8. When to knuckle

With the progress of wire technology, knuckle wire should NOT be a first line wiring technique in most CTO lesions. Knuckle wire should be used when there is vessel course ambiguity to reveal vessel course. Rarely in very calcified and tortuous long CTO, where high penetration wire wiring may perforate the vessel, knuckle wire can be considered. One final indication for knuckle wire is after difficult and long retrograde channel crossing in a long CTO where procedure time is long and radiation limit is nearly reached. In this situation knuckle wire can rapidly cross the CTO body allowing completion of the case before radiation limit is reached.