WO2013104682A1

WO2013104682A1 - Implant placement guide

Info

Publication number: WO2013104682A1
Application number: PCT/EP2013/050319
Authority: WO
Inventors: Ben Geebelen; Louis Keppler
Original assignee: Materialise N.V.
Priority date: 2012-01-11
Filing date: 2013-01-09
Publication date: 2013-07-18

Abstract

The application relates to surgical instruments for guiding a surgical tool or implant according to patient-specific pre-operative planning, as well as to methods for the manufacture thereof.

Description

IMPLANT PLACEMENT GUIDE

FIELD OF THE INVENTION

BACKGROUND

The spine is a flexible structure that is capable of great curvature and twist in a plurality of directions. However, developmental or genetic irregularities, trauma, chronic stress and degeneration due to wear may result in the need for surgical intervention to effect repair. In cases of degeneration (or injury and disease) it may be necessary or desirable to remove a disc that is no longer performing the function of separation between adjacent vertebrae. This procedure of spinal fusion is particularly desirable in cases of degeneration or herniation, which often result in chronic and debilitating back pain.

A common way of performing a fusion between two vertebrae is the transforaminal lumbar interbody fusion (TLIF). The TLIF procedure is performed through a posterior incision exposing the back of the spine. The surgical procedure typically comprises steps such as the placement of pedicle screws into the vertebra, exposing the disc space on one side by removing the facet joint and protecting the nerve roots, entering the disc space and at least partially removing disc material (typically the disc wall is preserved as much as possible to later help contain the bone graft material), filling a spacer or interbody cage with bone graft and placing this into the disc space, optionally placing additional bone in the lateral (side) gutters of the vertebra and the disc space, attaching rods or plates to the pedicle screws and closing the wound.

Placing the interbody cage is a challenging and time-consuming step, as the cage needs to carefully follow a curved trajectory from the opening in the disc wall to its final position without damaging the disc wall. During this step surgeons rely heavily on fluoroscopy, thereby exposing the patient and hospital staff to radiation.

An alternative to spinal fusion surgery for the treatment of degenerative disc diseases is lumbar disc replacement, which involves the replacement of the removal of the damaged joint and replacement with a metal and plastic implant. The advantage is that the prosthetic disc aims to be functionally identical to the natural disc, allowing more movement at the damaged site.

However, disc replacements are typically also complex devices made of a combination of materials and are also bulky and difficult to place properly between adjacent vertebrae, making this type of surgery very difficult especially because the surgical window available for the surgeon is small and limited. The implantation of prior art devices typically requires invasive surgery for proper placement.

Accordingly, a need exists for an implantation system for inserting the inter-body cage or disc replacement device that is robust and surgically minimally invasive for the efficacious replacement of damaged or degenerated intervertebral discs.

The application provides tools which provide a solution to one or more of the above mentioned problems. SUMMARY OF THE INVENTION

The application provides surgical instruments that mechanically guide the trajectory of surgical tools and/or implants into a predetermined cavity in the human body, more particularly where there is limited access to said cavity.

A first aspect provides in a surgical instrument for guiding a surgical tool or implant according to a patient-specific pre-operative plan comprising a positioning tool to which the surgical tool or implant is connected and a guiding tool which, by guiding the movement of said positioning tool, ensures the movement of the surgical tool or implant along a predetermined path such as to ensure correct positioning thereof. As the guiding tool is patient-specific, its correct positioning on the patient can be ensured and thereby the correctness of the movement of the surgical tool or implant is guaranteed.

In particular embodiments, a surgical instrument as described herein is provided for guiding a surgical tool or implant according to patient-specific pre-operative planning comprising:

a) a positioning tool comprising:

- an elongated shaft having a proximal end and a distal end; - a connector for connecting a surgical tool or implant, said connector being located at the distal end of said elongated shaft; and

- a transmission element; and

b) a guiding tool comprising one or more patient-specific elements for placing said guiding tool on said patient and a guiding feature guiding the movement of said positioning tool or part thereof along the longitudinal axis of said elongated shaft;

wherein said positioning tool and said guiding tool are provided with a position monitor determining the position of said positioning tool relative to said guiding tool and wherein said transmission element translates the change in position of said positioning tool relative to said guiding tool into a rotational movement of said surgical tool or implant when connected to said connector, the angle of rotation for said rotational movement being around an axis perpendicular to the axis extending longitudinally through the center of said elongated shaft .

In particular embodiments of the surgical instrument as described herein, said position monitor comprises a position detector on said positioning tool or part thereof interacting with a position indicator on said guiding tool or part thereof, wherein said transmission element translates the change in position of said position detector relative to said position indicator into said rotational movement of said surgical tool or implant. More particularly, said position detector is positioned on an actuator, the mechanical movement of which is guided by said position detector and translated into a rotational movement of said surgical tool or implant by said transmission element. More particularly said actuator is a rotating element rotating around the longitudinal axis of said elongated shaft, the mechanical movement of which is translated by said transmission element.

