Methods and apparatus for spinal reconstructive surgery and measuring spinal length and intervertebral spacing, tension and rotation

Abstract

Methods and apparatus are disclosed for performing spinal reconstructive surgery, including measuring spinal length in the Y-axis at the middle column, measuring intervertebral spacing in the Y-axis at the middle column, measuring intervertebral tension applied to the posterior longitudinal ligament, establishing the height of intervertebral spacers along the Y-axis at the middle column based on one or more of such measurements, measuring intervertebral rotation around the Y-axis, and measuring flexion-extension or anterior-posterior rotation around the X-axis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62 / 250,743 filed Nov. 4, 2015, and U.S. Provisional Patent Application Ser. No. 62 / 413,159 filed Oct. 26, 2016, both of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to methods and apparatus for spinal surgery, and more particularly relates to methods and devices for spinal reconstructive surgery, measuring spinal length and intervertebral spacing at the middle column, measuring intervertebral tension and establishing intervertebral spacer heights, and measuring intervertebral rotation.[0003]BACKGROUND INFORMATION[0004]Spinal reconstructive surgery may be used to correct anterior / posterior sagittal plane (Z-axis) imbalances ranging from abnormal (e.g., 40 mm) to severe (e.g., 90 mm) and / or to correct lateral coronal plane (X-axis) imbalances (e.g., greater than 20 mm). During such reconstructive surger...

AI Technical Summary

Benefits of technology

[0017]Embodiments of the present invention provide precise measurements at the middle column, thereby giving surgeons better guidance. Precise measurements may be integrated into an automated or robotic system. Ligament tension (i.e., PLL) may be used as a gauge for 3D spinal re-alignment / global spinal balance. The MC measurement gauge may ensure that vertebral bone and cage height match up with PLL tension. Benefits increase across multiple levels because small errors can otherwise be compounded across multiple levels. Problems from over / under distraction include: in cervical-chin on chest deformity; in lumbar-flat back syndrome; improper anterior load sharing; and pedicle screw breakage / cage dislodgement / pseudarthrosis. The present invention makes results more reproducible and predictable.

Problems solved by technology

Current products are not sufficient to provide full three-dimensional spinal re-alignment.

Current techniques do not account for the Y-axis, and the definition of vertical stability along the Y-axis of the human spine has not been adequately established.

Surgeons cannot rely on angles alone to restore three-dimensional spine alignment.

However, currently available products do not measure these parameters.

A shortcoming of conventional spinal column measurement techniques along the Y-axis is that overall sagittal alignment guides may be met but intervertebral spacing between a particular set of vertebrae may be severely impaired.

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