The operating microscope provides a significant intraoperative illumination and visualization of pathological tissue and anatomical structures, which makes the microneurosurgical procedure successful and safe. Thus, the microscope has become the mainstay instrument of neurosurgery[25]. However, there are some limitations in microscope including depth of field, illumination, and ergonomics when working in deep corridors[15]. Moreover, difficult maneuverability and encumbrance over the operative field are the motivations for the limited use of microscope during spinal procedures[16]. These limitations can influence the comfort of the surgeon and the surgical outcome[25]. Tools to improve these limitations are required.
It has been reported that the 3D exoscope has comparable results with the conventional operating microscope with good image quality and illumination during spinal surgery[22,23]. The 3D exoscope has a number of other advantages over the conventional operating microscope. Some studies reported the superiority of the exoscope compared with the operating microscope with regards to ergonomics and comfort[22,26]. The surgeons can straighten their back and even rest on the backrest in a heads-up position while performing surgery with exoscopes. The associated decrease of related exhaustion of ergonomics is important to preserving high-level surgeon performance over the course of a long case[27,28]. In addition, unlike the large frame and fixed bulky design of the conventional microscope, the other advantage of the 3D exoscope is related to its small size. The working distance is between 30 and 100 cm, which provides unobstructed working space to the surgeons. As a result, this allows for comfortable use of the exoscope in the course of the MIS-TLIF procedure, such as neural structure decompression and cage insertion. Furthermore, Sack et al.[29] reported their experience using a 3D exoscope for microsurgery and concluded that with the shared surgical view, exoscopes possessed obvious educational advantages compared with the conventional microscope. Some investigators believed that exoscopes could be an alternative to the conventional microscope in some spinal procedures[20,23].
Recently, Ariffin et al.[19] reported the application of the 3D exoscope system as a visualization tool in spine surgery. They reported oblique lateral interbody fusion, MIS-TLIF, tubular decompression, and tubular microdiscectomy performed by using exoscopes, highlighting the advantages of the 3D exoscope in terms of visualization and ergonomics during spinal surgery. Nevertheless, they did not provide surgical details concerning the different steps of MIS-TLIF (dissection, discectomy, decompression, endplates preparation, cage insertion) assisted by 3D exoscopes. We used the novel 3D-HD exoscope as a visualization tool for minimally invasive transforaminal lumbar interbody fusion. The exoscope was used during dissection, discectomy, decompression, and cage insertion. In particular, neural structure decompression is a delicate surgical step and often requires the application of microsurgical techniques to obtain adequate magnification. In this study, all the patients experienced excellent surgical outcomes after effective decompression. VAS and ODI score of all the patients were demonstrated to decrease postoperatively. With the excellent 3D surgical field provided by the exoscope system, it could help reduce the risk of nerve injury. No complications occurred in this study. Furthermore, surgeons can clearly identify the bleeding vessels which are conducive to the timely and accurate electric coagulation.
One of the main advantages of the 3D exoscope compared with the conventional microscope is the possibility to provide a 3D surgical field to the entire operating room. From learning perspectives, it makes more sense that the assistant observes the same view used by the primary surgeon intraoperatively. Therefore, it can facilitate resident and fellow education in complicated procedures. Some investigators also believed that the 3D exoscope served as an excellent teaching tool[22,29].
As already reported by the majority of authors, the one major disadvantage of the exoscope was the cumbersomeness in repositioning and refocusing[23,30]. This inconvenience is attributed to the mechanical holding arm. During surgical procedures, surgeons often need to refocus and reposition the scope without losing sight or moving hands off the surgical field. However, the exoscope system needs surgeons to move the mechanical arm to finish the repositioning and refocusing for getting a clear surgical field in different steps of the operation. It obliges the surgeon to stop the operation and move hands away from the operating table. Too many interruptions can limit the fluidity of surgery, increasing operation time. In addition, microsurgery means continuous use of both hands and in case of brisk bleeding having to adjust the instrument by hand might be extremely dangerous. Therefore, Rossini et al.[30] suggests the development of a footplate command mandatory for safe clinical utilization of the exoscope. Besides, although most neurosurgeons today are accustomed to an operative microscope, there is certainly a learning curve necessary before using the exoscope in spinal surgery. Belykh et al.[26] reported a significant learning curve exists for becoming accustomed to operating with the exoscope system. No doubt it could be a potential issue for operators who are not familiar with the comparable microscope setup. The surgeons involved in the study had previous experience utilizing the microscope and only had a short learning curve when performing the surgery with a 3D microscope.