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.
