WO1992014426A1

WO1992014426A1 - Improved external fixation frame assembly

Info

Publication number: WO1992014426A1
Application number: PCT/US1992/001345
Authority: WO
Inventors: Frank M. Lewis; Linda M. Trebing; David F. Miller
Original assignee: Danek Medical, Inc.
Priority date: 1991-02-20
Filing date: 1992-02-20
Publication date: 1992-09-03
Also published as: AU1443692A

Abstract

An arcuate frame assembly (10) for use in external fixation systems or devices is disclosed. The arcuate frame assembly (10) is comprised of an x-ray transparent or radiolucent frame segment (12) having a plurality of holes (16) drilled therethrough with counterbores sunk into both sides of the hole (16) for receiving therein an aluminum eyelet (14). The eyelet (14) is glued or press-fitted into the hole. The eyelets are made of aluminum which is a radiolucent material. The eyelets are color coded using aluminum anodizing techniques to produce a variety of colors. The color of the eyelets (14) installed into a particular frame assembly (10) signify the size or shape of the assembly (10) thereby enabling one to ascertain at a glance which arcuate frame assemblies (10) are designed to mate with one another to provide a circular assembly for encircling the limbs of a patient.

Description

IMPROVED EXTERNAL FIXATION FRAME ASSEMBLY

BACKGROUND OF THE INVENTION

This invention relates in general to external fixation devices and more specifically fixator rings constructed of no metalliς base materials.

External fixation devices have been known for many years and are particularly useful in the treatment of bone fractures wherein repositioning and immobilization of the fractured bone are necessitated. External fixation devices are orthopedic medical devices widely recognized as a viable means for treating fractures of the bones. Examples of such devices are shown in the patents to Fischer, U.S. Patent No. 4,308,863, Jaquet, U.S. Patent No. 4,365,624, and Alvarez Cambras, U.S. Patent No. 4,624,249.

Semi-circular members or frame segments encircle the broken bone and provide structural support for the rods and wires attached thereto in the Jaquet device. Jaquet suggests the frame segments are made of light alloys such as aluminum or titanium. Fischer suggests powdered metallurgy production techniques to minimize weight and provide maximum strength for the arcuate frame segments 12 and 12a disclosed therein. Alternatively, Fischer suggests that stainless steel or titanium are equally applicable as raw materials for constructing the frame segments.

During the period in which an external fixation device is attached to a patient's body, numerous x-rays of the bone are taken over a period of time in order to determine the patient's healing progress. When the component parts of the external fixation device are made of metallic materials, the x-ray photographs of the broken bones and the fixation system are difficult to read due to interference attributable to the external fixation system. Metallic parts of the fixation system obscure portions of the x-ray, making analysis of the healing process more difficult. In the alternative, additional x-rays can be taken at varying angles to avoid the interference created by the fixation system. Additional x-rays involved more exposure and are costly to the patient and/or insurance company, thus an external fixation system which obviates the necessity of multiple x-rays to examine the broken bones and diagnose the progress of the healing process is needed. Use of x-ray transparent materials in constructing the component parts of an external fixation device results in an x-ray photograph which is more easily analyzed by a medical practitioner.

SUMMARY OF THE INVENTION

A frame segment for use in an external fixation system, according to one embodiment of the present invention, comprises a nonmetallic member having a plurality of through holes and a plurality of eyelets attached to and situated in each of said through holes.

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One object of the present invention is to provide x-ray transparent or radiolucent structural components for an external fixation device.

Another object of the present invention is to reinforce and protect the wear areas of a frame segment forming a part of an external fixation system by attaching durable materials at locations wherein friction and contact with other structures of an external fixation system will occur.

These and other objects of the present invention will become more apparent from the following description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an arcuate frame assembly according to the present invention.

FIG. 2 is a perspective view of an eyelet used in the arcuate frame assembly of FIG. 1.

FIG. 3 is a cross-sectional view of the frame assembly of FIG. 1 looking in the direction of the arrows labeled 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now to FIG. 1, an arcuate frame assembly 10 according to the present invention is shown. The arcuate frame assembly 10 consists of arcuate frame segment 12 and eyelets 14. The eyelets 14 are set into stepped holes on both sides of the arcuate frame segment 12 and equally spaced in a circle around the center of the segment. The eyelets are mounted flush with surface A and surface B of frame segment 12. A through hole 16 passes through the eyelets 14 and the frame segment 12. The frame segment 12 is made of high strength, lightweight x-ray transparent materials such as carbon fiber composites. The eyelets 14 are made of aluminum or other radiolucent materials. The eyelets 14 provide increased strength and wear resistance at mounting hole locations wherein various hardware components of an external fixation system or device such as shafts, supports, rods and wires are attached.

