UNILATERAL EXTERNAL FIXATOR APPARATUS AND CONTROL METHOD

Abstract

A unilateral external fixator (“UEF”) and method of controlling the UEF. Apparatus comprises a central body connected to a first base and a second base via joints. Two angular adjustment screw assemblies control position between the central body and the first base. Two additional angular adjustment screw assemblies control position between the central body and the second base. A first axial adjustment screw assembly in the first base adjusts axial position of a first bone attachment base. A second axial adjustment screw in the second base adjusts axial position of a second bone attachment base. Method comprises uploading a first set of x-rays to a computer program, characterizing geometry of a bone deformity with the program, recommending frame geometry for correcting the deformity, then after surgery uploading a second set of x-rays with fixator attached, characterizing geometry again, calculating fixator adjustments necessary to align bones, and providing proposed fixator positions.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The invention is in the field of external fixators for gradual and controlled correcting broken bones and other bone deformities.

Description of the Related Art

In various orthopedic surgical procedures, it is necessary to secure two bone portions in a relatively fixed relationship to each other. The need for establishing such secured relationship is often a result of a bone fracture or other type of bone deformity. To ensure that the bone can regenerate in the proper orientation and fuse the fracture, it is important that the bone portions be fixed in the desired position during bone regeneration.

Various external fixators for the correction of bone deformities are known. For example, U.S. Pat. No. 7,449,023 B2 to Walulik et al. discloses a method and apparatus for external fixation and correction of bone using a unilateral fixator. However, using this apparatus is difficult for complex deformities in three dimensions. Surgeons have difficulty foreseeing the bone position in a plane other than that being corrected. For example, one can correct angulation on a frontal plane, and then the bone goes somewhere else on a sagittal plane.

Another example is EP 0814714 B1 to Taylor et al. Taylor teaches a circular fixator having two rings and six struts. It solves some of the problems of Walulik, but causes other problems for surgeons and patients. The hardware is complex and surgeons have difficulty seeing the surgical area due to the struts around the patient's extremity, and it is difficult to manage all the components, which include rings, struts, anchoring elements, and more, during surgery. Patients have difficulty carrying such a bulky device on their extremity. Adjusting strut lengths every day is not easy because at least three struts are outside of the patient's view. Femoral surgeries are very uncomfortable for the patient because the patient cannot get the legs close to one another, which greatly affects the patient's daily life.

What is needed, therefore, is an external fixator that does not have the problems of prior art apparatuses. The fixator should be controllable in multiple planes, positions should be foreseeable to the surgeons, the apparatus should not be bulky and difficult to use in daily life.

SUMMARY OF THE INVENTION

The present invention is a unilateral external fixator (“UEF”) and method of controlling the fixator that satisfies these needs. The apparatus comprises a central body connected to a first base and a second base via respective universal joints. Two angulation adjustment screw assemblies control geometrical position between the central body and the first base. Two additional angulation adjustment screw assemblies control geometrical position between the central body and the second base. A first axial adjustment screw in the first base adjusts axial position of a first bone attachment base. A second axial adjustment screw in the second base adjusts axial position of a second bone attachment base.

A method of correcting a bone deformity comprises the steps of providing a UEF, uploading a first set of x-ray images prior to surgery to a computer software program, characterizing the geometry of a bone deformity with the program, recommending a frame type, shape, and geometry of UEF for correcting the deformity. The method further comprises the steps of, after surgery uploading a second set of x-ray images with the fixator attached, characterizing the geometry again, sending the geometry to a correction algorithm of the program, calculating fixator adjustments necessary to align bone segments, providing visualization of aligned bone segments and proposed fixator positions for user approval, and providing a correction animation in three dimensions for correcting the bone deformity using the UEF. These and other benefits, features, and advantages will be made clearer in the accompanying description, claims, and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a first embodiment of the apparatus of the present invention.

FIG. 2 is a perspective view of a second embodiment of the apparatus of the present invention.

FIG. 3 is an exploded view of the embodiment of FIG. 1.

FIG. 4 is a front elevation of the embodiment of FIG. 1.

