Pridie-drillings
They are named after Kenneth Hampden Pridie (1906-1963), a British surgeon and orthopedist. 1953 he described a technique for opening the bone-marrow-space via fine drillings up to 3mm deep at a distance of several millimeters in order to heal full coat cartilage defects in the knee. Due to the heat generation during the drillings with the development of a necrosis (tissue death) around the drilling location this technique was replaced by micro fracturing.
Only recently this technique experiences a renaissance due to new drilling techniques.