[Treatment of staghorn calculi on the basis of composition and structure]

Most staghorn calculi are infection stones composed of struvite and/or carbonate apatite. Sometimes, cystine, uric acid, whewellite and brushite stones also assume a staghorn configuration when located in the kidney. It is very important in stone crushing to know the composition and architecture of the stones. Struvite stones show a concentric laminal structure and are fragile because of wide interstices of crystals and rich organic matrix. These stones usually contain many bacterial colonies in the interstices of crystals and bacteria break out of the stones when they are crushed. Therefore, perioperative administration of antibiotics is necessary for prevention of bacteremia and sepsis. Whewellite stones and uric acid stones have a smooth surface and reveal compact radial and laminal structure especially in the peripheral layer. They are very hard and are refractory to crushing, and the fragments are large. Cystine stones show a compact radial monomineral texture and are very hard. The fragments made by crushing are large. Therefore, combination therapy of stone crushing and irrigation of alkali solution may be useful for treatment of cystine stones as well as uric acid stones. Calcium phosphate stones, hydroxyapatite or brushite stones, are rare and are formed in hyperparathyroidism, Cushing syndrome and renal tubular acidosis. Hydroxyapatite stones are rich in matrix and fragile. Brushite stones reveal radiate structure and are hard. There is no general method of treatment for staghorn calculi but we should select the most reasonable method including open surgery for each case taking into consideration the stone composition, predisposing factors and possibility of stone residue and recurrence.