Progressive changes in robotic and computer-guided systems have significantly altered operating practice across different medical and surgical specialties. Surgical robots can extend the capabilities of surgeons by reducing fine tremors, increasing manual dexterity and offering real-time 3D visualisation during endoscopic surgery (1, 2). This allows for highly precise  movement in narrow and difficult-to-access spaces, and subsequently opens the door for minimally invasive surgery (Figure 1). In addition to enhancing surgical skills and improving ergonomics during surgery, minimally invasive surgery is associated with shorter hospitalisation and reduced risk of adverse complications (3, 4). Recent success of surgical robots, particularly the da Vinci Surgical System^® (Intuitive Surgical^™, Sunnyvale, CA), has created a thriving multibillion-dollar industry. Numerous companies are now focusing on this market in order to gain a stake in this valuable industry. Verily Life Sciences^™ (formerly Google Life Sciences^™) and Johnson & Johnson^™ are collaborating on the development of a surgical robotic system through Verb Surgical^™. Medtronic^™ has made sizeable investments in Mazor Robotics^™ that focusses on the development of surgical robots for spine and brain surgery. Furthermore, other less-known companies, such as Auris Surgical Robotics^™, Cambridge Medical Robotics^™ and TransEnterix Surgical^™, have each announced their own surgical robotics platform. While several novel teleoperated surgical robotic systems are expected to become available within the foreseeable future, the next generation of partial autonomous surgical robots, capable of suturing skin and creating soft-tissue anastomosis without direct input from surgeons, is already being tested in research laboratories (5).

A literature search was performed using MEDLINE, PubMed, Embase and Web of Science. The search term “robot* microsurgery” wasused for all four databases: MEDLINE, Embase, PubMed and Web of Science. Our search was limited to full-text articles written in English and published between January 2000 and July 2017. Only papers that directly utilised surgical robots in either a laboratory or clinical settings were included. Emphasis was put on feasibility studies, case reports, case series and so on, whereas literature reviews were excluded. Both human and animal studies were included in our search. For each paper, abstracts were assessed based on relevance to robotics within plastic reconstructive microsurgery. Publications purely related to other surgical specialties, such as urology and neurosurgery were excluded. In addition, engineering or technical papers proposing novel robotic systems were also omitted. Articles that passed initial screening were subsequently reviewed full text and data regarding limitations, disadvantages and barriers of surgical robotics in plastic and reconstructive microsurgery was extracted.

Our search yielded a total of 1,848 articles, and after removal of duplicates we obtained 962 unique articles. Eight hundred and forty articles were subsequently excluded after screening of abstracts based on our inclusion criteria as described in our methodology. Hundred and twenty-two full-text papers were assessed for further analysis, which resulted in exclusion of 84 articles and inclusion of 38 papers (Figure 2). Analysis of all papers in our review revealed that the 53% (n = 20) of papers that utilised surgical robotic systems during microsurgical procedures are feasibility studies. The remainder of papers were case series (n = 10), case reports (n = 4) and cohort studies (n = 2). The da Vinci Surgical System^® was the most common surgical robotic system that was used (n = 31). Other papers either used the Zeus Robotic Surgical System^®, Automated Endoscopic System for Optical Positioning^® (Computer Motion^™, Goleta, CA) or a custom surgical robot (Table 1).

