Cooperative robot assistant for vitreoretinal microsurgery: development of the RVRMS and feasibility studies in an animal model

Microsurgery Robots: Applications, Design, and Development

Microsurgical techniques have been widely utilized in various surgical specialties, such as ophthalmology, neurosurgery, and otolaryngology, which require intricate and precise surgical tool manipulation on a small scale. In microsurgery, operations on delicate vessels or tissues require high standards in surgeons' skills. This exceptionally high requirement in skills leads to a steep learning curve and lengthy training before the surgeons can perform microsurgical procedures with quality outcomes. The microsurgery robot (MSR), which can improve surgeons' operation skills through various functions, has received extensive research attention in the past three decades. There have been many review papers summarizing the research on MSR for specific surgical specialties. However, an in-depth review of the relevant technologies used in MSR systems is limited in the literature. This review details the technical challenges in microsurgery, and systematically summarizes the key technologies in MSR with a developmental perspective from the basic structural mechanism design, to the perception and human-machine interaction methods, and further to the ability in achieving a certain level of autonomy. By presenting and comparing the methods and technologies in this cutting-edge research, this paper aims to provide readers with a comprehensive understanding of the current state of MSR research and identify potential directions for future development in MSR.

A Symmetric-Actuating Linear Piezoceramic Ultrasonic Motor Capable of Producing a Scissoring Effect

Conventionally, to produce a linear motion, one motor's stator is employed to drive one runner moving forward or backward. So far, there is almost no report of one electromechanical motor or piezoelectric ultrasonic motor that can directly generate two symmetrical linear motions, while this function is desired for precise scissoring and grasping in the minimally invasive surgery field. Herein, we report a brand-new symmetric-actuating linear piezoceramic ultrasonic motor capable of generating symmetrical linear motions of two outputs directly without additional mechanical transmission mechanisms. The key component of the motor is an (2 × 3) arrayed piezoceramic bar stator operating in the coupled resonant mode of the first longitudinal (L₁) and third bending (B₃) modes, leading to symmetric elliptical vibration trajectories at its two ends. A pair of microsurgical scissors is used as the end-effector, demonstrating a very promising future for high-precision microsurgical operations. The sliders of the prototype show the following features: (a) symmetrical, fast relative moving velocity (~1 m/s) outward or inward simultaneously; (b) high step resolution (40 nm); and (c) high power density (405.4 mW/cm³) and high efficiency (22.1%) that are double those of typical piezoceramic ultrasonic motors, indicating the full capacity of symmetric-actuating linear piezoceramic ultrasonic motor working in symmetric operation principle. This work also has enlightening significance for future symmetric-actuating device designs.

Porcine training models for endoscopic and robotic reconstructive breast surgery: a preliminary study

Background

With recent advances in surgical techniques, minimally invasive methods for reconstructive breast surgery are being investigated. To enhance surgical proficiency through training and minimize predictable complications before human application, we conducted a preliminary experimental study of reconstructive breast surgery using a porcine model.

Methods

Between February and March 2019, four 3-month-old pigs underwent a bilateral mastectomy and immediate breast reconstruction with a latissimus dorsi (LD) flap or silicone implants. After performing the mastectomy by dissecting the pectoralis profundus in the subcutaneous plane, the pig was placed in the decubitus position, and ultrasound-guided marking was used to design the LD flap. The thoracodorsal artery was marked, and a 4-cm incision was made on the midaxillary line. An additional endoscopic incision was made in the inferior margin of the LD flap; a 2-hole approach was used for endoscopic LD flap elevation. In the silicone implant model, a silicone implant (Allergan, smooth, round type, 90 cc) was placed using a single incision (4-5 cm).

Results

Eight mastectomies followed by breast reconstruction with LD flap elevation or silicone implant models were performed on four pigs. Serious complications, such as active bleeding, did not occur. However, heat dispersion to the skin flap that became thinner by endoscopic dissection caused a second-degree burn in one pig.

Conclusions

This preliminary study of endoscopic or robot-assisted minimally invasive reconstructive breast surgery demonstrates that a porcine training model is a highly valuable experimental model for surface anatomy verification, incision plan selection, instrument selection, operator proficiency enhancement, and complication prevention.

Improved Integrated Robotic Intraocular Snake: Analyses of the Kinematics and Drive Mechanism of the Dexterous Distal Unit

Retinal surgery can be performed only by surgeons possessing advanced surgical skills because of the small, confined intraocular space, and the restricted free motion of the instruments in contact with the sclera. Snake-like robots may be essential for use in retinal surgery to overcome this problem. Such robots can approach the target site from suitable directions and operate on delicate tissues during retinal vein cannulation, epiretinal membrane peeling, and so on. We propose an improved integrated robotic intraocular snake (I2RIS), which is a new version of our previous IRIS. This study focused on the analyses of the kinematics and drive mechanism of the dexterous distal unit. This unit consists of small elements with reduced contact stress achieved by changing wire-hole positions. The kinematic analysis of the dexterous distal unit shows that it is possible to control the bending angle and direction of the unit by using two pairs of drive wires. The proposed drive mechanism includes a new pull-and-release wire mechanism in which the drive pulley is mounted at a right angle relative to the actuation direction (also, relative to the conventional direction). Analysis of the drive mechanism shows that compared to the previous drive mechanism, the proposed mechanism is simpler and easier to assemble and yields higher accuracy and resolution. Furthermore, considering clinical use, the instrument of the I2RIS is detachable from the motor unit easily for cleaning, sterilization, and attachment of various surgical tools. Analyses of the kinematics and drive mechanism and the basic functions of the proposed mechanism were verified experimentally on actual-size prototypes of the instrument and motor units.