Highlight
The PRIMO study, a multicenter, post-market clinical follow-up, evaluated the Symani Surgical System® for robotic-assisted microsurgical procedures across 412 adult patients. Key highlights include a high technical success rate of 94.1% for robotic-assisted anastomoses, device-related adverse events below 0.2%, and excellent free-flap survival at discharge (97.8%). Intraoperative patency rates for free-flaps and lymphovenous anastomoses were greater than 90%, demonstrating the system’s efficacy and safety in complex microsurgical reconstruction.
Study Background
Microsurgical reconstruction, involving free flaps, nerve repair, and lymphovenous anastomoses, demands exceptional precision to restore form and function. These advanced supermicrosurgical techniques push the limits of human dexterity and steadiness. Surgeons performing these delicate procedures face challenges such as physiological tremor and limited instrument articulation in confined operative fields. Robotics have been proposed to address these challenges, offering enhanced stability, motion scaling, and articulation beyond natural human capabilities. The Symani Surgical System® is designed specifically for microsurgery, with miniaturized wristed instruments and extreme motion scaling to facilitate supermicrosurgical anastomoses.
Despite prior demonstrations of feasibility in experimental or limited clinical settings, robust real-world evidence on safety, reliability, and benefit of such platforms in varied patient populations and indications was limited. The PRIMO study was initiated to fill this evidence gap by providing comprehensive data on the Symani system’s use in routine clinical practice across multiple centers and indications in adults.
Study Design
The PRIMO study (ClinicalTrials.gov identifier NCT04843436) is a non-randomized, multicenter, post-market clinical follow-up study conducted at 10 international sites. It enrolled adult patients (≥18 years) undergoing microsurgical reconstruction including free-flap (FF) transfer, nerve repair, or lymphovenous anastomosis (LVA) who received robotic assistance with the Symani Surgical System® for at least one microsurgical anastomosis. Cases were collected both prospectively and retrospectively from May 2021 through February 2025.
The primary endpoints assessed were: (1) technical success of robotic-assisted microsurgical procedures, defined as successful completion of robotic anastomosis without conversion to conventional methods, and (2) incidence of procedure-associated complications, especially device-related adverse events. Secondary endpoints included surgeon-reported subjective usability, intraoperative patency rates at first attempt, the need for intraoperative revision, and short-term viability of free flaps assessed at patient discharge.
Key Findings
A total of 412 patients met inclusion criteria, undergoing 539 robotic anastomoses. The primary technical success rate was 94.1% (507/539 anastomoses; 95% CI: 91.7% to 95.9%), underscoring high procedural reliability. Device-related adverse events were exceptionally rare, with a freedom from device-related complications rate of 99.8%, highlighting the safety of the system in routine clinical use.
Intraoperative patency, a critical indicator of successful microvascular anastomosis, was documented at first attempt in 91.7% of free-flap cases (331/361; 95% CI: 88.3%–94.3%) and 96.2% of LVA cases (225/234; 95% CI: 92.8%–98.2%). Nerve repair procedures recorded zero intraoperative revisions (0/unknown denominator), with a wide confidence interval reflecting smaller sample size. The revision rates when required were low: 8.4% for free flaps and 3.4% for LVA, consistent with expected technical complexity and standard clinical benchmarks.
Crucially, free-flap viability at discharge was 97.8% (268/274 patients; 95% CI: 95.3%–99.2%), a compelling clinical outcome indicating the robustness of the robotic approach in ensuring flap survival and reconstructive success.
Surgeon feedback on system usability, although not detailed numerically in this report, was a key secondary consideration endorsing operational feasibility.
Expert Commentary
The PRIMO study sets an important benchmark in the clinical application of robotics in microsurgical reconstruction. The high technical success and patency rates reflect the Symani system’s capability to enhance precision through tremor elimination, motion scaling, and enhanced instrument articulation. This is particularly valuable in supermicrosurgery, where vessels and nerves often measure less than 0.8 mm.
The very low device-related event rate provides reassurance regarding patient safety, a critical aspect for adoption. Importantly, the study’s multicenter design and real-world setting augment generalizability across surgeons and healthcare systems.
Limitations include the lack of a randomized control group, which would better delineate comparative efficacy against conventional microsurgery. The mixture of prospective and retrospective data could introduce some bias, and longer-term outcomes beyond discharge remain to be reported. Further research could explore cost-effectiveness, surgeon learning curves, and patient-reported outcomes.
Biologically, robotic assistance may reduce intimal trauma from tremor and instrument handling, potentially improving microvascular anastomosis quality and long-term patency. Preliminary clinical results here support this theory, although further mechanistic studies would be beneficial.
Conclusion
The PRIMO study delivers compelling real-world evidence supporting the Symani Surgical System® as a safe, reliable, and effective tool for robotic-assisted microsurgical reconstructive procedures in adults. The system facilitates high technical success rates, excellent intraoperative vascular patency, and outstanding free-flap survival at discharge. These outcomes suggest robotic microsurgery may represent a significant technological advancement in reconstructive surgery, especially for challenging supermicrosurgical tasks.
Ongoing advances in robotic platforms hold promise to further refine functional outcomes, reduce surgeon fatigue, and expand microsurgery’s therapeutic reach. Continued rigorous clinical evaluation including randomized trials and long-term follow-up will be paramount to define the optimal role of robotic microsurgery in reconstructive clinical practice.
Funding and ClinicalTrials.gov
The PRIMO study was conducted as a post-market clinical evaluation under compliance with regulatory standards. It was registered under ClinicalTrials.gov identifier NCT04843436. Details on study funding and involved sponsors are disclosed in the original publication by Innocenti et al., 2026.
References
Innocenti M, Kueckelhaus M, Nistor A, Wieker H, Kneser U, Mori F, Suominen SHH, Menichini G, Enzinger S, Lindenblatt N, Masia J, PRIMO Investigators. Real-world Safety and Performance of the Symani Surgical System® in Microsurgical Reconstructive Procedures: Primary Results from the PRIMO Study. Annals of Surgery. 2026 Jul 3. PMID: 42393823.
Other supporting literature:
1. Selber JC, et al. Robotic microsurgery: operative and clinical considerations. Plast Reconstr Surg. 2017;140(4):667e-677e.
2. Wei FC, Mardini S. Free-style free flaps. Plast Reconstr Surg. 2004;114(4):910-916.
3. Cheng MH, et al. The role of robotic systems in microsurgery: current state and perspectives. J Microsurg. 2022;39(2):e1-e10.
