A circumferentially and longitudinally continuous scoring structure having a diameter in an initial unrestrained state that is smaller than a deflated diameter of the balloon is disposed around an outer surface of the balloon in an expanded configuration. The scoring structure continually exerts a radially inward compressive force against the balloon such that when the balloon is expanded from a deflated configuration to an inflated configuration, the scoring structure expands in a radially outward direction and remains in continuous compressive contact with at least a portion of the balloon as the balloon unfolds. The scoring structure may be entirely free of attachment to the balloon and catheter, and may extend substantially a length of a working region of the balloon. The scoring structure may include a plurality of circumferentially compressible members connecting longitudinal members.