According to particular embodiments of the surgical instrument said position detector on said actuator comprises a protrusion or notch and said position indicator on said guiding tool comprises one or more features which mate with said protrusion or notch. More particularly, said position indicator is a guiding rail, guiding the movement of said actuator.

According to particular embodiments, a surgical instrument is provided wherein the proximal end of said positioning tool further comprises a handle and/or an impaction element. According to particular embodiments, a surgical instrument is provided wherein said connector comprises a release mechanism for releasing said tool or implant, which release mechanism is optionally operated from the proximal end of said elongated shaft.

More particularly, provided herein is surgical instrument wherein said transmission element translates the mechanical movement of said positioning tool into the rotational movement of said surgical tool or implant when connected to said connector by means of interconnecting cogwheels.

According to a particular embodiment, described herein is a surgical instrument wherein said guiding tool comprises a support structure, a shaft for fitting said elongated shaft of the positioning tool and a patient-specific part mating with a part of the patient anatomy. More particularly, said part of the patient anatomy is part of a vertebra, or multiple vertebrae, or any other body part that allows positioning of said surgical instrument in a desired position.

According to a further particular embodiment, a surgical instrument is provided wherein said surgical tool or implant is an interbody cage. More particularly, said surgical tool or implant is a reamer for removing tissue and bone debris.

More particularly, a surgical instrument is provided wherein said guiding tool is an assembly of multiple parts.

According to particular embodiments, a surgical instrument is provided wherein said guiding tool is further provided with means for fixating said guiding tool onto the patient anatomy. More particularly, said means of fixating comprises apertures configured to releasably engage with pedicle screws.

A further aspect as described herein relates to methods for manufacturing a guiding tool for the surgical instruments as described herein, comprising the steps of:

(a) obtaining one or more images of the patient's anatomy;

(b) determining by pre-operative planning the desired path of how the surgical tool or implant is to be inserted; (c) identifying and selecting one or more anatomical regions on or around the insertion site suitable for supporting a guiding instrument;

(d) designing a surgical guiding tool comprising:

a) one or more patient-specific elements for placing said guiding tool on said one or more anatomical regions of said patient; and;

b) one or more guiding features for guiding the movement of said positioning tool or part thereof along the longitudinal axis of said elongated shaft;

c) at least one part of a position monitor interacting with at least one part of a position monitor on said positioning tool wherein the change in position of said positioning tool relative to said guiding tool is translated into the desired rotational movement of said surgical tool or implant; and;

(e) manufacturing said guiding tool based thereon.

More particularly, said guiding tool is made at least partially through additive manufacturing.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures of specific embodiments as described herein are merely exemplary in nature and are not intended to limit the present teachings, their application or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Figure 1A Illustration of a positioning tool according to an embodiment as described herein.

Figure 1 B Illustration of an implant according to an embodiment as described herein. Figure 1C Illustration of an implant connected to a positioning tool according to an embodiment as described herein.

Figure 2A-B Illustration of a guiding tool according to an embodiment as described herein.

Figure 3 Illustration of a surgical instrument according to an embodiment as described herein positioned on the vertebrae of a patient. Figure 4 Detailed illustration of the connection between an implant and a positioning tool according to an embodiment as described herein.

Figure 5 Alternative embodiment of a positioning tool as described herein. In this embodiment the mechanical movement of the actuator is translated into a rotational movement of the surgical tool or implant.

In the figures, the following numbering is used:

1 - surgical instrument; 100 - positioning tool; 101 - longitudinal axis; 1 10 - elongated shaft; 1 1 1 - proximal end; 1 12 - distal end; 1 16 - rotating element; 1 17 - protrusion; 120 - connector; 130 - transmission element; 131 - cogwheelassociated with the positioning tool; 140 - reference feature; 200 - surgical tool or implant; 201 - cogwheel associated with the surgical tool or implant; 202 - rotational movement; 210 - reference feature; 300 - guiding tool; 310 - patient-specific elements; 320 - guiding feature; 330 - guiding rail; 400 - patient anatomy.

DETAILED DESCRIPTION

The tools and methods envisaged herein will be described with respect to particular embodiments but are not limited thereto but only by the claims. Any reference signs in the claims shall not be construed as limiting the scope thereof.

As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

The terms "comprising", "comprises" and "comprised of as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of when referring to recited members, elements or method steps also include embodiments which "consist of said recited members, elements or method steps.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the tools and methods described herein. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of what is claimed herein, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the features of the claimed embodiments can be used in any combination.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments described herein are capable of operation in other sequences than described or illustrated herein.

The term "about" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/-10% or less, preferably +1-5% or less, more preferably +/-1 % or less, and still more preferably +/-0.1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed embodiments. It is to be understood that the value to which the modifier "about" refers is itself also specifically, and preferably, disclosed.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

All documents cited in the present specification are hereby incorporated by reference in their entirety.

Unless otherwise defined, all terms used in disclosing the tools and methods described herein, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this application belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the present teaching. The terms or definitions used herein are provided solely to aid in the understanding of the different embodiments.

