A composition that includes (a) a prepolymer having at least one free isocyanate group that is capable of bonding to tissue and that cures in vivo upon exposure to water to form a polymer having a compressive modulus between 1.9 and 14.4 MPa and a tensile modulus between 5.0 and 30, and (b) an oil that is miscible in the prepolymer, the oil being selected from the group consisting of silicone oils, mineral oil, vegetable oils, and combinations thereof. The composition retains its integrity when delivered in an aqueous medium.