FIG. 5 is a plan view of the embodiment of FIG. 1.

FIG. 6 is a rear elevation of the embodiment of FIG. 1.

FIG. 7 is a side elevation of the embodiment of FIG. 1.

FIG. 8 is a perspective detail view of the rotator of the embodiment of FIG. 2.

FIG. 9 is an exploded view of the embodiment of FIG. 2.

FIG. 10 is a side elevation of the embodiment of FIG. 2.

FIG. 11 is a rear elevation of the embodiment of FIG. 2.

FIG. 12 is a plan view of the rotator assembly of the embodiment of FIG. 2.

FIG. 13 is an exploded perspective view of an angulation adjustment screw assembly.

FIG. 14 is a flow chart of a method of correcting a bone deformity with a UEF, pre-surgery.

FIG. 15 is a flow chart continuing the method of FIG. 14 post-surgery.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus of the present invention is made for fixating fractured bones while making it possible to precisely adjust the relative position and orientation to the needs. The facture could be caused by a trauma or an osteotomy during surgery. The unilateral external fixator (“UEF”) offers a very tight package and a wide range of adjustment positions. The challenge, however, is given by the non-linear behavior of the system. The adjustment screws do not correspond to linear motion as in a cartesian motion system. A linear movement, or any movement, requires the simultaneous change of multiple adjustment screws. The numerical method of the present invention achieves desired motion and control both position and orientation.

The UEF is given in two different configurations. The first, basic version allows the manipulation of a given bone structure in five degrees of motion. In particular, it supplies three perpendicular translations and two rotations. The extended, second version of the UEF carries an additional revolute joint, and therefore allows the manipulation of all six degrees of freedom. The method of the invention supplies a numerical solution to control both the position and the orientation of attached bone structures using the UEF.

FIG. 1 is a perspective view of a first embodiment of the UEF of present invention, providing five degrees of motion. The UEF assembly 100 comprises a central body 102 and a first base 104 in operative communication with the central body 102 via a first joint 108 disposed on a central body first side. The first joint can be a universal joint or a ball and socket joint. FIG. 1 shows it as a universal joint. A first bone attachment base 112 is fixed to a first longitudinal plane of the first base 104 for attaching the fixator to a lower bone or lower bone mockup 128. A first angulation adjustment screw assembly 116 is connected at a first end to the central body 102 and connected at a second end to the first base 104 along a longitudinal plane orthogonal to the first bone attachment base 112. A third angulation adjustment screw assembly 120 is connected at a first end to the central body 102 at a position orthogonal to that of the first angulation adjustment screw assembly 116 and connected at a second end to the first base 104 at a position orthogonal to that of the first angulation adjustment screw assembly 116. A first axial adjustment screw assembly 124 is in communication with the first base 104 that adjusts translation of the bone attachment 112 along a longitudinal axis of the first base 104.

A second base 106 is in operative communication with the central body 102 via a second joint 110 disposed on a central body second side opposite the central body first side. Like the first joint, the second joint 110 can be a universal joint or a ball and socket joint. FIG. 1 shows it as a universal joint. A second bone attachment base 114 is fixed to a first longitudinal plane of the second base 106 for attaching the fixator to an upper bone or upper bone mockup 130. A second angulation adjustment screw assembly 118 is connected at a first end to the central body 102 and connected at a second end to the second base 106 along a longitudinal plane orthogonal to the second bone attachment base 114. A fourth angulation adjustment screw assembly 122 is connected at a first end to the central body 102 at a position orthogonal to that of the second angulation adjustment screw assembly 118 and connected at a second end to the second base 106 at a position orthogonal to that of the second angulation adjustment screw assembly 118. A second axial adjustment screw 126 is in communication with the second base 106 that adjusts translation of the second bone attachment base 114 along a longitudinal axis of the second base 106.

FIG. 2 is a perspective view of a second embodiment of the UEF of present invention, providing six degrees of motion. The UEF assembly of FIG. 2 differs from that of FIG. 1 by replacing the first bone attachment base of FIG. 1 with a rotator assembly 140 fixed to the first base 104. A linking member 142 is adjustably attached to the rotator assembly 140 for attaching to the lower bone 128.

