System to be used with an implanting tool

Abstract

A system to be used with an implanting tool having a tip part. The system has a longitudinal axis and includes a polymeric screw having a head and an adapter between the screw and the implanting tool. The adapter includes a first part that fits the tip part of the implanting tool.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 11 / 802,692 filed 24 May 2007, which claims priority to Finnish patent application 20065349 filed 24 May 2006, the entire contents of both of which are hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to a system to be used with an implanting tool. There is a special adapter between a polymeric screw to be screwed and the implanting tool.BACKGROUND[0003]Metallic screws have been used for tissue fixation in surgical procedures since the 1940's. Metallic screws preferably made of stainless steel or titanium are still most commonly used in surgery. Metallic materials, however, are significantly stiffer than bone or other tissues in human body. This mechanical incompatibility of the fixation device with the healing tissue generates several problems, such as a stress shielding effect, the loosening of the fixation due to micr...

AI Technical Summary

Benefits of technology

Enables the use of standard surgical instruments for bioabsorbable screws, reducing surgical costs and preventing screw breakage during torque application, while ensuring secure fixation and easy removal without compromising aseptic conditions.

Problems solved by technology

This mechanical incompatibility of the fixation device with the healing tissue generates several problems, such as a stress shielding effect, the loosening of the fixation due to micro motion on the implant tissue interface, and the local necrosis of the tissue due to too high local stresses in the tissue.

Additionally, long term complications due to the corrosion products of the fixation devices are not uncommon.

Bioabsorption, on the other hand, diminishes the risk of long term complications.

Bioabsorbable fixation devices have not replaced the metallic fixation devices used in surgery as was expected already years ago.

There are several reasons for that, such as the lack of confidence on the bioabsorbable products among the clinicians used to perform the operations with metallic devices, and in some cases, the more demanding surgical technique related to the use of the bioabsorbable fixation device.

In the case of bioabsorbable fixation screws, the screw head design is strongly limited by the mechanical properties of the bioabsorbable polymer materials.

The material properties of bioabsorbable polymers do not allow the usage of standardised bone fixation screw heads, e.g. hexagonal or torx heads.

The problem with AO / ASIF compatible instruments and bioabsorbable screws is that the instruments have been designed to be used with metallic implants.

The mechanical properties of the bioabsorbable screws are not adequate to be able to use the AO / ASIF instruments with them.

Usually, the bioabsorbable screws have to be implanted with appropriate instrumentation that increases the costs of the operations.

The other problem with the use of bioabsorbable screws is the breaking off of the screw when twisted with the screwdriver.

Because surgeons are used to applying metallic screws that can withstand much more torque, the shift to bioabsorbable screws often results in using excessive torque with them.

The forces of such torque-limiters have been adjusted to metallic screws and cannot be used with bioabsorbable ones.

In many cases, they have also been designed to be used with electrical screwdrivers, which are not appropriate for bioabsorbable screws because it is important to use manual drivers to maintain a better response when tightening bioabsorbable screws.

Also, if the screw has been stuck, the secondary instrument has to be used to remove the screw.

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