A New Safe and Ergonomic Manipulation Tool for the Flank-Free Supine Position: "U-Pad"

One of the most important problems in the supine percutaneous approach to the kidney is the narrow surgical surface area (SSA) in the lumbar region. Herein, the spatial and angular geometric advantages of the U-shaped lumbar pad (U-Pad) used as a new positioning tool for safety and ergonomics in the supine percutaneous approach have been revealed. Data of patients who underwent endoscopic combined intrarenal surgery (ECIRS) using the U-Pad for kidney stones between March and September 2021 were prospectively collected. The demographic, preoperative, operative, and postoperative data of patients have been saved. The patients were positioned first with the standard gel pad (group 1) and then with the U-Pad (group 2). Both SSA (X and X+Y, cm²) and angular degree (α and β,°) calculations were compared. Fluoroscopy images with the same settings (97 kV/3.00 mA) were visually compared. In geometric data, trapezoidal area formula [(upper base + lower base) × height/2] and goniometer were used to compare with paired t-test. ECIRS was performed on 17 patients, 13 men and 4 women, with a median age of 39 (range 32-47). The median body mass index was 26.2 (23.5-29.1). Stone localization and features were recorded. The median SSA was calculated as 35.7 cm² in group 1 and 97.3 cm² in group 2, and it was calculated that the total SSA increased to 272.5% with a median of 61.6 cm² extra surgical area. Similarly, the downward manipulation angle was 32° (α°) in group 1, whereas it was 60.6° (β°) in group 2, and the median extra motion angle was calculated as 28.6° (89.3%). The U-Pad is a safe and rapid tool in the supine percutaneous approach to the kidney, providing at least two times the extra SSA and manipulation angle.