Deployment tool for distal bone anchors with secondary compression

Abstract

Deployment systems for deploying a bone fixation device are disclosed herein. One embodiment of a deployment system includes a syringe-shaped body configured to provide proximal traction to a bone fixation device in response to a compressive force between a finger grip and a plunger adapted to be engaged by the heel of a clinician's hand. The device may include a collet for gripping a proximal pin of a fixation device. The deployment device may also include a tool that includes an elongate body with a distal tip adapted to rotationally engage a bone fixation device in order to axially rotate the fixation device. A further deployment device embodiment includes a cauterizing tip for heat-cutting an excess portion of a pin of a bone fixation device.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional of U.S. patent application Ser. No. 10 / 790,671, filed Mar. 1, 2004, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 991,367, filed Nov. 13, 2001, now U.S. Pat. No. 6,890,333, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 934,467, filed Aug. 23, 2001, now U.S. Pat. No. 6,551,481, and claims priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60 / 464,398, filed Apr. 21, 2003, and claims priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60 / 451,296, filed Feb. 28, 2003, the entireties of the disclosures of each of which are incorporated herein by reference.BACKGROUND [0002] 1. Field of the Invention [0003] The invention relates in general to the field of bone anchors, and specifically to a deployment device for a bone anchor. [0004] 2. Description of the Related Art [0005]...

AI Technical Summary

Benefits of technology

The present invention provides a method and device for securing two bone fragments together. The method involves forming a bore through the first bone fragment and inserting a fixation device through the first bone fragment and into the second bone fragment. The fixation device has an elongate body with a proximal end and a distal end, with a helical anchor on the distal end and a retention structure on the body. A deployment device is used to apply a distal force to withdraw the elongate body with respect to the proximal anchor. The invention also provides a bone anchor deployment device that includes a bone fixation device and a deployment system. The technical effects of the invention include improved stability and secure fixation of bone fragments, as well as a simplified and efficient deployment process.

Problems solved by technology

However, portions of the femur are extremely susceptible to fracturing.

Fractures of the femur which extend into the neck of the bone are generally more difficult to treat than fractures restricted to the shaft of the femur.

The leading end portion of the implant typically includes means to positively grip the femoral head bone (external threads, expanding arms, etc.), but the inclusion of such gripping means can introduce several significant problems.

First, implants with sharp edges on the leading end portion, such as the externally threaded implants, exhibit a tendency to migrate proximally towards the hip joint weight bearing surface after implantation.

This can occur when the proximal cortical bone has insufficient integrity to resist distal movement of the screw head.

Such proximal migration under physiological loading, which is also referred to as femoral head cut-out, can lead to significant damage to the adjacent hip joint.

Also, the externally threaded implants can generate large stress concentrations in the bone during implantation which can lead to stripping of the threads formed in the bone and thus a weakened grip.

As a result, all fatigue loading is concentrated at the attached ends of the arms and undesirably large bending moments are realized at the points of attachment.

In addition, conventional threaded implants generally exhibit insufficient holding power under tension, such that the threads can be stripped out of the femoral head either by over-tightening during the implantation procedure or during post operative loading by the patient's weight.

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