Outcomes and complications of S2 alar iliac fixation technique in patients with neuromuscular scoliosis: experience in a third level pediatric hospital

3D CT modeling demonstrates the anatomic feasibility of S1AI screw trajectory for spinopelvic fixation in neuromuscular scoliosis

PURPOSE

In patients with neuromuscular scoliosis undergoing posterior spinal fusion, the S2 alar iliac (S2AI) screw trajectory is a safe and effective method of lumbopelvic fixation but can lead to implant prominence. Here we use 3D CT modeling to demonstrate the anatomic feasibility of the S1 alar iliac screw (S1AI) compared to the S2AI trajectory in patients with neuromuscular scoliosis.

METHODS

This retrospective study used CT scans of 14 patients with spinal deformity to create 3D spinal reconstructions and model the insertional anatomy, max length, screw diameter, and potential for implant prominence between 28 S2AI and 28 S1AI screw trajectories.

RESULTS

Patients had a mean age of 14.42 (range 8-21), coronal cobb angle of 85° (range 54-141), and pelvic obliquity of 28° (range 4-51). The maximum length and diameter of both screw trajectories were similar. S1AI screws were, on average, 6.3 ± 5 mm less prominent than S2AI screws relative to the iliac crests. S2AI screws were feasible in all patients, while in two patients, posterior elements of the lumbar spine would interfere with S1AI screw insertion.

CONCLUSION

In this cohort of patients with neuromuscular scoliosis, we demonstrate that the S1AI trajectory offers comparable screw length and diameter to an S2AI screw with less implant prominence. An S1AI screw, however, may not be feasible in some patients due to interference from the posterior elements of the lumbar spine.

Utilizing robotic-assisted navigation for pelvic instrumentation in pediatric patients with neuromuscular scoliosis: a technical note and case series

Pelvic fixation is commonly used in correcting pelvic obliquity in pediatric patients with neuromuscular scoliosis and in preserving stability in adult patients with lumbosacral spondylolisthesis or instances of traumatic or osteoporotic fracture. S2-alar-iliac screws are commonly used in this role and have been proposed to reduce implant prominence when compared to traditional pelvic fusion utilizing iliac screws. The aim of this technical note is to describe a technique for robotically navigated placement of S2-alar-iliac screws in pediatric patients with neuromuscular scoliosis, which (a) minimizes the significant exposure needed to identify a bony start point, (b) aids in instrumenting the irregular anatomy often found in patients with neuromuscular scoliosis, and (c) allows for greater precision than traditional open or fluoroscopic techniques. We present five cases that underwent posterior spinal fusion to the pelvis with this technique that demonstrate the safety and efficacy of this procedure.

The Utilization of Dual Second Sacral Alar-Iliac Screws for Spinopelvic Fixation in Patients with Severe Kyphoscoliosis

OBJECTIVES

As a new pelvic fixation technique, the dual S2AI screws fixation technique could provide highly stable distal strength, and have wide clinical prospect in the correction of severe kyphoscoliosis. However, the ideal trajectory parameters, indications and clinical outcomes of this technique have not been reported so far. This study aimed to determine the anatomical parameters of dual S2AI screws in the normal Chinese adult population, investigating the indications of this technique and evaluating the feasibility and clinical outcomes.

METHODS

Fifteen males and 15 females with normal pelvis underwent a pelvic CT scan to determine ideal dual S2AI screws trajectories. Sagittal angle (SA), transverse angle (TA), maximal length (ML), sacral length, and skin distance were measured. Subsequently, we retrospectively reviewed the data of 16 patients (seven males and nine females) who underwent dual S2AI screw fixation and 23 patients who underwent single S2AI screw fixation between January 2014 and December 2019. Preoperative, postoperative, and latest follow-up measurements of Cobb angle, coronal balance (CB), spinal pelvic obliquity (SPO), and regional kyphosis (RK) were obtained. The mean follow-up time was 16.7 ± 7.1 months (range: 12-30 months). Independent t-test was used to determine the difference in the analysis of the trajectories. The paired sample non-parametric Wilcoxon test was performed to assess the changes in radiographic parameters between different time points and different groups.

