Biomechanical advantages of dual over single iliac screws in lumbo-iliac fixation construct

Object Pelvic fixation is a crucial adjunct to many lumbar fusions to avoid L5–S1 pseudarthrosis. It is useful for treatment of kyphoscoliosis, high-grade spondylolisthesis, L5–S1 pseudarthrosis, sacral tumors, lumbosacral dislocations, and osteomyelitis. The most popular method, iliac fixation, has drawbacks including hardware prominence, extensive muscle dissection, and the need for connection devices. S-2 alar iliac fixation provides a useful primary or salvage alternative. The authors describe their techniques for using stereotactic navigation for screw placement. Methods The O-arm Surgical Imaging System allowed for CT-quality multiplanar reconstructions of the pelvis, and registration to a StealthStation Treon provided intraoperative guidance. The authors describe their technique for performing computer-assisted S-2 alar iliac fixation for various indications in 18 patients during an 18-month period. Results All patients underwent successful bilateral placement of screws 80–100 mm in length. All placements were confirmed with a second multiplanar reconstruction. One screw was moved because of apparent anterior breach of the ilium. There were no immediate neurological or vascular complications due to screw placement. The screw length required additional instruments including a longer pedicle finder and tap. Conclusions Stereotactic guidance to navigate the placement of distal pelvic fixation with bilateral S-2 alar iliac fixation can be safely performed in patients with a variety of pathological conditions. Crossing the sacroiliac joint, choosing trajectory, and ensuring adequate screw length can all be enhanced with 3D image guidance. Long-term outcome studies are underway, specifically evaluating the sacroiliac joint.

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Strategy for obtaining solid fusion at L5–S1 in adult spinal deformity: risk factor analysis for nonunion at L5–S1

Journal of Neurosurgery Spine ◽

10.3171/2020.2.spine191181 ◽

2020 ◽

Vol 33 (3) ◽

pp. 323-331 ◽

Cited By ~ 1

Author(s):

Ki Young Lee ◽

Jung-Hee Lee ◽

Kyung-Chung Kang ◽

Sung Joon Shin ◽

Won Ju Shin ◽

...

Keyword(s):

Risk Factors ◽

Retrospective Study ◽

Spinal Deformity ◽

Sagittal Balance ◽

Interbody Fusion ◽

Adult Spinal Deformity ◽

Ct Scans ◽

Iliac Screws ◽

Iliac Fixation

OBJECTIVEMaintaining lumbosacral (LS) arthrodesis and global sagittal balance after long fusion to the sacrum remains an important issue in the surgical treatment for adult spinal deformity (ASD). The importance and usefulness of LS fixation have been documented, but the optimal surgical long fusion to the sacrum remains a matter for debate. Therefore, the authors performed a retrospective study to evaluate fusion on CT scans and the risk factors for LS pseudarthrosis (nonunion) after long fusion to the sacrum in ASD.METHODSThe authors performed a retrospective study of 59 patients with lumbar degenerative kyphosis (mean age 69.6 years) who underwent surgical correction, including an interbody fusion of the L5–S1, with a minimum 2-year follow-up. Achievement of LS fusion was evaluated by analyzing 3D-CT scans at 3 months, 6 months, 9 months, 1 year, and 2 years after surgery. Patients were classified into a union group (n = 36) and nonunion group (n = 23). Risk factors for nonunion were analyzed, including patient and surgical factors.RESULTSThe overall fusion rate was 61% (36/59). Regarding radiological factors, optimal sagittal balance at the final follow-up significantly differed between two groups. There were no significant differences in terms of patient factors, and no significant differences with respect to the use of pedicle subtraction osteotomy, the number of fused segments, the proportion of anterior versus posterior interbody fusion, S2 alar iliac fixation versus conventional iliac fixation, or loosening of sacral or iliac screws. However, the proportion of metal cages to polyetheretherketone cages and the proportion of sacropelvic fixation were significantly higher in the union group (p = 0.022 and p < 0.05, respectively).CONCLUSIONSLS junction fusion is crucial for global sagittal balance, and the use of iliac screws in addition to LS interbody fusion using a metal cage improves the outcomes of long fusion surgery for ASD patients.

