Purpose
This study aims to identify risk factors and changes in spino-pelvic parameters associated with Sacroiliac (SI) joint degeneration.
Materials and Methods
This multicenter retrospective study included 472 patients who underwent fusion surgery at three hospitals between March 2021 and February 2024. SI joint degeneration was assessed using seven indicators: sclerotic changes, erosion, osteophyte formation, intra-articular bone formation, joint space narrowing, intra-articular gas formation, and subchondral cysts. CT scans were performed preoperatively and 6 months postoperatively. The patients were divided into two groups: those with progression of SI joint degeneration and those without. Standing whole spine lateral X-rays were used to measure a total of 10 spinopelvic parameters both preoperatively and at 6 months postoperatively. Statistical analysis was performed using two-sample t-tests and multivariable logistic regression.
Results
Among the 472 patients, 135 (28.6%) showed progression of SI joint degeneration. When comparing the two groups, age (p=0.022), alcohol consumption (p=0.001), smoking (p<0.001), and S1 involvement (p=.04) were associated with SI joint degeneration. Regarding spino-pelvic parameters, patients with SI joint degeneration exhibited significant changes in thoracic kyphosis (p=0.017) and pelvic tilt (p=0.049).
Conclusions
Sacrum fixation, smoking, alcohol consumption, and age can be significant risk factors for SIJ degeneration following lumbar fusion surgery.

Objective
The purpose of this study is to investigate the radiological risk factors and differences in spinopelvic parameters for radiologic degenerative changes in the sacroiliac joint after lumbar or lumbosacral fusion surgery.
Materials and Methods
From 2019 to 2020, 116 patients diagnosed with lumbar and sacral degenerative diseases who underwent lumbar or lumbar sacral fusion were included. The degenerative changes of the sacroiliac joint were measured by CT performed before and 6 months after surgery, and divided into two groups according to the presence or absence of radiographic degeneration. Evaluation factors for radiographic degeneration include sclerotic changes, erosion, osteophyte formation, intra-articular bone formation, joint space narrowing, intra-articular gas formation and subchondral cysts were evaluated. Spinopelvic radiologic parameters and surgery-related parameters including lumbar lordosis, sacral slope, pelvic incidence, global tilts, and T1PA between the two groups were analyzed using Student's t-tests and chi-square tests to determine the difference between continuous and non-continuous variables between groups. Logistic regression analysis was used for the analysis of risk factors for degeneration for SI joints after lumbar or lumbosacral fusion surgery.
Results
There was no statistically significant difference between the demographic data and surgery-related data between the group with and without sacroiliac joint degenerative changes. There was also no statistical difference in the rate of degenerative changes in the sacroiliac joint according to the presence or absence of S1 in the fusion segment. (degeneration group vs non-degeneration group; 45.5% vs 39.8%, p: 0.574) There were statistically significant differences between the two groups in lumbar lordosis (LL), pelvic angle of incidence (PI), and PI-LL. (LL; 27.2±12.0 vs. 39.8±11.3, PI; 51.3±12.0 vs. 57.2±12.6. and PI-LL; 24.1±17.0 vs 17.4±13.9, p: <0.001, 0.023, and 0.030) As risk factors for radiographic degenerative changes in the sacroiliac joint, lumbar lordosis (LL), pelvic incidence (PI), sacral inclination (SS), and sagittal vertical axis (SVA) were statistically significant factors. (lumbar lordosis Odd ratio: 0.851, 95% CI: 0.791-0.917, p-value <0.001)
Conclusions
Lumbar lordosis and pelvic incidence are related as risk factors for radiographic degenerative changes in the sacroiliac joint after surgery in patients with lumbar spinal fusion.