Nanofracture is a procedure whereby a narrow 'pick' is used to make 9mm deep holes through the bone plate under the joint cartilage, with the purpose of encouraging blood and bone marrow cells to enter the area and help repair the defect.
Comparison of nanofracture with microfracture
The pick is smaller than the microfracture pick. A 'needling' technique may also be used, passing a needle into the bone via a cannulated nanofracture pick.
Reviewing subchondral cartilage surgery: considerations for standardised and outcome predictable cartilage remodelling. Benthien JP and Behrens P. Int Orthop. 2013 Nov; 37(11): 2139–2145.