Use of iliac screw associated with more correction of lumbar lordosis than S2-alar-iliac screw for adult spinal deformity

Abstract

Background To date, there is a paucity of reports clarifying the change of spinopelvic parameters in patients with adult spinal deformity (ASD) who underwent long segment spinal fusion using iliac screw (IS) and S2-alar-iliac screw (S2AI) fixation. Methods A retrospective review of consecutive patients who underwent deformity correction surgery for ASD between 2013 and 2017 was performed. Patients were divided into two groups based on whether IS or S2AI fixation was performed. All radiographic parameters were measured preoperatively, immediately postoperatively, and the last follow-up. Demographics, intraoperative and clinical data were analyzed between the two groups. Additionally, the cohort was subdivided according to the postoperative change in pelvic incidence (PI): subgroup (C) was defined as change in PI ≥5° and subgroup (NC) with change < 5°. In subgroup analyses, the 2 different types of postoperative change of PI were directly compared. Results A total of 142 patients met inclusion criteria: 111 who received IS and 31 received S2AI fixation. The IS group (65.6 ± 26°, 39.8 ± 13.8°) showed a significantly higher change in lumbar lordosis (LL) and upper lumbar lordosis (ULL) than the S2AI group (54.4 ± 17.9°, 30.3 ± 9.9°) (p < 0.05). In subgroup (C), PI significantly increased from 53° preoperatively to 59° postoperatively at least 50% of IS cohort, with a mean change of 5.8° (p < 0.05). The clinical outcomes at the last follow-up were significantly better in IS group than in S2AI group in terms of VAS scores for back and leg. The occurrence of sacroiliac joint pain and pelvic screw fracture were significantly greater in S2AI group than in IS group (25.8% vs 9%, p < 0.05) and (16.1% vs 3.6%, p < 0.05). Conclusions Compared with the S2AI technique, the IS technique usable larger cantilever force demonstrated more correction of lumbar lordosis, and possible increase in pelvic incidence. Further study is warranted to clarify the clinical impaction of these results.

Modified unilateral iliac screw fixation with partial reduction in the treatment of high-grade spondylolisthesis at L5/S1 in adult patients: introduction of key technique, report of clinical outcomes and analysis of spinopelvic parameters

“…Thus, we postulate that: on the one hand, the patient positioning of slight hip extension during surgery might cause the anterior rotation of the sacrum, resulting in intraoperative increase of PI, which would be nally maintained by the application of sacroiliac xation, on the other hand, incremental stress to SIJ after spinopelvic xation accelerates SIJ degeneration, inducing an increasing motion. In this study, we nd the PI is increased by an average of 4.3° at the nal follow-up, which is smaller than the ndings of Lee et al xation was well-introduced by many authors [19,36,48,49]. The change in PI after S2AI instrumentation may be due to direct xation and modi cation of the SIJ, which have been reported by cadaveric study [50].…”

Can Pelvic Incidence Change After Lumbo-Pelvic Fixation for Adult Spine Deformity, and Would the Change be Affected by the Type of Pelvic Fixation?

“…Ishida et al hypothesized that S2AI screws might prevent postoperative increases in PI by rigidly fixing the SI joint. Conversely, Luo et al found a significant change in PI (>5°) in more than 50% of patients treated with IS screws as compared with only 13% of patients with S2AI screws 27 . Finally, other papers showed minimal changes in postoperative PI in patients operated for ASD with lumbo-pelvic fixation 28 .…”

“…Conversely, Luo et al found a significant change in PI ( > 5°) in more than 50% of patients treated with IS screws as compared with only 13% of patients with S2AI screws. 27 Finally, other papers showed minimal changes in postoperative PI in patients operated for ASD with lumbo-pelvic fixation. 28 However, these papers only compared mean PI as opposed to the categorization of significant change in PI, which might have diluted the findings.…”

Direct Iliac Screw vs Sacral-2-Alar-Iliac Screws Technique for Sacropelvic Fixation: Technical Nuances and a Review of the Literature

“…Recently, a study by Luo et al showed that the use of subcrestal iliac screw fixation is associated with greater correction of lumbar lordosis and a possible increase in pelvic incidence when compared with S2AI screw in patients treated for adult spinal deformity. 28 They described the iliac screw entry point as approximately 10 mm between the posterior edge of the iliac crest and the posterior surface of the sacrum and connected with a lateral connector to the rod below the S1 pedicle screw. Additionally, the screw was deeply inserted, making the screw head flush with the cortex of the iliac bone with the aim of lowering the risk of screw prominence.…”