This application is a National Stage Application of PCT/IB2018/052590, filed 13 Apr. 2018, which claims the benefit of Serial No. 10/2017000041980, filed 14 Apr. 2017 in Italy, and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above-disclosed applications.

FILED OF THE INVENTION

It is an object of the present invention a robotic surgical assembly.

In particular, the present invention relates to a robotic microsurgical assembly.

The present invention relates to a robotic microsurgical assembly of the type comprising a master tool and a surgical instrument.

The present invention relates to a surgical instrument as well as to a slave assembly for robotic surgery.

BACKGROUND

In robotically-assisted or robotic surgery under the master—slave paradigm, the surgeon typically operates a master tool to control the motion of surgical instruments. The master tool (“the master”) detects motion of the surgeon's hand. The master tools can be connected to a master tool manipulator including actuators to provide positioning and force feedback on the master tool. The master tools are coupled to a slave manipulator (“the slave”) including actuators, that manipulates, internally articulates and more generally operates the medical or surgical instruments. Such medical instruments can be connected and disconnected from the slave. A sterile barrier is usually provided between the slave and the medical instruments.

Robotic assemblies for surgery or microsurgery comprising multi-joint robotic arms operating surgical instruments are known in the field. For instance, document U.S. Pat. No. 7,155,316 discloses a robotic assembly for performing brain microsurgery under MRI (Magnetic Resonance Imaging) guidance comprising an MRI-based image acquisition system and two multi-joint arms, each with three rotary joints with vertical axes to avoid direct gravity loads (as shown for instance in FIG. 7 of said document U.S. Pat. No. 7,155,316), each connected to its respective end-effector endowed with an internal degree of freedom of motion for gripping.

It is also notable that the execution of the principal surgical primitives, such as tissue tensioning and anastomotic suturing, requires the ability to orient the surgical instrument tip in a large spatial cone of directions and to rotate the instrument around its longitudinal axis (roll), for example to guide the needle through the tissue with the tip of the needle holder instrument, in a similar manner as the human hand is jointed at the wrist and the elbow.

Robotic assemblies for surgery or microsurgery comprising a teleoperated master-slave system are generally known, as described, for example, in document U.S. Pat. No. 6,963,792 and, more specifically for the microsurgical application in U.S. Pat. No. 6,385,509 and US-2014-0135794, that describe kinematic solutions for the movement of the surgical instrument tip that require coordination of a plurality of joints in a serial kinematic chain that clutter the operating field. Such encumbrance effect is increasingly pronounced as the joints articulating the tip of the instrument are further away from the tip itself. Moreover said micro-surgical systems do not allow adequate movement, and more specifically adequate reorientation, of the instrument tip when in an operating site inside a lesion as little as 10 centimeters from the surface of the skin.

The adoption of robotic technologies can bring about great benefits, allowing both a high degree of miniaturization of the instruments and scaling the size of the movements in the operating field, hence eliminating the effect of physiological tremor and easing the manual task. For example, microsurgical procedures are carried out in several phases of the reconstruction of biological tissues, such as for example in the execution of blood vessel anastomosis, comprising small diameter vessels and nerves. Such procedures are carried out to reconstruct anatomy after the occurrence of traumatic lesions or of lesions produced by surgical removal of tissue, to reattach limbs and to revascularize tissues, all performed in an open surgery set-up given the pre-existence of a superficial lesion.

Others examples of application of microsurgical techniques are found in transplant surgery, neurosurgery or in vascular surgery, as well as in surgery around and inside the eye, and in the inner ear, as in the case of cochlear implants. Also the prominent surgical procedure of cardiac by-pass comprises the critical step of anastomosis of the coronary arteries. The need for instrument miniaturization is also felt in other surgical techniques, for example in minimal invasive surgery, such as laparoscopy and endoscopy, that are aimed at limiting the invasiveness of surgical instruments on biological tissue. With reference to laparoscopy, the technical solutions known in the art do not allow a satisfactory miniaturization of the diameter of the laparoscopic instruments employed in Single Incision Laparoscopic Surgery or Single Port Surgery. Moreover, it is worth noticing that the endoscopes typically employed in minimally-invasive-surgery (MIS) have an instrument channel with a diameter between 1 and 3.2 millimeters. Such dimensions limit the functionality of current surgical instrumentation available through the endoscope instrument channel, which at present is typically just capable of gripping action.

Document U.S. Pat. No. 5,710,870 discloses an example of double-jointed joint which connects two adjacent robot members, and wherein such double-jointed joint is suitable for providing a single degree of freedom to said two adjacent robot members connected by means of said double-jointed joint.

