A subcutaneously formed in place orthopedic fixation device is provided, such as for fixation of the spine or other bone or bones. The device comprises an inflatable member, such as a tubular balloon. A heat source is provided in thermal communication with the interior of the balloon. The balloon is positioned at a treatment site while in a flexible, low crossing profile configuration. The balloon is thereafter inflated with a hardenable media, and heated to accelerate hardening of the media. Methods and delivery structures are also disclosed.