RESULTS

For both male and females, the proximal S2AI screws had significantly higher TA and ML, but a lower SA than distal screws. Females showed significantly more caudal (SA: 25.03° ± 2.32° vs. 29.82° ± 2.47°, t = 7.742, P < 0.001) trajectories of distal screw. Additionally, ML in the females were significantly shorter than that in males (106.81 mm ± 6.79 mm vs. 101.63 mm ± 6.55 mm, t = 3.007, P = 0.003, 124.41 mm ± 7.57 mm vs. 116.23 mm ± 7.03 mm, t = 4.337, P < 0.001). Eight had unilateral and eight had bilateral dual S2AI screw placement. Respectively, both the single S2AI and dual S2AI groups showed significant postoperative improvement of Cobb angle, RK angle and SPO angle. In patients with dual S2AI screws fixation, two patients found that screws loosening occurred in one of dual screws at 1-year follow-up, and in patients with single S2AI screws fixation, six patients found screw loosing as well as two patients found screw breakage at 1-year follow-up. None of all patients had any prominent loss of correction.

CONCLUSION

The ideal trajectory of dual S2AI screw could be well established. The dual S2AI screw fixation technique is feasible in patients with severe kyphoscoliosis, and provides satisfactory correction of deformity with few postoperative complications.

CLINICAL OUTCOMES OF PATIENTS UNDERGOING CORRECTION OF NEUROMUSCULAR SCOLIOSIS WITH A CONTROLLED HOSPITAL PROTOCOL – PRELIMINAR OUTCOMES

ABSTRACT Objectives: To identify the main hospital outcomes of patients undergoing surgical correction of neuromuscular scoliosis and to assess complication rates and achievement of mobility goals after the use of a managed protocol. Methods: This is a longitudinal, retrospective study, with data obtained six months after the application of a protocol in 103 patients of both sexes submitted to surgical correction of neuromuscular scoliosis, at a tertiary level hospital in São Paulo, between June and December 2018 (pre-protocol) and between May and September 2019 (post-protocol). Data from patients who had previously undergone other orthopedic spine surgeries were excluded. In addition to the data for epidemiological characterization of the underlying diseases, the clinical characteristics and complications were analyzed. Results: Of the 103 patients evaluated, there was a predominance of females (53.4%) and a mean age of 14.9 years. The most frequent diagnosis was cerebral palsy, the mean angle of curvature was 75°, and the most frequently observed comorbidities were lung diseases (25%). The protocol was partially adhered to by professionals and after its implementation, there was a significant decrease in pain and the systemic inflammatory response syndrome (SIRS), prevention of immobility and a low rate of infection. Conclusions: The use of a protocol focused on patients undergoing correction of neuromuscular scoliosis led to reduced complications of SIRS and reduced pain; kept the surgical site infection rate low, and prevented short-term immobility. Level of evidence III; Retrospective study.

Ambulatory capacity following fusion to the sacrum with pelvic fixations pediatric spinal deformity patients

OBJECTIVE

To investigate outcomes of ambulatory pediatric patients fused to the sacrum with pelvic fixation.

STUDY DESIGN

Retrospective cohort.

BACKGROUND

Historically in the pediatric spinal deformity literature, long fusions to the sacrum with pelvic fixation have been limited to non-ambulatory patients with pelvic obliquity. This analysis assesses the impact of how long fusions that include pelvic fixation in ambulatory pediatric patients.

METHODS

Consecutive pediatric patients undergoing fusion to the sacrum with pelvic fixation with any ambulatory capacity at a tertiary academic pediatric spine program from 2016 to 2018 were included in this review. Patient demographics, surgical details, and postoperative results were collected and analyzed to identify the impact on postoperative gait and ambulation function. Outcomes were determined from PROMIS, Parent Proxy Mobility questionnaires, as well as an institution specific pediatric gait questionnaire.

