Different acute behaviors of pelvic incidence after long fusion to sacrum between elderly patients with severe and minor sagittal deformity: a retrospective radiographic study on 102 cases

A Comprehensive Analysis of the Behavior of Pelvic Incidence After Different Posterior Spinal Procedures in Elderly Patients With Spinal Deformity

“…Our previous study confirmed the inevitable role that global sagittal malalignment played in the disparity of PI. 11 PI was found increased after long fusion to sacrum in elderly ASD patients with severe sagittal deformity, while was relatively invariable after the same surgical procedure in those with minor sagittal deformity. Long fusion constructs to S1 leading to motion in SIJ has been demonstrated in Mushlin et al’s biomechanical investigation of SIJ in human cadaveric specimens.…”

“… 19 Therefore, this variation in postoperative PI could be considered as a secondary change compensating for the spinal sagittal malalignment under lax SIJ in elderly patients. 11 …”

“…Besides the changes during operation, PI could also alter spontaneously after posterior spinal surgeries. 7 , 8 , 11 Cecchinato et al 8 reported an acute spontaneous increase of PI in 27 ASD patients who underwent long lumbar fusion to sacrum without pelvic fixation. Lee et al 7 also found PI was gradually increased at different follow-up time after lumbar fusion to sacrum without pelvic fixation in 18 ASD patients.…”

“…Our previous findings supported their speculation that PI spontaneously increased in elderly ASD patients with severe sagittal deformity after long lumbar fusion to sacrum, while was relatively invariable in those with minor sagittal deformity. 11 …”

“…Our previous findings supported their speculation that PI spontaneously increased in elderly ASD patients with severe sagittal deformity after long lumbar fusion to sacrum, while was relatively invariable in those with minor sagittal deformity. 11 Despite a few studies focusing on the PI variation after surgery, the data pool is still insufficient to analyze surgical or other potential factors contributing to the postoperative modification of this parameter. The purposes of this study are to evaluate the PI behavior after different posterior spinal procedures in elderly patients with spinal coronal or sagittal deformity, to determine the potential associated factors with the variability in PI after spinal surgery and to comprehensively analyze its mechanisms.…”