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EP-4740890-A2 - AUTOMATED ROBOTIC RETRACTOR

EP4740890A2EP 4740890 A2EP4740890 A2EP 4740890A2EP-4740890-A2

Abstract

Systems and methods for robotic retraction of tissues in a surgical field. Two retractor mechanisms are used on either side of an incision. Each retractor is adapted to be held by a robotic arm, which applies force on the retractor mechanism to pull dissected tissue away from the incision, thus revealing the operative field. A force sensor is employed to measure the force on the retractor, an optional tracking sensor may be used to measure the extent of tissue retraction in two or three dimensions, and both sources of information provided to the robotic controller. By monitoring feedback from either the force sensor or the tracking sensor, the system is able to maintain equal retraction on both sides of the incision. The retractor elements incorporate mechanisms that move down the tissue as the retractors are pulled laterally.

Inventors

  • ZEHAVI, ELI
  • SHOHAM, MOSHE
  • USHPIZIN, Yonatan
  • TURGEMAN, AVI

Assignees

  • Mazor Robotics Ltd.

Dates

Publication Date
20260513
Application Date
20211102

Claims (10)

  1. A system for bilateral robotic retraction of tissue, comprising: two robotic arms (104A, 104B, 204A, 204B, 313), each having a retractor element (101A, 101B, 201A, 201B, 301) at its distal portion; a force sensor (106A, 106B) associated with each retractor element (101A, 101B, 201A, 201B, 301), each force sensor (106A, 106B) being adapted to provide an output signal according to the force exerted by its associated retractor element (101A, 101B, 201A, 201B, 301) on the tissue; and a controller (105) configured to: receive the output signals, control the motion of the robotic arms (104A, 104B, 204A, 204B, 313), and maintain forces applied by the two retractor elements (101A, 101B, 201A, 201B, 301) below a predetermined allowable limit of force, such that motion of the two retractor elements (101A, 101B, 201A, 201B, 301) is generated in opposing directions away from a surgical opening, characterized in that at least one of the retractor elements (101A, 101B, 201A, 201B, 301) comprises a moving set of protrusions positioned to grip the tissue surface, such that an upward motion of the protrusions generates an associated downward motion of the retractor element (101A, 101B, 201A, 201B, 301) into the retraction opening.
  2. The system according to claim 1, wherein the predetermined level of force is selected such that an allowable pressure exerted by each retractor element (101A, 101B, 201A, 201B, 301) on the tissue it retracts is less than the pressure level at which damage would be caused to that tissue.
  3. The system according to claim 1, further comprising tracking sensors (108A, 108B) adapted to track the position of each retractor element (101A, 101B, 201A, 201B, 301), the tracking sensor (108A, 108B) output signals enabling the controller (105) to confirm that each retractor element (101A, 101B, 201A, 201B, 301) is located at an equal distance from the surgical opening.
  4. The system according to claim 1, wherein the controller (105) uses a robotic co-ordinate system to maintain an equidistant position of the retractor elements (101A, 101B, 201A, 201B, 301) from their initial positions at the commencement of the retraction process.
  5. The system according to claim 1, wherein the controller (105) is adapted to actuate the motion of the protrusions in the retractor elements (101A, 101B, 201A, 201B, 301) in accordance with the measured extent of retraction.
  6. The system according to claim 5, wherein at least one retractor element (301) comprises two connected sets of interdigitating fingers (302, 303), a first set of fingers (302) being fixedly attached to the robotic arm (313), and a second set (303) being pivotally connected to the first set of fingers (302) in their proximal region, and attached to the first set of fingers (302) by a rotating crank element at their distal end, such that eccentric rotation of the distal end of the second set of fingers (303) generates a crawling motion of the retractor element (301).
  7. The system according to claim 5, wherein at least one retractor element (301) comprises a belt, tread, or chain drive (311) adapted to generate the downward motion of the retractor element (301) into the retraction opening.
  8. The system according to claim 5, wherein the tracking sensor (108A, 108B) measures the extent of retraction in three-dimensional space, such that the position of the tissue relative to that determined in an operative plan can be verified.
  9. The system according to claim 1, wherein the controller (105) is adapted to maintain the position of the robotic arms (104A, 104B, 204A, 204B, 313) holding the retractor elements (101A, 101B, 201A, 201B, 301) when a predetermined force is reached.
