SmartArm: robotic surgical system performs suturing on neonatal chest model

The current use of robotic surgeries is confined mainly to adult patients. The reason is purely physical: in infants, the available ‘workspace’ is very small, which limits the use of current automated surgical techniques.

A recent study published on aimed to analyze the feasibility of using currently available robotic systems to perform such operations in neonatal settings.

The experimental setup for the esophageal suturing using the SmartArm surgical system. Image credit: Courtesy of the researchers, arXiv:2101.00741

TEF (tracheoesophageal fistula) and EA (esophageal atresia) are two known congenital esophagus disorders that need to be treated through robotic surgical systems. TEF requires disconnecting the esophagus and the trachea in the newborn. In EA, the esophagus is present in two disjoint parts that had to joint through surgery. The challenge posed in this phase is related to the anatomises that have to be performed on the neonatal trachea/esophagus.

The workspace constraint needs to be considered with utmost accuracy. To improve the outcomes of such surgeries, esophagus and chest models of neonates are developed which can be used for the practice of pediatric surgeons. These models were used by the research team to implement the SmartArm technique.

The research paper discusses treatment of TEF and EA disorders within a neonate chest model using the SmartArm system. This technique requires thin dexterous robotic instruments, teleoperation algorithms, and strategies to avoid a collision. The technique used in SmartArm was validated through the endonasal procedure using the head model of a newborn child.

Material and methods 

Neonate surgical setup was composed of two sections and also included a specific control strategy, all of which are briefly described below:

– Patient side

The patient side (PS) has two robotic manipulators on each side, with an overall 9-DOF (degrees of freedom). The robotic manipulator is composed of SmartArm and has 6-DOF, and each one is further equipped with a 3-DoF 20-cm-long 3.5-mm-diameter instrument. The endoscope holder holds a rigid endoscope to monitor the workspace.

The entire process is monitored through a 4-mm-diameter endoscope, and the suture is handled by a 3-mm-diameter forceps and a 3-mm-diameter needle driver.

– Operator side (OS)

There are two haptic interfaces at the OS, which are composed of a customized stylus. The robot in the PS receives signals from the interfaces in the OS.

– Control strategy

The control strategy on the PS is implemented using the quadratic-programming (QP) based controller and a Cartesian impedance controller on OS.

Experimental details

An experiment was conducted to demonstrate the capability of a SmartArm robotic system. The chest and the esophagus models were designed with utmost accuracy by the medical students at Nagoya University. The main aim of the experiment was to judge the feasibility of the entire setup. Current research does not include a comparison with the manual surgical process, and therefore it was published as a feasibility study.

A medical operator inexperienced in this type of surgery was chosen to tie the esophagus using SmartArm. Ten observations were taken to get a good understanding of the time taken to complete the process with SmartArm. The operator was required to make a two-tie knot (a knot that cannot be tightened despite pulling the thread).

To make a note of the time, the initial time was noted when the needle touched the esophagus, and the ending time was marked once the two-tie knot was done. All the parameters within the PS and OS were either kept constant or were in pilot trials.


Typically, it is considered that a professional surgeon might take 5 minutes to accomplish the task. Taking 5 minutes as the upper limit, the researchers discovered that operator with limited experience reached the upper limit two times out of 10. This leads to a logical assumption that an experienced medical operator could easily fulfill the required time limitations on a constant basis, and potentially even significantly reduce the overall duration of the procedure.

Final thought

Authors conclude, that this is the first successful robot-aided suturing feasibility demonstration on a neonatal model. The results of the experiment were quite close to results from real practice, which leads to a logical assumption that SmartArm could be used for surgeries in such and similar constrained workspaces. In the future work, the researchers aim to use the SmartArm system to compare its precision and workload against the manual surgery performed by an expert.

Source: Marinho, M.~M., Harada, K., Deie, K., Ishimaru, T., Mitsuishi, M. 2021. SmartArm: Suturing Feasibility of a Surgical Robotic System on a Neonatal Chest Model / arXiv210100741. Link:


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