Sutureless Purely Off-clamp Robotic Partial Nephrectomy: Evidence from a Randomized Controlled Noninferiority Trial

Postoperative renal functional decline after partial nephrectomy is increasingly recognized as a multifactorial phenomenon. Mir et al. identified three main mechanisms potentially responsible for postoperative renal injury: parenchymal loss during tumor excision, ischemic injury related to hilar clamping, and reconstructive injury caused by renorrhaphy.¹

Over the years, surgical innovation has mainly focused on the first two modifiable factors. Pure tumor enucleation aimed to preserve healthy renal parenchyma by following the natural pseudocapsular plane (instead of sacrificing a rim of uninvolved tissue, as occurs with enucleoresection).² Similarly, off-clamp surgery has been developed to minimize ischemia-reperfusion injury,^3-5 although the true impact of renal hilum clamping remains debated. Indeed, growing evidence suggests that ischemic damage does exist, although its clinical impact becomes more evident in patients with baseline renal impairment or highly complex tumors requiring prolonged warm ischemia times.^3-6

Reconstructive injury has received comparatively less attention. Yet experimental and clinical evidence suggests that cortical renorrhaphy is not biologically neutral. Renal reconstruction may compress and distort healthy parenchyma, producing a wedge of ischemic damage extending beyond the resection bed.⁷ Conversely, controlled monopolar coagulation appears to induce a more superficial and spatially limited injury, potentially offering an alternative strategy for hemostasis without cortical compression.^7,8

This is the conceptual basis of our sutureless purely off-clamp robotic partial nephrectomy program.

The rationale of our randomized controlled trial was not simply to compare two technical variants of robotic partial nephrectomy. By performing surgery off-clamp and systematically attempting tumor enucleation whenever feasible, the study was specifically designed to isolate the biological cost of renorrhaphy itself.⁹ In this setting, ischemic injury was eliminated and parenchymal loss was minimized; therefore, the comparison between sutureless partial nephrectomy and renorrhaphy could focus on the independent impact of reconstruction.

Our prospective randomized single-surgeon non-inferiority trial demonstrated formal statistical non-inferiority of the sutureless approach compared with standard renorrhaphy in terms of surgical and functional outcomes up to 12 months.⁹ These findings support the safety and feasibility of omitting cortical renorrhaphy in selected patients undergoing purely off-clamp robotic partial nephrectomy.

Of course, these results should be interpreted carefully. In many standard-risk patients—with two functioning kidneys, small renal masses, limited resection beds, and expected warm ischemia times below 10 minutes—the functional consequences of ischemia or reconstruction may be subtle and difficult to detect. However, the fact that damage is not easily measurable does not mean that it does not exist. Much like dust hidden beneath a carpet, renal injury may remain clinically invisible in low-risk patients while becoming critically relevant in fragile patients or complex surgical scenarios. This is where the concept becomes clinically meaningful: patients with solitary kidneys, pre-existing CKD, large or endophytic tumors, and cases requiring wider resection or prolonged ischemia are precisely those in whom every avoidable source of renal damage matters most.^3-5 These patients may benefit most from a strategy combining pure enucleation, off-clamp surgery, and selective omission of renorrhaphy.

Ultimately, the importance of this trial extends beyond the technical comparison between two approaches. It supports a broader conceptual shift: renal functional preservation after partial nephrectomy should not focus exclusively on ischemia, but on the progressive elimination of all avoidable sources of biological injury to the kidney. Among these, the biological cost of renorrhaphy may have long remained the least visible, yet perhaps also one of the most underestimated.

Written by: Aldo Brassetti,¹ Gabriele Tuderti,¹ Umberto Anceschi,¹ Alfredo Maria Bove,¹ Eugenio Bologna,¹ Lorenzo Capecchi,¹ Giuseppe Chiacchio,¹ Simone D'annunzio,¹ Mariaconsiglia Ferriero,¹ Rocco Simone Flammia,¹ Salvatore Guaglianone,¹ Sabrina Iuculano,¹ Claudia Denaro,¹ Arianna Di Luzio,¹ Costantino Leonardo,¹ Leslie Claire Licari,¹ Riccardo Mastroianni,¹ Leonardo Misuraca,¹ Flavia Proietti,¹ Isabella Sperduti,² Giuseppe Simone¹

Uro-Oncology Program, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
Clinical Trial Center-Biostatistics & Bioinformatics, IRCCS Regina Elena National Cancer Institute, Rome, Italy.

References:

Mir MC, Ercole CE, Takagi T, et al. Decline in renal function after partial nephrectomy: etiology and prevention. J Urol. 2015;193:1889–1898. doi:10.1016/j.juro.2015.01.093.
Minervini A, Campi R, Lane BR, et al. Impact of resection technique on perioperative outcomes and surgical margins after partial nephrectomy for localized renal masses: A prospective multicenter study. J Urol. 2020;203:496–504. doi:10.1097/JU.0000000000000611.
Thompson RH, Lane BR, Lohse CM, et al. Every minute counts when the renal hilum is clamped during partial nephrectomy. Eur Urol. 2010;58:340–345. doi:10.1016/j.eururo.2010.05.047.
Brassetti A, Cacciamani GE, Mari A, et al. On-Clamp vs Off-Clamp Robot-Assisted Partial Nephrectomy for cT2 Renal Tumors: Retrospective Propensity-Score-Matched Multicenter Outcome Analysis. Cancers (Basel). 2022;14:4431. doi:10.3390/cancers14184431.
Tuderti G, Brassetti A, Mastroianni R, et al. Expanding the limits of nephron-sparing surgery: Surgical technique and mid-term outcomes of purely off-clamp robotic partial nephrectomy for totally endophytic renal tumors. Int J Urol. 2022;29:282–288. doi:10.1111/iju.14763.
Antonelli AD, Cindolo L, Sandri M, et al. The role of warm ischemia time on functional outcomes after robotic partial nephrectomy: a radionuclide renal scan study from the CLOCK randomized trial. World J Urol. 2023;41:1337–1344. doi:10.1007/s00345-023-04356-y.
Bahler CD, Sundaram CP. Effect of renal reconstruction on renal function after partial nephrectomy. J Endourol. 2016;30(Suppl 1):S37–S41. doi:10.1089/end.2016.0055.
Brassetti A, Misuraca L, Anceschi U, et al. Sutureless purely off-clamp robot-assisted partial nephrectomy: avoiding renorrhaphy does not jeopardize surgical and functional outcomes. Cancers (Basel). 2023;15:698. doi:10.3390/cancers15030698.
Brassetti A, Tuderti G, Anceschi U, et al. Sutureless Purely Off-Clamp Robotic Partial Nephrectomy: Evidence from a Randomized Controlled Noninferiority Trial. Eur Urol. 2026. doi:10.1016/j.eururo.2026.04.019.

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