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A comprehensive biomechanical analysis of sacral alar iliac fixation: an in vitro human cadaveric model

Journal of Neurosurgery Spine ◽

10.3171/2018.8.spine18328 ◽

2019 ◽

Vol 30 (3) ◽

pp. 367-375 ◽

Cited By ~ 4

Author(s):

Bryan W. Cunningham ◽

Paul D. Sponseller ◽

Ashley A. Murgatroyd ◽

Jun Kikkawa ◽

P. Justin Tortolani

Keyword(s):

Sacroiliac Joint ◽

Fatigue Loading ◽

Axial Rotation ◽

Biomechanical Analysis ◽

Segmental Motion ◽

Destructive Testing ◽

Flexion Extension ◽

Iliac Screws ◽

Iliac Fixation

OBJECTIVEThe objective of the current study was to quantify and compare the multidirectional flexibility properties of sacral alar iliac fixation with conventional methods of sacral and sacroiliac fixation by using nondestructive and destructive investigative methods.METHODSTwenty-one cadaveric lumbopelvic spines were randomized into 3 groups based on reconstruction conditions: 1) S1–2 sacral screws; 2) sacral alar iliac screws; and 3) S1–iliac screws tested under unilateral and bilateral fixation. Nondestructive multidirectional flexibility testing was performed using a 6-degree-of-freedom spine simulator with moments of ± 12.5 Nm. Flexion-extension fatigue loading was then performed for 10,000 cycles, and the multidirectional flexibility analysis was repeated. Final destructive testing included an anterior flexural load to construct failure. Quantification of the lumbosacral and sacroiliac joint range of motion was normalized to the intact spine (100%), and flexural failure loads were reported in Newton-meters.RESULTSNormalized value comparisons between the intact spine and the 3 reconstruction groups demonstrated significant reductions in segmental flexion-extension, lateral bending, and axial rotation motion at L4–5 and L5–S1 (p < 0.05). The S1–2 sacral reconstruction group demonstrated significantly greater flexion-extension motion at the sacroiliac junction than the intact and comparative reconstruction groups (p < 0.05), whereas the sacral alar iliac group demonstrated significantly less motion at the sacroiliac joint in axial rotation (p < 0.05). Absolute value comparisons demonstrated similar findings. Under destructive anterior flexural loading, the S1–2 sacral group failed at 105 ± 23 Nm, and the sacral alar iliac and S1–iliac groups failed at 119 ± 39 Nm and 120 ± 28 Nm, respectively (p > 0.05).CONCLUSIONSAlong with difficult anatomy and weak bone, the large lumbosacral loads with cantilever pullout forces in this region are primary reasons for construct failure. All reconstructions significantly reduced flexibility at the L5–S1 junctions, as expected. Conventional S1–2 sacral fixation significantly increased sacroiliac motion under all loading modalities and demonstrated significantly higher flexion-extension motion than all other groups, and sacral alar iliac fixation reduced motion in axial rotation at the sacroiliac joint. Based on comprehensive multidirectional flexibility testing, the sacral alar iliac fixation technique reduced segmental motion under some loading modalities compared to S1–iliac screws and offers potential advantages of lower instrumentation profile and ease of assembly compared to conventional sacroiliac instrumentation techniques.

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Preliminary experience using S1–alar iliac fixation with navigation: technical note

Journal of Neurosurgery Spine ◽

10.3171/2021.1.spine201744 ◽

2021 ◽

Vol 35 (6) ◽

pp. 774-779

Author(s):

Bo Li ◽

Andrew K. Chan ◽

Praveen V. Mummaneni ◽

John F. Burke ◽

Michael M. Safaee ◽

...

