pelvic osteotomy in combination with the new fixation system.

Keyphrases: fixation, ilium, osteotomy, pelvis

In: Joshua William Giles and Aziliz Guezou-Philippe (editors). Proceedings of The 25th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery, vol 8, pages 85-88.

Links:	https://easychair.org/publications/paper/fL1H
	https://doi.org/10.29007/1wms

BibTeX entry

@inproceedings{CAOS2025:Towards_Y_Shaped_Pelvic,
  author    = {Emmy Ezendam and Chien Nguyen and Edsko Hekman and Moyo Kruyt and Gabriëlle Tuijthof},
  title     = {Towards a Y-Shaped Pelvic Osteotomy To Address Loss of Lumbar Lordosis},
  booktitle = {Proceedings of The 25th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery},
  editor    = {Joshua William Giles and Aziliz Guezou-Philippe},
  series    = {EPiC Series in Health Sciences},
  volume    = {8},
  publisher = {EasyChair},
  bibsource = {EasyChair, https://easychair.org},
  issn      = {2398-5305},
  url       = {/publications/paper/fL1H},
  doi       = {10.29007/1wms},
  pages     = {85-88},
  year      = {2026}}

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