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Graft Fixation Device

a technology of grafts and fixing devices, which is applied in the direction of prosthesis, osteosynthesis devices, ligaments, etc., can solve the problems of degenerative arthritis, articular hamstring graft fixation techniques, and injuries of physically active peopl

Inactive Publication Date: 2008-09-18
UNIV OF COLORADO THE REGENTS OF
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]In one embodiment, the invention provides a fixation device, which may fix a soft tissue graft, like a tendon or ligament graft, to a bone with little risk of damaging the soft tissue graft during insertion.

Problems solved by technology

Injuries to ligaments are common, and patients who are physically active are generally more susceptible to such ligament injuries.
ACL injuries cause instability in the knee joint which, when left untreated, may lead to degenerative arthritis.
Conventional extra-articular hamstring graft fixation techniques have complications, such as suture stretch, graft tunnel motion and so-called windshield wiper effect where the size of the intra-articular drill hole end will increase due to graft movement in the drill-hole.
Also the use of screws as fixation implants for soft tissue grafts in anterior crucial ligament procedures is complicated due to: 1) the threads of the screw cutting the grafts during screw installation if the screw is too big in relation to the tendon and / or if the space between the drill hole and tendon grafts is too small; 2) the threads of the screw damaging the tendon during screw installation; 3) the tendon rotating with the screw during screw installation so that the optimal position of the grafts is lost and / or the grafts are damaged; 4) divergence of the grafts and / or screw occurring; and 5) the bio-absorbable screw breaking during insertion.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

SMP Fabrication

[0153]Tert-butyl acrylate (tBA) monomer (Aldrich), poly (ethyleneglycol) dimethacrylate (PEGDMA) cross-linker (Aldrich), and the photoinitiator 2,2-dimethoxy-2-phenylacetophen one (Aldrich) were used in their as-received condition without further purification. A polymer solution was formulated by combining 10 wt % PEGDMA, 0.1 wt % initiator, with the balance tBA. Other crosslinker / momomer ratios can be considered and can range from 1 wt %-99 wt % cross-linker. Other photoinitiators include acetophenone, anisoin, anthraquinone, benzene chromium tricarbonyl, benzil, benzoin, benzoin ethyl ether, berizoin isobutyl ether, benzoin methyl ether, benzophenone, 4-benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, 4,4′-bis(diethylamino)-4′ benzophenone, 4,4′-bis(dimethylamino)-4′benzophenone, camphorquinone, 2-chlorothioxanthen-9-one, dibenzosuberenone, 2,2-diethoxyacetophenone, 4,4′-dihydroxybenzophenone, 4-(dimethylamino)benzophenone, 4,4′-dimethylbenzil...

example 2

SMP Thermomechanical Characterization

[0157]The polymer samples were tested using a Perkin Elmer Dynamic Mechanical Analyzer (DMA-7). A three-point flexural configuration was used for glass transition (Tg), strain recovery, and stress recovery tests (FIG. 24 inset). The three-point flexure loading allowed reasonable stress / strain levels in the sample for the temperature range spanning the glassy to the rubbery state. In particular, this configuration allowed 30% maximum bending strain over a 5 mm span during the stress and strain recovery tests. FIG. 24 shows a comparison between the PEGDMA copolymer and PLA, which is a biodegradable polymer used in tibial devices. The drop in storage modulus as temperature increases indicates the material is transforming from a glassy or stiff state to a rubbery state. Also, Tg may be defined in relation to the peak of the tan delta curve.

[0158]The glassy storage modulus is an indication of the material's stiffness. A SMP plug will have a stiffness ...

example 3

Plug Manufacturing

[0160]The test plug material was machined from a 45 wt % PEGDMA ratio to 55% PMMA (poly methyl methacrylate) with a 0.1% photo initiator and mixed in a 14 mm diameter glass test tube. The open end of the test tube was blocked off with a rubber stopper and the test tube plus solution was placed in a 0° C. water bath under a UV lamp for 10 minutes. The glass test tube was then removed leaving a 14 mm PEGPMMA cylinder with a glass transition temperature (Tg) of 40° C. The plugs were machined from the cylinder stock using coconut oil as lubricant and spinal speeds of 450 RPM to be approximately 11.5 mm in diameter and 25.4 mm in length. The edges of the device were filleted to 0.5 mm radii to ensure the device would not shear a soft tissue (tendon) on contact.

[0161]In addition, various unconstrained (or un-deformed) shapes were created to demonstrate multiple forms of possible unconstrained shapes, shown in FIG. 7. Unconstrained shapes and their differences from post-i...

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PUM

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Abstract

In one aspect a device is disclosed for use as a bone implant comprising, a body having a pre-implantation shape and a post-implantation shape different from the pre-implantation shape. The body is configured to change from the pre-implantation shape to the post-implantation shape in response to the body being activated. The body is configured to be inserted in a bone recess while the body is in the pre-implantation shape. In another aspect a method is disclosed comprising inserting a cable member into a recess in a bone, inserting a retention device into the recess, the retention device containing a shape memory material, and activating the shape memory material.

Description

RELATED APPLICATIONS [0001]This application claims the benefit of U.S. Provisional Application No. 60 / 667,876 filed Apr. 1, 2005, which application is hereby incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002]The invention was sponsored by National Science Foundation Grant No. NSF-DMI-0200495 and a National Institute of Health Grant No. NIH-HL-067393 and the government has certain rights to this invention.BACKGROUND OF THE INVENTION [0003]Ligaments are strong fibrous soft tissue connecting the articular ends of bones to bind them together and to facilitate or limit motion. Injuries to ligaments are common, and patients who are physically active are generally more susceptible to such ligament injuries. The anterior cruciate ligament (ACL) of the knee joint is a ligament frequently injured by such patients. ACL injuries cause instability in the knee joint which, when left untreated, may lead to degenerative arthritis. Because of this...

Claims

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Application Information

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IPC IPC(8): A61B17/56
CPCA61B17/0401A61B2017/0448A61F2/0811A61F2002/0835A61F2002/0858A61F2002/0864A61L27/16A61F2002/0888A61F2210/0014A61L27/50A61L2400/16A61L2430/02A61F2002/0882A61B2017/00871
Inventor GALL, KENNETHTYBER, JEFFREYYAKACKI, CHRISBARTZ, REED
Owner UNIV OF COLORADO THE REGENTS OF
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