Exoscope-assisted spine surgery: Current applications and future directions

Abstract

Spine surgery is continually evolving, with the application of new technologies often serving as a catalyst for improved clinical outcomes. Exoscope-assisted spinal surgery has recently emerged as a notable technological advancement offering a refined approach to visualisation, thereby potentially contributing to improved surgical precision, reduced complication rates, and optimised patient outcomes. The application of exoscopes have improved spine surgeries such as spinal fusion procedures, decompression surgeries, instrumentation surgeries, minimally invasive and complex surgeries. These improvements include enhanced visualisation, improved ergonomics, improved surgical precision, reduced operation times and postoperative infection rates. The integration of robotics in exoscope-assisted spine surgery enables autofocus function, ensuring the integrity of the sterile field, providing superior image quality, resolution, and three-dimensional perception. However, challenges such as decrease in depth perception and the lack of long-term follow-up data hinder its widespread adoption. Ethical considerations regarding patient safety, technology dependency, and health inequity add another dimension to these challenges. Despite these challenges, exoscope-assisted spine surgery holds significant potential for transforming clinical practice and improving patient outcomes. This review seeks to provide a concise overview of the benefits and limits of exoscope-assisted spine surgeries, while highlighting its challenges and ethical considerations. Addressing these limitations by conducting large-scale clinical trials and exploring the integration of artificial intelligence (AI) could assist in realising the potential of exoscopes in spine surgery.”

Graphical abstract

Abbreviations

TLIF

Transforaminal Lumbar Interbody Fusion

ALIF

Anterior Lumbar Interbody Fusion

ACDF

Anterior Cervical Discectomy and Fusion

QoL

Quality of Life

OM

Operative Microscopy

3D

Three-Dimensional

HD

High-Definition

LMICs

Low- and Middle-Income Countries

AI

Artificial Intelligence

MISS

Minimally Invasive Spine Surgery

4K

4K Ultra High Definition

5-ALA

5-aminolevulinic acid

ICG

Indocyanine Green

1. Introduction

Spine surgery is continually evolving, with the application of new technologies often serving as a catalyst for improved clinical outcomes. Within this context, exoscope-assisted spinal surgery has recently emerged as a notable technological advancement. It offers a refined approach to visualisation, thereby potentially contributing to improved surgical precision, reduced complication rates, and optimised patient outcomes.^1,2

In contrast to conventional operating microscopes (OM), which require surgeons to look directly through eyepieces, exoscopes employ cutting-edge optics and camera systems to relay real-time, high-definition images to an external monitor. The exoscope system is engineered with an optical scope positioned extracorporeally, thereby facilitating two- or three-dimensional (2D or 3D) visualisation capabilities. The resultant imagery is displayed on a high-resolution monitor. Newer, next-generation exoscopes are often equipped with advanced 4K-3D technology, specialised light filters for 5-aminolevulinic acid (5-ALA) and indocyanine video-angiography, pneumatic arms, configurable operative settings, multiscreen outputs, extended focus distances, and enhanced magnification ratios.³

Visualisation is critical in spinal surgery, playing an instrumental role in diagnosis, surgical planning, and implementation. Whilst traditional surgical microscopes have long been the mainstay of surgical visualisation, they possess limitations in delivering optimal visual fields.⁴ Exoscopes, however, offer superior visualisation, magnification, and adjustable camera angles, surpassing traditional microscopes in these aspects.^5,6 Exoscopes also confer ergonomic advantages.^7,8,9 Furthermore, the exoscope may have strong pedagogical advantages.^10,11

Nonetheless, there are significant challenges to widespread adoption of the exoscope, including decreased depth perception.^11,12,13 Surgeons have also reported experiencing discomfort due to 3D (three-dimensional) glasses.¹⁰ Further ethical concerns regarding patient safety, dependence on technology, and health inequity compound these challenges. Despite these obstacles, the potential of exoscope-assisted spinal surgery to transform clinical practice is substantial. Consequently, future research must focus on addressing these limitations, integrating robotics and AI, and robust evaluation of long-term patient outcomes11.¹¹

This review provides an overview of current applications and future directions of exoscope-assisted spinal surgery, with a particular emphasis on its benefits and limitations. This review serves to provide an exhaustive understanding of the latest technology for surgeons, thereby promoting clinical practice, and also provides strategic direction for subsequent research. Recognising the significance of understanding the current state and future prospects of exoscope-assisted spinal surgery is indispensable for surgeons and healthcare professionals, as it will facilitate evidence-based adoption of this technology.