FIG. 3 is an exploded view of the embodiment of FIG. 1 and shows additional components that are not visible in the view of FIG. 1. A first cross 132 is disposed between the central body 102 and the first base 104, and is part of the first universal joint 108. A second cross 134 is disposed between the central body 102 and the second base 106, and is part of the second universal joint 110.

The first bone attachment base 112 is in sliding communication with the first base 104 and is translated along the longitudinal axis of the first base by adjusting the first axial adjustment screw 124. The second bone attachment base 114 is in sliding communication with the second base 106 and is translated along the longitudinal axis of the second base by adjusting the second axial adjustment screw 126.

FIGS. 4-6 show the front elevation, plan view, and rear elevation of the UEF of FIG. 1 respectively. FIG. 7 shows the side elevation.

FIG. 8 is a perspective view of the rotator assembly 140 of the embodiment of FIG. 2. The rotator assembly 140 comprises a mounting adapter 144 having structure for attaching the rotator assembly to the first base 104 as shown in FIG. 2. A rotating inner part 146 is secured in a rotating relationship along a groove or track in the mounting adapter as shown in FIG. 8. Note the angular gradations on the mounting adapter 144 and the hash mark on the rotating inner part 146 that assists a user in locating the rotating inner part 146 in a desired orientation. Also note the mounting structures in the rotating inner part for adjustably attaching the linking member that is shown in FIG. 2.

FIG. 9 is an exploded view of the embodiment of FIG. 2 and shows additional components that are not visible in the view of FIG. 2. Like with the first embodiment, a first cross 132 is disposed between the central body 102 and the first base 104, and is part of the first universal joint 108. A second cross 134 is disposed between the central body 102 and the second base 106, and is part of the second universal joint 110.

The rotator assembly 140 is in sliding communication with the first base 104 and is translated along the longitudinal axis of the first base by adjusting the first axial adjustment screw 124. The second bone attachment base 114 is in sliding communication with the second base 106 and is translated along the longitudinal axis of the second base by adjusting the second axial adjustment screw 126.

FIGS. 10-12 show the side elevation, rear elevation, and plan view of the UEF of FIG. 2 respectively.

FIG. 13 is an exploded perspective view of an angulation adjustment screw 150, and shows the components and details of any of the first through fourth angulation adjustment screw assemblies 116-122. A joint is disposed at the first and second ends of the angulation adjustment screw assemblies, and the particular joint shown in FIG. 13 is a ball and socket joint. The joint could also be a universal joint, not shown. The angulation adjustment screw assembly 150 comprises a barrel 152, a threaded rod 154, and an adjustment nut 156 that engages the barrel 152 and threaded rod 154. Rotating the adjustment nut 156 adjusts the overall length of the angulation adjustment screw assembly. The barrel comprises at least one window 158 through which an operator can see an end of the threaded rod 154, or an indicator structure connected to the threaded rod. Preferably, length gradations are applied to the barrel 152 that assist an operator in adjusting the overall length of the angulation adjustment screw assembly by matching the position of the end of the threaded rod with a desired gradation.

For a ball and socket joint, a first pin receiver 160 is disposed on one end of the barrel 152 and is adapted to receive a first pin 164. A second pin receiver 162 is disposed on one end of the threaded rod 154 and is adapted to receive a second pin 166. As shown in FIG. 1, first and second pins, which are not numbered in FIG. 1, are attached to the central body 102 and one of the first base 104 or the second base 106.

Next, a method to control the movement of the UEF to correct a bone deformity is presented. The method requires the inverse kinematic control of the kinematic structure, with respect to an arbitrary, user-defined reference point. The solution to the problem is an algorithm, which allows computer-based evaluation and supplies the user with the required settings that achieve desired position and orientation. The solution should also consider the limitations of motion of the given device.

