The incidence of kidney stones (urolithiasis) has surged in both developing and developed countries, affecting approximately 15% of the global population. From 2010 to 2019, diagnoses of kidney and ureteral stones rose by 8% in Germany, 26% in France, and 15% in England. Correspondingly, the number of surgical stone removal procedures increased by 3%, 38%, and 18%, respectively. Common treatments include extracorporeal shock wave lithotripsy (ESWL), ureterorenoscopy (URS) with lithotripsy, and percutaneous nephrolithotomy (PCNL).
URS, depending on stone size, has become a preferred method due to advancements in intraoperative imaging and laser technology. Despite these improvements, small fragments often remain post-intervention, leading to recurrent stones. Complete removal of all fragments is crucial to significantly reduce recurrence rates. Current literature suggests a high recurrence rate with residual fragments, impacting healthcare costs and patient quality of life.
A key objective in endourological research is optimizing the stone clearance rate. Techniques like coagulum lithotomy and the autologous blood clot technique have been developed to enhance residual stone removal after laser fragmentation. These methods benefit selected patients but are not widely adopted due to complications such as reduced intraoperative visibility and long coagulum formation times.
Recently, a two-component hydrogel system called mediNiK® (Purenum GmbH, Germany) was developed. This biocompatible gel can be applied through an endoscope after stone fragmentation and large fragment retrieval to embed smaller fragments and dust, forming a removable conglomerate. MediNiK® has demonstrated effectiveness in embedding and removing stone residues and is already in clinical use in Europe, showing potential for optimizing stone removal.
A multicenter study has assessed the safety and tolerability of mediNiK® in standard URS (Open, randomized, multicentre study to evaluate the safety, tolerability, and performance of mediNiK® compared to standard treatment in kidney stone removal - DRKS00030532). Results indicate the gel is safe and tolerable. However, further data from larger cohorts and comparisons with conventional URS are necessary before widespread adoption of mediNiK®.
Male or female subjects aged ≥ 18 years
Evidence of nephrolithiasis on presentation of a preoperative computer tomography (CT) scan not older than 6 months
Minimum size of the kidney stones defined as >10mm in the longest axis in the preoperative CT.
Ability to read, write and speak German
Participation in another clinical trial for kidney stone removal in the last 6 months
Subjects with gastrointestinal cancer who have not been in remission for at least 2 years
Subjects with a single kidney, horseshoe kidney or other anatomical abnormalities that may increase the risk of surgery for the subject
Subjects with untreated ureteral stenosis or renal stenosis and narrow ureteropelvic junction/ureterovesical junction
Crossover
Standard of Care Ureterorenoscopy
Procedure/SurgeryThe patient provides written informed consent and is positioned in the supine position. After disinfection, sterile draping, and single-shot antibiotic administration a rigid cystoscopy is performed. Intubation of the ostium with a hydrophilic guidewire and placed into the renal pelvis under fluoroscopic control. After a semirigid URS, a working sheath is placed up to the Kidney. A flexible URS with lithotripsy with a Thulium lase is then performed to dust the stones. The fragments are retrieved for analysis. Finally, a double-J or mono-J stent and a transurethral catheter are placed.
Standard of Care Ureterorenoscopy with MediNiK
Procedure/SurgeryThe patient provides written informed consent and is positioned in the supine position. After disinfection, sterile draping, and single-shot antibiotic administration a rigid cystoscopy is performed. Intubation of the ostium with a hydrophilic guidewire and placed into the renal pelvis under fluoroscopic control. After a semirigid URS, a working sheath is placed up to the Kidney. A flexible URS with lithotripsy with a Thulium lase is then performed to dust the stones. The fragments are retrieved for analysis. Application of MediNiK to embbed the residual stones in the hydrogel and extract it with a basket. Finally, a double-J or mono-J stent and a transurethral catheter are placed.
Stone free Rate after URS
To answer the primary research question, a comparison of the SFR between the two surgical procedures is planned using the chi-square test. In order to be able to show a statistically significant difference with regard to the surgical procedures according to the current data situation (75 % vs. 95 %), a sample size of 120 was defined with a power of 80 % and a significance level of 0.025 (the significance correction is made due to the definition of two co-primary endpoints in relation to the definition of freedom from stones).
Surgery Duration
• Duration of surgery (minutes, continuous): defined as the time from transurethral entry with the cystoscope to ureteral stent insertion in the affected kidney)
Laser duration
• Laser duration (minutes, continuous): defined as the time until the stone is sufficiently dusted
Basketing duration
• Basketing duration (minutes, continuous): defined as the time until the fragments are completely captured and removed
Complication
• Complication rates according to Clavien Dindo (I-IV); the type and number (%) are recorded
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