A prospective randomized trial comparing 2 lithotriptors for stone disintegration and induced renal trauma

We compare the efficacy and resulting kidney trauma of the HM3 (Dornier Medical Systems, Inc., Marietta, Georgia) and Lithostar Plus (Siemens, Issaquah, Washington) lithotriptors in a prospective randomized trial treating calix and renal pelvis stones.

Patients with a solitary renal pelvic stone 2 cm. or less in diameter or a solitary calix stone 1 cm. or less in diameter were randomized for treatment with the HM3 or Lithostar Plus. Stone disintegration and dilatation of the pyelocaliceal system were evaluated by abdominal plain x-ray and renal ultrasound 1 day and 3 months after treatment. Kidney trauma was determined by measurement of N-acetyl-beta-glucosaminidase and beta-galactosidase (NAG) in pretreatment urine and 4, 12-hour urine samples collected within the first 2 days after extracorporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc.).

Of 167 patients with 176 stones 91 were randomized to the HM3 and 85 to the Lithostar Plus lithotriptor group. The preoperative stone burden was comparable in both groups. On postoperative day 1 patients treated with the HM3 or Lithostar Plus were stone-free or had fragments 2 mm. or less (91% and 65%, p <0.001), 3 to 5 mm. (8% and 25%, p = 0.003) and 6 mm. or greater (1% and 10%, p = 0.008), respectively. Patients treated with the HM3 had less posttreatment dilatation of the collecting system (p = 0.01). Obstructive pyelonephritis occurred in 1% of the HM3 and 8% of the Lithostar Plus group (p = 0.02). Re-treatment rate was 4% in the HM3 and 13% in the Lithostar Plus group (p = 0.05). Mean excretion of urinary NAG per treatment (including re-treatments) was comparable in both groups but NAG excretion in relation to stone volume and shock wave number 12 to 24 hours after ESWL was significantly higher in the HM3 group (p <0.05). At 3-months postoperatively 89% of the patients treated with the HM3 and 87% treated with the Lithostar plus were stone-free with no dilatation of the collecting system.

This prospectively randomized study indicated that the HM3 is still the gold standard in regard to disintegration of pelvicaliceal stones. Stone disintegration with the HM3 is better with fewer shock waves, re-treatment rate is lower, and posttreatment dilatation of the collecting system and complications such as obstructive pyelonephritis are less than those with the Lithostar Plus. ESWL induced kidney trauma is minor and resolves within 2 days. The HM3 delivers more energy per shock wave into the kidney as assessed by urinary NAG.