The inputs to the expected algorithm are the dimensions of the UEF, the location and the orientation of two fractured bone segments, as well as an initial position and orientation and a target position and orientation. The expected output is the set of adjustment settings to change the current position to a desired target position. The settings include, but are not limited to, settings for rotation adjustment screws, axial adjustment screws, and for the rotator assembly. The transition from initial to target position should follow a trajectory with a user-defined number of intermediate steps.

The method includes the two embodiments of the UEF, the basic version with five degrees of freedom (DOF) as shown in FIG. 1 and the extended version with the full range of six DOF as shown in FIG. 2.

The modeling and simulation of kinematic structures used as manipulators have always been a central issue in the area of robotics, as this forms the basis for both research and the implementation of robotic systems. While the matter is of highly complex nature, the modeling process itself is often more of a necessary but recurrent prerequisite, rather than being of key interest. Especially concerning dynamic systems such as manipulators, the area of robotics has developed several unified methods for their kinematic description and the calculation of dynamic forces. These methods simplify both documentation and implementation of complex linear and non-linear systems. Furthermore, as general requirements in robotics are often of similar nature, these commonly used methods are well-suited for numeric implementation in real-time systems.

Turning to FIG. 14, a method 200 of correcting a bone deformity with a unilateral external fixator comprises the steps of first uploading a first set of x-ray images of the bone deformity taken prior to surgery without the fixator to a computer software program 202. Then, automatically, with the computer software program, perform the steps of detecting bone segment edges and segmentation 204, identifying whether an x-ray image is a coronal plane image, or a sagittal plane image 206, identifying whether the extremity is a left or right extremity 208, finding mid diaphyseal lines for each bone segment 210, finding joint orientation lines and joint orientation angles 212, identifying the deformity and bone segment positions 214, identifying at least one cora point 216, and recommending a frame type, shape, osteotomy level, and geometry for the bone deformity to be corrected using the unilateral external fixator 218. Note that, as used in this specification and in the claims, the term “cora” means “center of rotation of angulation.”

After surgery, the method continues with the steps shown in FIG. 15. The next step is uploading a second set of x-ray images with the fixator taken after surgery to the computer software program 220.

Then, automatically, with the computer software program, perform the steps of detecting bone segment edges and segmentation 222, identifying whether an x-ray image is a coronal plane image, or a sagittal plane image 224, identifying whether the extremity is a left or right extremity 226, localizing landmarks and reference segments in the coronal plane image and/or the sagittal plane image 228, representing the calculated angles in the coronal plane image and/or in the sagittal plane image 230, identifying the deformity and bone segment positions 232, identifying cora points 234, identifying fixator components and/or markers 236, identifying fixator geometric positions 238, matching fixator positions and bone segment positions 240, sending bone segment position parameters and fixator references with necessary correction parameters, such as translation, angulation, distraction/compression and/or rotation requirements entered by a user or surgeon to a correction algorithm of the computer software program 242, calculating fixator adjustments necessary to align bone segments 244, providing visualization of aligned bone segments in two and three dimensions and proposed fixator positions for user approval 246, and providing a correction simulation and/or animation with modeled three dimensional bone and fixator model to a user for correcting the bone deformity with the unilateral external fixator 248.

The computer software program can be an artificial intelligence (“AI”) application. An input prompt for the AI application can comprise the first set of x-ray images and the second set of x-ray images.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

TABLE OF REFERENCE NUMBERS
Reference
Number Description
100    unilateral external fixator assembly
102    central body
104    first base
106    second base
108    first joint
110    second joint
112    first bone attachment base
114    second bone attachment base
116    first angulation adjustment screw assembly
118    second angulation adjustment screw assembly
120    third angulation adjustment screw assembly
122    fourth angulation adjustment screw assembly
124    first axial adjustment screw
126    second axial adjustment screw
128    lower bone mockup
130    upper bone mockup
132    first cross
134    second cross
140    rotator assembly
142    linking member
144    mounting adapter
146    rotating inner part
150    angulation adjustment screw assembly
152    barrel
154    threaded rod
156    adjustment nut
158    window
160    first pin receiver
162    second pin receiver
164    first pin
166    second pin
200    method of correcting a bone deformity with a UEF
202    upload first set of x-ray images
204    detect edges and segmentation
206    identify type of image
208    identify whether the extremity is left or right
210    find mid diaphyseal lines
212    find joint orientation lines and angles
214    identify the deformity
216    identify at least one cora point
218    recommend frame type, shape, geometry, and location
220    upload second set of x-ray images
222    detect bone segment edges and segmentation
224    identify type of image
226    identify whether the extremity is left or right
228    localize landmarks and reference segments
230    represent calculated positions in images
232    identify the deformity
234    identify cora points
236    identify fixator components and/or markers
238    identify fixator position
240    match fixator position and bone segments
242    send positions and references to correction algorithm
244    calculate fixator adjustments
246    provide visualization for approval
248    provide correction simulation to user

