US-12626358-B2 - Methods and systems for determining adjustment prescriptions of external fixation devices

US12626358B2US 12626358 B2US12626358 B2US 12626358B2US-12626358-B2

Abstract

The present disclosure provides methods for determining an adjustment prescription of an external fixation device affixed to anatomical structures. The methods include obtaining at least two digital radiographic images of differing orientations of the external fixation device and anatomical structures in an initial arrangement. The methods also include identifying fiducial markers of the external fixation device and an axis of the anatomical structures in the at least two radiographic images. The methods include providing a virtual manipulatable three-dimensional model of the external fixation device and the anatomical structures. The methods include providing an adjustment prescription of strut assemblies of the external fixation device based on a user determined desired arrangement of the anatomical structures that rearranges the anatomical structures from the initial arrangement to the desired arrangement via at least one user selected waypoint. The user determined desired arrangement of the anatomical structures is determined via the three-dimensional model.

Inventors

Michael Mullaney

Assignees

ARTHREX, INC.

Dates

Publication Date: 20260512
Application Date: 20200218

Claims (10)

1 . A method of determining an adjustment prescription of an external fixation device affixed to anatomical structures comprising bone segments, comprising: obtaining at least two digital radiographic images of differing orientations of the external fixation device and anatomical structures in an initial arrangement; identifying fiducial markers of the external fixation device in the at least two radiographic images, wherein identifying fiducial markers of the external fixation device in the at least two radiographic images comprises creating individually scaled digital fiducial markers for each fiducial in the radiographic images by correcting distortion of the radiographic images, wherein correcting distortion of the radiographic images comprises: determining a first ratio of the summation of the fiducial markers in the radiographic image in pixels the expected summation of a dimension of the actual fiducial markers of the external device to determine a volumetric scale of the radiographic image in pixels per unit of fiducial measure; determining a second ratio of the pixels per fiducial unit of measure to the expected resolution in pixels per image unit of measure of the radiographic image; adjusting the volumetric scale of the radiographic image based on the second ratio generating an adjusted volumetric scale; scaling the radiographic image in accordance with the adjusted volumetric scale generating volume-scaled identified fiducials; determining individual ratios of dimensions of e volume-scaled identified fiducials to the expected fiducial dimension on an individual fiducial basis; and utilizing the individual ratios to create the individually scaled digital fiducial markers for each fiducial on the radiographic image; identifying an axis of the anatomical structures in the at least two radiographic images; providing a virtual manipulatable three-dimensional model of the external fixation device and the anatomical structures from the identified fiducial markers, the at least two radiographic images and the identified axis of the anatomical structures; receiving a correction input via the three-dimensional model defining a user determined desired arrangement of the three-dimensional model of the bone segments of the anatomical structures; receiving a waypoint input defining at least one user selected waypoint that defines an intermediate arrangement of the anatomical structures, wherein the intermediate arrangement of the anatomical structures defines a pathway of the movement of the anatomical structures between the initial arrangement and the user determined desired arrangement; and providing an adjustment prescription of strut assemblies of the external fixation device based on the user determined desired arrangement of the anatomical structures that rearranges the anatomical structures from the initial arrangement to the desired arrangement via the at least one user selected waypoint, wherein the user determined desired arrangement of the anatomical structures is determined via the three-dimensional model.
2 . The method of claim 1 , wherein the external fixation device is a hexapod type external fixation device.
3 . The method of claim 1 , wherein the method is implemented in a computer system.
4 . The method of claim 1 , wherein the pathway of the movement of the anatomical structures is defined by a plurality of waypoints as a plurality of waypoint inputs.
5 . The method of claim 1 , wherein the anatomical structures are represented by bone segment models and the user defined waypoint identifies the position and orientation of the bone segment models with respect to each other between the initial arrangement and the desired arrangement.
6 . A computer system configured to perform a method, the method comprising: correcting distortion of a radiographic image of a plurality of fiducial markers of an external fixation device and anatomical structures, comprising: analyzing the radiographic image to identify the fiducial markers; determining a calculated summation of a dimension of the fiducial markers identified; determining a first ratio of the calculated summation of the fiducial markers in the radiographic image in pixels to an expected summation of a corresponding expected fiducial dimension of the actual fiducial markers of the external fixation device to determine a volumetric scale of the radiographic image in pixels per unit of fiducial measure; determining a second ratio of the pixels per fiducial unit of measure to an expected resolution in pixels per image unit of measure of the radiographic image; adjusting the volumetric scale of the radiographic image based on the second ratio generating an adjusted volumetric scale; scaling the radiographic image in accordance with the adjusted volumetric scale generating volume-scaled identified fiducials; determining individual ratios of dimensions of the volume-scaled identified fiducials to the expected fiducial dimension on an individual fiducial basis; and utilizing the individual ratios of each of the fiducial markers to generate individually scaled digital fiducial markers for each of the fiducial markers identified.
7 . A method of correcting distortion of a radiographic image of a plurality of fiducial markers of an external fixation device and anatomical structures, comprising: analyzing the radiographic image to identify the fiducial markers; determining a calculated summation of a dimension of the fiducial markers identified; determining a first ratio of the calculated summation of the fiducial markers in the radiographic image in pixels to an expected summation of a corresponding expected fiducial dimension of actual fiducial markers of the external fixation device to determine a volumetric scale the radiographic image in pixels per unit of fiducial measure; determining a second ratio of the pixels per fiducial unit of measure to an expected resolution in pixels per unit of measure of the radiographic image; adjusting the volumetric scale of the radiographic image based on the second ratio generating an adjusted volumetric scale; scaling the radiographic image in accordance with the adjusted volumetric scale generating volume-scaled identified fiducials; determining individual ratios of dimensions of the volume-scaled identified fiducials to the expected fiducial dimension on an individual fiducial basis; and utilizing the individual ratios of each of the fiducial markers to generate individually scaled digital fiducial markers for each of the fiducial markers identified.