Keyword(s):

Interbody Fusion ◽

Screw Fixation ◽

Technical Note ◽

Fixation Technique ◽

Short Segment ◽

Pelvic Fixation ◽

Iliac Screws ◽

Iliac Fixation ◽

Term Data

Traditional iliac screws and S2–alar iliac (S2-AI) screws are common methods used for pelvic fixation, and many surgeons advocate pelvic fixation for long-segment fixation to the sacrum. However, in patients without severe deformities and only degenerative conditions, many surgeons may choose S1 screws only. Moreover, even with S2-AI screws, there is more muscular dissection than with using S1 screws, and the rod connection can be cumbersome in both S2-AI fixation and placing iliac screws. Using a surgical video, artist’s illustration, and intraoperative photographs, the authors describe the S1-AI screw fixation technique that allows for single-screw sacral and iliac fixation, requires less distal dissection of the sacrum, allows for easier rod connection, and may be an option in degenerative conditions needing pelvic fixation. However, this is a preliminary feasibility study, and in long fusion constructs, this type of fixation has only been used in conjunction with L5–S1 anterior lumbar interbody fusion (ALIF), and there are no long-term data on the use of this screw fixation technique without ALIF. In short-segment revision fusions, this technique may be considered for salvage in cases of large halos in the sacrum from loosened S1 screw fixation.

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Navigated iliac screw placement may reduce radiation and OR time in lumbopelvic fixation of unstable complex sacral fractures

European Journal of Orthopaedic Surgery & Traumatology ◽

10.1007/s00590-021-02892-7 ◽

2021 ◽

Author(s):

M. F. Hoffmann ◽

E. Yilmaz ◽

D. C. Norvel ◽

T. A. Schildhauer

Keyword(s):

Radiation Exposure ◽

Operative Time ◽

Pelvic Ring ◽

Screw Placement ◽

Fluoroscopy Time ◽

Complication Rates ◽

Lumbopelvic Fixation ◽

Navigation Group ◽

Iliac Screws ◽

Iliac Screw

Abstract Purpose Instability of the posterior pelvic ring may be stabilized by lumbopelvic fixation. The optimal osseous corridor for iliac screw placement from the posterior superior iliac spine to the anterior inferior iliac spine requires multiple ap- and lateral-views with additional obturator-outlet and -inlet views. The purpose of this study was to determine if navigated iliac screw placement for lumbopelvic fixation influences surgical time, fluoroscopy time, radiation exposure, and complication rates. Methods Bilateral lumbopelvic fixation was performed in 63 patients. Implants were inserted as previously described by Schildhauer. A passive optoelectronic navigation system with surface matching on L4 was utilized for navigated iliac screw placement. To compare groups, demographics were assessed. Operative time, fluoroscopic time, and radiation were delineated. Results Conventional fluoroscopic imaging for lumbopelvic fixation was performed in 32 patients and 31 patients underwent the procedure with navigated iliac screw placement. No differences were found between the groups regarding demographics, comorbidities, or additional surgical procedures. Utilization of navigation led to fluoroscopy time reduction of more than 50% (3.2 vs. 8.6 min.; p < 0.001) resulting in reduced radiation (2004.5 vs. 5130.8 Gy*cm2; p < 0.001). Operative time was reduced in the navigation group (176.7 vs. 227.4 min; p = 0.002) despite the necessity of additional surface referencing. Conclusion For iliac screws, identifying the correct entry point and angle of implantation requires detailed anatomic knowledge and multiple radiographic views. In our study, additional navigation reduced operative time and fluoroscopy time resulting in a significant reduction of radiation exposure for patients and OR personnel.