Claims

1. A unilateral external fixator comprising: a central body;a first base in operative communication with the central body via a first joint disposed on a central body first side; the first joint comprising one of: a ball and socket joint; ora universal joint comprising a first cross;a first angulation adjustment screw assembly connected at a first end to the central body and connected at a second end to the first base;a third angulation adjustment screw assembly connected at a first end to the central body at a position orthogonal to that of the first angulation adjustment screw assembly and connected at a second end to the first base at a position orthogonal to that of the first angulation adjustment screw assembly;a first axial adjustment screw assembly in communication with the first base along a longitudinal axis of the first base;a second base in operative communication with the central body via a second joint disposed on a central body second side opposite the central body first side; the second joint comprising one of: a ball and socket joint; ora universal joint comprising a second cross;a second angulation adjustment screw assembly connected at a first end to the central body and connected at a second end to the second base;a fourth angulation adjustment screw assembly connected at a first end to the central body at a position orthogonal to that of the second angulation adjustment screw assembly and connected at a second end to the second base at a position orthogonal to that of the second angulation adjustment screw assembly; anda second axial adjustment screw assembly in communication with the second base.

2.-5. (canceled)

6. The unilateral external fixator of claim 1, further comprising respective angulation adjustment screw assembly joints disposed at each of the first end and second end of each angulation adjustment screw assemblies that connect the respective angulation adjustment screw assemblies to the central body and a respective first base or second base, each angulation adjustment screw assembly joint comprising either a ball and socket joint or a universal joint.

7. The unilateral external fixator of claim 1, the first base further comprising a first bone attachment base that is axially adjusted by the first axial adjustment screw assembly; andthe second base further comprising a second bone attachment base that is axially adjusted by the second axial adjustment screw assembly.

8. The unilateral external fixator of claim 1, further comprising a semi-circular or circular rotator assembly fixed to and in sliding communication with the first base.

9. The unilateral external fixator of claim 8, wherein the rotator assembly comprises; a mounting adapter fixed to and in sliding communication with the first base;a rotating inner part secured in a rotating relation with the mounting adapter; anda linking member adjustably secured to the rotating inner part.

10. A method of correcting a bone deformity with a unilateral external fixator comprising the steps of: uploading a first set of x-ray images of the bone deformity taken prior to surgery without the fixator to a computer software program;automatically, with the computer software program, performing the steps of: detecting bone segment edges and segmentation;identifying whether an x-ray image is a coronal plane image, or a sagittal plane image;identifying whether the extremity is a left or right extremity;finding mid diaphyseal lines for each bone segment;finding joint orientation lines and joint orientation angles;identifying the deformity and bone segment positions;identifying at least one cora point; andrecommending a frame type, shape, geometry, and position for the bone deformity to be corrected using the unilateral external fixator;uploading a second set of x-ray images with the fixator taken after surgery;automatically, with the computer software program, performing the steps of: detecting bone segment edges and segmentation;identifying whether an x-ray image is a coronal plane image, or a sagittal plane image;identifying whether the extremity is a left or right extremity;localizing landmarks and reference segments in the coronal plane image and/or the sagittal plane image;representing the calculated geometrical positions of bone segments in the coronal plane image and/or in the sagittal plane image;identifying the deformity and bone segment positions;identifying cora points;identifying fixator components and/or markers;identifying fixator geometric positions;matching fixator positions and bone segment positions;sending bone segment position parameters and fixator references with necessary correction parameters, the correction parameters comprising angulation, translation, distraction/compression, and/or rotation requirements that may be entered by user to a correction algorithm of the computer software program;calculating fixator adjustments necessary to align bone segments;providing visualization of aligned bone segments in two and three dimensions and proposed fixator positions for user approval; andproviding a correction simulation and/or animation with modeled three dimensional bone and fixator model to a user for correcting the bone deformity with the unilateral external fixator.