2. Methods

This narrative review focused on the applications and future directions of exoscope technology in spine surgery, adopting a rigorous methodology to ensure an encompassing search of the published literature.

The criteria for inclusion accepted a variety of study designs, such as observational, case–control, cohort, and randomised controlled trials. Studies involving both adult and paediatric populations were considered, and the review considered all manifestations of exoscope-assisted spinal surgery. Only articles written in English were considered. No timeline was applied.

For the literature search, databases such as PubMed, EMBASE, Google Scholar, and the Cochrane Library were used. Search terms included "exoscope-assisted surgery", "spinal surgery", “minimally invasive surgery” and "robotic spine surgery". A manual search was also conducted to identify references from recently published, procedure-specific reviews. Abstracts and unpublished studies were excluded from the review.

The review, employing an exhaustive and methodological approach, aimed to offer a high-quality academic assessment of the present applications and future possibilities of exoscope technology in spine surgery. This process allowed for an extensive synthesis of relevant findings, providing insights potentially applicable to a wide range of surgical procedures.

3. Advantages of exoscope-assisted spine surgery

3.1. Improved visualisation and ergonomics

The past decade has witnessed an increase in preference for exoscope-assisted procedures such as TLIF (transforaminal lumbar interbody fusion), ALIF (anterior lumbar interbody fusion), ACDF (anterior cervical discectomy and fusion), and laminectomy, due to their superior magnification, illumination, and visualisation of the surgical field compared with traditional microscopic techniques.^2,5,7,12, 13, 14 Additionally, the exoscope provides increased clarity and precision target treatment, which has been associated with a reduction in surgeon fatigue. This reduction is largely due to the ergonomic benefits observed in ALIF, TLIF, and discectomy procedures.² The ergonomic benefits, including reduced physical strain and improved manoeuvrability within the surgical field, have been realised in these spinal surgeries, owing to the separation of the surgeon from the optical system.^2,6,7,11,12,14, 15, 16, 17 Although currently disputed, some studies in TLIF and ALIF have indicated that the exoscope's improved depth perception, a key element in spine surgery, may assist surgeons in identifying microstructural anatomy.

These advantages, when combined with the exoscope's ability to provide unobstructed access to small and deep surgical fields, create ample room for the insertion and manipulation of instruments.⁵

3.2. Improved surgical outcomes and efficiency

The exoscope's superior magnification and high-definition (HD), 3D view have been associated with a lower incidence of postoperative complications such as dural tears and neural injuries in spine surgeries including TLIF, ALIF, ACDF, and laminectomy.^{2,6,7,9,10,14,16,18} Notably, cervical discectomies conducted using 3D exoscopes have reported fewer complications, including vascular and nerve injuries, rupture of internal fixation (i.e., the failure or breakage of surgically implanted spine-stabilising hardware), and displacement of interbody fusion cages, alongside a reduction in surgical time.^12,15,19 Such improvements may mitigate the viewing limitations commonly encountered in conventional endoscopic procedures.⁷ Specifically, in ALIF procedures, postoperative courses have been uneventful with minimal pain, enabling early patient mobilisation and shorter hospital stays.⁵

The application of exoscopes in TLIF and ALIF procedures has been correlated with improved patient outcomes, as evidenced by reduced back pain and disability scores, and a lack of general and instrument-related complications.^5,10 Moreover, the exoscope's depth of field, the extent of which is currently under debate when compared to the traditional operating microscope, has been credited for reducing the frequency and duration of repositioning and refocusing during surgical procedures.¹⁰

Although currently disputed, the increased depth of field, in conjunction with ergonomics, ease of movement and the assistant engagement, could all contribute to a reduction in surgical time, which is known to decrease patient perioperative complications.^7,15,20 This could potentially improve efficiency and clinical outcomes while reducing operation time and complication rates.^2,10

The incorporation of robotics in exoscope-assisted spine surgery enables surgeons to achieve challenging visualisation angles. Enabled by a robotic arm with autofocus capabilities, this technology takes a step further with features like visual camera tracking and automatic robotic arm adjustment. These features enable the exoscope's robotic arm with a camera to automatically track surgical instruments, such as the suction, and adjust its positioning, focus, and lighting in real-time, minimising the level and frequency of physical contact required with the microscope and the risk of disrupting the sterile field. These advancements contribute to superior image quality, resolution, and 3D perception.^6,14,18