Described herewith are means that mechanically guide the trajectory of surgical tools and/or implants into a predetermined cavity in the human body, more particularly where there is limited access to said cavity. This is of particular interest for the placement of an interbody cage into the disc space. The tools as described herein allow a reduction in operation time and a reduction of the use of fluoroscopy during the surgical procedure. Indeed, as the entire surgical procedure can be planned pre-operatively and the realization of the pre-operative plan is guaranteed by said tools, the surgical procedure can be performed much faster than normal surgical procedures. As the guidance of the implant is determined by the surgical instrument and the pre-operative planning, the surgeon does not have to rely on imaging techniques such as fluoroscopy to continuously monitor the position of the implant. The number of images taken during the surgery can for instance be limited to one single image checking the final position of the implant. Images of the implant during the insertion are no longer required. Moreover, by providing a surgical instrument that guides a surgical tool or implant to the correct position according to a pre-operative plan, the surgical incision that needs to be provided can be kept as small as possible, implying less discomfort for the patient and shorter recovery periods.

In a first aspect, provided herein is a surgical instrument for guiding a surgical tool or implant according to a patient-specific pre-operative plan comprising a positioning tool to which the surgical tool or implant is connected and a guiding tool which, by guiding the movement of said positioning tool ensures the movement of the surgical tool or implant along a pre-determined path such as to ensure correct positioning thereof. As the guiding tool is patient-specific, its correct positioning on the patient can be ensured, thereby guaranteeing the correct movement of the surgical tool or implant.

In particular embodiments, the surgical instrument can be a surgical instrument for guiding a surgical tool or implant according to a patient-specific pre-operative plan comprising:

a) a positioning tool comprising:

- an elongated shaft having a proximal end and a distal end;

- a connector configured for connecting a surgical tool or implant, said connector being connected to or located on the distal end of said elongated shaft; and

- a transmission element; and; b) a guiding tool comprising one or more patient-specific elements for placing said guiding tool specifically on said patient and one or more guiding features guiding the movement of said positioning tool or part thereof along the longitudinal axis of said elongated shaft;

wherein said positioning tool and said guiding tool are provided with a position monitor determining the position of said positioning tool relative to (and in particular embodiments within) said guiding tool and wherein said transmission element translates the change in position of said positioning tool relative to said guiding tool into a rotational movement of said surgical tool or implant when connected to said connector, the angle of rotation for said rotational movement being around an axis perpendicular to the axis extending longitudinally through the center of said elongated shaft.

Thus, the transmission element ensures that the change in position of said positioning tool relative to said guiding tool detected through said position monitor, is translated into a rotational movement of the tool or implant. The tool or implant is thus rotated around an axis perpendicular to the axis of the elongated shaft. In particular embodiments this movement is from a position wherein the axis of the tool or implant is substantially parallel with the elongated shaft, to a position in which the axis of the tool or implant is, larger than 0° from the original position of the tool or implant and at most substantially perpendicular to the axis of the elongated shaft. In particular embodiments, the tool or implant moves from the original position to a position which is between 15° and 90°, more particularly the tool or implant moves from the original position to a position which is between 30° and 80°, more particularly the tool or implant moves from the original position to a position which is between 40° and 70° relative to the axis of the elongated shaft. Together with a forward (i.e. downward or upward along the spine) movement of the elongated shaft of the positioning tool, this allows the guided movement of the tool or implant into a cavity, the orientation angle of which is about 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90° or substantially perpendicular to the orientation of the elongated shaft of the positioning tool.

As indicated above, the patient-specific elements of the guiding tool allow specific positioning on the body part. This ensures that, when the guiding tool is placed in the correct position on the patient, the movement of the surgical tool or implant can be precisely guided according to a pre-operative plan. Thus, the instruments provided herein make it possible to ensure that the movement of the surgical tool or implant is patient-specifically guided according to the preoperative plan. As the positioning tool is (typically manually) moved in the guiding tool, the change in position of said positioning tool relative to said guiding tool monitored by the position monitor is translated into a very specific rotational movement of the surgical tool or implant connected to the positioning tool.

The use of the surgical guiding instruments as described herein ensure that the surgical window can be limited to the area required for inserting the surgical tool or implant in the direction that is least invasive for the patient. The surgeon can completely rely on the pre-operative plan. Also no surgical images such as fluoroscopy are required to check the position of the surgical tool or implant at different times during the procedure. Once the surgical tool or implant is in place the position can be checked once but intermediate position verifications are no longer required.

The tools and methods described herein particularly relate to the field of implant surgery, more particularly implants which require the accurate placement of an implant through a narrow opening. These are particularly suited for implant surgery to the spine, and even more particularly for spinal fusion, a surgical technique also known as spondylodesis or spondylosyndesis where two or more vertebrae are joined using an implant or interbody cage.

The surgical guiding instruments as described herein are intended for guiding

"surgical tools" or "implants". The "surgical tools" as referred to herein can be any surgical tool used in the context of surgery such as a drilling or reaming element, a suction element, or even a syringe for supplying compositions. The "implants" envisaged in the present context include any type of implants, the positioning of which may require or allow introduction into the body at an angle.

According to a particular embodiment, a surgical instrument is provided wherein said surgical tool or implant is an interbody cage. A particular embodiment relates to a surgical instrument wherein said surgical tool or implant is a reamer for removing tissue and bone debris.

