In this multicenter RCT, Monofix®-PDO was comparable to V-Loc™ in terms of both safety and efficacy in patients undergoing RAPN, meeting both the primary and secondary outcomes. There were also clinical benefits of using Monofix®-PDO in patients with moderate to high complexity tumors. Based on the known finding that conventional suture materials are more time-consuming and that the knots may be prone to breakage or extrusion [9], our findings suggest that Monofix®-PDO can be considered an effective alternative suture material for RAPN, potentially expanding the utilization of partial nephrectomy, even in cases involving complex renal masses [10].

Barbed sutures, especially V-loc™, are now widely utilized in various minimally invasive surgical fields. For example, in a laparoscopic myomectomy RCT comparing barbed versus conventional sutures, they demonstrated significant benefits such as reduced surgery time, decreased bleeding, and improved surgical convenience compared to conventional sutures [11]. Similarly, in a robotic-assisted laparoscopic hysterectomy comparative analysis, when compared to interrupted vicryl sutures, V-loc™ substantially reduced the time required for vaginal cuff closure, with less blood loss and less observed granulation tissue [12]. In the field of general surgery, in obese patients undergoing laparoscopic gastric bypass surgery, these sutures effectively reduced the time required for intestinal anastomosis [13]. In the field of urology, in robot-assisted radical prostatectomy, barbed sutures offered advantages in terms of continence rate, length of catheterization, and other surgical outcomes [14]. Many other urological surgeries have reported the clinical benefits of barbed sutures, such as robot-assisted radical cystectomy [15] and robot-assisted laparoscopic pyeloplasty [16].

In this clinical trial, we specifically targeted patients who underwent RAPN because it was hypothesized that using barbed sutures could yield maximal benefits in this context. A systematic review and meta-analysis by Lin et al. included eight cohort studies (one RAPN, five laparoscopic partial nephrectomies, one open partial nephrectomy, and one combination of laparoscopic and open partial nephrectomy) [17] and concluded that barbed sutures significantly reduced the operative time, warm ischemic time, and postoperative complications. The benefits of barbed sutures in partial nephrectomy appear clear; however, no head-to-head comparison studies have been conducted on each suture material. Sammon et al. conducted a prospective study specifically, using V-Loc™ barbed suture in RAPN. Their results highlighted a notable reduction in warm ischemic time with the use of barbed sutures [1]. In the meanwhile, although retrospective data, studies by Shang et al. and Xu et al. reported that using Quill™ barbed sutures led to a low complication rate and significantly shorter warm ischemic time [18, 19].

We expected three key benefits from using this new suture material. Firstly, we aimed to prove that the new suture does not compromise bed suture time and warm ischemic time compared to the existing V-Loc™ sutures. Secondly, our goal was to reduce the labor of surgical nurses by reducing suture preparation time and achieve surgical standardization and safety by eliminating the need for additional items like Hem-o-lok®, Lapra-ty®, or extra tie knots, which are required when using V-Loc™ for bed suturing. Indeed, the time needed for suture material preparation was significantly shorter with Monofix®-PDO compared to V-Loc™. Thirdly, the study considered the clinical perspectives discussed by Sammon et al., who reported challenges when using barbed sutures in their RAPN procedures [1]. Notably, V-Loc™ lacked barbs in the first 2 cm, necessitating readjustment and occasionally engaging with tissue, making them challenging to manage. In contrast, the Monofix®-PDO utilized in this study had a shorter barb-free zone, which enhanced its usability. We also achieved bed suture time savings from the three clinical perspectives mentioned above in moderate-to-high-complexity tumor cases.

Despite the promising results, this study has several limitations. First, safety outcomes and renal function were presented up to a three-month follow-up period. However, it would be valuable to provide data with an extended follow-up duration, as there are concerns regarding potential inflammation or fibrosis induced by the suture barbs, particularly in the case of urinary tract reconstruction [20]. Also, in terms of renal function, long term data will be needed to confirm the clinical efficacy of this new suture material. This prolonged follow-up data could offer a more comprehensive understanding of the safety profile. Second, the clinical trial employed a stratified design, categorizing patients into the T1a vs. other groups. Notably, the “others” category predominantly comprised T1b tumors, and their representation in the study was relatively small (n = 31/174). Therefore, the results pertain primarily to T1a tumors, raising concerns about generalizing these findings to tumors of all sizes in the context of RAPN. Additionally, for the T1a tumors, while the sample size was sufficient to support our findings, having fewer than 100 patients in each group may limit the generalizability of our results. Third, a distinctive feature of this study was its exclusive focus on barbed sutures for bed suturing, i.e., the inner layer of the renorrhaphy. Consequently, a pre-defined standardization of the outer layer renorrhaphy technique across institutions and surgeons is lacking. Furthermore. In a similar context, tumors initially considered sutureless were excluded, which could be seen as a limitation, as this decision was based on the individual judgment of surgeons at each institution. However, this effect was likely minimized through stratification by institution during the randomization process. It is noteworthy that despite this limitation, there were no significant differences in warm ischemic time or bed suture time between the control and treatment groups. This suggests that the findings of this study may have mitigated the clinical impact of this limitation. These limitations should be considered when interpreting the results and considering the broader applicability of Monofix®-PDO sutures in RAPN procedures. Future research efforts could focus on evaluating the long-term outcomes and conducting cost-effectiveness analyses of Monofix®-PDO and V-Loc™ suturing techniques in a larger and more diverse patient population. Additionally, comparative studies incorporating advanced imaging techniques and functional outcomes assessments could further clarify the optimal choice of suturing materials in renal mass surgery. Additionally, this study was conducted on a group that underwent double-layer renorrhaphy; however, since systemic review and meta-analysis have reported that single-layer renorrhaphy is superior in terms of renal function preservation [21], it would be beneficial to conduct a comparative analysis with a single-layer renorrhaphy group in future research.