  10. The system according to claim 1, wherein the surgical opening is an incision along the dorsal midline of a subject, and the tissue being retracted are muscles located on either side of the dorsal midline.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application number 63/114,964, filed on November 17, 2020, and entitled "Automated Robotic Retractor", the entirety of which is hereby incorporated by reference. FIELD The present disclosure describes technology related to the field of surgical robotics, especially for mechanisms of automating the retraction of soft tissue. BACKGROUND The ability to retract soft tissue that is positioned between a surgical opening or skin incision, and a surgical site which may lie many centimeters below the surface, is an essential component of successful surgical procedures performed in an open operation. Traditional mechanical retractors may employ a scissors-type opening mechanism, or may be simple, one-sided hook-based tools of many shapes, sizes, and applications, depending on the location or surgical procedure for which they are used. More complex retractors, such as the Seton-type retractor, supplied by several major manufacturers of surgical equipment, have also been developed based on a rectangular or circular metal frame with screws to tighten retractor hooks in specific locations, usually under tension or pressure, to enable a larger opening in the tissue. Both scissors-type bilateral retractors and single hook designs, as well as a metal frame with screws, are limited by positioning them repeatedly and manually throughout the application. A further advance in surgical retraction is to automate the positioning or holding of retractor elements. Several endeavors have been made to design a system with automated control of surgical retractor positioning. A danger with tissue retraction and fixed positioning of a retractor, whether manual or automatic, is applying more pressure than the tissue can withstand without undergoing traumatic damage. Excessive pressure may cause both hypoperfusion and mechanical tissue injury. The disclosures of each of the publications mentioned in this section and in other sections of the specification, are hereby incorporated by reference, each in its entirety. SUMMARY The present disclosure describes new exemplary systems for robotically actuated tissue retraction, which overcome at least some of the disadvantages of existing robotic retractor systems. In one embodiment, the system is based on a set of mechanical retractors that operate on either side of a surgical incision. The system can be used either with a surgeon generated incision, or using a robotic system to generate the incision, the robotic system optionally being the same system as that providing the automatic retraction procedure. A common procedure would be to perform a midline incision or tissue dissection for a spinal fusion procedure. In such a procedure, retraction of several layers of subdermal connective tissue, fascia, and paraspinal muscles is generally needed to enable access to the vertebrae undergoing surgical fusion. With retraction of many layers of tissue, the incision can unintentionally be shifted asymmetrically to one side relative to the deeper tissue layers and the anatomic features on which the operation is to be performed. The surgeon may then also lose his/her reference position with respect to anatomical landmarks in the region of interest. If the operation is being carried out using a registration process using identification markers on the skin, it is crucial that the deeper tissues on either side of midline maintain their relative position to the midline, or relative to the initial position of the incision relative to the deeper layers of tissue. An accidental shift of the deeper layers of the surgical opening to the right or left of the midline incision has the potential to disrupt the registration process, thereby creating a misalignment between the surgical plan and the actual tissue features. Misalignment by even a few millimeters can result in damage to nerve tissue, having serious consequences for the outcome of a procedure based on, for instance, opening up a vertebral lamina or a vertebral foramen that is only centimeters or even millimeters in diameter. Likewise, in a manually performed dissection procedure, a shift in the surgical field to either side of the intended midline has the potential to mislead the surgeon, as known anatomical landmarks may not be visible in the anticipated location during surgical dissection. The disclosed system, according to one exemplary implementation, uses a pair of retractors or retractor elements or mechanisms, each held by a robotic retractor arm. Each retractor mechanism is fitted with or connected to a force sensor that determines the lateral force applied to the retractor inserted into an incision, as it is forced outwards by its robotic arms. A predetermined force level is set, based on known safe levels of pressure on a given area of tissue, also therefore based on the width of the retractor elements. For a long period of retraction, this level may corresp