TiRobot Debuts in the Orthopedic OR

Anusha Das

Thomas Jefferson High School for Science and Technology

This article placed 1st in the 2023 Teknos Summer Writing Contest.

Picture an executioner swinging the trap door from under the prisoner. The prisoner rappels down until the rope pulls taut, causing their neck to suddenly bend back, crushing their cervical vertebrates’ protruding processes into shards. This fracture is aptly named a hangman's fracture [9].

The neck is a vulnerable body part. The upper spine houses a cornucopia of vital nervous and vascular structures, and its intricately layered anatomy makes treating fractures in the vertebrae a formidable challenge [4]. Though the practice of hanging men is no longer prevalent, modern day humans are still subject to hangman’s fracture and other life threatening neck injuries. For instance, when a passenger is not secured by a seat belt or cushioned by an airbag,  inertia from a vehicle collision can cause them to launch forward into the windshield. Just like when a person is hanged, the victim’s neck hyperextends backward. In fact, any high force trauma, such as a fall or a blunt force to the front of the skull, can injure the neck from the sheer impact of the spinous processes jabbing into each other [9].

If that was not alarming enough, the risk for high force fracture injuries may be 10 times greater for older individuals [1]. This is due to bones being composed of dynamic living cells with carefully calibrated lifecycles. As humans age, cells begin to lose the ability to detect and respond to biochemical stimuli. This holds true for all cells, including osteoblasts: the cells responsible for depositing bone. Though the exact biochemical culprits are unknown, osteoblasts become less numerous, and there is a net decrease in bone over time [1]. Vertebral bones gradually lose structural integrity as a result. 

Once a cervical vertebra is fractured, every treatment option comes with significant risks. For a hangman’s fracture, the risk of neurovascular damage is simply too high for surgery [9].  Thus, casts and braces, such as the halo vest, are currently the most accepted solutions. Although noninvasive, the halo vest is a daunting device that immobilizes the entire upper back and head for 12 weeks, severely limiting daily life. Plus, even after 12 weeks, there is a chance for nonunion of the bone fragments [9]. For odontoid fractures, another type of neck fracture, there has been a growing popularity for surgical intervention. Unlike hangman’s fractures, odontoid fractures are lower from the base of the head so surgery is a safer option and research shows surgery results in a faster recovery [7]. Even so, surgery holds many possible complications. One of the currently available surgical options involves screwing the C1 to the C2 vertebrae, but that fixation limits the range of neck rotation. The second option would be to insert a pars-pedicle screw extending from the front to back of a single vertebrate, preserving almost all range of motion but at the cost of requiring a larger incision [2]. 

Yet another aspect to consider is the kind of surgery: open or percutaneous. Open surgery gives the surgeon better visibility, but the patient may suffer more trauma, bleeding, and muscle atrophy [3]. Alternatively, percutaneous surgery is a minimally invasive method that utilizes a needle-like probing tool. However, extensive fluoroscopy imaging, basically a real-time x-ray technique, exposes both the physician and patient to significant amounts of radiation [3, 4, 10].  Even with an experienced surgeon, the dense anatomy may cause malposition of the bone or nerve damage [7]. 

To alleviate the need to choose between major treatment risks, the Chinese Food and Drug Administration certified the TiRobot in 2016, a semiautonomous portable robot arm that assists in percutaneous surgery [11]. The TiRobot may soon work side by side with surgeons worldwide, its metallic drills piercing into the bone under the nape of the neck. But the question that remains is: Will the TiRobot be a silver bullet to the vertebral fracture dilemma or will outcomes not improve from traditional freehand surgery?

TiRobot, short for Tianji Orthopedic Surgery Robot, has breakthrough improvements in 3D perspective navigation and consists of three systems [11]. The first is the navigation system where the surgeon can map out a drill trajectory based on fluoroscopy photographs taken in three planes. Second, is the optical tracking system, where the robot automatically positions and steers itself to follow the aforementioned trajectory. Third, is the robotic arm, which threads the opening for the screw to insert [7, 9]. 

Knowing its potential, the TiRobot seems like the perfect device for accuracy and safety. But the literature evaluating the TiRobot brings to light some contrasting results. In one of its first cases in 2016, there appeared to be three guarantees: a reduced amount of radiation exposure due to quicker fluoroscopy, a smaller incision minimizing blood loss and fascia trauma, and most importantly, the screw’s accuracy only deviated 0.9 mm from the trajectory [7]. A recent 2023 study analyzed the insertion of 60 screws and proved similar results. For example, the average incision was 1 cm, compared to the traditional 4 cm. Additionally, 91% of the screws were successfully placed, compared to the usual success rate of accurate screw placement which is 77%-89% [9]. However, two even larger studies relating to the lower and mid spine revealed no significant difference in blood loss or rate of traumatic damage which are arguably the most important considerations [3, 10].  This finding, coupled with no difference in length of hospital stay or rate of infection, and markedly higher costs, presents a significant drawback. In one case, robot surgery reportedly increased expenses by $3200 [2]. 