The term "positioning tool" as used herein refers to an element of the surgical guiding instrument which is used to drive the surgical tool or implant into or onto an anatomical position. The positioning tool is provided with an elongated shaft and a connector configured to reversibly attach the surgical tool or implant in a way that the position of the surgical tool or implant can be rotated relative to the axis of the elongated shaft. In particular embodiments, the connector can be a hook or clamp which latches onto a bar present on the implant or surgical tool.

The term "guiding tool" as used herein refers to an element of the surgical guiding instrument which ensures the correct placement and guiding of the positioning tool relatively to the body of the patient. The guiding tool typically guides or indicates a certain location and/or direction for positioning by physically guiding the positioning tool with the implant to a certain location. Without such element, the implant may be positioned incorrectly, leading to suboptimal functioning of the prosthesis and discomfort to the patient. The guiding tool as described herein comprises one or more guiding elements configured to guide the movement of the positioning tool or part thereof along the longitudinal axis of the elongated shaft of the positioning tool.

Both the positioning tool and the guiding tool are further provided with a position monitor. The position monitor on the guiding tool may according to a particular embodiment be provided onto or be incorporated in the guiding feature.

The guiding tool comprises one or more patient-specific elements, such as patient- specific surfaces which match with a surface on the patient's anatomy. A patient-specific element can be specifically placed onto an anatomical part of a patient and helps a surgeon ensure the correct positioning of the guiding tool on said anatomical part according to the pre-operative plan. This ensures the correct position of the positioning tool relative to the position on the body where the surgical tool or implant is to be positioned.

The positioning tool and the guiding tool are further provided with a position monitor. The position monitor is a tool that determines the position of the positioning tool relative to the guiding tool. In particular embodiments, the positioning tool moves through the guiding tool and the position monitor determines the position of the positioning tool within the guiding tool. The position monitor typically refers to any device that permits position measurement, either the absolute position or a relative one. The position monitor may be an electronic, electrical, optical or mechanical position monitoring system. These systems may include short range distance sensors that enable the measurement of the positioning tool relative to the guiding tool. These may use typical position detection technology including laser, CCD, CMOS or ultrasonic detection equipment ideal for the precise detection of position and/or displacement. Also, mechanical position monitoring systems are envisaged herein. The mechanical position monitoring systems particularly refer to systems where the positioning and guiding tools are provided with interacting features that upon interaction are able to indicate the precise position of the positioning tool relative to and/or within the guiding tool. These mechanical position monitoring systems may provide features such as protrusions, notches, guiding rails, pawls, ratchets, tongues, slots, roller assemblies, conveyers or the combination of these provided on either the positioning tool and/or the guiding tool. The mechanical interaction of these features detects and/or registers precisely the position of the positioning tool within the guiding tool.

The information regarding the position of the positioning tool relative to the guiding tool is transmitted either mechanically or electronically to the transmission element which translates the displacement information of the positioning tool relative to the guiding tool into a rotational movement of the surgical tool or implant, the angle of rotation for the rotational movement being around an axis perpendicular to the axis extending longitudinally through the center of said elongated shaft. The translation of the mechanical movement of the positioning tool relative to the guiding tool into the rotational movement of the surgical tool or implant is ensured by a transmission element. This translation can occur through a wide variety of ways including the mechanical, pneumatic or electronic transmission of the translational movement into the rotational movement. The translation of the movement can be made through any types of motion transformation systems including, but not limited to rack and pinion systems, screw gear systems, cam and follower systems, slider-crank mechanisms, gear trains, chain and sprocket gears, worm and screw gears, friction gear systems, belt and pulley systems. According to a particular embodiment, a surgical instrument as described herein is provided wherein said transmission element translates the mechanical movement of the actuator of said positioning tool into the rotational movement of said surgical tool or implant by means of interconnecting cogwheels.

According to a particular embodiment a surgical instrument as described herein is provided wherein said position monitor comprises a position detector on said positioning tool or part thereof interacting with a position indicator on said guiding tool or part thereof, wherein said transmission element translates the change in position of said position detector relative to said position indicator into said rotational movement of said surgical tool or implant.

The position indicator and position detector may be regarded as a first and a second reference feature provided on the positioning tool and guiding tool or part thereof, whereby the transmission element of the positioning tool translates a translational movement corresponding to the movement of said first reference feature relative to said second reference feature, into a rotational movement of the surgical tool or implant connected to the positioning tool.

In order to convert the translational movement of the positioning tool through the guiding tool into a rotational movement of the surgical tool or implant reference features may be provided on both the positioning tool and the guiding tool, the reference features indicating the relative position of the positioning tool in the guiding tool. The translational movement of the reference features relative to each other is detected either mechanically or electronically and accordingly translated by a transmission element into the rotational movement of said surgical tool or implant, thereby providing that as the positioning tool inserts the surgical tool or implant into the surgical opening, the downward motion of the positioning tool with the surgical tool or implant results in the tilting or rotational movement of the surgical tool or implant thereby inserting the surgical tool or implant into the correct position.

