Long Construct Pedicle Screw Reduction and Residual Forces are Decreased Using a Computer-Assisted Spinal Rod Bending System

Tohmeh, Antoine; Isaacs, Robert E.; Dooley, Zachary A.; Turner, Alexander W.

doi:10.1016/j.spinee.2014.08.348

Cited by 8 publications

(12 citation statements)

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“…In a next step, the target rod shape is converted into a set of bending positions and bending angles which are provided to the surgeons for execution with a proprietary bending tool. A study showed that navigation of the bending process with their solution reduced the forces exerted on the screws during rod implantation ( Tohmeh et al, 2014 ). Even though their study supports the use of computer-assisted methods for the rod bending process, the system has never become state-of-the-art.…”

Section: Introductionmentioning

confidence: 99%

Marker-free surgical navigation of rod bending using a stereo neural network and augmented reality in spinal fusion

Atzigen

Liebmann

Hoch

et al. 2022

Medical Image Analysis

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Section: Introductionmentioning

confidence: 99%

Marker-free surgical navigation of rod bending using a stereo neural network and augmented reality in spinal fusion

Atzigen

Liebmann

Hoch

et al. 2022

Medical Image Analysis

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“…The relevance of such mismatches has long been dismissed as dedicated reduction devices are typically available to assist the surgeon in assembling the construct. These devices mechanically force the spinal rod into the head of the screw but do not control the exerted forces, which may lead to excessive reaction forces that may result in clinical complications [4].…”

Section: Introductionmentioning

confidence: 99%

Misaligned spinal rods can induce high internal forces consistent with those observed to cause screw pullout and disc degeneration

et al. 2021

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BACKGROUND CONTEXT: Manual contouring of spinal rods is often required intraoperatively for proper alignment of the rods within the pedicle screw heads. Residual misalignments are frequently reduced by using dedicated reduction devices. The forces exerted by these devices, however, are uncontrolled and may lead to excessive reaction forces. As a consequence, screw pullout might be provoked and surrounding tissue may experience unfavorable biomechanical loads. The corresponding loads and induced tissue deformations are however not well identified. Additionally, whether the forced reduction alters the biomechanical behavior of the lumbar spine during physiological movements postoperatively, remains unexplored. PURPOSE: To predict whether the reduction of misaligned posterior instrumentation might result in clinical complications directly after reduction and during a subsequent physiological flexion movement. STUDY DESIGN: Finite element analysis. METHODS: A patient-specific, total lumbar (L1−S1) spine finite element model was available from previous research. The model consists of poro-elastic intervertebral discs with Pfirrmann grade-dependent material parameters, with linear elastic bone tissue with stiffness values related to the local bone density, and with the seven major ligaments per spinal motion segment described as nonlinear materials. Titanium instrumentation was implemented in this model to simulate a L4, L5, and S1 posterolateral fusion. Next, coronal and sagittal misalignments of 6 mm each were introduced between the rod and the screw head at L4. These misalignments were computationally reduced and a physiological flexion movement of 15˚was prescribed. Non-instrumented and wellaligned instrumented models were used as control groups. RESULTS: Pulling forces up to 1.0 kN were required to correct the induced misalignments of 6 mm. These forces affected the posture of the total lumbar spine, as motion segments were predicted to rotate up to 3 degrees and rotations propagated proximally to and even affect the L1−2 level.

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“…Navigation is performed either by patient‐specific instruments, 7 optical tracking systems 8,9 or, more recently, by augmented reality based solutions 10,11 . Several approaches for the navigation of bending the rod implant were also introduced 12,13 . The commercially available Bendini rod bending system (NuVasive, Inc.), for example, captures the 3D positions of implanted pedicle screw heads by means of a pointing device equipped with infrared‐reflective spheres and an optical infrared tracking system 12 .…”

Section: Introductionmentioning

confidence: 99%

“…Several approaches for the navigation of bending the rod implant were also introduced 12,13 . The commercially available Bendini rod bending system (NuVasive, Inc.), for example, captures the 3D positions of implanted pedicle screw heads by means of a pointing device equipped with infrared‐reflective spheres and an optical infrared tracking system 12 . From these 3D positions, the rod geometry can be calculated and transferred to the surgeon as a set of rod bending instructions.…”

Section: Introductionmentioning

confidence: 99%

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HoloYolo: A proof‐of‐concept study for marker‐less surgical navigation of spinal rod implants with augmented reality and on‐device machine learning

Atzigen

Liebmann

Hoch

et al. 2020

Robotics Computer Surgery

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Background Existing surgical navigation approaches of the rod bending procedure in spinal fusion rely on optical tracking systems that determine the location of placed pedicle screws using a hand‐held marker. Methods We propose a novel, marker‐less surgical navigation proof‐of‐concept to bending rod implants. Our method combines augmented reality with on‐device machine learning to generate and display a virtual template of the optimal rod shape without touching the instrumented anatomy. Performance was evaluated on lumbosacral spine phantoms against a pointer‐based navigation benchmark approach and ground truth data obtained from computed tomography. Results Our method achieved a mean error of 1.83 ± 1.10 mm compared to 1.87 ± 1.31 mm measured in the marker‐based approach, while only requiring 21.33 ± 8.80 s as opposed to 36.65 ± 7.49 s attained by the pointer‐based method. Conclusion Our results suggests that the combination of augmented reality and machine learning has the potential to replace conventional pointer‐based navigation in the future.

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Long Construct Pedicle Screw Reduction and Residual Forces are Decreased Using a Computer-Assisted Spinal Rod Bending System

Cited by 8 publications

References 0 publications

Marker-free surgical navigation of rod bending using a stereo neural network and augmented reality in spinal fusion

Marker-free surgical navigation of rod bending using a stereo neural network and augmented reality in spinal fusion

Misaligned spinal rods can induce high internal forces consistent with those observed to cause screw pullout and disc degeneration

HoloYolo: A proof‐of‐concept study for marker‐less surgical navigation of spinal rod implants with augmented reality and on‐device machine learning

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