Method for augmenting, reducing, and repairing bone with thermoplastic materials

Abstract

A method for augmenting a tissue including introducing into the tissue a first thermoplastic material at a first condition; treating the first thermoplastic material to achieve a second condition that includes an at least partially crystalline skin; and introducing a second material into the tissue whereby the first thermoplastic material and the second material are contained by the at least partially crystalline skin. Also a method of fracture reduction in a tissue including exposing to gamma radiation a mass of polycaprolactone characterized by a first shape; heating the mass of irradiated polycaprolactone above its melting temperature; introducing the heated mass of polycaprolactone into the tissue annulus to deform it from the first shape; allowing the material to return to the first shape.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is based off and claims priority to U.S. Provisional Patent application No. 60 / 799,283, filed May 10, 2006, the content of which is hereby incorporated herein by reference in its entirety.INCORPORATION BY REFERENCE [0002] Each and every reference cited herein is hereby incorporated by reference as if set forth in its entirety herein. TECHNICAL FIELD OF THE INVENTION [0003] Generally, the present invention relates to methods and materials for augmenting and repairing bone. BACKGROUND OF THE FIELD OF THE INVENTION [0004] Current standards for attaching implants such as plates to bones often constitute screws in a plurality of shapes. The purpose of these screws is to transfer the load from one bone fragment to the plate or nail and back to a secondary bone fragment. [0005] To ensure this load transfer, the screws must have a good connection in the bone and the plate. The connection between the plate and the screw can be ac...

AI Technical Summary

Problems solved by technology

However, even angular stable constructs fail in osteoporotic bone because of a lack of stability in the bone to screw interface.

Treating osteoporotic fractures in these areas can be very challenging for the surgeon because the screws can not find sufficient purchase in the weak trabecular structure.

Each of these methods has disadvantages.

For example, disadvantages of using PMMA include the permanent non-resorbing nature of PMMA.

It remains within the body after the fracture has healed and removal of the material is nearly impossible once implanted.

PMMA is initially too runny to handle and can quickly become too difficult to implant and the state of the material is not reversible.

PMMA has a minimal ductility, can bind to metals making screw removal difficult, and can be difficult to control the direction of implantation.

PMMA can either extravasate into the canal of the diaphysis (rendering it ineffective), into the joint space or become vascularized (leading to an embolism).

Furthermore, PMMA includes a risk of thermal necrosis due to the exothermic reaction during curing.

The calcium phosphate materials will not properly set unless the surrounding tissue is near 37° C. It can be difficult to control the direction of implantation of calcium phosphates and calcium phosphates can either extravasate into the canal of the diaphysis (rendering it ineffective), into the joint space or become vascularized (leading to an embolism).

Calcium phosphates include suboptimal mechanical properties while they often have adequate compressive strength, they have little tensile strength, flexural strength or ductility.

Furthermore, additional calcium phosphate material will not bond to calcium phosphate material that has already set and the drillability and screwability of the calcium phosphate is limited.

The addition of reinforcing fibers actually renders the cement less advantageous for hardware augmentation since the fiber will be filtered by the trabecular structure surrounding the hardware and will impede perfusion.

However the material remains suboptimal for the application.

PMMA is commonly used for vertebroplasty procedures but suffers from many of the problems stated above.

Calcium phosphate cements can be used as well, but also with the above limitations.

Further, in these types of applications there often exists a need to reduce the fractures or to compress the surrounding bone, which the existing materials are not capable of doing.

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