The exoscope's comparatively diminutive size allows for ease of use from the early surgical stages, such as cervical soft tissue dissection, neural structure decompression, and cage insertion, all of which require unrestricted manoeuvrability of the screw and cage holders under direct vision.²¹ The 3D robotic digital microscope integrated in exoscope-assisted spine surgery has demonstrated satisfactory outcomes in various procedures, incorporating an endoscopic arm to facilitate the execution of minimally invasive approaches.^14,18

Unlike the OM, whose larger size can sometimes prove cumbersome, the exoscope's comparatively diminutive size offers advantages from the early stages of surgery. This is particularly beneficial during procedures such as cervical soft tissue dissection, neural structure decompression, and cage insertion, where unrestricted manoeuvrability of the screw and cage holders under direct vision is critical.²¹ The 3D robotic digital microscope integrated into exoscope-assisted spine surgery has shown promising outcomes in various procedures. The integration of this technology employs an endoscopic arm, which assists in carrying out minimally invasive approaches.^14,18

3.3. Teamwork and educational advantages

The integration of exoscopes into surgical practice has not only improved procedure quality but also proven to be a valuable tool for education and teamwork.^2,4,10 Unlike traditional OM that provides a limited view, the exoscope offers shared 3D HD visualisation. This inclusive perspective allows surgeons, anaesthetists, nurses, and medical students to cooperatively participate in procedures, enriching their learning experience.¹⁰

Adapting to the exoscope offers several advantages, including a shorter learning curve compared to endoscopic techniques.^2,5,9,13 It is important to note, however, that endoscopic spine surgery operates in a distinct domain and is minimally invasive, requiring specific skills and techniques that make it not directly comparable to exoscopic methods. Combined with the inclusive view from the 4K (4K Ultra High Definition) monitor, the exoscope emerges as an attractive technological alternative.^7,15

A noteworthy capability of the exoscope is its ability to create high-quality videos from the surgeon's viewpoint. These offer superior didactic potential for surgical anatomy instruction compared to videos recorded through microscopes.²¹ The use of robotic exoscope systems has improved communication and collaboration among multidisciplinary teams, largely due to the shared viewing platform.^14,18 This inclusivity makes these systems an especially valuable tool in teaching environments where training residents is a priority, marking a new era of accuracy, safety, and innovation in spine surgery.¹¹ (see Table 1)

Table 1.

Summary of methodology.

Methodology Steps	Description
Literature Search	PubMed, EMBASE, Google Scholar, and the Cochrane Library.
Inclusion Criteria	-Randomised controlled trials, prospective and retrospective cohort studies, case–control studies, case series. -Studies involving both paediatric and adult populations. -Studies involving comorbidity and previous treatments. -No timeline restrictions
Exclusion Criteria	-Standalone abstracts -Case reports -Posters -Unpublished or non-peer-reviewed studies -Non-English studies
Search Terms	Keywords include "exoscope-assisted surgery”, "spinal surgery", “minimally invasive surgery”, "robotic surgery"
Additional Search	A manual search was performed to include references from recently published procedure-specific and disease-specific reviews related to exoscope-assisted spinal surgery.
Sample Size Requirement	No strict sample size requirement

A summary of the advantages of applying exoscopes in spine surgery is provided in Table 2.

Table 2.

Advantages of exoscope in spine surgeries.

Advantages	Description
Improved Visualisation and Ergonomics2,5, 6, 7,11,12,14, 15, 16, 17	•Superior magnification, illumination and visualisation compared to traditional OM. •Excellent clarity and precision target treatment, reducing surgeon fatigue. •Ergonomic benefits, mitigating physical pain. •Enhanced surgical field manoeuvrability, as the surgeon is separated from the optical system. •Unobstructed access and deep surgical fields. •Improved depth perception. •Superior image quality, resolution, and 3D perception, made possible by a robotic arm with autofocus.
Improved Surgical Outcomes and Efficiency2,6,7,9,10,14,16,18	•Low incidence of postoperative complications such as dural tears and neural injuries. •No postoperative complication, enabling early patient mobilisation and shorter hospital stays. •Decreased back pain and disability scores. •Reduction in perioperative bleeding. •Ensures the integrity of the sterile field. •Ease of use for early surgical stages, such as cervical soft tissue dissection and cage insertion.
Teamwork and Educational Advantages2,4,5,7,9, 10, 11,13, 14, 15,18	•Real-time observation by the entire surgical team, due to the 3D HD monitor. •Facilitates cooperation between surgeons, anaesthetists, nurses, and medical students. •Improved teamwork, enhanced collaboration. •Shorter learning curve, user-friendly. •Immersive surgical experience. •Creation of high-quality video.

