A Randomized, Single-Blind Clinical Trial Comparing Robotic-Assisted Fluoroscopic-Guided with Ultrasound-Guided Renal Access for Percutaneous Nephrolithotomy

Abstract

Purpose: We conducted a randomized, single-blind clinical trial comparing the surgical outcomes of robotic-assisted fluoroscopic-guided (RAF group) and ultrasound-guided (US group) renal access in mini-percutaneous nephrolithotomy (PCNL).

Materials and methods: We recruited patients who underwent mini-PCNL with ureteroscopic assistance for large renal stones between January 2020 and May 2021. Block randomization was performed using online software. Automated needle target with x-ray was used for fluoroscopic-guided renal access in the RAF group. PCNL was performed by residents using a pneumatic lithotripsy system with 16.5Fr/17.5Fr tracts. The primary outcome was single puncture success, and the secondary outcomes were stone-free rate, complication rate, parameters measured during renal access and fluoroscopy time.

Results: In total, 71 patients (35 in US group, 36 in RAF group) were enrolled. No difference was seen in the single puncture success rate between the US and RAF groups (34.3% and 50.0%, p=0.2). In 14.3% cases in the US group vs no cases in the RAF group, the resident was unable to obtain access due to difficult targeting (p=0.025). The mean number of needle punctures was significantly fewer, and the median duration of needle puncture was shorter in the RAF group (1.83 vs 2.51 times, p=0.025; 5.5 vs 8.0 minutes, p=0.049, respectively). The stone-free rate at 3 months after surgery was 83.3% and 70.6% in the RAF and US groups, respectively (p=0.26). Multivariate analysis revealed that RAF guidance reduced the mean number of needle punctures by 0.73 times (p=0.021).

Conclusions: RAF renal access in mini-PCNL may have further potential applications in this field.

Keywords: artificial intelligence; kidney calculi; nephrolithotomy, percutaneous; robotic surgical procedures; ureteroscopy.

Figure 1.

Study flowchart. Asterisk indicates block randomization, which was performed with adjustment for age, sex, laterality, total stone burden, hydronephrosis grade and presence of staghorn stones.

Figure 2.

RAF percutaneous renal access. A, fluoroscopic image of an upper calyceal stone. B, a needle insertion point on the patient’s skin is marked under the fluoroscopic confirmation of renal collecting system. C and D, the software monitor view connected to the device and C-arm. The robotic arm is mounted on the patient’s back and keeps the target calyx in the inner yellow circle. Three marker balls are detected for calibration, then a needle is set in the holder before alignment (C). After the alignment, the needle trajectory is determined as a bull’s-eye position and automatically positioned by the robotic arm (D). E, the external view of the device with needle after the alignment. F, the needle is inserted from the targeted upper calyx. The C-arm is tilted to visualize the depth. G, the wire placement into the collecting system is confirmed by both fluoroscopy and the ureteroscopic view (inset).