Medical instruments comprising a jointed subassembly suitable to work on the patient are generally known in the art. For example, document WO-2010-009221 shows a robotic surgical instrument comprising a distally jointed subassembly, capable of providing three degrees of freedom of motion, respectively pitch, yaw and grip, employing four actuation cables. Such cables slide inside guiding channels, or sheaths, present inside the body of the articulating device.

Said technical solution limits the miniaturization of the robotic articulating device, because friction between the guiding channels surfaces and the cables that slide inside them limits the positioning precision achievable by the articulating device. As it is known in the art, as the physical dimensions of a medical instruments are reduced, difficulties arise which are related to the increase of relevance of superficial forces, such as friction, that become dominant over volume forces. Such a phenomenon requires to resort to solutions that minimize friction forces, and at the same time reduce lost motions of mechanics to a minimum.

The loss of positioning precision of an articulating device is a fundamental technological obstacle to further miniaturization of articulating instrument, since, with miniaturization, also the stiffness of the driving members (tendons) goes down with the second power of their diameter, making it even more difficult to overcome friction for the precise positioning of the instrument tip. Moreover such a solution requires a tendon guiding system comprising channels and guiding surfaces that surround the cables that make the pitch and yaw links, as well as the instrument shaft, very difficult to miniaturize using known fabrication methods, such as for example injection molding and machining, and would be prone to have several locations of mechanical weakness.

In order to simplify the miniaturization of a surgical instrument, said document WO-2010-009221 indicates the advantageous opportunity of reducing the number of actuation tendon terminations, associated to three degrees of freedom, from six to four, exploiting for actuation the torque that cables terminated on the yaw link apply on the pitch link (seeFIG. 4-A of cited document) and requires to such purpose to pull and release selectively such cables, thanks to a kinematic mechanism comprising a number of gears. Moreover, the driving system described requires that each end of an actuation tendon is attached to a winch, that selectively winds the tendon inducing the pull.

The presence of mechanical aspects such as said winch and said teeth, which are notoriously subject to lost motion, creates a difficult to drive a miniature articulation, because lost motion in the drive system is translated into an angular play at the joint, that increase as the articulating device gets smaller. Said driving system is also unsuited to keep a low preload on the actuation cables to further limit friction and wear.

Moreover, the solutions described for tendon termination comprise tortuous paths meant to trap the tendon in some sections. Such solutions require the use of cables that are sufficiently resistant to survive such trapping, such as steel cables or cables with larger diameter than otherwise required.

For example, document US-2002-128661 shows actuation cables which are routed through guide holes provided for in the instrument shaft, wherein each of said actuation cables touches with a distal portion thereof a single link and it is firmly secured thereto. A further similar example is given by document U.S. Pat. No. 6,676,684.

Further examples of actuation cables for surgical instruments suited to slide, when pulled or pushed, inside sheaths or guiding channels, for example obtained on the lateral surfaces of pulleys, are disclosed in documents U.S. Pat. Nos. 6,371,952, 6,394,998 and WO-2010-005657.

Specifically, the latter document discloses a solution where actuation cables follow trajectories that cross as they go around pulleys that comprise guiding channels to avoid that such cables interfere with one another, a condition that limits their efficacy in transmitting motion to the articulating device, such as for instance in case of bundling up or sliding of one tendon onto another one. The provision of idle pulleys, necessarily with a diameter close to half of the instrument diameter (as shown in FIG. 4 of cited document WO-2010-005657) and attached to the links, and specifically to the main structural body of the links, for example to links integral with the instrument shaft, or to the pitch link, to guide the tendon to cross, is a considerable obstacle to miniaturization.

Moreover the provision of grooves and walls to realize the channels for the actuation cables is a further obstacle to the miniaturization of the shaft or cannula diameter of a medical, or surgical, instrument.

The document US-2003-0034748 discloses a solution suitable for reducing the diameter of the surgical instrument to 5.1 millimeters. This instrument foresees the use of a series of disks that function as vertebra, providing some bending at bending radius larger than the instrument diameter.

Nevertheless, this solution is not appropriate for achieving a compact joint that can extend for approximately one instrument diameter, or in other words, has a radius of curvature similar to its diameter. This is instead achievable by those articulations described in the documents cited above which are based on a pivot-type joint, comprised of a pure axis of rotation, for example implemented as pin joints, clevis, etc.

A further obstacle to the miniaturization of jointed or articulated devices is the challenge of fabricating and assembling three dimensional micromechanical parts with sufficient precision at a reasonable process cost. The need to develop relatively high forces at the tip in devices with a sub-millimeter size suggests the use extremely rigid metals for such components, such as for example tool steel.