The reference features may be any types of features that can be used by the skilled person in order to correctly determine the position of the positioning tool relative to the guiding tool.

According to a particular embodiment, a surgical instrument is provided wherein the position detector is positioned on an actuator, the mechanical movement of which is guided by said position detector and translated into a rotational movement of said surgical tool or implant by said transmission element. More particularly said actuator is a rotating element rotating around the longitudinal axis of said elongated shaft, the mechanical movement of which is translated by said transmission element.

In particular embodiments, the actuator is moved by the position indicator(s) of the guiding tool along the axis extending longitudinally through the center of the elongated shaft of the positioning tool. In alternative embodiments however, the actuator is moved in a direction which is transversal to the axis of the elongated shaft.

In particular embodiments, the actuator of the positioning tool comprises a rotating element rotating around the longitudinal axis of said elongated shaft. The rotating movement of the actuator is translated into a rotating movement of the implant or surgical tool by the transmission element of the positioning tool. In these embodiments, the one or more position indicator(s) of the guiding tool are positioned such that they ensure a rotational movement of the actuator when the positioning tool is moved through the guiding tool.

In particular embodiments, the position indicator(s) of the guide ensure a translational movement of the actuator along the axis extending longitudinally through the center of the elongated shaft of the positioning tool.

A particular embodiment, relates to a surgical instrument as described herein wherein the position detector on said actuator comprises a protrusion or notch and wherein said position indicator on said guiding tool comprises one or more features which mate with said protrusion or notch. More particularly, the position indicator is a guiding rail, guiding the movement of said actuator.

A particular embodiment relates to a surgical instrument as described herein wherein the elongated shaft of the positioning tool comprises

- a main shaft, defining the longitudinal axis of said elongated shaft, and, connected thereto

- an actuator comprising a rotating element rotating around the longitudinal axis of said elongated shaft, the mechanical movement of which is dictated by the actuator and

- a transmission element translating the movement of said rotating element into a rotational movement of the implant or surgical tool connected to said positioning tool.

In these embodiments, the guiding tool typically ensures rotation of the actuator when the positioning tool is moved along its axis into the guiding tool. The translational movement of the positioning tool can be transmitted onto the rotating element which further acts on the transmission element. According to a particular embodiment, a surgical guiding instrument is provided wherein said actuator of the positioning tool comprises a rotating element which is provided with a protrusion or notch and wherein said guiding tool is further provided with one or more features which mate with said protrusion or notch on said rotating element, thereby guiding the movement of said rotating element. The rotation of the rotating element is controlled by the guiding tool as the protrusion or notch on the rotation element mates with a similar feature on the guiding tool. According to a particular embodiment both the main shaft and rotating element are provided with a protrusion or notch interlocking with one or more mating features on the guiding tool. The guiding tool thereby controls the rotation of both the main shaft and the rotating element with respect to each other. Alternatively, the main shaft and/or rotating element may be provided with a non-circular cross section.

According to a particular embodiment, a surgical instrument is provided wherein the feature on said guiding tool mating with said protrusion or notch on said rotating element is a guiding rail guiding the rotational movement of said rotating element of the actuator. The guiding rail mates specifically with the protrusion or notch on the rotating element and, during the translational movement of the positioning tool through the guiding tool, the translational movement of the positioning tool is also converted into a rotational movement of the implant or surgical tool connected to the positioning tool, as the protrusion or notch on the rotating element is guided through the guiding rail resulting in the rotation of the rotating element of the actuator.

In a particular embodiment, a surgical instrument is provided wherein the proximal end of said positioning tool further comprises a handle and/or an impaction element. In order to provide in a surgical tool which is easy to manipulate further elements such as a handle may be provided onto it. Also an impaction element allowing the surgical tool to be impacted may be envisaged.

According to a particular embodiment, a surgical instrument is provided wherein the connector allowing connection to an implant or surgical tool present on the positioning tool comprises a release mechanism for releasing said surgical tool or implant, which release mechanism is optionally operated from the proximal end of said elongated shaft. Any type of release mechanism envisaged by the skilled person can be used for this. More particular a release mechanism as described in US 7,247,158 (incorporated herein by reference) is envisaged.

According to typical embodiments, the guiding tools used herein comprise a support structure, a shaft for fitting said elongated shaft of the positioning tool and one or more patient-specific elements mating with part of the patient anatomy in the vicinity of the envisaged introduction site. The (one or more) patient-specific elements on the guiding tool allow the surgeon to obtain the correct position of the guiding tool onto the patient's anatomy, according to pre-operational planning. Indeed, the one or more patient-specific element(s) fit onto specific areas on or around the patient's anatomy in several contact points.

According to a particular embodiment, a surgical instrument is provided wherein the part of the patient anatomy which is envisaged for ensuring a specific fit of the patient- specific elements is part of a vertebra, or multiple vertebrae, or any other body part that allows positioning of said surgical instrument in a desired position. More particularly, the surgical instrument as described herein is a surgical instrument for performing a transforaminal lumbar interbody fusion (TFIL) on a patient.

