The Exoscope versus operating microscope in microvascular surgery: A simulation non-inferiority trial

Abstract

Background: The Exoscope is a novel high-definition digital camera system. There is limited evidence signifying the use of exoscopic devices in microsurgery. This trial objectively assesses the effects of the use of the Exoscope as an alternative to the standard operating microscope (OM) on the performance of experts in a simulated microvascular anastomosis.

Methods: Modus V Exoscope and OM were used by expert microsurgeons to perform standardized tasks. Hand-motion analyzer measured the total pathlength (TP), total movements (TM), total time (TT), and quality of end-product anastomosis. A clinical margin of TT was performed to prove non-inferiority. An expert performed consecutive microvascular anastomoses to provide the exoscopic learning curve until reached plateau in TT.

Results: Ten micro sutures and 10 anastomoses were performed. Analysis demonstrated statistically significant differences in performing micro sutures for TP, TM, and TT. There was statistical significance in TM and TT, however, marginal non-significant difference in TP regarding microvascular anastomoses performance. The intimal suture line analysis demonstrated no statistically significant differences. Non-inferiority results based on clinical inferiority margin (Δ) of TT=10 minutes demonstrated an absolute difference of 0.07 minutes between OM and Exoscope cohorts. A 51%, 58%, and 46% improvement or reduction was achieved in TT, TM, TP, respectively, during the exoscopic microvascular anastomosis learning curve.

Conclusions: This study demonstrated that experts' Exoscope anastomoses appear non-inferior to the OM anastomoses. Exoscopic microvascular anastomosis was more time consuming but end-product (patency) in not clinically inferior. Experts' "warm-up" learning curve is steep but swift and may prove to reach clinical equality.

Keywords: Exoscope; Microscopy; Microsurgery; Microvascular anastomosis; Video telescope operating monitor.

Fig. 1.. Microvascular anastomosis simulation using Exoscope

(A) The sequence of microsuture in the protocol bi-angulation technique used for microvascular anastomosis. (B) Illustration of the Modus V (Synaptive Medical Inc.) operating room setup [4]. (C) 1. Exoscope, 2. High-definition (4K) screen, 3. Hand-motion analyzer electromagnetic source, 4. Microsurgical operating field and instrumentation, 5. Hand-motion analyzer sensors. (D) System status overlay display of Modus V Exoscope device with system settings appearing on video display.

Fig. 2.. OM versus Exoscope–HMA microsuture performance

Box-plots diagrams comparison of experts’ performance for: (A) total pathlength (TP), (B) total movements (TM), (C) total time (TT) performing an interrupted microsuture on operating microscope (OM) and Exoscope (Exo). HMA, hand-motion analyzer. ^a)Statistically significant.

Fig. 3.. OM versus Exoscope–HMA anastomosis performance

Box-plots diagrams comparison of experts’ performance for: (A) total pathlength (TP), (B) total movements (TM), (C) total time (TT) performing microvascular anastomoses with the operating microscope (OM) and Exoscope (Exo). HMA, hand-motion analyzer. ^a)Statistically significant.

Fig. 4.. Exoscope microvascular anastomosis learning curve

Performance after nine repetitions versus the operating microscope (OM) performance in total pathlength (TP), total time (TT), and total movements (TM) (red lines).

Fig. 5.. Overall surgical performance indicators

Radar chart demonstrating overall surgical performance indicators for operating microscope (OM) and Exoscope.

Fig. 6.. Non-inferiority outcomes OM versus Exoscope

Clinical inferiority of the use of the Exoscope versus the operating microscope (OM) in microvascular anastomosis is demonstrated with total time margin of equivalence of 10 minutes.