A plane-to-plane joint is configured for securing planar segments of one or more sheet materials together without the need for additional fasteners. The upper body is provided with a handle so that the tool may be manually held by the surgeon with the opposing bills in position in the prosthesis. A heat emitter may be positioned within the housing for emitting a necessary amount of heat for calibration purposes. The system can further determine a location of the audio source relative to the reference point. The resin composition of the present invention comprises a biodegradable resin as a main resin component, but can provide molded articles excellent in hydrolysis resistance, mechanical characteristics, and dimensional stability.