Fourteen papers examined the use of surgical robotics in live humans patients (13–26), five studies exclusively focussed on human cadaver specimens (27–31), while two papers described the use of surgical robots in both human cadavers and live patients (32, 33). Fourteen papers evaluated the use of surgical robotics exclusively in animal models (9–12, 34–43), and one paper used both animal models and human cadaver material (44). A relatively small proportion of papers (n = 2) that were included in our review used artificial material to investigate the use of surgical robotic systems in reconstructive microsurgery (45, 46). Nearly all studies, 93% (n = 13) that described the use of surgical robots in live human patients utilised the da Vinci Surgical System^®. The exact versions of the da Vinci Surgical System^® used across the different studies, for example, da Vinci S^®, da Vinci Si^®, da Vinci Xi^®, could not be determined due to this specific data being omitted from a number of papers that were included in our review. Only one single study did not use the da Vinci Surgical System^® in patients, instead the Automated Endoscopic System for Optical Positioning^® was used. A total of 114 patients were operated on with the assistance of surgical robotics. Despite accounting for only 35% of studies (14, 15, 20, 22, 23, 25, 32), head and neck surgery accounted for 51% (n = 58) of patients that were operated on with the aid of surgical robotics. Reconstruction of the oropharynx following malignancy was the most common indication for transoral robotic-assisted surgery. Among this cohort, 40 patients underwent oropharyngeal reconstruction using a free radial forearm fasciocutaneous flap (14, 15, 20, 23, 25, 32), 4 patients were reconstructed using an anterolateral thigh flap (14, 20, 23), 1 patient benefitted from a facial artery myomucosal flap (23) and 1 patient had their defect repaired via primary closure (23). Apart from oropharyngeal malignancy, 10 patients underwent transoral robotic-assisted surgery for cleft palate repair (22) and 2 patients had scalp defects repaired using a free latissimus dorsi muscle flap (32). Breast surgery was the second most common surgical procedure during which surgical robotic systems were used (n = 26) (13, 32). Twenty patients had internal mammary vessels harvested using the Automated Endoscopic System for Optical Positioning^® for breast reconstruction (13). Six patients underwent robotic harvest of the latissimus dorsi muscle for free muscle transfer reconstruction of the breast (32). Furthermore, 12 patients underwent robot-assisted reconstructive upper-limb surgery during (18, 19, 21, 24), 7 patients received surgery for lower limb defects (24, 26, 33), 6 patients were operated on for pelvic reconstruction (26) and 5 patients had brachial plexus surgery (16, 17, 24) (Table 2). 

Analysis of any disadvantages or drawbacks of using surgical robotics for plastic reconstructive microsurgery, revealed five common obstacles (Table 1). Seventeen papers highlighted that the use of surgical robotics was associated with an increase in operating room time. Factors contributing to the increase in time were additional time necessary for setting up the surgical robot before a procedure (12, 15, 16, 36) and the additional time required to perform then actual procedure. Li et al. noted that total completion time was 2.6 times longer using a robotic-assisted technique compared to conventional microsurgery (9). Similarly, cleft palate repair by Nguyen et al., showed that the mean surgical duration for transoral robotic-assisted surgery was 122 ± 8 min, compared to 87 ± 6 min for the control group (22). An increase in operating time can partially be accounted to difficulties with surgical tools. Seventeenpapers mentioned that the current tools available in current robotic systems are inadequate for reconstructive microsurgical procedures. The lack of true microsurgical instruments creates a barrier for surgeons to handle delicate equipment and tissue. Consequently, needle tearing and difficulties in manipulating tissue has been observed. Interestingly, 16 papers mention that the lack of haptic feedback during surgery can be considered as a deficit. Simultaneously, several authors state that visual feedback can compensate for the lack of tactile feedback when operating on fragile tissue. While surgical robots are nowadays a common occurrence many hospitals across the world, the cost of acquiring and maintaining a surgical robot has been a frequent point of concern. Subsequently, 13 papers argue the cost of surgical robots prohibit their use. Especially in plastic surgery, limited data exists on the clinical benefits of surgical robots over conventional surgical intervention that would justify the adaptation of surgical robotics in common practice. Only one study assessed long-term outcome between robotic-assisted surgery compared to conventional reconstructive surgery. They discovered that functional post-operative outcomes 3 months following robotic-assisted oropharyngeal reconstruction is superior to conventional surgery (p = 0.005) (25). Finally, 10 papers highlighted that the size of surgical robotics can proof problematic in smaller operating theatres. Most operating rooms are not designed to facilitate large robots, therefore surgical workflow can be impeded.

