Percutaneous nephrolithotomy, also known as “hole extraction”, is a method to remove stones (especially deer-horn and cast stones) from the kidney without incision. A small hole of about 0.7 cm in diameter is used to break up the stone and clip it out with Holmium laser. Indications for surgery: 1. All kidney stones requiring open surgical intervention, including complete and incomplete deerstalker stones, ≥2 cm kidney stones, symptomatic stones in the renal calyces or diverticula, stones that are difficult to be crushed by extracorporeal shock wave and those that have failed treatment. 2.Large stones in the upper ureter above L4, with heavy obstruction or length diameter >1.5 cm; or ureteral stones due to polyp encapsulation and ureteral tortuosity, ineffective ESWL or failed ureteral placement. 3. Special types of kidney stones, including pediatric kidney stones with obvious obstruction, kidney stones in obese patients, kidney stones combined with pelvic-ureteral junction obstruction or ureteral stenosis, isolated kidney combined with stone obstruction, horseshoe kidney combined with stone obstruction, transplanted kidney combined with stone obstruction, and kidney stones without effusion, etc.