Biodegradable polyurethanes: biodegradable low adherence films for the prevention of adhesions after surgery.

Adhesions commonly occur after internal disease or surgery. The natural healing response leads to the formation of vascular and avascular adhesions after inflammatory diseases and surgical interventions. A barrier film could be incorporated during surgery between layers of tissues that must not adhere to one another. The film would be biodegradable so that it disappears over a period of time, and would ideally be two sided, allowing relative movement at that interface, while being firmly anchored on the opposite side to prevent displacement. Polyesterurethane-polydimethylsiloxane graft polymers are synthesised. Chemical characterisation of the polymer is performed by using Fourier transform infrared spectroscopy and gel permeation chromatography. In vitro hydrolytic degradation is carried out in which films are immersed at 37 degrees C in alkaline solution. Degradation is assessed by tensile testing as a function of time to determine the degradation of mechanical strength, infrared spectroscopy, and mass loss. A titration method is also used to determine quantitatively the hydrolytic degradation. In order to study the adhesions of films, an in-vitro model based on a gelatine test, which is simple and rapid, is described. Suitable candidate films investigated from the in-vitro work are subjected to in vivo tests for both biodegradation and their ability to prevent adhesion.