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Updated: Oct 24, 2025
09:07
An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model
Published on: May 31, 2017
7.8K
Factors Affecting Pedicle Screw Insertional Torque in Spine Deformity Surgery
Kotaro Oda1, Tetsuro Ohba1, Yokomichi Hiroshi2
1Department of Orthopaedic Surgery, University of Yamanashi, Chuo-city, Yamanashi, Japan.
Spine
|August 12, 2021
Summary
The optimal screw/pedicle ratio for rigid pedicle screw fixation differs between adult spinal deformity (ASD) and adolescent idiopathic scoliosis (AIS) patients. This ratio aids surgeons in selecting appropriate pedicle screw diameters for spinal corrective surgery.
Area of Science:
- Spine surgery
- Orthopedic biomechanics
- Spinal instrumentation
Background:
- Rigid pedicle screw fixation is crucial for successful spinal deformity correction and fusion.
- Screw fixation strength is influenced by insertion accuracy and bone quality.
- Insertional torque predicts screw fixation strength and is linked to screw loosening.
Purpose of the Study:
- To identify factors associated with pedicle screw insertional torque.
- To compare optimal insertion factors for rigid fixation in adult spinal deformity (ASD) versus adolescent idiopathic scoliosis (AIS).
- To determine the ideal screw/pedicle ratio (S/P) for rigid pedicle screw fixation.
Main Methods:
- Retrospective observational study of consecutive patients.
- Compared insertion torque of 324 screws (ASD) and 58 screws (AIS) at L1-L3.
- Assessed the association between screw/pedicle ratio and insertion torque using spline curve analysis.
Main Results:
- Pedicle and screw diameter positively correlated with insertion torque in both ASD and AIS.
- Optimal S/P ratio for rigid fixation in ASD was <1.
- Optimal S/P ratio for rigid fixation in AIS was 1-1.25.
Conclusions:
- An optimal S/P ratio for rigid pedicle screw fixation exists and varies between ASD and AIS patients.
- The S/P ratio is a valuable tool for preoperative planning of screw diameter selection.
- This finding aids in optimizing pedicle screw fixation during spinal corrective surgery.
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