External fixation system

• US 4,600,000 A
• Filed: 04/01/1985
• Issued: 07/15/1986
• Est. Priority Date: 09/16/1982
• Status: Expired due to Term

• Current Assignee: Stryker Technologies Corporation
• Original Assignee: Charles C. Edwards
• Inventors: Edwards, Charles C.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): Isabella, David J.
• Application Number:
  US06/718,077
• Time in Patent Office: 470 Days
• Field of Search: 128/92 A, 128/92 B, 128/92 C, 128/92 EB, 403/221, 403/222
• US Class Current: 606/54
• CPC Class Codes: A61B 17/6491 allowing small-scale motion of bone ends

Abstract

An external fixation system includes as one of its frame components at least one dynamic coupling which is mounted to a respective frame rod. The coupling includes a sleeve member telescoped over the rod with a stop member on the rod on each side of the sleeve member. The stop member located toward the bone fracture may be adjustably locked to change its position on the rod and thus permit selective controlled sliding movement of the rod in the sleeve member.

Claims

1. In an external fixation system wherein sets of pins are mounted from a frame on longitudinally opposite sides of a bone fracture, the improvement being said frame including a coupling comprising a rod for being generally longitudinally disposed from one set of pins on one side of the fracture to another set of pins on the other side of the fracture, a sleeve member having a longitudinal passageway extending therethrough, said rod being slidably positioned in said sleeve member, remote stop means coupled to said rod on the side of said sleeve member remote from the fracture, inner stop means coupled to said rod on the side of said sleeve member toward the fracture, adjustable locking means for selectively locking said inner stop means to said rod at a preselected position thereon to control the distance between said stop means whereby the degree of sliding movement of said rod within said sleeve member may be varied to provide a dynamic coupling thereof, said remote stop means and said inner stop means being coupled to said rod without any other components between each stop means and said sleeve whereby said sleeve may directly contact said stop means during said sliding movement, said sleeve member comprising a housing having a longitudinal bore, an inner sleeve positioned in said longitudinal bore and slidably receiving said rod, the outer diameter of said inner sleeve being smaller than the inner diameter of said longitudinal bore to provide clearance between said inner sleeve and the inner surface of said bore whereby said sleeve may be tilted to a position within said bore which is nonparallel with respect to said bore, a stabilizing insert being removably positioned within said housing in said clearance to prevent tilting of said inner sleeve within said bore, and said housing being adapted to be disassembled to permit removal of said insert to permit tilting of said inner sleeve within said outer bore.

2. The system of claim 1 including shock absorber means in at least one of said stop means disposed toward said sleeve member.

3. The system of claim 2 including shock absorber means in each of said stop means.

4. The system of claim 2 wherein said shock absorber means is a washer mounted in its stop means around said rod.

5. The system of claim 4 wherein said washer is made from an elastomeric material.

6. The system of claim 1 wherein said inner stop means is a split sleeve mounted around said rod, and said adjustable locking means comprises clamp means spanning the open ends of said split sleeve.

7. The system of claim 6 wherein said shock absorbing means is a washer mounted in said split sleeve around said rod disposed toward said sleeve member.

8. The system of claim 7 wherein each of said stop means is a split sleeve having a washer therein.

9. The system of claim 1 wherein said coupling further includes means for selectively adjusting the orientation of said rod about its own axis and about an axis perpendicular to its own axis and linearly in a vertical plane.

10. The system of claim 1 including a plurality of said couplings.

11. The system of claim 10 wherein said frame is a quadrilateral frame, and said coupling being mounted at selected corners of said frame.

12. The system of claim 11 wherein at least one of said rods is a single straight element spanning a respective pair of said sets of pins.

13. The system of claim 1 wherein said rod has a completely smooth outer surface.

14. The system of claim 1 including a second rod, each of said rods being carried by a portion of said coupling, and each of said portions of said coupling carrying a respective rod being provided with mating roughened surfaces so as to permit a virtually infinite number of gradations in the relative angulation of said rods.

15. In a method of treating a bone fracture by use of an external fixation system which includes mounting sets of pins from a frame on longitudinally opposite sides of the bone fracture with the frame including longitudinally extending rods secured to coupling means, the improvement being providing as at least one of the coupling means a sleeve member mounted around a respective rod with an inner stop mounted on the rod on the side of the sleeve member toward the bone fracture and with a remote stop mounted on the rod on the side of the sleeve remote from the bone fracture, forming the sleeve member from a housing having a longitudinal bore with an inner sleeve located in the bore and with the inner sleeve having an outer diameter less than the diameter of the housing bore to provide clearance therebetween whereby the inner sleeve may tilt within the housing, removably positioning a stabilizing insert in the clearance between the inner sleeve and the housing, slidably mounting the rod in the inner sleeve, mounting each stop against the sleeve member to minimize any sliding movement of the rod in the sleeve member during the initial stage of healing to maintain the bone fracture in static neutralization, and subsequently moving the inner stop a preselected distance away from the remote stop to permit a controlled amount of sliding movement of the rod in the sleeve member.