S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up

Smith, Evan J.; Kyhos, Justin; Dolitsky, Robert; Yu, Warren; O’Brien, Joseph R.

doi:10.1016/j.jspd.2017.05.004

Cited by 28 publications

(21 citation statements)

References 21 publications

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“…S2AI screw loosening was found in 67% of patients, and S1 screw loosening in 12% of patients 2 years after ASD surgery. Previous studies found that S2AI screw loosening was found in 2.9%-10.4% [5,7,11]. The incidence of S2AI screw loosening found in our study was more than that reported previously.…”

Section: A B C D Econtrasting

confidence: 53%

“…The incidence of S2AI screw loosening found in our study was more than that reported previously. The difference was because we evaluated screw loosening using CT, while previous studies used conventional radiographs [7,11]. We consider that our 2-year postoperative evaluation using CT is more accurate than that of previous studies.…”

Section: A B C D Ementioning

confidence: 96%

“…Risk factors for loosening of S1 pedicle screws and iliac screw have been investigated [9,10]. Some studies found a possible etiology of S2AI screw loosening [11,12], that is, S2AI screws penetrating the sacroiliac joint without bone fusion of the joint. However, apparently no studies have analyzed the risk factors for S2AI screw loosening.…”

Section: Introductionmentioning

confidence: 99%

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Risk Factors for Loosening of S2 Alar Iliac Screw: Surgical Outcomes of Adult Spinal Deformity

et al. 2020

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To determine the risk factors for S2 alar iliac (S2AI) screw loosening and its association with lumbosacral fusion in patients with adult spinal deformity (ASD). Overview of Literature: S2AI screws have been widely used for ASD surgery in recent years. However, no studies have analyzed the risk factors for loosening of S2AI screws and its association with lumbosacral fusion. Methods: Cases of 50 patients with ASD who underwent long spinal fusion (>9 levels) with S2AI screws were retrospectively reviewed. Loosening of S2AI screws and S1 pedicle screws and bone fusion at the level of L5-S1 at 2 years after surgery were investigated using computed tomography. In addition, risk factors for loosening of S2AI screws were determined in patients with ASD. Results: At 2 years after surgery, 33 cases (66%) of S2AI screw loosening and six cases (12%) of S1 pedicle screw loosening were observed. In 40 of 47 cases (85%), bone fusion at L5-S1 was found. Pseudarthrosis at L5-S1 was not significantly associated with S2AI screw loosening (19.3% vs. 6.3%, p=0.23), but significantly higher in patients with S1 screw loosening (83.3% vs. 4.9%, p<0.001). On multivariate logistic regression analyses, high upper instrumented vertebra (UIV) level (T5 or above) (odds ratio [OR], 4.4; 95% confidence interval [CI], 1.0-18.6; p=0.045) and obesity (OR, 11.4; 95% CI, 1.2-107.2; p=0.033) were independent risk factors for S2AI screw loosening. Conclusions: High UIV level (T5 or above) and obesity were independent risk factors for S2AI screw loosening in patients with lumbosacral fixation in surgery for ASD. The incidence of lumbosacral fusion is associated with S1 screw loosening, but not S2AI screw loosening.

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Section: A B C D Econtrasting

confidence: 53%

Section: A B C D Ementioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Risk Factors for Loosening of S2 Alar Iliac Screw: Surgical Outcomes of Adult Spinal Deformity

et al. 2020

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“…Smith et al found that 86 patients without pre-operative pseudoarthrosis who underwent S2AI screw fixation had a 95.3% fusion rate at 2 to 5 years of follow-up [22]. Interestingly, 10.4% of patients had evidence of S2 loosening on imaging, including two cases that required hardware removal and one that required S2AI instrumentation exchange after pseudarthrosis developed.…”