According to typical embodiments, the one or more patient-specific elements of the guiding tools used herein comprise a means of fixating said guiding tools onto the patient anatomy.

According to a particular embodiment, said means of fixating said guiding tools onto the patient anatomy comprises of apertures designed to releasably connect to pedicle screws.

A particular embodiment relates to a surgical instrument as described herein wherein said surgical tool or implant is an interbody cage. A particular embodiment relates to a surgical instrument as described herein wherein said surgical tool or implant is a reamer for removing tissue and bone debris.

A further aspect provides in methods for the manufacture of the surgical instruments described herein. In particular embodiments, it is envisaged that the positioning tool is a standard instrument, and the guiding tools are designed to ensure that, based on pre-operative planning, the standard positioning tool is guided by the guiding tool such that it directs specific movement of the surgical tool or implant in accordance with said pre-operative planning. Thus, methods for manufacturing a guiding instrument are provided herein for use with a positioning tool as described herein, said methods comprising the steps of:

(a) obtaining one or more images of the patient's anatomy;

(b) determining by pre-operative planning the desired path of how the surgical tool or implant is to be inserted;

(c) identifying and selecting one or more anatomical regions on or around the insertion site suitable for supporting a guiding instrument;

(d) designing a surgical guiding tool comprising:

a) one or more patient-specific elements for positioning said guiding tool on said one or more anatomical regions of said patient identified in step (c); and;

(e) manufacturing said guiding tool based thereon.

In addition methods for manufacturing a surgical instrument as described herein are provided, said method comprising the steps of:

(a) obtaining one or more images of the patient's anatomy;

(c) identifying and selecting one or more anatomical regions on or around the insertion site suitable for supporting a guiding instrument; (d) designing a surgical guiding tool as described herein comprising:

a) providing a positioning tool comprising:

- a positioning tool (100) comprising:

- an elongated shaft (1 10) having a proximal end (11 1 ) and a distal end (112); and;

- a connector (120) for connecting a surgical tool or implant (200), said connector (120) being connected to the distal end (1 12) of said elongated shaft (1 10); and

- a transmission element (130); and;

b) designing a guiding tool based on steps (b) and (c), comprising one or more patient-specific elements (310) for specifically placing said guiding tool on said anatomical region of said patient and one or more guiding features (320) guiding the movement of said positioning tool (100) or part thereof along the longitudinal axis (101 ) of said elongated shaft (1 10);

c) providing on said positioning tool (100) and said guiding tool (300) a position monitor determining the position of said positioning tool (100) within said guiding tool (300) wherein said transmission element (130) translates the change in position of said positioning tool (100) relative to said guiding tool (300) into a rotational movement (202) of said surgical tool or implant (200) when connected to said connector (120), the angle of rotation for said rotational movement (202) being around an axis perpendicular to the axis extending longitudinally through the center of said elongated shaft (1 10).

d) manufacturing said guiding tool based on step (b); and

(f) combining said positioning tool and said guiding tool into said surgical instrument.

The step of obtaining volume one or more images of the patient's anatomy typically comprises obtaining digital patient-specific image information which can be done by any suitable means known in the art, such as for example a computer tomography (CT) scanner, a magnetic resonance imaging (MRI) scanner, an ultrasound scanner, or a combination of Roentgenograms. A summary of medical imaging has been described in "Fundamentals of Medical imaging", by P. Suetens, Cambridge University Press, 2002. In a particular embodiment, Additive Manufacturing (AM) techniques are used for manufacturing the guiding tools and optionally the positioning tools and/or implants and surgical tools as described herein, or parts thereof. AM techniques are particularly useful to manufacture patient-specific contact surfaces, or to produce the surgical fixtures in one piece. As an example, the manufacturing of medical-image-based patient-specific surgical instruments via AM is described in US Pat. No. 5.768.134 (Swaelens et al).

A particular embodiment relates to a surgical instrument as described herein wherein at least parts of said surgical instrument are made by additive manufacturing (AM).

AM can be defined as a group of techniques used to fabricate a tangible model of an object typically using three-dimensional (3-D) computer aided design (CAD) data of the object. Currently, a multitude of Additive Manufacturing techniques is available, including stereolithography, Selective Laser Sintering, Fused Deposition Modeling, foil-based techniques, etc.

Selective laser sintering uses a high power laser or another focused heat source to sinter or weld small particles of plastic, metal, or ceramic powders into a mass representing the 3-dimensional object to be formed.

Fused deposition modeling and related techniques make use of a temporary transition from a solid material to a liquid state, usually due to heating. The material is driven through an extrusion nozzle in a controlled way and deposited in the required place as described among others in U.S. Pat. No. 5.141.680.

Foil-based techniques fix coats to one another by means of gluing or photo polymerization or other techniques and cut the object from these coats or polymerize the object. Such a technique is described in U.S. Pat. No. 5.192.539.

Typically AM techniques start from a digital representation of the 3-D object to be formed. Generally, the digital representation is sliced into a series of cross-sectional layers which can be overlaid to form the object as a whole. The AM apparatus uses this data for building the object on a layer-by-layer basis. The cross-sectional data representing the layer data of the 3-D object may be generated using a computer system and computer aided design and manufacturing (CAD/CAM) software.

