Biomechanics of a laterally placed sacroiliac joint fusion device supplemental to S2 alar-iliac fixation in a long-segment adult spinal deformity construct: a cadaveric study of stability and strain distribution

Clinicoradiological Outcomes and Complication Profiles of Bilateral Dual Sacral-Alar-Iliac Screws versus Bilateral Single Sacral-Alar-Iliac Screws in Patients with Spinal Deformity Who Underwent Grade 3 or 4 Spinal Osteotomies: A Retrospective Comparative Study

OBJECTIVE

To compare short-term clinical and radiological outcomes and complication profiles between bilateral dual sacral-2-alar-iliac (S2AI) screw and bilateral single S2AI screw fixation techniques in patients who underwent grade 3 or 4 spinal osteotomies.

METHODS

A retrospective review of 83 patients treated with bilateral dual S2AI screws and 32 patients treated with bilateral single S2AI screws was conducted between 2018 and 2020 with a minimum 1-year follow-up. Clinical and radiological outcomes of patients and incidence of perioperative complications, including rod breakage, screw dislodgment, proximal junctional kyphosis, proximal junctional failure, need for reoperation, and systemic adverse effects, were collected and statistically compared between the groups.

RESULTS

With a mean follow-up of 18.2 months, rod fracture (6.0% vs. 18.7%, P = 0.03), screw dislodgment (0 vs. 12.5%, P < 0.01), and S2AI screw loosening (1.2% vs. 18.7%, P < 0.01) were significantly lower in the dual S2AI screws group than in the single S2AI screws group. However, the reoperation rate was similar between the 2 groups (24.1% vs. 34.3%, P = 0.26). No significant differences in clinical and radiological outcomes as well as proximal junctional kyphosis (10.8% vs. 18.7%, P = 0.25) and proximal junctional failure (9.6% vs. 18.7%, P = 0.18) were identified between the 2 groups.

CONCLUSIONS

The dual S2AI screw fixation technique showed more advantages over the single S2AI screw fixation technique with reduced incidence of screw dislodgment, rod fractures, and sacral-alar-iliac screw loosening.

Biomechanical evaluation of multiple pelvic screws and multirod construct for the augmentation of lumbosacral junction in long spinal fusion surgery

Background: Posterior long spinal fusion was the common procedure for adult spinal deformity (ASD). Although the application of sacropelvic fixation (SPF), the incidence of pseudoarthrosis and implant failure is still high in long spinal fusion extending to lumbosacral junction (LSJ). To address these mechanical complications, advanced SPF technique by multiple pelvic screws or multirod construct has been recommended. This was the first study to compare the biomechanical performance of combining multiple pelvic screws and multirod construct to other advanced SPF constructs for the augmentation of LSJ in long spinal fusion surgery through finite element (FE) analysis.

Methods: An intact lumbopelvic FE model based on computed tomography images of a healthy adult male volunteer was constructed and validated. The intact model was modified to develop five instrumented models, all of which had bilateral pedicle screw (PS) fixation from L1 to S1 with posterior lumbar interbody fusion and different SPF constructs, including No-SPF, bilateral single S2-alar-iliac (S2AI) screw and single rod (SS-SR), bilateral multiple S2AI screws and single rod (MS-SR), bilateral single S2AI screw and multiple rods (SS-MR), and bilateral multiple S2AI screws and multiple rods (MS-MR). The range of motion (ROM) and stress on instrumentation, cages, sacrum, and S1 superior endplate (SEP) in flexion (FL), extension (EX), lateral bending (LB), and axial rotation (AR) were compared among models.

Results: Compared with intact model and No-SPF, the ROM of global lumbopelvis, LSJ, and sacroiliac joint (SIJ) was decreased in SS-SR, MS-SR, SS-MR, and MS-MR in all directions. Compared with SS-SR, the ROM of global lumbopelvis and LSJ of MS-SR, SS-MR, and MS-MR further decreased, while the ROM of SIJ was only decreased in MS-SR and MS-MR. The stress on instrumentation, cages, S1-SEP, and sacrum decreased in SS-SR, compared with no-SPF. Compared with SS-SR, the stress in EX and AR further decreased in SS-MR and MS-SR. The most significantly decreased ROM and stress were observed in MS-MR.

