2.5. Arthroscopic preparation of chondral defect

The knee was approached via antero-lateral and antero-medial arthroscopic portals and normal saline was infused under pressure (approximately systolic blood pressure). A Wolf cannula (Karl Storz GmbH, Tuttlingen, Germany) was inserted superolaterally as an outflow cannula. The articular cartilage lesions were carefully debrided using curettes and shavers; burrs were used if the subchondral bone was sclerotic. Micro-drilling was performed using a 3.0 mm-diameter drill to a depth of 5 mm at intervals of 3–5 mm in the lesion.