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Spino-pelvic alignment after surgical correction for developmental spondylolisthesis
Hubert Labelle1, Pierre Roussouly, Daniel Chopin
1Division of Orthopaedics, Sainte-Justine University Center Hospital, 3175 Côte Sainte-Catherine Rd, Montreal, QC H3T 1C5, Canada. hubert.labelle@recherche-ste-justine.qc.ca
Summary
Surgical correction of developmental spondylolisthesis improves spinal and pelvic alignment, particularly in patients with unbalanced pelvis. Reduction techniques may benefit those with retroverted pelvis, enhancing overall patient outcomes.
Area of Science:
- Orthopedics
- Spine Surgery
- Radiology
Background:
- Developmental spondylolisthesis at L5-S1 presents challenges in surgical correction.
- Controversy exists regarding the necessity and methods of reducing spondylolisthesis.
- In situ fusion has limitations, while spinal instrumentation for reduction shows promise but lacks defined indications.
Purpose of the Study:
- To analyze changes in spino-pelvic sagittal alignment after surgical correction of L5-S1 developmental spondylolisthesis.
- To test the hypothesis that surgical correction improves spinal shape and pelvic orientation.
- To investigate the impact of reduction on pelvic balance in different patient subgroups.
Main Methods:
- Retrospective multi-center analysis of 73 patients with developmental spondylolisthesis.
- Evaluation of standing lateral digitised X-rays before and after surgery (average 1.9-year follow-up).
- Measurement of spinal and pelvic parameters using specialized computer software for high reliability.
Main Results:
- Pelvic incidence remained unchanged; L5 Incidence, lumbo-sacral-angle, and lumbar lordosis significantly decreased towards normal values.
- Pelvic tilt, sacral slope, and thoracic kyphosis showed minimal initial changes but significant improvements in pelvic alignment after subgroup classification.
- 40% of patients shifted between balanced and unbalanced pelvis groups, mostly from unbalanced to balanced, with distinct changes in sacral slope and pelvic tilt based on initial pelvic balance.
Conclusions:
- Surgical repositioning of L5 over S1 significantly improves pelvic balance and lumbar lordosis, particularly in patients with abnormal pelvic retroversion.
- Pelvic shape is not altered by surgical reduction, but alignment is.
- Subdividing patients into balanced and unbalanced pelvis groups is crucial, supporting reduction for the unbalanced, retroverted pelvis subgroup.