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Minimally Invasive Techniques for Iliac Bolt Placement: 2-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opab001 ◽

2021 ◽

Vol 20 (4) ◽

pp. E292-E292

Author(s):

Travis Hamilton ◽

Mohamed Macki ◽

Thomas M Zervos ◽

Victor Chang

Keyword(s):

Minimally Invasive ◽

Imaging System ◽

Pedicle Screws ◽

Vertical Axis ◽

Spinal Diseases ◽

Open Approach ◽

Sagittal Vertical Axis ◽

Pelvic Fixation ◽

Iliac Screws ◽

Invasive Techniques

Abstract As the popularity of minimally invasive surgery (MIS) continues to grow, novel techniques are needed to meet the demands of multisegment fixation for advanced spinal diseases. In one such example, iliac bolts are often required to anchor large fusion constructs, but MIS technical notes are missing from the literature. A 67-yr-old female presented with a symptomatic coronal deformity: preoperative pelvic incidence = 47°, pelvic tilt = 19°, and lumbar lordosis = 29°, sagittal vertical axis = +5.4 cm with 30° of scoliosis. The operative plan included T10-ilium fusion with transforaminal interbody grafts at L2-3, L3-4, L4-5, and L5-S1. The intraoperative video is of minimally invasive placement of iliac bolts using the O-Arm Surgical Imaging System (Medtronic®). The patient consented to the procedure. A mini-open exposure that remains above the fascial planes allows for multilevel instrumentation with appropriate decompression at the interbody segments. After the placement of the pedicle screws under image-guidance, the direction is turned to the minimally invasive iliac bolts. Following the trajectory described in the standard open approach,1 the posterior superior iliac spine (PSIS) is identified with the navigation probe, which will guide the Bovie cautery through the fascia. This opening assists in the trajectory of the navigated-awl tap toward the anterior superior iliac spine (ASIS). Next, 8.5 mm x 90 mm iliac screws were placed in the cannulated bone under navigation. After intraoperative image confirmation of screw placement, the contoured rods are threaded under the fascia. The setscrews lock the rod in position. MIS approaches obviate cross-linking the rods, rendering pelvic fixation more facile. This technique allows for minimal dissection of the posterior pelvic soft tissue while maintaining adequate fixation.

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Reconstruction after Subtotal Sacrectomy for Sacral Ewing’s Sarcoma Using Tibial Allograft Strut Grafting: A Case Report

Case Reports in Oncology ◽

10.1159/000513117 ◽

2021 ◽

pp. 296-302

Author(s):

Ryosuke Hirota ◽

Makoto Emori ◽

Yoshinori Terashima ◽

Kousuke Iba ◽

Noriyuki Iesato ◽

...

Keyword(s):

Surgical Treatment ◽

Ewing’S Sarcoma ◽

Mechanical Stability ◽

Ewing's Sarcoma ◽

Lumbar Vertebrae ◽

Iliac Screws ◽

Sacral Tumor ◽

Sacral Resection ◽

High Mechanical Stability ◽

Rectal Dysfunction

We present the case of a 15-year-old girl. Two months after becoming aware of pain, she was diagnosed with a sacral tumor and referred to our department. She was diagnosed with a sacral Ewing’s sarcoma; after chemotherapy, it was determined that the tumor could be resected, so surgical treatment was performed. The sacrum and ilium were partially resected at the lower end of S1, and the lumbar vertebrae and pelvis were fixed with a pedicle screw and two iliac screws on each side of L3, and the sacral resection was reconstructed with a tibial strut allograft. No tumor recurrence or metastasis has been observed 1 year postoperatively. She developed bladder and rectal dysfunction, but she remained independent in activities of daily living and her daily life was not limited. The bone fusion in the reconstructed area confirmed the lack of instrumentation looseness. Surgical treatment for sacral Ewing’s sarcoma was performed to cure the patient. We believe that the tibial allograft contributed to the patient’s ability to walk on her own due to its high mechanical stability. Postoperative bone healing was observed with the same material, suggesting that the tibial allograft is useful for similar procedures.

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