Hence there is a felt need to provide a jointed or articulated medical instrument, or an assembly comprising an jointed or articulated device, which is structurally and functionally suitable for extreme miniaturization without compromising its reliability and safety.

There is also a felt need to provide a jointed or articulated medical instrument, or an assembly comprising a jointed device, suitable for carrying out a wide variety of medical-surgical therapies.

Then, there is a felt need to provide a jointed or articulated medical instrument, or an assembly comprising a jointed or articulated device, that is durable and able to undergo periodic maintenance without compromising its sterility or reliability.

There is a felt need to provide a jointed or articulated medical instrument, or an assembly comprising a jointed device, that requires simplified manufacturing and assembly compared to known solutions.

The need is felt to miniaturize medical instruments.

The need is felt to reduce the known dimensions of medical instruments.

For example, document WO-2014-151952 shows a medical instrument comprising a plurality of links forming a joined device, said medical instrument having actuation cables wrapping around a plurality of pulleys rotatably supported on shaft provided cantilevered on the links of the medical instrument. This solution is characterized by a high number of parts, and the layout of said pulleys provided on said shafts forces to machining said shaft to resist to the stresses arising from the use of the medical instrument, therefore this solution results unsuitable for miniaturization, in fact this device could not measure less than 10 millimeters in diameter. Similar solutions are shown, for example, in documents U.S. Pat. No. 6,676,684, US-2009-0112230 and US-2003-135204.

It is therefore felt the need of reducing the number of parts which forms the medical instrument.

For example, document WO-03-001986 shows a medical instrument comprising a plurality of disc-shaped links forming a joined device, wherein each of said links comprises a plurality of holes for guiding the actuation cables. Said holes keep the actuation cables within said links, avoiding that they depart from said links, avoiding that they take up space around the links and avoiding that they create pinch points, all such scenarios being unacceptable for surgical applications, for example for safety reasons. Said holes also guide the actuation cables avoiding that a mechanical advantage they have in applying a pull force to a said link is reduced when said actuation cables depart from said links.

Therefore, this solution is unsuitable for miniaturization as it is highly unsatisfactory performing micrometric holes in such links, and at the same time, it is unsatisfactory providing actuation cables which slide inside such holes without damaging.

It is therefore felt the need of obtaining an accurate guiding of the actuation cables without providing micrometric holes in the links and at the same time to reduce the number of parts which forms the medical instrument.

For example, document US-2008-177285 discloses a medical instrument comprising a plurality of links, wherein some links comprise two protruding pins suitable to guide the deflection of the actuation cables. Although satisfactory under some points of views, such solution is also unsuitable for miniaturizing, as the protruding pins dimension cannot be reduced without compromise the integrity of the links composing the medical instrument.

Therefore, the need is felt to provide a miniaturized medical instrument, having a plurality of links actuated by means of actuation cables, without compromise the structural resistance, and thus the safety when in use, of the medical instrument.

For example document US-2016-0051274 discloses a wrist mechanism (FIG. 15) including rolling element joints to provide improved miniaturization to instrument diameters between 1 and 5 millimeters. Such solution fails to provide an improved solution for the routing of actuation tendons, which are still guided through holes in the link members, which are difficult to miniaturize. The solution also requires sharp bends to the cables at the entrance and exit of said holes, creating points of weakness.

Similarly document US-2017-0020615 discloses a wrist subassembly (FIG. 5-A) with a reduces number of parts that fails to provide a solution to route the actuation tendons without the use of guide holes that are required to exert a large lateral force on the tendons to keep them on their path, creating likely points of weakness and friction for said tendons.

Similarly document EP-2415418, discloses a wrist subassembly (FIG. 4 and FIG. 5) including a double-joined joint, that provide advantages for the decoupled control of the wrist joints. The solution still relies on the employment of a number of guide idler pulleys to route the actuation cables, thus a large number of parts that are difficult to miniaturize and assemble.

Similarly, document US 2016-0302876 discloses a wrist subassembly (FIG. 1 and FIG. 2) including a double-jointed pitch joint connecting the first link to the second link. The proposed solution includes a pair of actuation tendons that are routed over a idler pulleys (reference numbers 54 and 58), which are pinned to the structural body of respectively link one and link two, to actuate the third (yaw) link. The presence of idler pulleys pinned to the structural link members limits the miniaturization of the instrument diameter due to the minimum diameter of available idler pulleys and weakness of their inner ring support.

Therefore, it is strongly felt the need to miniaturize surgical instruments for robotic surgery.

Solution

A scope of the invention described here is to overcome the limitations of known solutions as described above and to provide a solution to the needs mentioned with reference to the state of the art.