8 . The method of claim 7 , wherein the method is implemented in a computer system.
9 . A computer program product comprising: a non-transitory computer readable storage medium storing instructions that, when executed by a processor, cause the processor to perform a method of correcting distortion of a radiographic image of a plurality of fiducial markers of an external fixation device and anatomical structures, the method comprising: analyzing the radiographic image to identify the fiducial markers; determining a calculated summation of a dimension of the fiducial markers identified; determining a first ratio of the calculated summation of the fiducial markers in the radiographic image in pixels to an expected summation of a corresponding expected fiducial dimension of actual fiducial markers of the external fixation device to determine a volumetric scale of the radiographic image in pixels per unit of fiducial measure; determining a second ratio of the pixels per fiducial unit of measure to an expected resolution in pixels per image unit of measure of radiographic image; adjusting the volumetric scale of the radiographic image based on the second ratio generating an adjusted volumetric scale; scaling the radiographic image in accordance with the adjusted volumetric scale generating volume-scaled identified fiducials; determining individual ratios of dimensions of the volume-scaled identified fiducials to the expected fiducial dimension on an individual fiducial basis; and utilizing the individual ratios of each of the fiducial markers to generate individually scaled digital fiducial markers for each of the fiducial markers identified.
10 . The method according to claim 6 , wherein the scaling of the radiographic image moves the fiducial markers to scaled positions.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority benefit from International Application No. PCT/US2018/047880 filed on Aug. 24, 2018, which claimed priority from U.S. provisional application No. 62/549,841 filed Aug. 24, 2017, each of which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION Embodiments of the disclosure are directed to treating musculoskeletal conditions, including skeletal fractures. More specifically, methods and systems for securing and placing segments of a bone or bones in desired locations are disclosed. In some embodiments of the disclosure, methods and systems are used to generate a computer model of a fixation device and bone segments. Through operations on the model, desired placement of the bones segments and operation of an external fixation device to achieve such desired placement is determined quickly and accurately regardless of the initial configuration of the fixation device. The operations required to create the desired placement of the bones segments may then be enacted on the corresponding fixation device and bone segments to treat the musculoskeletal condition. BACKGROUND OF THE INVENTION Devices and methods of treating skeletal fractures using ring external fixation structures are well known in the art. For example, many external ring fixators based on the general concept of a Stewart platform (often referred to as hexapods) have been developed and are used to manipulate anatomical structures, such as bone segments, into a desired arrangement (such as to, ultimately, achieve fixation thereof). Hexapods or Stewart platforms include six degree of freedom (6DOF) parallel manipulators or struts extending between at least a pair of platforms (e.g., rings) that serve as anatomical fixation platforms. The platforms are affixed to the anatomical structures of interest, and the platforms are manipulated via the struts to in turn manipulate the anatomical structures into a desired placement. Hexapods are thereby able to manipulate one or more bone segment or other anatomical structure of interest relative to a base in all three orthogonal axis translations (X, Y, Z position) and all rotations about those three orthogonal axes (roll, pitch, yaw pose). For example, U.S. Pat. Nos. 5,702,389; 5,728,095; 5,891,143; 5,971,984; 6,030,386; 6,129,727 and International PCT Patent Application No. PCT/US2017/017276 disclose many Stewart platform based external fixators, which are each expressly incorporated herein by reference in their entirety. In use, after the platforms of a hexapod are affixed to two or more bone segments (or other anatomical structures), the struts are manually individually incrementally adjusted (i.e., length adjustment two or more struts) over time to slowly manipulate the platforms and, thereby, the bone segments into a desired placement. This incremental adjustment of the struts to ultimately achieve the desired placement is typically done by medical personnel and/or the patient according to an adjustment or fixation prescription or plan. An adjustment prescription typically includes a strut adjustment schedule or directions that directs the medical personnel and/or the patient to incrementally adjust the length of the struts over time intervals to reorient the bone segments from an initial placement or arrangement to the desired placement or arrangement. An adjustment prescription may be determined via a computer assisted program or system. For example, some adjustment prescriptions are determined by a computer based system or program that provides to the user a two or three-dimensional model of a hexapod or other external fixation system affixed to anatomy of interest, such as bone segments. Some such adjustment prescription programs and systems utilize radiography images (e.g., x-rays) of the patient with the affixed hexapod taken along two or more anatomical planes to form the three-dimensional model. These programs and systems allow the user to utilize the model illustrating the hexapod and anatomy to manipulate the hexapod and anatomy into an arrangement wherein the anatomy is at a desired placement or arrangement, such as to achieve fixation of bone segments for example. The computer based system or program then automatically creates the entire adjustment prescription based on the current condition of the hexapod and anatomy and the desired placement of the anatomy. The user is thereby unable to control, dictate or customize the adjustment prescription. A typical radiography machine that produces the radiography images used by many adjustment prescription systems and methods utilizes a beam of X-rays (or other form of electromagnetic radiation) via a generator that is projected toward the hexapod affixed to the patient, which is often referred to as projectional radiography. A certain amount of X-rays are absorbed by the hexapod and the anatomy patient, dependent upon the density and composition thereof. Any X