It is worth noting that robots working hand-in-hand with healthcare providers is not a revolutionary suggestion. Robots have been permeating hospitals for over 20 years [5]. In fact, as Merriam Webster defines it, robots could be any computer-controlled device that mimics complex human movements or behaviors. Under this umbrella, the journal “Communications of ACM” considers scheduling software for clinicians, prosthetics for amputees, microbots for diagnosticians, monitoring electronics for nurses, and automated trauma sonography for EMTs as robots [6]. What makes the TiRobot revolutionary is the leap it makes in percutaneous surgery compared to its older relative, the Da Vinci robot.

While the Da Vinci robot is only capable of laparoscopic surgery, a minimally invasive surgery for the abdomen, the TiRobot is unparalleled because it is effective in orthopedic surgeries. Nonetheless the Da Vinci robot, at its time, was also revolutionary, so it can provide clues to the future of the TiRobot. Although the Da Vinci robot was uncommon at first, the U.S. Department of Defense reported that in every quarter from 2015 to 2018, there was approximately a 10% increase in the number of robot-assisted laparoscopic surgeries in military treatment facilities. Researchers attributed the breakneck growth of robots gradually proving superior to traditional methods, to surgeons’ becoming more comfortable using Da Vinci[2]. This foreshadows that the TiRobot may follow the same growth trend. Furthermore, the TiRobot industry already demonstrates signs of expanding because the TiRobot is debuting in other orthopedic surgeries. For instance, it has started participating in posterior pelvic surgery, becoming the only robot to do so [8].  Retrospectives studies reveal improvements in pelvic surgery that parallel the improvements in TiRobot-assisted spinal surgery [4, 8].

Perhaps the days of large incisions exposing pulsating organs and layered fascia clinging to bone are over. When imagining the future of surgery, it would be more realistic to envision an armada of robotic tools plunging into the anatomy that lies under our skin. 

References

[1] Boskey, A. L., & Coleman, R. (2010). Aging and bone. Journal of dental research, 89(12), 1333–1348. https://doi.org/10.1177/0022034510377791

[2] Grasso, S., Dilday, J., Yoon, B., Walker, A., & Ahnfeldt, E. (2019). Status of Robotic-Assisted Surgery (RAS) in the Department of Defense (DoD). Military Medicine, 184(9/10), e412–e416. https://doi.org/10.1093/milmed/usz145

[3] Lin, S., Wang, F., Hu, J., & Tang, L. (2022). Comparison of the Accuracy and Safety of TiRobot‐Assisted and Fluoroscopy‐Assisted Percutaneous Pedicle Screw Placement for the Treatment of Thoracolumbar Fractures. Orthopaedic Surgery, 14(11), 2955–2963. https://doi.org/10.1111/os.13504

[4] Long, T., Li, K., Gao, J., Liu, T., Mu, J., Wang, X., Peng, C., & He, Z. (2019). Comparative Study of Percutaneous Sacroiliac Screw with or without TiRobot Assistance for Treating Pelvic Posterior Ring Fractures. Orthopaedic Surgery, 11(3), 386–396. https://doi.org/10.1111/os.12461

[5] Riek, L. D. (2017). Healthcare Robotics. Communications of the ACM, 60(11), 68–78. https://doi.org/10.1145/3127874

[6] S., Hiranya., Prathap, L., Priya, V. V., & S., P. (2020). A Review on Role of Robots in Healthcare Setting: An Emerging Change in Healthcare Service. International Journal of Pharmaceutical Research (09752366), 12(1), 1486–1490. https://doi.org/10.31838/ijpr/2020.12.01.245

[7] Tian, W., Wang, H., & Liu, Y. (2016). Robot-assisted Anterior Odontoid Screw Fixation: A Case Report. Orthopaedic Surgery, 8(3), 400–404. https://doi.org/10.1111/os.12266

[8] Wang, B., Cao, J., Chang, J., Yin, G., Cai, W., Li, Q., Huang, Z., Yu, L., & Cao, X. (2021). Effectiveness of Tirobot-assisted vertebroplasty in treating thoracolumbar osteoporotic compression fracture. Journal of Orthopaedic Surgery & Research, 16(1), 1–7. https://doi.org/10.1186/s13018-021-02211-0

[9] Zhao, J. et al. Robot-assisted percutaneous pars–pedicle screw fixation for treating Hangman’s fracture. Journal of Orthopaedic Surgery & Research, [s. l.], v. 18, n. 1, p. 1–6, 2023. DOI 10.1186/s13018-023-03765-x. Disponível em: https://research.ebsco.com/linkprocessor/plink?id=032480df-e5e4-3957-a836-ea60a9278c9e.

[10] Zhao, C., Zhu, G., Wang, Y., & Wu, X. (2022). TiRobot‑assisted versus conventional fluoroscopy-assisted percutaneous sacroiliac screw fixation for pelvic ring injuries: a meta‑analysis. Journal of Orthopaedic Surgery & Research, 17(1), 1–14. https://doi.org/10.1186/s13018-022-03420-x

[11] Zhu, Z., Xiao, C., Tan, B., Tang, X., Wei, D., Yuan, J., Hu, J., & Feng, L. (2021). TiRobot‐Assisted Percutaneous Cannulated Screw Fixation in the Treatment of Femoral Neck Fractures: A Minimum 2‐Year Follow‐up of 50 Patients. Orthopaedic Surgery, 13(1), 244–252. https://doi.org/10.1111/os.12915