Minimum 2-Year Analysis of S2-Alar-Iliac Screw Fixation for Adult Spinal Deformity

Kappa: Preliminary Results on a Novel Technique for Pelvic Fixation in Adult Spinal Deformity Correction

Study Design

Retrospective cohort study.

Objectives

Pelvic fixation in degenerative spinal deformation is as crucial as demanding. Several pelvic anchoring technics have been described, but loosening rates remain high for most solutions. Here is described the "Kappa" technic, combining ilio-sacral screws to S2A1 screws at 2 years of follow-up.

Methods

Thirteen patients that underwent a spinal deformity correction with "Kappa" fixation to the pelvis and with more than 2 years of follow-up were prospectively included in this study. The surgical technic is described, and clinical and radiographic data have been collected for all patients.

Results

The population exhibited an important pre-operative sagittal imbalance (mean SVA of 104,4 mm, mean PI-LL mismatch of 22,8°) that had improved significatively after surgery (mean SVA of 75,5 mm and mean PI-LL mismatch of 4,9°). No loosening of pull-out of the implants was to deplore at 2 years of follow-up.

Conclusions

The association of ilio-sacral screw, resistant to pull-out because of the traction axis perpendicular to the construct, to S2A1 screws, known to be effective in sagittal balance restoration seems to be an effective and safe option to pelvic fixation for adult spinal deformity correction.

Level of Evidence

IV.

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

Sacropelvic (SP) fixation is the immobilization of the sacroiliac joint to attain lumbosacral fusion and prevent distal spinal junctional failure. SP fixation is indicated in numerous spinal conditions (eg, scoliosis, multilevel spondylolisthesis, spinal/sacral trauma, tumors, or infections). Many SP fixation techniques have been described in the literature. Currently, the most used surgical techniques for SP fixation are direct iliac screws and sacral-2-alar-iliac screws. There is currently no consensus in the literature on which technique carries more favorable clinical outcomes. In this review, we aim to assess the available data on each technique and discuss their respective advantages and disadvantages. We will also present our experience with a modification of direct iliac screws using a subcrestal approach and outline the future prospects of SP fixation.

The Incidence of Iliac Screw-Related Complications After Long Fusion Surgery in Patients with Adult Spinal Deformity

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the long-term clinical outcome and incidence of iliac screw-related complications in patients with adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

Rigid lumbosacral fixation is crucial to achieve optimal global alignment and successful long-term clinical outcomes.

METHODS

The data of eligible patients with ASD who underwent spinopelvic fixation using bilateral iliac screws with at least 5-year follow-up periods were retrospectively analyzed. Iliac screw loosening and rod breakage between the S1 and iliac (S1/IL) screws were defined as distal instability (DI). Demographic data, health-related quality of life scores, and spinopelvic parameters in the DI group were compared with those in the non-DI group. Sub-group analyses were performed between the cases with and without alignment change after rod fracture at S1/IL.

RESULTS

Of the 159 patients, the data of 110 patients (15 men, 95 women; mean age, 67.8 yr) were analyzed. The follow-up rate was 69%. Forty-five (41%) patients showed DI (29 cases [26%] in screw loosening, 16 cases [15%] in rod breakage). Eight patients (7.3%) required revision surgery because of iliac screw-related complications. No significant differences were observed in the Oswestry Disability Index and Scoliosis Research Society questionnaire (revised) scores between the DI and non-DI groups. The patients with iliac screw loosening showed significantly greater values of preoperative pelvic incidence, pelvic tilt (PT), and postoperative PT, and T1-pelvic angle. In patients with rod breakage at S1/IL, five patients (31%) who had associated mechanical complications showed an alignment change between pre and post rod breakage. They showed significantly higher and lower rates of high-grade osteotomies and L5/S interbody fusion, respectively.

CONCLUSION

The incidence rate of iliac screw-related complications was relatively high. However, they had a little effect on sagittal alignment deterioration and there were few cases that required revision surgery.Level of Evidence: 4.

S2-Alar-Iliac Screw Fixation versus Iliac Screw Fixation in the Treatment of Sacral Fractures

PURPOSE

To compare the short-term therapeutic effects of S2-alar-iliac (S2AI) screw fixation and iliac screw fixation techniques in managing sacral fractures.

METHODS

From September 2015 to May 2020, 42 patients with sacral fractures who underwent lumbopelvic fixation by a single surgeon were analyzed. The patients were divided into the S2AI screw group (19 patients) and the iliac screw group (23 patients). Operative data, reduction quality, postoperative complications, and functional outcomes were evaluated.

RESULTS

The incidence of unplanned reoperation was significantly different between patients treated with S2AI screws than in those treated with iliac screws (0 versus 6, p = 0.02). The mean intraoperative estimated blood loss was 405.26 ± 229.67 mL in the S2AI screw group and 539.13 ± 246.32 mL in the iliac screw group (P = 0.08). No significant difference was observed in either group regarding the quality of reduction, functional outcome, or low back pain. The reduction quality based on the Matta criteria and excellent/good outcomes were 21/2 in the iliac screw group and 17/2 in the S2AI screw group. The functional outcomes based on the Majeed score and excellent/good/fair outcomes were 17/3/3 in the iliac screw group and 17/1/1 in the S2AI screw group. No complications, including implant breakage, loosening of the implant, or loss of reduction were found in either group during follow-up.

CONCLUSION

Both S2AI screws and iliac screws were effective in the treatment of sacral fractures. The use of S2AI screws, however, was independently associated with fewer unplanned reoperations for surgical site infection, wound dehiscence, and symptoms of screw protrusion than the use of iliac screws.