4. Limitations, ethical considerations and future prospects in exoscope-assisted spine surgery

4.1. Current limitations of exoscope-assisted spine surgery

Despite several benefits, such superior visualisation and improved ergonomics, the adoption of exoscope in spine surgery isn't without its challenges.²

While the benefits of exoscope-assisted spine surgery are increasingly recognised, there is ongoing debate about the effect of exoscope-assisted surgery on depth perception, in comparison to traditional OM. Various studies, spanning procedures like ACDF, TLIF, long approaches, and robotic surgery, have suggested that exoscope-assisted spine surgery may provide inferior depth perception, a quality inherently stronger in conventional OM.^8,9,11, 12, 13, 14 This limitation has presented a considerable obstacle, causing hesitation to adopt exoscopic techniques, despite attempts to rectify the issue with flat view adaptation.^11,14

Moreover, a study found the image quality of current 3D 4K monitors to be inferior to optical visualisation in simulated spine surgery.²² In terms of perioperative bleeding, while one study found a reduction in two-level TLIF procedures using 3D exoscope,⁸ another reported higher average blood loss compared to the OM group in ACDF procedures.⁹

In addition, the combination of robotic integration and exoscope spine surgery has been observed to compromise image sharpness at high magnification, especially compared to traditional microscopy. The Modus V system, for instance, slows down procedures and increases risk due to its need for 3D imaging.¹⁴ Moreover, the absence of fluorescence modules like 5-ALA and ICG (Indocyanine Green) also presents a disadvantage.¹⁴

Operational changes required for exoscope use and potential discomfort due to 3D glasses are additional concerns.^2,10 Also, the significant cost of integrated systems, for example of the Modus V Synaptive System priced between £521,000 and £580,000,⁶ may slow adoption, especially in low and middle-income countries.⁹

A notable gap exists in literature regarding long-term data on the benefits and potential complications of exoscope-assisted spine surgery. This emphasises the need for future research for a comprehensive understanding of its implications on patient outcomes. Therefore, while exoscope and robotic integration shows promise, addressing these limitations is critical for its broad adoption and optimal use. The limitations and ethical challenges with using exoscope-assisted spine surgery have been illustrated in Fig. 1.

Fig. 1.

Limitations and ethical challenges in exoscope-assisted spine surgery.

4.2. Ethical considerations in exoscope-assisted spine surgery

exoscope-assisted spine surgeries introduce multiple ethical issues that healthcare professionals must carefully address to ensure patient safety, autonomy, and responsible technology use.

Firstly, the novel nature of exoscopes emphasises the need for thorough informed consent. Patients should receive detailed information about the procedure and the alternative of traditional OM. The proposal to use an exoscope must be discussed preoperatively, with assurance that patients have the capacity to make informed decisions and provide consent.²³ Moreover, despite the scarcity of literature on exoscope-assisted spine surgery and the pressing need for research to fully assess its effectiveness, maintaining the security of patient data is of critical importance, requiring strict adherence to ethical guidelines.

Technology dependence is another ethical concern. Although exoscopes can improve visualisation and precision,^2,14 surgeons must avoid over-reliance on this technology. The surgeon's clinical judgement and expertise should remain central to decision-making in spine surgery.

The introduction of exoscopes might also widen health inequities globally. The high cost of the exoscope technology, could slow its adoption in low-resource settings, particularly in LMICs, thereby exacerbating healthcare disparities worldwide. Thus, it is essential to develop strategies for cost-effective exoscope use.²⁵

By considering and addressing these ethical considerations, healthcare professionals can responsibly integrate exoscope technology into spine surgery while prioritising patient welfare.

4.3. Future prospects for exoscope integration in spine surgery

The use of exoscopes in spine surgery has demonstrated multiple advantages for both spine surgeons and patients, with improved visualisation and ergonomics for surgeons, and reduced complications and significantly improved symptoms for patients.^7,14,15 Given the discordant conclusions drawn by several studies, large-scale clinical trials, preferably randomised, and comparative studies are vital to establish the impact of exoscope use.^11,24 Multicentre trials focusing on complex procedures could provide a more nuanced understanding, potentially influencing the future application of this technology in spine surgery. Addressing ethical limitations should also occur to encourage more widespread adoption of exoscope-assisted surgery.