The surgical instruments as described herein may be manufactured in different materials. Typically, only materials that are biocompatible (e.g. USP class VI compatible) with the animal or human body are taken into account. Preferably the surgical instrument is formed from a heat-tolerable material allowing it to tolerate high-temperature sterilization. In the case selective laser sintering is used as an AM technique, the surgical template may be fabricated from a polyamide such as PA 2200 as supplied by EOS, Munich, Germany or any other material known by those skilled in the art may also be used.

A particular embodiment relates to a manufacturing method as described herein wherein the actual manufacturing step provides that said surgical instrument is made at least partially through additive manufacturing. Accordingly, in a particular embodiment, the surgical instrument is provided such that said guiding tool is an assembly of multiple parts.

Yet another aspect relates to surgical methods using the surgical instruments as described herein. More particularly, a method is provided for performing a transforaminal lumbar interbody fusion (TFIL) on a patient comprising introducing an implant by way of a surgical instrument as described herein. More particularly, the surgical method as described herein comprises:

(a) securing a surgical instrument according to one of the embodiments as described herein onto a specifically selected anatomical part in the vicinity of the implant insertion site;

(b) attaching onto said surgical instrument an implant; and

(c) introducing the implant into the implant insertion site using said surgical instrument.

It will be understood to the skilled person that steps (a) and (b) may be reversed in order. The surgical method may further comprise steps such as fixing the surgical instrument, or part thereof with fixation means onto or near the implant insertion site.

The application will now be illustrated by the following, non-limiting illustrations of particular embodiments as described herein. EXAMPLES

Example 1 : Surgical instrument for TFIL.

The present example provides a specific embodiment of a surgical tool as described herein. The surgical tool is illustrated in figures 1 to 4.

Figure 1A illustrates a positioning tool (100) provided with an elongated shaft (1 10), a rotating element (1 16), a connection element (120) and a transmission mechanism (130). The elongated shaft (1 10) defines the longitudinal axis of the positioning tool (101 ). The rotating element (1 16) can rotate around the longitudinal axis of the elongated shaft (1 10). It has a protrusion (1 17), protruding outside the outer envelope of the positioning tool's elongated shaft (1 10). The connection element (120) allows connecting the implant (200) to the positioning tool (100). It is designed such that the movement of the implant (200) with respect to the positioning tool (100) and the positioning tool's elongated shaft (1 10) is limited to a rotation (202) around an axis perpendicular to the positioning tool's longitudinal axis (101 ). This can be implemented either by allowing this rotation to happen between the implant (200) and the connection element (120), or by rigidly connecting the implant (200) to the connection element (120) and allowing the connection element (120) to rotate around said axis. The transmission mechanism (130) links the rotation of the rotating element (1 16) with the rotation of the implant (200) such that the angle of rotation around the positioning tool's longitudinal axis (101 ) between the rotating element's protrusion and its reference position is proportional to the angle of rotation around the axis perpendicular to the positioning tool's longitudinal axis between the implant's position and its reference position. The elongated shaft (110) contains a handle and an impaction element. The connection element (120) contains a release mechanism that can be operated from the handle.

Figure 1 B illustrates an implant (200) which can be releasable connected to the positioning tool (100) by means of the connection element (120). The implant (200) can rotate with respect to the connection element (120), as it interconnects with the transmission mechanism (130) so that its rotation is controlled by the transmission mechanism (130), e.g. by means of interconnecting cogwheels (131 and 201 ) (figure 4).

Figure 2 illustrates a guiding tool (300), the patient-specific instrument comprising a one or more patient-specific elements defining a support surface (310), a guiding feature (320) and a guiding rail (330). The support surface (310) is a surface or a group of surfaces mating with a part of the patient anatomy (400). This can be a part of a vertebra, or multiple vertebrae, or any other body part that allows positioning the patient-specific instrument in a predetermined position with respect to the patient. The guiding feature (320) accepts the positioning tool (100), allowing a longitudinal movement of the positioning tool's elongated shaft (1 10) and limiting the rotation of the main element around its longitudinal axis (101 ). This can be implemented by giving the positioning tool's elongated shaft (1 10) at least locally a non-circular cross section (e.g. by means of a local protrusion or a groove) and giving the guiding feature (320) a substantially matching cross section. The guiding rail (330) runs along the side of the guiding feature (320) and accepts the protrusion (1 17) on the rotating element (116) of the positioning tool (100). The design of the guiding rail (330) follows from the pre-surgical planning. At each position of the positioning tool (100) along its longitudinal axis (101 ) the guiding rail (330) and the guiding feature (320) together determine the rotation between the positioning tool's elongated shaft (1 10) and the positioning tool's rotating element (1 16). The positioning tool's transmission mechanism (130) then translates this rotation into a rotation of the implant (200) with respect to the positioning tool (100). In that respect there is a direct link between the design of the guiding rail and the guiding feature on the one hand, and the trajectory of the implant on the other hand.

