Midwest Stone Institute

Over the past three decades, electrohydraulic extracorporeal shock wave therapy (ESWT) as a treatment modality for equine orthopaedic disorders has sparked exponential interest among practitioners, but its clinical applications are quickly evolving and a current review highlighting modernised equine clinical use is lacking. The objective of this review is to summarise the most current ESWT technology, evidence for its use, proposed mechanisms of action and clinical applications in horses while also highlighting the areas requiring further investigation. The three ways to generate a shock wave are through electrohydraulic, electromagnetic or piezoelectric mechanisms, but over the last decade, electrohydraulic systems have predominated due to the ability to focus and control a therapeutic waveform. Shock waves' primary physical effect is believed to be via mechanotransduction leading to cellular activation and downstream signalling. Experimentally, ESWT's effects on osseous, connective tissue and wound healing via various mechanisms of action have been reported both in the human and veterinary literature. Clinical trials have investigated ESWT's orthopaedic application including osteoarthritis, thoracolumbar pain, navicular syndrome, tendinopathy and proximal suspensory desmopathy, with its concomitant use with biologics representing an area of active research. Direct ESWT protocol comparisons in terms of long-term efficacy with variables of energy, depth and exposed tissue types are still lacking with evidence-based recommendations being largely anecdotal. Technical advancements to facilitate the safe and judicious use of ESWT include human and equine hearing protection, light sedation and/or patient restraint. Efforts to ensure the safe and judicious use of ESWT and its analgesic effects are ongoing.

To evaluate the efficacy of three lithotripter configurations that utilize the Medstone STS treatment head. From 1999 through 2002, 13,131 patients were treated with the Medstone STS fixedsite unit (STS-FIX; 52%), the mobile coach-transportable unit (STS-MOB; 26%), or the modular operating-room unit (STS-T; 22%). All units were staffed by a rotating schedule of the same ten SWL-certified radiological technicians. The treating urologists reported follow-up that included plain abdominal radiography to document stone-free rate (no residual fragments) and the need for auxiliary procedures or re-treatment. An efficiency quotient (EQ) was calculated for each unit. The overall stone-free rate for the STS-FIX, STS-MOB, and the STS-T was 59%, 62%, and 65%, respectively. The STS-FIX had the lowest stone-free rate for lower-pole stones (48%) and stones 21 mm to 30 mm (30%) compared with the STS-MOB (57% and 62%, respectively) and the STS-T (59% and 54%, respectively). However, the STS-FIX had a higher stone-free rate in the middle ureter (86%) than the STS-T (67%) and STS-MOB (65%). The STS-FIX required more post-SWL procedures overall (12%) than the STSMOB (4%) and STS-T (5%). The re-treatment rates for the STS-FIX, STS-MOB, and STS-T were 7%, 6%, and 6%, respectively. The STS-T had the highest overall EQ (59) followed by the STS-MOB (56) and the STSFIX (50). New configurations of the STS lithotripter have a significant positive impact on efficacy compared with the original fixed machine. Availability of real-time fluoroscopy with the STS-T may impact the higher EQ of this machine.

The treatment results obtained in children using an unmodified Dornier HM3 or a Medstone STS lithotripter for renal and ureteral stones were compared. The Dornier HM3 was used to treat 28 renal and 10 ureteral stones, while the Medstone STS was used to treat 73 renal and 34 ureteral stones. The treatment results were compared using the chi-square test to determine statistical significance. The stone-free rate, retreatment rate, and post-SWL secondary-procedure rate were 68%, 4%, and 0, respectively, with the Dornier HM3 and 93%, 6%, and 3.6%, respectively, with the Medstone STS for single renal stones and 80%, 0, and 0, respectively, with the Dornier HM3 and 82%, 0, and 5.9%, respectively, with the Medstone STS for single ureteral stones. Abnormal anatomy (horseshoe kidney, allograft kidney) or functional interference with the passage of fragments (urinary diversion, neurogenic bladder) was present in 16% of the children treated with the Dornier HM3 compared with 5% of those treated with the Medstone STS (p = 0.36). The treatment results with the unmodified Dornier HM3 and the Medstone STS were similar except for the statistically significantly higher stone-free rate for single renal stones obtained with the Medstone STS. The difference was most likely attributable to the smaller number of children with abnormal anatomy or functional interference with the passage of fragments who were treated with the Medstone.

Extracorporeal shock wave lithotripsy (ESWL) has now evolved to the point where most treatments are rendered either without the need for anesthesia or with the use of only minimal, intravenous sedation. The Siemens Lithostar machine was originally designed to be used with intravenous sedation in combination with local anesthesia. Herein, we report use of a transcutaneous electrical nerve stimulator unit to achieve satisfactory analgesia in patients undergoing shock wave lithotripsy. Overall, 60% of patients were able to undergo treatment with only a TENS unit. More importantly, when the total number of shock waves was limited to 3,000 or fewer, 90% of patients were able to undergo therapy without any supplemental intravenous or local anesthesia. The TENS unit is inexpensive to use, noninvasive, has no associated morbidity, and allows for the same degree of stone fragmentation as is seen with more invasive forms of anesthesia.