Effects of Modifying Hinotori Surgical Robot System on the Learning Curve of Robot-Assisted Radical Prostatectomy

The hinotori Surgical Robot System (HSRS) is the first surgical robotic system developed in Japan and has recently become more widely used worldwide. A key advantage of HSRS is that it can be modified without changing the platform model itself. This study aimed to determine the effect of HSRS modification on the learning curve for robotic-assisted radical prostatectomy (RARP).

Between December 2020 and February 2025, 482 RARP procedures using HSRS were performed by 21 cockpit surgeons. Among these, 320 cases performed by 16 surgeons at our hospital and affiliated institutions were analyzed. According to the timing of HSRS modification, cases were divided into two groups: Group A (before modification) and Group B (after the latest modification, including reduced arm floating sensation, fewer emergency stops due to arm collision, and addition of a hand-switch clutch function). The K-value, defined as the slope of the linear regression line for chronological changes in cockpit time excluding lymph node dissection (LND), was calculated and compared between groups.

Of the 320 cases (median age 70 years, range 45-81), 143 were in Group A and 177 in Group B. The median K-value in Group B (-0.27495; range -1.7421 to 0.1002) was significantly better than in Group A (0.0691; range -0.237 to 5.3544; p = 0.0277). In Group B, cockpit time excluding LND decreased with experience, and K-values were not associated with prior case number (p = 0.5018).

HSRS modification was associated with a more favorable learning curve for cockpit time in RARP.