Published in:
01-05-2016 | Case Report
Sacroiliac joint luxation after pedicle subtraction osteotomy: report of two cases and analysis of failure mechanism
Authors:
Yann Philippe Charles, Bo Yu, Jean-Paul Steib
Published in:
European Spine Journal
|
Special Issue 1/2016
Login to get access
Abstract
Background
Sagittal decompensation after pedicle subtraction osteotomy (PSO) is considered as late onset complication. Several mechanisms have been suggested, but little attention has been paid to the caudal end of lumbar instrumented fusion, especially sacral iliac joint (SIJ) deterioration.
Methods
Clinical histories and radiographic sagittal parameters of two patients with SIJ luxation after PSO are presented. The biomechanical failure mechanism and risk factors are analysed.
Results
Two patients underwent correction of fixed anterior sagittal imbalance by PSO, followed by pseudarthrosis revision surgery. Both of them sustained persistent sacroiliac pain, progressive recurrence of anterior imbalance and progressive pelvic incidence (PI) increase around 10°. An acute bilateral SIJ luxation occurred in both patients leading to sharp increase or PI around 20°. One patient was treated by SIJ fusion and the other patient was placed on non-weight-bearing crutch ambulation for 1 year. Both patients had a high preoperative PI (95° and 78°). A theoretical match between lumbar lordosis (LL) and PI was not achieved by PSO. Osteopenia was present in both patients. Computed tomography evidenced L5–S1 pseudarthrosis and sacroiliac joint violation by pelvic or sacral ala screws.
Conclusion
Patients with high PI might seek for further compensation at their SIJ when lacking LL after PSO. Chronic anterior imbalance might lead to progressive weakening of sacroiliac ligaments. Initial circumferential lumbosacral fusion and accurate iliac screw fixation might reduce stress on implants, risk for pseudarthrosis, implant failure and finally SIJ deterioration. Bone mineral density should further be investigated preoperatively.