Following a variety of proof of concept studies in animal models and human cadavers, significant success has been documented in utilising surgical robots in patients within plastic surgery. There is a wide range of surgical procedures in which robotic surgery is feasible, including head and neck reconstruction, free-flap harvest and nerve reconstruction (Table 2). Improved visualisation of the operating field, enhanced dexterity and elimination of tremor are valuable aids when performing complex procedures on microscopic level. Consequently, the potential of surgical robotics is promising. Despite positive results from feasibility studies, uptake of surgical robotics within plastic surgery has been limited. The use of surgical robotics in day-to-day practice is restricted to a small subset of procedures, which is congruent with currently available literature. The majority of studies considered in this review are case reports or small case series with less than five patients. These provide valuable insight into important aspects of plastic surgery, such as microvascular anastomosis and nerve repair that form the basis of complex reconstruction. Although this may act as a stepping stone to conduct further research into surgical robotics in reconstructive microsurgery on a larger scale, this has not yielded in publication of larger studies. Yet, one area within the field of plastic surgery is currently leading the game when it comes to utilising surgical robots in common practice. Robotic head and neck reconstruction has seen remarkable progress over the last few years. Transoral robotic surgery is currently gaining popularity and is providing new approaches to oropharyngeal access in resection of cancers and cleft palate reconstruction. To date, results from transoral surgery have been promising, and importantly, data indicating this has been derived from comparative cohort studies (15, 25). Biron et al. compared transoral robotic surgery (n = 18) to the lip-splitting mandibulotomy approach (n = 29) for primary resection of oropharyngeal carcinomas with radial forearm free-flap reconstruction. Patients who underwent robotic resection and reconstruction were discharged from hospital approximately 5.3 days earlier, and estimated overall cost of admission was lower ($18,522.18 vs $24,932.16) compared to conventional surgery (15). Analysis of functional outcome by Tsai et al. between robotic-assisted free-flap oropharyngeal reconstruction (n = 14) and conventional free-flap reconstruction (n = 33) revealed that Functional Intraoral Glasgow Scale (47) was significantly better 3 months post-operatively in patients who underwent robotic reconstruction (p = 0.005) (25). As the indications for surgical robots are gradually increasing, the demand for adequate training and obtaining hands-on experience is rising. As such, the level of interest in this field is emerging and driven the creation of professional bodies, such as the Robotic-Assisted Microsurgical & Endoscopic Society (RAMES), to provide surgeons with training opportunities with robotic technology. Nevertheless, while increasing awareness of surgical robots through educational events encourages adaption of such systems on a larger scale, the future of surgical robots mainly will rely on the outcome of larger clinical studies. The availability of strong evidence from large studies is essential in order to determine if there is an overall benefit of surgical robotics over conventional microsurgery. A lack of meaningful evidence is currently the main barrier in order to assess whether surgical robots should be incorporated within plastic surgery on a larger scale.

Criticising technology based on what it is not capable of doing and pointing out flaws may be easy. Yet, highlighting such deficiencies and reflecting on what aspects could be improved is an essential tool to advancing its practice. Numerous research has highlighted that surgical robots can offer substantial benefits when operating. Surgical robots allow surgeons to perform extremely fine manoeuvres within narrow spaces that are near impossible during conventional surgery. Despite numerous advances of surgical robotics and the associated improved clinical outcomes seen in several surgical specialties, the robotic systems that are currently available do not offer overall benefits over conventional reconstructive microsurgery. On one hand, current systems are not designed to capture the full scope of complex reconstructive surgical procedures. While at the same time, microsurgical procedures themselves are not designed to make use of the full potential of surgical robots. Instead of trying to adapt surgical robots to current practice, more success may be achieved by designing microsurgical procedures around surgical robots. Surgical robots offer theoretical benefits that could make complex microsurgery more convenient, yet there are significant barriers that have prevented integrating surgical robotics in common practice. To date, no systems exist that are specifically designed for plastic and reconstructive microsurgery. Without adequate microsurgical instrumentation and training, surgeons will be hesitant to adapt robotic systems in their operating theatre. Current microsurgical procedures are not designed to make use of the full potential of surgical robots. A lack of strong quantitive data can be considered as a limitation of this review, there is nevertheless strong evidence that, without the deficiencies mentioned being resolved, little change can be expected within the foreseeable future.

YT: review design, data collection, data analysis and wrote the manuscript. PL: clinical advisor and data collection. JW: study supervision, review design and data interpretation. All authors reviewed and edited the manuscript.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.