The arcuate frame assembly 10 is used in conjunction with a variety of rods, bolts, wires and threaded shafts -(none of which are shown) to form an external fixation device which provides external frame support for positioning broken bones in held position while the bones heal. Such devices are shown in the patents discussed in the Background of the Invention section above.

Referring now to FIG. 2, an eyelet 14 is shown. The eyelet

14 consists of a large diameter portion 20 and a small diameter portion 18 with a hole 16 passing through the center of eyelet

14. Although the eyelet 14 shown is circular in shape, other shapes such as square, elliptical, etc. are contemplated for eyelet 14.

Referring now to FIG. 3, a cross section of the arcuate frame assembly 10 looking in the direction of the arrows 3 is shown. The arcuate frame segment 12 receives the eyelets 14 into stepped holes provided by counterbores in the top surface

A and bottom surface B of arcuate frame segment 12. The counterbores are sized so that the eyelets 14 may be press-fitted into the counterbored holes of the frame segment

12. Alternatively, the eyelets 14 may be glued to the arcuate frame segment using an adhesive. Large diameter 20 and small diameter 18 of eyelet 14 fit snugly within the counterbored hole 16 of frame segment 12. A threaded shaft (not shown) inserted in hole 16 and secured to frame assembly 10 by nuts

(not shown) permits the assembly of an external fixation device without the need for washers (not shown) to be placed against the surface of the carbon fiber ring. The washers were heretofore used to prevent undue wear caused by fixation wires and hardware attached to the frame segment.

The aluminum eyelets hold fixation wires better than a steel washer used in conjunction with a steel frame segment because the aluminum eyelet 14 is a softer metal. Therefore the aluminum eyelets resist slipping of fixation wires mounted therein. Further, the aluminum eyelets 14 can be anodized to color code various available sizes of the arcuate frame assembly 10, thereby giving an orthopedic surgeon or medical practitioner "at a glance" information regarding the size of a particular arcuate frame assembly and which arcuate frame assemblies will mate with one another to provide a completed assembly which encircles a broken bone or limb of a patient.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

What is claimed is:

1. A frame segment for use in an external fixation system comprising: rigid radiolucent frame segment means including a plurality of holes defined therethrough for engaging and providing structural support for components of an external fixation system; and radiolucent means attached to said holes for protecting said frame segment means from friction and wear from components of the external fixation system engaged to said frame segment means.

2. A frame segment for use in a system for external fixation of bones in animals, comprising: a rigid non-metallic frame member having a plurality of holes defined therethrough; and a plurality of eyelets received within corresponding ones of said plurality of holes.

3. The frame segment of claim 2, wherein said frame member is composed of a first radiolucent material.

4. The frame segment of claim 3, wherein said first radiolucent material is a carbon fiber composite material.

5. The frame segment of claim 2, wherein said plurality of eyelets are composed of a second radiolucent material different from said first radiolucent material.

6. The frame segment of claim 5, wherein said second radiolucent material is aluminum.

7. The frame segment of claim 2, wherein: each of said plurality of holes includes a first counterbored portion defined from a first surface of said frame member; and each of said plurality of eyelets is configured to be received within said first counterbored portion to sit substantially flush with said first surface of said frame π-ember.

8. The frame segment of claim 7, wherein: each of said plurality of holes includes a second counterbored portion defined from a second surface of said frame member opposite said first surface; and said plurality of eyelets includes a pair of said eyelets each for a corresponding one of said plurality of holes, one each of said pair of said eyelets received within said first counterbored portion and said second counterbored portion. ltt

9. The frame segment of claim 2, wherein each of said plurality of eyelets is configured to be press-fit into said corresponding one of said plurality of holes.

10. The frame segment of claim 2, wherein said frame member has an arcuate shape.

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11. The frame segment of claim 2, wherein said plurality of eyelets is color-coded in relation to the size of said frame member, whereby the color of said eyelets provides an immediate visual indication for selection of said frame member for external fixation of a bone.