Section: Discussionmentioning

confidence: 99%

A Case Series That Supports the Application of the S2AI Technique for Fractures and Failures After Lumbosacral Fusion

et al. 2019

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Background: Sacral fractures and failures are uncommon after lumbosacral fusion but have received increasing attention in the surgical literature. They can be difficult to diagnose, making timely treatment difficult. No consensus has been reached on the characteristics of these complications or on optimal treatment. Questions/Purposes: The goal of this retrospective case series is to contribute additional cases of these uncommon complications of lumbosacral fusion to the surgical literature to help clinicians to anticipate, diagnose, characterize, manage, and treat sacral fractures and failures after lumbosacral fusion. Methods: The medical records of five patients who experienced a sacral fracture or failure after lumbosacral fusion between January 2012 and November 2017 were identified and reviewed retrospectively. Records were reviewed for age, sex, clinical presentation, previous management, outpatient clinical records, imaging, and post-operative course. Results: Four patients in the series experienced a sacral fracture and one experienced hardware failure. All patients presented with elevated pain and underwent revision surgery. Radiographic detection of the fracture or failure occurred at a mean of 11.2 weeks (range, 3 to 24 weeks) after initial surgery, and the mean age of patients was 68.2 years (range, 63 to 80 years). Of the five patients, four were female; two had been diagnosed with osteoporosis and two with osteopenia. In our case series, the S2-alar-iliac (S2AI) technique was used with success in all five cases. Conclusion: Fractures and failures after lumbosacral fusion can be difficult to diagnose because of delayed presentation, nonspecific presenting symptoms, and a lack of identifiable mechanism. A high index of suspicion is required to detect these uncommon complications, and patients have responded well to both conservative and surgical treatments.

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“…By using a more medial starting point than with traditional iliac screws, the need for offset connectors was eliminated, which improved the profile of the implant construction, limiting soft tissue dissection, and avoiding the typical skin complications of the iliac screws. [7][8][9][10] The original description of the technique was made in an American pediatric and adult population. 9,10 There is also a description in Asian populations.…”

Section: Introductionmentioning

confidence: 99%

Tomographic Study of the S2-Alar-Iliac Screw Technique in Brazilian Men

et al. 2019

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Objective The use of pedicle screws was a milestone for modern spinal surgery. This type of fixation, due to its superior biomechanics, gave greater fixation power, greater capacity to withstand the pulling forces and, therefore, greater stability and lower rates of pseudoarthrosis. Fixation of the lumbosacral junction, even with the development of these new implants, remains a challenge mainly because the considerable rates of pseudoarthrosis. The use of iliac screws solves the biomechanical difficulties. However, its use shows high rates of surgical wound problems. The S2-Alar-Iliac screw (S2AI) came as a solution to these complications. The lack of studies about anatomical and anthropometric parameters in the Brazilian population justifies the study. Methods Eleven hip tomographies of Brazilian adult males were analyzed by four evaluators. The right and left sides were considered. In each patient, measurements were made of greater and shorter bone length, greater and smaller bone diameter, distance from the entry point to the skin, sagittal and axial angles related to the hypothetical insertion of an S2AI screw and compared to the same measurements obtained with the iliac screw. Results The mean bone length was 136.7 mm, the greatest bone diameter was 24.8 mm, the smallest bone diameter was 19.7 mm and the distance from the screw to the skin was 42.1 mm for the S2AI screw. Conclusions The obtained data present an average of the sample that can be useful in the decision of the surgical technique in the studied group. Level of evidence I; Diagnostic Studies (Anatomical Investigation).

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S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up

Abstract: Level III.

Cited by 28 publications

References 21 publications

Risk Factors for Loosening of S2 Alar Iliac Screw: Surgical Outcomes of Adult Spinal Deformity

Risk Factors for Loosening of S2 Alar Iliac Screw: Surgical Outcomes of Adult Spinal Deformity

A Case Series That Supports the Application of the S2AI Technique for Fractures and Failures After Lumbosacral Fusion

Tomographic Study of the S2-Alar-Iliac Screw Technique in Brazilian Men

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