Methods for determining spine instability and for eliminating the impact of patient effort on stability determinations
Inventors
Hipp, John A. • Wharton, Nicholas
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-10226223-B2
Publication Date
2019-03-12
Expiration Date
Abstract
The present disclosure describes a method for determining spinal instability, more particularly, a method for quantifying the type and extent of spinal instability in a standardized way. The disclosure also describes a method comprising measurement of the intervertebral rotation and intervertebral translation between a vertebrae pair using simple images, and from these measurements, determining if one or more vertebrae pair of the spine is unstable. Finally, the disclosure describes software that may be used to quantify the type and extent of spinal instability.
Core Innovation
The invention is directed to a computer implemented method for analyzing intervertebral motion of a spine by acquiring digital images of a first vertebra and a second vertebra in a first position and in a second position, wherein the degree of intervertebral rotation between the two positions is greater than 3 degrees. At least one landmark on a vertebra is detected or acquired on at least one image in the first position, and the location of the at least one landmark is electronically transferred to the same vertebra on the at least one image in the second position. The digital images are aligned to allow for measurements comparing the vertebrae in the first and second positions.
The method determines the rotation and translation required to subsequently align images of the second vertebra in the first position and the second position, measures the degree of vertebral rotation, and measures the translation of the landmark on the first vertebra between the first and second positions while holding the second vertebra fixed. The intervertebral translation measurement is normalized based upon a vertebral dimension, and the intervertebral translation is divided by the intervertebral rotation to give a normalized translation per degree of rotation (TPDR) that is independent of vertebrae size. TPDR is used as a quantified measure of spinal instability derived from intervertebral motion measured from simple radiographs.
In certain implementations, TPDR is standardized using an asymptomatic population, and a level-specific stability metric is expressed as standard deviations from an asymptomatic radiographically normal population. The analysis includes reducing patient-effort effects by the TPDR normalization and by landmark selection, with optional center-of-rotation and paradoxical-motion correction.
Claims Coverage
The independent claim is directed to a computer implemented method that normalizes intervertebral translation by intervertebral rotation to obtain a vertebra-size independent TPDR using landmark transfer and aligned image measurements. Based on the partial claim set provided, only one independent claim is explicitly identified, and it focuses on the core TPDR normalization workflow.
Landmark-transfer based aligned measurement of intervertebral rotation and translation
Detecting or acquiring the location of at least one landmark on a vertebra on at least one image in the first position; electronically transferring the location of the at least one landmark on the vertebra on the at least one image in the first position to the same vertebra on the at least one image in the second position; aligning digital images of the vertebrae in the first and second positions to allow for measurements comparing images of the vertebrae in the first and second positions; determining the rotation and translation required to subsequently align images of the second vertebra in the first and second positions; and measuring the degree of vertebral rotation between the first and second vertebrae in the first and second positions.
Vertebral dimension normalization and TPDR computation independent of vertebrae size
Measuring the translation of the landmark on the first vertebra between the first and second positions while holding the second vertebra fixed; normalizing the intervertebral translation measurement based upon a vertebral dimension; and dividing the intervertebral translation by the intervertebral rotation to give a normalized translation per degree of rotation (TPDR) that is independent of vertebrae size.
Across the explicitly provided independent claim material, the core claim coverage is the computation of a vertebra-size independent TPDR metric from aligned first/second-position digital images using landmark transfer, rotation measurement, translation measurement, and normalization.
Stated Advantages
TPDR is independent of vertebrae size.
TPDR reduces patient-effort effects via translation-per-degree-of-rotation normalization.
Documented Applications
Quantifying spinal instability by measuring intervertebral rotation and intervertebral translation from digital images (including simple radiographs), producing a stability metric expressed relative to an asymptomatic radiographically normal population.
Using asymptomatic radiographically normal TPDR population data to support reliability and predictive correlations, including correlations with facet fluid sign, pre-op lumbar fusion findings, outcome prediction, and longitudinal trend analysis.
Interested in licensing this patent?