The Tripole lead family, with their unique tripolar electrode array, is the only family of leads principally designed to target back pain. Tripole Paddle leads are shielded to provide unidirectional stimulation.
References
1Struijk J, Holsheimer J. Transverse tripolar spinal cord stimulation: theoretical performance of a dual channel system. Med Biol Eng Comput. 1996 Jul;34(4):273–9.
2Oakley JC. Transverse tripolar spinal cord stimulation: results of an international multicenter study. Neuromodulation 2006;9(3):192-203.