GB1102118A - Collagen sponges - Google Patents

Abstract

In the manufacture of a collagen sponge for use in surgical procedures, untanned reconstituted collagen tape prepared as described in Specification 1,019,711 is washed successively with a solution containing 0.1% by weight sodium chloride and with water. According to Example 1, the washed and wet tape is added to water containing a minor proportion of acetic acid and is allowed to swell. After agitation and addition of further water to give a mixture containing 0.5% by weight collagen, the mixture is homogenized by pumping. After placing in a stainless steel tray, the resulting collagen dispersion is frozen and lyophilized to produce a sponge which then is subjected to a heat fixation process to increase tensile strength and to prevent excessive reswelling when placed in water. According to Example 2, an aqueous saturated solution of carbonic acid is added to the washed and drained tape which then is dispersed by stirring and allowed to swell. After stirring, the mixture is homogenized. After placing on a stainless steel form, the collagen dispersion is frozen and lyophilized to produce a sponge which is dried at elevated temperature. The sponge, which is in the form of a sheet having a network of interconnected channels extending therethrough, thereafter is perforated with holes to permit increased flow of liquid into and through the sponge; the sponge may be perforated in die punch apparatus as used for sheet metal perforation. In order to improve liquid resistance and handling properties the sponge may be tanned, for example prior to perforation, with formaldehyde, chrome alum, tannic acid or phosphoric acid.ALSO:In addition to the network of interconnected channels extending therethrough, a collagen sponge is perforated with holes. The sponge is in the form of a sheet having two principal surfaces, the holes being normal to, and extendthrough, both these surfaces. The holes permit increased flow of liquid into and through the sponge and reduce the tendency of the sponge to float away from a wound to which it is applied. The holes preferably are between 0.1 mm. and 3.0 mm. in diameter and may be spaced 2 mm. apart. In order to improve liquid resistance and handling properties, the sponge may be tanned, for example prior to perforation, with formaldehyde, chrome alum, tannic acid or phosphoric acid, thereby to provide a water-insoluble tanned sponge body. Examples decribe in detail the preparation of tanned and untanned sponges from untanned reconstituted collagen tape prepared as described in Specification 1,019,711, the sheet of sponge being perforated in die punch apparatus as used for sheet metal perforation.