RESULTS

25 patients met inclusion criteria. 96.0% of patients had non-idiopathic scoliosis. 48% (12/25) of patients had previous spinal surgery. Median fusion levels were 17.0. 40% (10/25) had preoperative motor and gait deficits and only one patient with a documented decline at postoperative clinical examination. All 25 patients retained ambulatory capacity following their spinal fusion to the sacrum with pelvic fixation. 64% (16/25) of patients or family members completed the postoperative gait questionnaire. The mean PROMIS T-score was 43.4 (95% CI 36.5-50.0) for intact patients. The postoperative gait questionnaires revealed that 75% (6/8) of neurologically intact patients stated they would have the surgery again. 100% (8/8) of these patients noted an improved posture and 25% (2/8) reported a subjective decrease in ambulatory capacity status/post fusion to the sacrum. 100.0% (8/8) of limited ambulatory patients stated they would have the surgery again and noted improved posture with only 25% (2/8) noting a subjective decrease in ambulation postoperatively.

CONCLUSION

In appropriately selected pediatric spinal deformity patients fusion to the sacrum using pelvic fixation can maintain ambulation with high overall surgical satisfaction.

LEVEL OF EVIDENCE

III.

Clinical Effectiveness of S2-Alar Iliac Screws in Spinopelvic Fixation in Pediatric Neuromuscular Scoliosis: Systematic Literature Review

STUDY DESIGN

Systematic literature review.

OBJECTIVES

To comprehensively review the S2-alar iliac (S2-AI) screw technique for pelvic fixation in pediatric neuromuscular scoliosis.

METHODS

Articles identified from the PubMed and EMBASE databases were reviewed for relevance and applicability, and the studies were summarized.

RESULTS

Eight articles met the inclusion criteria. A total of 277 pediatric patients underwent spinopelvic fixation using S2-AI fixation for neuromuscular scoliosis; the mean follow-up was 3 years (range = 0.75-6 years). Six articles had level III evidence (5 retrospective cohort studies, 1 observational study), and 2 articles had level IV evidence (case series). Wound complications occurred in 34 (12.2%) patients. Instrumentation complications occurred in 36 patients (13.0%), including lucency around the screw (6.5%), screw fracture (3.6%), disengaging of the set/screw or rod from the tulip head (2.8%), and screw displacement (0.7%). Three patients (1.1%) required reoperation for instrumentation failures. The overall reoperation rate-including 3 hardware replacements and 3 cases of L5-S1 pseudarthrosis-was 2.1%. The mean Cobb angle correction was 51.4°, and the mean pelvic obliquity correction was 14.8°; deformity correction was maintained at 3- and 5-year follow-ups. There were 10 (3.6%) cases of implant prominence/implant-related pain, 1 case of sacroiliac joint pain (resolved with longer screw placement), and no major neurological or vascular complications secondary to S2-AI screw placement.

CONCLUSIONS

This review suggests that the use of S2-AI screws in pediatric neuromuscular scoliosis is efficacious with a reasonable safety profile and provides a useful technique for pelvic fixation in children with scoliosis.

USE OF ALAR-ILIAC S2 SCREW TECHNIQUE IN SCOLIOSIS SECONDARY TO MYELOMENINGOCELE

ABSTRACT Objective: To evaluate retrospectively the results related to the use of pelvic fixation with alar-iliac S2 screw in individuals with myelomeningocele. Methods: Retrospective study of cases surgically treated with this technique, between January 2015 and March 2018 at the Pequeno Principe Children's Hospital. Radiographic images and clinical records were analyzed in search of complications. Results: Twelve patients with mean age of 13.3 years were treated at the time of surgery. The mean follow-up was 11.5 months. The mean of the highest magnitude curve measured by the Cobb angle in the preoperative period was 83.8°; while in the last postoperative follow-up was 29.5° (correction of 65%). The mean pelvic obliquity was 23.1° in the preoperative period and in the postoperative was 7.1° (correction of 69%). Only 2 cases (17%) with complications associated with material failure at the level of sacroiliac fixation, due to the unilateral release of the head of the polyaxial S2 iliac screw. Conclusions: The technique of pelvic fixation in the scoliosis secondary to myelomeningocele with the use of S2 alar-iliac screws has shown satisfactory results, with only two complications (17%) directly related to pelvic fixation in the operated cases. Level of Evidence IV; Series of Cases.