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In a nonhomogeneous rod made up of steel and brass, restrained at both ends and subjected to a temperature change, several steps are involved in calculating the stress and compressive load. Due to the problem's static indeterminacy, one end support is disconnected, allowing the rod to experience the temperature change freely. Next, an unknown force is applied at the free end, triggering deformations in the rod's steel and brass portions. These deformations are then calculated and added together...

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Related Experiment Video

Updated: Jul 11, 2026

An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model

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

Construct-construct "rail technique" decreases screw strain during spinal deformity corrective maneuvers: a

Alekos A Theologis¹, Jason DePhillips², Nathaniel A Myers³

¹Department of Orthopaedic Surgery, University of California - San Francisco (UCSF), 500 Parnassus Ave, MUW 3rd Floor, San Francisco, CA, 94143, USA. alekos.theologis@ucsf.edu.

Spine Deformity

|March 28, 2025

Summary

The "rail" technique significantly reduces screw strain during spinal deformity correction, lowering the risk of screw pull-out and plow. This method distributes strain more evenly across pedicle screws near the osteotomy.

Keywords:

3-Column osteotomy Cantilever bending Correction techniques Segmental compression Spinal deformity

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Last Updated: Jul 11, 2026

An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model

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Published on: May 31, 2017

Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device

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Optimizing Minimally Invasive Spine Surgery: A Fully 3D CT O-Arm Navigated Workflow in MIS TLIF

Optimizing Minimally Invasive Spine Surgery: A Fully 3D CT O-Arm Navigated Workflow in MIS TLIF

Published on: October 17, 2025

Area of Science:

Spinal surgery biomechanics
Orthopedic implant research

Background:

Spinal osteotomies are crucial for correcting deformities.
Pedicle screw fixation is a common method for stabilizing the spine.
High screw strain can lead to construct failure, such as screw pull-out or plow.

Purpose of the Study:

To compare screw strains adjacent to a simulated spinal osteotomy.
To evaluate strains under segmental compression (SC) and cantilever bending (CB).
To assess strains with traditional constructs versus a construct-to-construct lateral accessory rod ('rail').

Main Methods:

10 PCF foam blocks instrumented with 6 pedicle screws each.
Strain gauges measured real-time screw strains.
SC and CB performed over traditional midline rods or the 'rail' construct.

Main Results:

The 'rail' technique significantly reduced screw strains near the osteotomy compared to traditional SC.
Maximum screw strains were significantly lower with 'rail' SC and CB.
Screw strain was more evenly distributed across all screws with the 'rail' technique.

Conclusions:

The 'rail' accessory rod significantly lowers pedicle screw strain adjacent to spinal osteotomies.
This technique may reduce the risk of screw pull-out and plow during deformity correction.
Further cadaveric studies are recommended to validate these findings in clinical scenarios.