Browsing by Subject "Pedicle Screws"

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    ItemOpen Access
    A bony Chance fracture through L1 following posterior spinal fusion for adolescent idiopathic scoliosis: a case report.
    (Spine deformity, 2021-05) Rocos, Brett; Kato, So; Lebel, David; Lewis, Stephen

    Study design

    Case report.

    Introduction

    Instrumented posterior fusion using pedicle screws has been the mainstay of the surgical correction of adolescent idiopathic scoliosis since it was popularised by Roy-Camille in the 1970s. The aim of this case report is to describe the occurrence and salvage of an L1 chance fracture occurring through the lower instrumented vertebra following pedicle screw placement for posterior spinal instrumented fusion in the treatment of adolescent idiopathic scoliosis (AIS).

    Case report

    A 15-year-old female patient underwent T2-L1 posterior instrumented fusion for a Lenke 1b deformity. The selection of fusion levels was made based upon standing and bending radiographs which showed a non-structural lumbar curve. Early recovery was uneventful. At 6 months post-operatively, the patient reported new deformity and pain. A chance fracture at L1 was diagnosed and subsequent extension of instrumentation to L3 was carried out. Final post-operative recovery was uneventful and the patient returned to an active lifestyle.

    Conclusion

    Several factors can contribute to the occurrence of a fracture through an instrumented pedicle. This case shows that there must be due consideration of the small pedicle at L1 when it is chosen as the LIV.
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    Cervical Spine Pedicle Screw Accuracy in Fluoroscopic, Navigated and Template Guided Systems-A Systematic Review.
    (Tomography (Ann Arbor, Mich.), 2021-10) Mahmoud, Arin; Shanmuganathan, Kanatheepan; Rocos, Brett; Sedra, Fady; Montgomery, Alexander; Aftab, Syed
    Background: Pedicle screws provide excellent fixation for a wide range of indications. However, their adoption in the cervical spine has been slower than in the thoracic and lumbar spine, which is largely due to the smaller pedicle sizes and the proximity to the neurovascular structures in the neck. In recent years, technology has been developed to improve the accuracy and thereby the safety of cervical pedicle screw placement over traditional fluoroscopic techniques, including intraoperative 3D navigation, computer-assisted Systems and 3D template moulds. We have performed a systematic review into the accuracy rates of the various systems. Methods: The PubMed and Cochrane Library databases were searched for eligible papers; 9 valid papers involving 1427 screws were found. Results: fluoroscopic methods achieved an 80.6% accuracy and navigation methods produced 91.4% and 96.7% accuracy for templates. Conclusion: Navigation methods are significantly more accurate than fluoroscopy, they reduce radiation exposure to the surgical team, and improvements in technology are speeding up operating times. Significantly superior results for templates over fluoroscopy and navigation are complemented by reduced radiation exposure to patient and surgeon; however, the technology requires a more invasive approach, prolonged pre-operative planning and the development of an infrastructure to allow for their rapid production and delivery. We affirm the superiority of navigation over other methods for providing the most accurate and the safest cervical pedicle screw instrumentation, as it is more accurate than fluoroscopy and lacks the limitations of templates.
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    Low-Density Pedicle Screw Constructs Are Associated with Lower Incidence of Proximal Junctional Failure in Adult Spinal Deformity Surgery.
    (Spine, 2022-03) Durand, Wesley M; DiSilvestro, Kevin J; Kim, Han Jo; Hamilton, David K; Lafage, Renaud; Passias, Peter G; Protopsaltis, Themistocles S; Lafage, Virginie; Smith, Justin S; Shaffrey, Christopher I; Gupta, Munish C; Klineberg, Eric O; Schwab, Frank J; Gum, Jeffrey L; Mundis, Gregory M; Eastlack, Robert K; Kebaish, Khaled M; Soroceanu, Alexandra; Hostin, Richard A; Burton, Douglas C; Bess, Shay; Ames, Christopher P; Hart, Robert A; Daniels, Alan H; International Spine Study Group

    Study design

    Retrospective cohort study.

    Objective

    Determine whether screws per level and rod material/diameter are associated with incidence of proximal junctional kyphosis (PJF).