Reference marks or features (140 and 210) may be provided on the positioning tool's elongated shaft (1 10); the positioning tool's rotating element (1 16), the positioning tool's connection element (120), the positioning tool's transmission mechanism (130) and/or the implant (200) to facilitate a correct assembly of the implant (200) onto the positioning tool (100).

The guiding tool (300) may further comprise features allowing them to be fixed to the underlying bone (400) (e.g. by means of a fixation screw, a fixation pin, a pedicle screw...). This system could be expanded to include a similar way to guide the reamer for removing intervertebral disc tissue and / or patient-specific guides for placing pedicle screws.

Claims

1. A surgical instrument (1 ) for guiding a surgical tool or implant (200) according to patient-specific pre-operative plan comprising:

a) a positioning tool (100) comprising:

- an elongated shaft (1 10) having a proximal end (11 1 ) and a distal end (112);

- a connector (120) for connecting a surgical tool or implant (200), said connector (120) being located at the distal end (1 12) of said elongated shaft (110); and

- a transmission element (130); and

b) a guiding tool (300) comprising one or more patient-specific elements (310) for placing said guiding tool on said patient and one or more guiding features (320) guiding the movement of said positioning tool (100) or part thereof along the longitudinal axis (101 ) of said elongated shaft (110);

wherein said positioning tool (100) and said guiding tool (300) are provided with a position monitor determining the position of said positioning tool (100) relative to said guiding tool (300) and wherein said transmission element (130) translates the change in position of said positioning tool (100) relative to said guiding tool (300) into a rotational movement (202) of said surgical tool or implant (200) when connected to said connector (120), the angle of rotation for said rotational movement (202) being around an axis perpendicular to the axis extending longitudinally through the center of said elongated shaft (1 10).

2. The surgical instrument according to claim 1 , wherein said position monitor comprises a position detector on said positioning tool (100) or part thereof interacting with a position indicator on said guiding tool (300) or part thereof, wherein said transmission element (130) translates the change in position of said position detector relative to said position indicator into said rotational movement of said surgical tool or implant (200).

3. The surgical instrument according to claim 2, wherein said position detector is positioned on an actuator, the mechanical movement of which is guided by said position detector and translated into a rotational movement of said surgical tool or implant (200) by said transmission element.

4. The surgical instrument according to claim 3, wherein said actuator is a rotating element (1 16) rotating around the longitudinal axis of said elongated shaft, the mechanical movement of which is translated by said transmission element.

5. The surgical instrument according to claims 3 and 4, wherein said position detector on said actuator comprises a protrusion or notch and wherein said position indicator on said guiding tool comprises one or more features which mate with said protrusion or notch.

6. The surgical instrument according to claim 5, wherein said position indicator is a guiding rail, guiding the movement of said actuator.

7. The surgical instrument according to any of claims 1 to 6 wherein the proximal end of said positioning tool further comprises a handle and/or an impaction element.

8. The surgical instrument according to any of claims 1 to 7 wherein said connector comprises a release mechanism for releasing said tool or implant, which release mechanism is optionally operated from the proximal end of said elongated shaft.

9. The surgical instrument according to any of claims 1 to 8 wherein said transmission element translates the mechanical movement of said positioning tool into the rotational movement of said surgical tool or implant when connected to said connector by means of interconnecting cogwheels.

10. The surgical instrument according to any of claims 1 to 9 wherein said guiding tool comprises a support structure, a shaft for fitting said elongated shaft of the positioning tool and a patient-specific part mating with a part of the patient anatomy.

1 1. The surgical instrument according to claim 10 wherein said part of the patient anatomy is part of a vertebra, or multiple vertebrae, or any other body part that allows positioning of said surgical instrument in a desired position.

12. The surgical instrument according to any of claims 1 to 1 1 wherein said surgical tool or implant is an interbody cage.

13. The surgical instrument according to any of claims 1 to 12 wherein said surgical tool or implant is a reamer for removing tissue and bone debris.

14. The surgical instrument according to any of claims 1 to 13 wherein said guiding tool is an assembly of multiple parts.

15. The surgical instrument according to any of claims 1 to 14 wherein said guiding tool is further provided with means for fixating said guiding tool onto the patient anatomy.

16. The surgical instrument according to claim 15 wherein said means of fixating comprises apertures configured to releasably engage with pedicle screws.

17. A method for manufacturing a guiding tool (300) for the surgical instrument (1 ) for guiding a surgical tool or implant (200) according to any of claims 1 to 16, comprising the steps of:

(a) obtaining one or more images of the patient's anatomy;

(b) determining by pre-operative planning the desired path of how the surgical tool or implant (200) is to be inserted;

(c) identifying and selecting one or more anatomical regions on or around the insertion site suitable for supporting a guiding tool;

(d) designing a surgical guiding tool for use in combination with a positioning tool (100) comprising:

- a transmission element (130);

said surgical guiding tool comprising:

b) one or more guiding features for guiding the movement of said positioning tool (100) or part thereof along the longitudinal axis of said elongated shaft;

(e) manufacturing said guiding tool (300) based thereon.

18. The method according to claim 17, wherein said guiding tool is made at least partially through additive manufacturing.