Clinical Decision Making and Localised Surgical Correction of Symptomatic Levels in Postural Degenerative Scoliosis and Sagittal Spinopelvic Malalignment

Background: This study aims to determine if 1) loss of lumbar lordosis, often associated with degenerative scoliosis, is structural or largely due to positional factors secondary to spinal stenosis 2) addressing symptomatic levels with decompression and posterolateral fusion in selected patients resulting in improvement of sagittal malalignment and 3) degree of sagittal plane correction achieved with local fusion could be predicted by routine preoperative imaging. Methods: A retrospective study with collected imaging data of surgically treated DS patients who underwent decompression and instrumented fusion at symptomatic levels was performed. Pre and postoperative plain radiographs and preoperative MRI’s of spinopelvic region were analyzed. LL, pelvic incidence, pelvic tilt, and sacral slope were assessed. For surgical strategy, all patients presented with a preoperative PI-LL mismatch greater than 10°. Postoperative complications were assessed. Results: Preoperative MRI’s and lumbar extension radiographs revealed a mean LL of 42°and 48°, in 68 patients (mean follow-up 29 months). LL postoperatively was corrected to a mean PI-LL of 10°. Patients who achieved PI-LL mismatch within 10o on preoperative extension lateral lumbar radiographs, 62.5 % were able to maintain a PI-LL mismatch within 10° on their initial postoperative films.37.5 % were not able to achieve that mismatch on extension radiographs (p=0.001, OR=9.58).54.2 % were able to achieve a PI-LLless than10° on initial postoperative radiographs, when preoperative MRI revealed a PI-LL mismatch within 10°. Only 20.5 % achieved that goal postoperatively if their mismatch was greater than 10o on their MRI (p=0.003, OR=4.25). Conclusion: With the surgical intervention at symptomatic levels in DS patients, we achieved a PI-LL mismatch to within 10°. The loss of LL observed preoperatively may be largely positional rather than structural. The amount of LL correction observed after surgery can be predicted by ima