Regarding robotic integration, a significant area for improvement in the Modus V system is the addition of a 3D camera.¹⁴ Furthermore, introducing fluorescence modules such 5-ALA and ICG, and ensuring endoscopic and navigation compatibility could broaden the spectrum of procedures. Developing tissue recognition features such as digital and confocal microscopes for pathology might also prove valuable for performing safer surgery.¹⁴

Considering the novelty of exoscopes, comprehensive training in the laboratory may be beneficial before clinical application.¹⁴ This approach ensures that neurosurgeons are comfortable using the new technology and can maintain patient safety. Challenges require innovative solutions to overcome operational setup changes and tackle the potential ethical concern of increasing health inequity. For instance, a new, affordable exoscope-assisted MISS setup, which is easy to prepare and suitable for use in LMICs.^4,24 Preliminary evidence has demonstrated that this cost-effective exoscope is safe and feasible for TLIF, and can be obtained for a fraction of the cost of conventional microscopes.⁵ The advantages of this system necessitate further studies to evaluate its safety and efficacy.

Finally, the implementation of AI models in exoscope-assisted spinal surgery could be a promising avenue to explore. The integration of AI subsets, such as augmented reality, has been shown to reduce shifts in spine surgeons' focus and procedure disruption.²⁵ This application could be adapted to exoscope-assisted spine surgery.

The future prospects of exoscope-assisted spine surgery and its integration with robotics and potentially augmented reality are likely to catalyse further advancements in this field. As the technology matures and gains more widespread acceptance, it has the potential to improve surgical outcomes and minimise complications. Future prospects with exoscope-assisted spine surgery have been illustrated in Fig. 2.

Fig. 2.

Future Prospects with exoscope-Assisted Spine Surgery.

5. Study limitations

While this review seeks to evaluate exoscope technology in spine surgery comprehensively, it is important to acknowledge certain limitations. The scope, while extensive, may only address a selection of the emerging applications and developments of exoscopes in this field. There may exist a publication bias as positive or significant findings are more often published, which could potentially sway overall conclusions. The quality and heterogeneity of the included studies could introduce variability into the data and results.

There is a lack of long-term follow-up data in the literature, restricting a thorough evaluation of persistent benefits and possible complications. The specified inclusion criteria might introduce bias, and some pertinent studies may have been unintentionally omitted. A detailed cost-effectiveness analysis was not undertaken, and further investigation into the learning curve associated with transitioning to exoscope-assisted methods is required.

Considering the novelty of the exoscope as a technology, the available literature on the topic is not only limited but also in certain instances, conflicting. This is a significant limitation that not just affects this review, but also exemplifies a broader scarcity of evidence-based research in this emerging field. It is important to acknowledge that this review serves as a foundational resource intended to guide future, more definitive research. Existing studies present conflicting views on the benefits of exoscopes, with some studies reporting superior depth perception and a greater depth of field^2,10,15 and others indicating poorer depth perception with the exoscope compared to the OM.^8,9,11, 12, 13, 14 Additionally, several studies do not differentiate the outcomes of various surgical procedures.^2,15,16 Consequently, the conclusions drawn may lack comprehensiveness and definitiveness.

Lastly, this review could be subject to language bias. Only full-text English articles were eligible for inclusion, meaning that pertinent studies may have been overlooked. To overcome this limitation, future reviews should engage language experts to ensure the inclusion of all relevant non-English articles on the subject.

6. Conclusion

In conclusion, exoscope technology holds considerable promise for improving spine surgery, providing superior visualisation, ergonomics, and surgical precision. The integration of robotics further augments its potential for facilitating safer and more efficient procedures. Although certain limitations and ethical considerations currently exist, it is likely that ongoing advancements and training will overcome these challenges, paving the way for more widespread adoption. As additional clinical evidence emerges, exoscope-assisted spine surgery has the potential to significantly transform surgical outcomes and patient experiences, marking a notable advancement in the field of spine surgery.

CRediT authorship contribution statement

Tomas Ferreira: Writing – review & editing, Writing – original draft, Methodology, Conceptualization. Sakshi Roy: Writing – review & editing, Writing – original draft, Methodology. Joecelyn Kirani Tan: Writing – review & editing, Writing – original draft, Methodology. Wireko Andrew Awuah: Writing – review & editing, Writing – original draft, Methodology, Conceptualization. Vallabh Shet: Writing – review & editing, Writing – original draft, Methodology. Favour Tope Adebusoye: Writing – review & editing, Writing – original draft, Methodology. Nicholas Aderinto: Writing – review & editing, Writing – original draft, Methodology. Toufik Abdul-Rahman: Writing – review & editing, Writing – original draft, Methodology.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.