Conclusion: Both multiple pelvic screws and multirod construct could increase the mechanical stability of LSJ and reduce stress on instrumentation, cages, S1-SEP, and sacrum. The MS-MR construct was the most adequate to reduce the risk of lumbosacral pseudarthrosis, implant failure, and sacrum fracture. This study may provide surgeons with important evidence for the application of MS-MR construct in the clinical settings.

Comparative Clinical Efficacy and Safety of Sacral-2-Alar Iliac Screw Versus Iliac Screw in the Lumbosacral Reconstruction of Spondylodiscitis

OBJECTIVE

This study aimed to evaluate the clinical efficacy and safety of S2-alar-iliac (S2AI) and iliac screw (IS) techniques in treating lumbosacral spondylodiscitis.

METHODS

Between January 2020 and January 2022, 28 patients suffering from lumbosacral spondylodiscitis underwent lumbosacral fixation and were divided into the IS group (14 patients) and the S2AI group (14 patients). Surgical details, demographic characteristics, preoperative and postoperative Oswestry Disability Index, visual analog scale, and complications were analyzed.

RESULTS

Twenty-eight patients were included in this study, including 14 patients treated with IS and 14 patients treated with S2AI. The 2 groups were similar in sex, age, follow-up period, total drainage volume, hospitalization stay, and fusion time. (P > 0.05) The estimated blood loss and surgical time of S2AI during surgery were significantly lower than those of IS. (P < 0.05) The visual analog scale and Oswestry Disability Index scores significantly improved in both groups from preoperative to the last follow-up. Sacroiliac joint pain was found in both groups in the follow-up period, but the incidence was not significantly different (P = 0.663). Compared with the IS approach, the incidence of symptomatic screw prominence was lower in the S2AI group, but the difference was not significant. (P = 0.088).

CONCLUSIONS

S2AI, as well as IS techniques, can achieve promising results for reconstructing lumbosacral stability in spondylodiscitis. In addition, the S2AI technique can also reduce surgical trauma and operation time.

Schizophrenia: A Narrative Review of Etiopathogenetic, Diagnostic and Treatment Aspects

Although schizophrenia is currently conceptualized as being characterized as a syndrome that includes a collection of signs and symptoms, there is strong evidence of heterogeneous and complex underpinned etiological, etiopathogenetic, and psychopathological mechanisms, which are still under investigation. Therefore, the present viewpoint review is aimed at providing some insights into the recently investigated schizophrenia research fields in order to discuss the potential future research directions in schizophrenia research. The traditional schizophrenia construct and diagnosis were progressively revised and revisited, based on the recently emerging neurobiological, genetic, and epidemiological research. Moreover, innovative diagnostic and therapeutic approaches are pointed to build a new construct, allowing the development of better clinical and treatment outcomes and characterization for schizophrenic individuals, considering a more patient-centered, personalized, and tailored-based dimensional approach. Further translational studies are needed in order to integrate neurobiological, genetic, and environmental studies into clinical practice and to help clinicians and researchers to understand how to redesign a new schizophrenia construct.

Beyond the pedicle screw-a patent review

PURPOSE

This review provides an overview of the patent literature on posteriorly placed intrapedicular bone anchors. Conventional pedicle screws are the gold standard to create a fixation in the vertebra for spinal fusion surgery but may lack fixation strength, especially in osteoporotic bone. The ageing population demands new bone anchors that have an increased fixation strength, that can be placed safely, and, if necessary, can be removed without damaging the surrounding tissue.

METHODS

The patent search was conducted using a classification search in the Espacenet patent database. Only patents with a Cooperative Patent Classification of A61B17/70 or A61B17/7001 concerning spinal positioners and stabilizers were eligible for inclusion. The search query resulted in the identification of 731 patents. Based on preset inclusion criteria, a total of 56 unique patents on different anchoring methods were included, reviewed and categorized in this study.

RESULTS

Five unique fixation methods were identified; (1) anchors that use threading, (2) anchors that utilize a curved path through the vertebra, (3) anchors that (partly) expand, (4) anchors that use cement and (5) anchors that are designed to initiate bone ingrowth. Of the anchor designs included in this study, eight had a corresponding commercial product, six of which were evaluated in clinical trials.

CONCLUSION

This review provides insights into worldwide patented intrapedicular bone anchors that aim to increase the fixation strength compared to the conventional pedicle screw. The identified anchoring methods and their working principles can be used for clinical decision-making and as a source of inspiration when designing novel bone anchors.