11. The method of claim 10 further comprising the step of providing the unilateral external fixator, the fixator comprising: a central body;a first base in operative communication with the central body via a first joint disposed on a central body first side;a first angulation adjustment screw assembly connected at a first end to the central body and connected at a second end to the first base;a third angulation adjustment screw assembly connected at a first end to the central body at a position orthogonal to that of the first angulation adjustment screw assembly and connected at a second end to the first base at a position orthogonal to that of the first angulation adjustment screw assembly;a first axial adjustment screw assembly in communication with the first base along a longitudinal axis of the first base;a second base in operative communication with the central body via a second joint disposed on a central body second side opposite the central body first side;a second angulation adjustment screw assembly connected at a first end to the central body and connected at a second end to the second base;a fourth angulation adjustment screw assembly connected at a first end to the central body at a position orthogonal to that of the second angulation adjustment screw assembly and connected at a second end to the second base at a position orthogonal to that of the second angulation adjustment screw assembly; anda second axial adjustment screw assembly in communication with the second base.

12. The method of claim 11, wherein either the first joint or the second joint is a universal joint or a ball and socket joint.

13. The method of claim 11, the fixator further comprising: a first bone attachment base that is axially adjusted by the first axial adjustment screw assembly; anda second bone attachment base that is axially adjusted by the second axial adjustment screw assembly.

14. The method of claim 11, the fixator further comprising a semi-circular or circular rotator assembly fixed to and in sliding communication with the first base.

15. The method of claim 10, the computer software program comprising an artificial intelligence application.

16. The method of claim 15, wherein an input prompt for the artificial intelligence application comprises the first set of x-ray images and the second set of x-ray images.

17. A method of correcting a bone deformity with a unilateral external fixator comprising the steps of: a) providing a unilateral external fixator comprising: a central body;a first base and a second base in operative communication with the central body via respective joints;andangulation adjustment screw assemblies and axial adjustment screw assemblies connected to the central body and the first and second base that adjust the relative positions of the first base and second base;b) uploading a first set of x-ray images of the bone deformity taken prior to surgery without the fixator to a computer software program;c) automatically characterizing the geometry of the bone deformity with the computer software program;d) recommending, using the computer software program, a frame type, shape, and geometry for the bone deformity to be corrected using the unilateral external fixator;e) uploading a second set of x-ray images with the fixator taken after surgery;f) automatically characterizing the geometry of the bone deformity and fixator after surgery with the computer software program;g) getting direction from a user for planning the correction, meaning a final relationship between the bone segments, or getting approval from the user for a recommended correction plan by the computer software program;h) sending the characterized geometry to a correction algorithm of the computer software program;i) calculating fixator adjustments necessary to align bone segments;j) providing visualization of aligned bone segments in two and three dimensions and proposed fixator position for user approval; andk) providing a correction simulation and/or animation with modeled three dimensional bone and fixator model to a user for correcting the bone deformity with the unilateral external fixator.

18. The method of claim 17, wherein either the respective joints is a universal joint or a ball and socket joint.

19. The method of claim 17, the fixator further comprising: a first bone attachment base that is axially adjusted by the first axial adjustment screw assembly; anda second bone attachment base that is axially adjusted by the second axial adjustment screw assembly.

20. The method of claim 17, the fixator further comprising a semi-circular or circular rotator assembly fixed to and in sliding communication with the first base.

21. The method of claim 17, the computer software program comprising an artificial intelligence application.

22. The method of claim 21, wherein an input prompt for the artificial intelligence application comprises the first set of x-ray images and the second set of x-ray images.