A novel technique for stabilising sacroiliac joint dislocation using spinal instrumentation: technical notes and clinical outcomes

Purpose Currently, sacroiliac joint dislocations, including crescent fracture–dislocations, are treated using several techniques that have certain issues. We present the technical details and clinical outcomes of a new technique, anterior sacroiliac stabilisation (ASIS), performed using spinal instrumentation. Methods ASIS is performed with the patient in a supine position via the ilioinguinal approach. The displacements are reduced and fixed by inserting cancellous screws from the sacral ala and iliac brim; the screw heads are bridged using a rod and locked. We performed a retrospective review of patients with iliosacral disruption who underwent ASIS between May 2012 and December 2020 at two medical facilities. The patients were assessed for age, sex, injury type, associated injuries, complications, functional outcome by evaluating the Majeed pelvic score after excluding the sexual intercourse score and fracture union. Results We enrolled 11 patients (median age: 63 years). The median operative time was 195 min, median blood loss was 570 g, and eight patients (72.3%) required blood transfusion. The sacral and iliac screws had a diameter of 6.0–8.0 mm and 6.2–8.0 mm, and a length of 50–70 mm and 40–80 mm, respectively. Bone union was achieved with no marked loss of reduction in the median follow-up period of 12 months in all cases. The median Majeed score at the final follow-up was 85/96. Conclusion ASIS is a rigid internal fixation method that provides angular stability. Despite invasiveness issues compared to iliosacral screw fixation, this method is easy to confirm and achieves precise reduction.

Spinopelvic fixation: modern technical solutions

The paper presents the second part of literature review devoted to modern techniques of spinopelvic fixation for various pathologies of the spine and injuries to the spine and pelvis. The review is non-systematic and was conducted using PubMed and eLibrary databases of medical literature. Modern techniques of spinopelvic fixation using screws installed in the ilium are highlighted, including anatomical and biomechanical features, clinical results of application, as well as the implementation of spinopelvic fixation for tumor lesions of the sacrum, including the use of customized implants and additive technologies. The features of classical installation of iliac screws and installation by the S2AIS technique are considered, and their advantages and disadvantages and possible complications are evaluated.

Posterior resection of sacral osteosarcoma utilizing cement-infused chest tube interbody reconstruction and lumbopelvic fusion

Background: Primary osteosarcoma (OS) of the spine is very rare. En bloc resection of spinal OS is challenging due to anatomical constraints. Surgical planning must balance the benefits of en bloc resection with its potential risks of causing a significant neurological deficit. In this case, we successfully performed a posterior-only approach for decompression with S1 reconstruction via a cement-infused chest tube interbody device, along with a navigated L4 to pelvis fusion. Case Description: A 49-year-old female presented with a primary sacral OS. Computed tomography (CT) and magnetic resonance (MR) imaging revealed an S1 lytic vertebral body lesion with severe stenosis and progressive L5 on S1 anterior subluxation. Surgical decompression with tumor resection and S1 corpectomy with S1 reconstruction via a cement-infused 32-French chest tube interbody device accompanied by L4 -pelvis fusion utilizing S2-alar-iliac screws was completed. 6 months postoperatively, the patient continues to have significant pain relief and the instrumentation remains intact. Conclusion: A 49-year-old female with an S1 OS successfully underwent a posterior-only approach that included an S1 corpectomy with anterior column reconstruction via a cement-infused chest tube interbody plus a navigated L4 to pelvis fusion.

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

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.

Utilization of S1 Foraminal Hooks for Augmentation of S1 Screws in Adult Spinal Deformity Surgery: Comparative Study With Iliac Screws

