Implantable prosthetic or tissue expanding device

Abstract

A keratin hydrogel-filled implantable prosthetic device. One device is a breast implant for augmenting or reconstructing a human breast including an envelope containing a keratin hydrogel. One keratin hydrogel is formed from a solid precursor which forms a keratin hydrogel upon addition of water. One source of keratin is human hair. In one method, an envelope suitable for implantation and a solid keratin hydrogel precursor are provided. The solid can be in fibrous or powder form. The solid precursor can be inserted into the envelope interior. A small incision near the breast can be made and the envelope inserted into the incision. After insertion, water can be injected into the envelope interior, preferably through the incision and through a self-sealing port in the envelope. In one method, the implant is provided as a kit, with the envelope and keratin hydrogel provided. The hydrogel can be injected into the envelope either before or after insertion into the breast area. One kit has a powdered, keratin hydrogel precursor disposed within the envelope interior, awaiting the addition of water, preferably after insertion of the implant into the body.

Description

PRIORITY AND CROSS REFERENCE TO CO-PENDING APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 09 / 394,783 filed Sep. 13, 1999. This present application is also related to U.S. patent application Ser. No. 09 / 330,550, filed Jun. 11, 1999, entitled SOLUBLE KERATIN PEPTIDE, and U.S. patent application Ser. No. 09 / 394,782, filed Sep. 13, 1999, entitled WATER ABSORBENT KERATIN AND GEL FORMED THEREFROM.FIELD OF THE INVENTION [0002] The present invention is generally related to medical prostheses or implants for augmentation, tissue expansion or replacement of soft tissue, including breast implants. In particular, the present invention is related to implants filled with a keratin hydrogel. BACKGROUND OF THE INVENTION [0003] Breast augmentation and reconstruction through medical procedures has been performed by physicians for decades. Early attempts using filler materials alone, without an enclosing envelope, had less than optimal long-term effec...

AI Technical Summary

Benefits of technology

[0011] The keratin suspension may be heated, and is preferably heated to boiling for a time sufficient to swell the keratin. The keratin suspension may be stirred without heat for a longer period of time to allow a more complete association or reaction between the sulfonic acid groups and the base cations. The continued reaction time at or near room temperature, or even below room temperature while stirring is contemplated by the inventors to allow the base cations to approach and bind to the keratin anionic sites with a lower incidence of peptide backbone degradation that could occur with continued boiling. The cations for use in the present invention, therefore, must be able to interact with the anionic cysteic acid groups in the keratin material. The use of the term “cations” or “monovalent cations” in the present disclosure and claims is an indication of those cations that are able to form such an interaction. After a sufficient reaction time, the keratin solid may be removed from the suspension by filtration, for example, and dried, leaving a solid salt formed of the keratin sulfonic acid or cysteic acid groups and base cations. This solid may be shredded into a fibrous form and / or ground into a finely divided powder. This solid may be used in certain embodiments, or it may be hydrated by adding water, for example, and the hydrogel, or viscoelastic hydrogel thus formed may be used in certain embodiments.

[0026] Implants made with a hydratable keratin solid offer particular advantages over other implants, especially in implants that involve a large amount of material, such as breast or gluteal pad implants. In a preferred method of use, the hydratable keratin solid in powder or fiber form may be added to an envelope interior prior to insertion, and water may then be injected into the envelope after implantation, thus forming the hydrogel in situ. In the practice of this embodiment, the implant envelope containing a dry solid will have a small volume relative to the size of the final implant, thereby allowing a relatively small incision for insertion of the implant. In certain applications, it may be more advantageous to implant an empty envelope, again allowing for a relatively small incision, to form a hydrogel outside the body and then injecting the hydrogel into the envelope through a large bore needle, for example. It is also understood that implants may be formed with the hydrogel in place in the envelope prior to implantation.

[0027] Tissue expanders made with a hydratable keratin solid offer particular advantages over other tissue expanders, especially tissue expanders which require volume adjustments which are made through an externally filled tube. The use of an external filling is often uncomfortable and inconvenient for the patient, and can lead to an increased incidence of infection. In a preferred method of use, the hydratable keratin solid in powder or fiber form may be added to a tissue expander envelope interior. The permeation of body fluids through the envelope can be controlled through the use of certain materials and engineering principle well known to those skilled in the art. The control of the diffusion rate has the effect of controlling the hydration rate of the keratin solid and thus, the expansion rate of the hydrogel thus formed. The expansion rate can thus be controlled in-situ, without the use of an external fill tube. This method of use would lead to a more comfortable and convenient tissue expander with lower incidence of infection. Alternatively, the hydration rate of the keratin solid can be controlled by controlling the absorbency of the keratin solid during manufacture as described herein. A solid tissue expander formed from an absorbent keratin solid with a controlled absorption rate would have the advantage of expanding its volume at a controlled rate in-situ, and thus providing the same advantages as noted previously.

[0030] Hair is a preferred source of keratin for the present invention. In particular, human hair is a preferred source. In one method, hair is harvested from the intended implant recipient. While any human hair is believed suitable as a source, the use of hair from the intended recipient may provide a psychological and allergenic advantage relative to hair from other sources.

Problems solved by technology

Early attempts using filler materials alone, without an enclosing envelope, had less than optimal long-term effects on appearance and health.

The use of silicone gel-filled silicone envelopes gave improved long-term appearance but has created concerns for manufacturers, surgeons and patients due to possible leakage of the silicone gel from the envelopes into the body.

Another issue in the field of breast reconstruction and in the healing of open wounds is the use of tissue expanders.

Unfortunately, in order to change the volume of the tissue expander a needle must be inserted into the envelope, thus requiring penetration of the tissue and causing pain and an increased possibility of infection.