    Summary of background data

    PJF is a common and particularly adverse complication of adult spinal deformity (ASD) surgery. There is evidence that the rigidity of posterior spinal constructs may impact risk of PJF.

    Methods

    Patients with ASD and 2-year minimum follow-up were included. Only patients undergoing primary fusion of more than or equal to five levels with lower instrumented vertebrae (LIV) at the sacro-pelvis were included. Screws per level fused was analyzed with a cutoff of 1.8 (determined by receiver operating characteristic curve (ROC) analysis). Multivariable logistic regression was utilized, controlling for age, body mass index (BMI), 6-week postoperative change from baseline in lumbar lordosis, number of posterior levels fused, sex, Charlson comorbidity index, approach, osteotomy, upper instrumented vertebra (UIV), osteoporosis, preoperative TPA, and pedicle screw at the UIV (as opposed to hook, wire, etc.).

    Results

    In total, 504 patients were included. PJF occurred in 12.7%. The mean screws per level was 1.7, and 56.8% of patients had less than 1.8 screws per level. No differences were observed between low versus high screw density groups for T1-pelvic angle or magnitude of lordosis correction (both P > 0.15). PJF occurred in 17.0% versus 9.4% of patients with more than or equal to 1.8 versus less than 1.8 screws per level, respectively (P < 0.05). In multivariable analysis, patients with less than 1.8 screws per level exhibited lower odds of PJF (odds ratio (OR) 0.48, P < 0.05), and a continuous variable for screw density was significantly associated with PJF (OR 3.87 per 0.5 screws per level, P < 0.05). Rod material and diameter were not significantly associated with PJF (both P > 0.1).

    Conclusion

    Among ASD patients undergoing long-segment primary fusion to the pelvis, the risk of PJF was lower among patients with less than 1.8 screws per level. This finding may be related to construct rigidity. Residual confounding by other patient and surgeon-specific characteristics may exist. Further biomechanical and clinical studies exploring this relationship are warranted.Level of Evidence: 3.
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    Optimal surgical care for adolescent idiopathic scoliosis: an international consensus.
    (European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2014-12) de Kleuver, Marinus; Lewis, Stephen J; Germscheid, Niccole M; Kamper, Steven J; Alanay, Ahmet; Berven, Sigurd H; Cheung, Kenneth M; Ito, Manabu; Lenke, Lawrence G; Polly, David W; Qiu, Yong; van Tulder, Maurits; Shaffrey, Christopher

    Purpose

    The surgical management of adolescent idiopathic scoliosis (AIS) has seen many developments in the last two decades. Little high-level evidence is available to support these changes and guide treatment. This study aimed to identify optimal operative care for adolescents with AIS curves between 40° and 90° Cobb angle.

    Methods

    From July 2012 to April 2013, the AOSpine Knowledge Forum Deformity performed a modified Delphi survey where current expert opinion from 48 experienced deformity surgeons, representing 29 diverse countries, was gathered. Four rounds were performed: three web-based surveys and a final face-to-face meeting. Consensus was achieved with ≥ 70% agreement. Data were analyzed qualitatively and quantitatively.

    Results

    Consensus of what constitutes optimal care was reached on greater than 60 aspects including: preoperative radiographs; posterior as opposed to anterior (endoscopic) surgical approaches; use of intraoperative spinal cord monitoring; use of local autologous bone (not iliac crest) for grafts; use of thoracic and lumbar pedicle screws; use of titanium anchor points; implant density of <80% for 40°-70° curves; and aspects of postoperative care. Variability in practice patterns was found where there was no consensus. In addition, there was consensus on what does not constitute optimal care, including: routine pre- and intraoperative traction; routine anterior release; use of bone morphogenetic proteins; and routine postoperative CT scanning.