Objective: To compare the outcomes of S1 foraminal hooks and iliac screws regarding fusion rate at the lumbosacral junction and protective effects on S1 screws.Methods: From January 2017 to December 2019, consecutive patients who underwent long fusions (uppermost instrumented vertebra at or above L1) to the sacrum for adult spinal deformity were enrolled. Patients were divided into S1 foraminal hook group and iliac screw group. Radiographic parameters and the incidence of pseudarthrosis and instrument failure at the lumbosacral junction were compared between the groups.Results: Twenty-nine patients (male:female = 1:28) with a mean age of 73.6 ± 6.8 years were evaluated. Sixteen patients (55.2%) had S1 foraminal hook fixation and 13 patients (44.8%) had iliac screw fixation. Lumbar lordosis, sacral slope, and sagittal vertical axis did not differ between the groups preoperatively and postoperatively. The rate of L5/S1 pseudarthrosis was significantly higher in S1 foraminal hook group (5 of 16, 31.3%), compared to iliac screw group (0 of 13, 0%; p = 0.048). Instrument failure at the lumbosacral junction trended toward a higher rate in S1 foraminal hook group (6 of 16, 37.5%) than in iliac screw group (1 of 13, 7.7%), without statistical significance (p = 0.09). Proximal junctional kyphosis/failure occurred less often in S1 foraminal hook group (2 of 16, 12.5%) than in iliac screw group (3 of 13, 30.8%) without statistical significance (p = 0.36).Conclusion: Treatment with S1 foraminal hooks achieved equivalent satisfactory sagittal correction with proportioned alignment compared to that with iliac screws. However, S1 foraminal hooks did not provide enough structural support to the lumbosacral junction in long fusions to the sacrum.

Innovative sacropelvic fixation using iliac screws and triangular titanium implants

Purpose Sacropelvic fixation is frequently used in combination with thoracolumbar instrumentation for the correction of severe spinal deformities. The purpose of this study was to explore the effects of the triangular titanium implants on the iliac screw fixation. Our hypothesis was that the use of triangular titanium implants can increase the stability of the iliac screw fixation. Methods Three T10-pelvis instrumented models were created: pedicle screws and rods in T10-S1, and bilateral iliac screws (IL); posterior fixation and bilateral iliac screws and triangular implants inserted bilaterally in a sacro-alar-iliac trajectory (IL-Tri-SAI); posterior fixation and bilateral iliac screws and two bilateral triangular titanium implants inserted in a lateral trajectory (IL-Tri-Lat). Outputs of these models, such as hardware stresses, were compared against a model with pedicle screws and rods in T10-S1 (PED). Results Sacropelvic fixation decreased the L5-S1 motion by 75–90%. The motion of the SIJ was reduced by 55–80% after iliac fixation; the addition of triangular titanium implants further reduced it. IL, IL-Tri-SAI and IL-Tri-Lat demonstrated lower S1 pedicle stresses with respect to PED. Triangular implants had a protective effect on the iliac screw stresses. Conclusion Sacropelvic fixation decreased L5-S1 range of motion suggesting increased stability of the joint. The combination of triangular titanium implants and iliac screws reduced the residual flexibility of the sacroiliac joint, and resulted in a protective effect on the S1 pedicle screws and iliac screws themselves. Clinical studies may be performed to demonstrate applicability of these FEA results to patient outcomes.

Bilateral open sacroiliac joint fusion during adult spinal deformity surgery using triangular titanium implants: technique description and presentation of 21 cases

OBJECTIVE Pelvic fixation enhances long constructs during deformity surgery. Subsequent loosening of iliac screws and pain at the pelvis occur in as many as 29% of patients. Concomitant sacroiliac (SI) fusion may prevent potential pain and failure. The objective of this study was to describe a novel surgical technique and a single institution’s experience using bilateral SI fusion during adult deformity surgery with S2-alar-iliac (S2AI) screws and triangular titanium rods (TTRs) placed with navigation. METHODS The authors reviewed open SI joint fusions with TTR performed between August 2019 and March 2020. All patients underwent lumbosacral fusion through a midline approach and bilateral S2AI pelvic fixation in the caudal teardrop, followed by TTR placement just proximal and cephalad to the S2AI screws using intraoperative CT imaging guidance. RESULTS Twenty-one patients were identified who received 42 TTRs, ranging in size from 7.0 × 65 mm to 7.0 × 90 mm. Three TTRs (7%) were malpositioned intraoperatively, and each was successfully repositioned during index surgery without negative sequelae. All breaches occurred in a medial and cephalad direction into the pelvis. Incremental operative time for adding TTR averaged 8 minutes and 33 seconds per implant. CONCLUSIONS Image-guided open SI joint fusion with TTR during lumbosacral fusion is technically feasible. The bony corridor for implant placement is narrower cephalad, and implants tend to deviate medially into the pelvis. Detection of malpositioned implant is aided with intraoperative CT, but this can be salvaged. A prospective randomized clinical trial is underway that will better inform the impact of this technique on patient outcomes.