Comparison of Outcomes and Surgical Time Between Cortical and Medullary Suture vs. Medullary-Only Suture: Cortex Clinical Trial

To investigate the clinical impact of a potentially modifiable surgical variable, namely, the choice of suture technique during renal reconstruction, on patient outcomes following robot-assisted partial nephrectomy.

The preservation of renal function has become a central concern in the surgical management of renal tumors, especially given the long-term consequences of chronic kidney disease on patient morbidity and mortality. Partial nephrectomy is preferred for localized renal masses as it allows for oncologic control while maintaining renal function. Traditionally, renorrhaphy involves a two-layer closure including both medullary and cortical sutures. However, recent literature suggests that omitting the cortical suture may reduce renal parenchymal volume loss and warm ischemia time, while possibly introducing a higher rate of minor complications.

Despite growing interest in minimally invasive nephron-sparing techniques, robust prospective and randomized trials directly comparing single-layer (medullary-only) and double-layer (cortical and medullary) renorrhaphy remain scarce. The single-layer technique, first proposed to address concerns over unnecessary cortical compression and ischemic injury, is gaining attention for its simplicity and potential advantages in reducing blood loss and operative time.

This trial aims to evaluate whether avoiding cortical suturing during robot-assisted partial nephrectomy leads to improved postoperative renal function, reduced blood loss, and shorter surgical duration. Patients will be randomly assigned to undergo either medullary-only renorrhaphy or the conventional dual-layer approach. Both techniques will be assessed for their effect on warm ischemia time, complication rates, renal volume loss, and surgical efficiency.

The study will enroll 80 patients undergoing partial nephrectomy for renal masses, distributed evenly across the two intervention groups. This sample size was calculated to ensure statistical power to detect differences in estimated blood loss, the primary outcome. A broad range of secondary outcomes will be measured at multiple postoperative time points, including estimated glomerular filtration rate, renal volume, incidence of surgical complications, and quality of life indicators.

By employing a randomized, prospective, and blinded design, the trial seeks to minimize bias and deliver high-quality evidence to guide future surgical decision-making. Ultimately, the study aims to clarify whether cortical renorrhaphy can be safely omitted without compromising patient outcomes, potentially simplifying surgical technique and improving recovery profiles in this patient population.

Inclusion criteria

• Diagnosis of renal mass confirmed by computed tomography (CT) or magnetic resonance imaging (MRI)
• Indication for partial nephrectomy
• Written informed consent
• Expected survival of at least 6 months
• Eastern Cooperative Oncology Group (ECOG) score performance status ≤ 1
• Negative serum or urine pregnancy test within 24 hours before surgery for women of childbearing potential
• Recovery from any prior therapy-related toxicity to grade 1 or better
• If a biopsy has been performed, pathology consistent with renal cell carcinoma (RCC)

Exclusion criteria

• Solitary kidney
• Multiple or bilateral renal masses if more than one mass is operated on simultaneously or within less than 4 months
• Hepatic or renal toxicity grade ≥ 2 with glomerular filtration rate (GFR) < 30 according to Common Terminology Criteria for Adverse Events (CTCAE v4)
• Bleeding diathesis
• Inability to maintain anticoagulation for surgery
• Participation in another experimental trial simultaneously or within 30 days prior to enrollment
• Significant acute or chronic medical, neurological, or psychiatric condition that could compromise safety, limit study completion, or impair study objectives in the opinion of the Principal Investigator