    Conclusions

    International consensus was found on many aspects of what does and does not constitute optimal operative care for adolescents with AIS. In the absence of current high-level evidence, at present, these expert opinion findings will aid health care providers worldwide define appropriate care in their regions. Areas with no consensus provide excellent insight and priorities for future research.
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    The effect of posterior polyester tethers on the biomechanics of proximal junctional kyphosis: a finite element analysis.
    (Journal of neurosurgery. Spine, 2017-01) Bess, Shay; Harris, Jeffrey E; Turner, Alexander WL; LaFage, Virginie; Smith, Justin S; Shaffrey, Christopher I; Schwab, Frank J; Haid, Regis W
    OBJECTIVE Proximal junctional kyphosis (PJK) remains problematic following multilevel instrumented spine surgery. Previous biomechanical studies indicate that providing less rigid fixation at the cranial aspect of a long posterior instrumented construct, via transition rods or hooks at the upper instrumented vertebra (UIV), may provide a gradual transition to normal motion and prevent PJK. The purpose of this study was to evaluate the ability of posterior anchored polyethylene tethers to distribute proximal motion segment stiffness in long instrumented spine constructs. METHODS A finite element model of a T7-L5 spine segment was created to evaluate range of motion (ROM), intradiscal pressure, pedicle screw loads, and forces in the posterior ligament complex within and adjacent to the proximal terminus of an instrumented spine construct. Six models were tested: 1) intact spine; 2) bilateral, segmental pedicle screws (PS) at all levels from T-11 through L-5; 3) bilateral pedicle screws from T-12 to L-5 and transverse process hooks (TPH) at T-11 (the UIV); 4) pedicle screws from T-11 to L5 and 1-level tethers from T-10 to T-11 (TE-UIV+1); 5) pedicle screws from T-11 to L-5 and 2-level tethers from T-9 to T-11 (TE-UIV+2); and 6) pedicle screws and 3-level tethers from T-8 to T-11 (TE-UIV+3). RESULTS Proximal-segment range of motion (ROM) for the PS construct increased from 16% at UIV-1 to 91% at UIV. Proximal-segment ROM for the TPH construct increased from 27% at UIV-1 to 92% at UIV. Posterior tether constructs distributed ROM at the UIV and cranial adjacent segments most effectively; ROM for TE-UIV+1 was 14% of the intact model at UIV-1, 76% at UIV, and 98% at UIV+1. ROM for TE-UIV+2 was 10% at UIV-1, 51% at UIV, 69% at UIV+1, and 97% at UIV+2. ROM for TE-UIV+3 was 7% at UIV-1, 33% at UIV, 45% at UIV+1, and 64% at UIV+2. Proximal segment intradiscal pressures, pedicle screw loads, and ligament forces in the posterior ligament complex were progressively reduced with increasing number of posterior tethers used. CONCLUSIONS Finite element analysis of long instrumented spine constructs demonstrated that posterior tethers created a more gradual transition in ROM and adjacent-segment stress from the instrumented to the noninstrumented spine compared with all PS and TPH constructs. Posterior tethers may limit the biomechanical risk factor for PJK; however, further clinical research is needed to evaluate clinical efficacy.
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    The medicolegal impact of misplaced pedicle and lateral mass screws on spine surgery in the United States.
    (Neurosurgical focus, 2020-11) Sankey, Eric W; Mehta, Vikram A; Wang, Timothy Y; Than, Tracey T; Goodwin, C Rory; Karikari, Isaac O; Shaffrey, Christopher I; Abd-El-Barr, Muhammad M; Than, Khoi D
    Spine surgery has been disproportionately impacted by medical liability and malpractice litigation, with the majority of claims and payouts related to procedural error. One common area for the potential avoidance of malpractice claims and subsequent payouts involves misplaced pedicle and/or lateral mass instrumentation. However, the medicolegal impact of misplaced screws on spine surgery has not been directly reported in the literature. The authors of the current study aimed to describe this impact in the United States, as well as to suggest a potential method for mitigating the problem.This retrospective analysis of 68 closed medicolegal cases related to misplaced screws in spine surgery showed that neurosurgeons and orthopedic spine surgeons were equally named as the defendant (n = 32 and 31, respectively), and cases were most commonly due to misplaced lumbar pedicle screws (n = 41, 60.3%). Litigation resulted in average payouts of $1,204,422 ± $753,832 between 1995 and 2019, when adjusted for inflation. The median time to case closure was 56.3 (35.2-67.2) months when ruled in favor of the plaintiff (i.e., patient) compared to 61.5 (51.4-77.2) months for defendant (surgeon) verdicts (p = 0.117).