Polymer hydrogels

Claim 2

Soft tissue implants, for the replacement andlor enhancement of human or animal soft tis sue, composed of a hydrogel comprising (a) a gel able polysaccharide and/or protein or polypeptide and (b) a polymer of a hydrophilic acrylic and/or methacrylic acid derivative.

Claim 3

Implants as claimed in claim 1 in which the hydrogel comprises (a) agar-agar (agarose) and (b) cross-linked polyacrylamide.

Claim 4

Implants as claimed in claim 2 in which the ratio of component (a) to component (b) is in the range 1:3 to 1:4.

Claim 5

Implants as claimed in any of claims 1-3 which the water content of the hydrogel is 95 to 98- by weight.

Claim 6

implants as claimed in any of claims 1-4 in the form of breast-shaped prostheses.

Claim 7

The use of the hydrogel defined in claim 1 for the preparation of a soft tissue implant for re placement and/or enhancement of human or ani mal soft tissue. There was no evidence of significant biodegrada-

Claim 8

The use of said hydrogel as claimed in claim tion at three months and no evidence of skin sensi- 115 6 for the preparation of an implant for replacement tivity developing. (b) Reconstructive Surgery Studies; rats. Two studies were carried out in the rat: in the first a large muscle defect In the sacrospinalis muscle in the lunbar region was replaced with polyacrylamideagarose and the fascia closed over it, while in the second a pair of "breast implants" were placed subcutaneously or retropectoral in the anterior tho- racic region. The muscle implants were studied after six weeks and six months. There was no functional disability in the animals and the implant site was not palpable through the skin in life. There was a minimal fibrous capsule (<70urn) around the implant and there appeared to be hypertrophy of and/or enhacement of fatty tissue.

Claim 9

The use of said hydrogel as claimed in claim 7 in which said implant is a breast prosthesis.

Claim 10

The use of said hydrogel as claimed in claim 6 for the preparation of an implant for replacement and/or enhacement of muscle tissue.

Claim 11

The hydrogel as defined in claim 1 for use in the preparation of an implant for replacement and/or enhancement of human or animal soft tissue. Printed in the UK for HMSO, D8818935, 1.86, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.