Retractable Cutting Guide

Abstract

The present invention relates to a cutting guide (18) intended to be connected to a surgical cutting instrument (10) comprising a casing (12), a cutting blade (16), a sliding mechanism (20) connected to the casing (12), a sliding unit (22) coupled to the casing (12) by the sliding mechanism (20) and cooperating with the sliding mechanism (20) by sliding therewith, a blade retaining element (24) held by the sliding unit (22) and designed to cooperate with the cutting blade (16) to maintain the blade (16) aligned with a sliding axis (X'), and an abutment element (26) held by the sliding unit (22) for abutting against an abutting body part. The sliding mechanism (20) and sliding unit (22) are configured to be positioned below the cutting blade (16) in the use configuration, and the sliding unit, blade retaining element and abutment element remain static with respect to the anatomical element when the cutting guide is actuated.

Description

[Technical Field]

[0001] The present invention relates to the field of surgical cutting instruments, and more particularly to the field of surgical cutting guides. [Background technology]

[0002] When cutting a patient's bone, particularly during the bone preparation stage of a joint replacement procedure such as a total knee replacement, surgeons use well-known surgical cutting instruments, usually sagittal saws. Such instruments comprise an oscillating blade that oscillates in a plane P, known as the cutting plane P. During the cutting procedure, the surgeon may apply a certain force / pressure to the instrument. Under this pressure, the blade, due to its thinness, tends to bend when it contacts the bone, thereby causing the blade to deviate from the original cutting plane. The object of the present invention is to reduce this bending effect in order to keep the blade as close as possible to the cutting plane P.

[0003] To do so, the present application is directed to a retractable cutting guide.

[0004] The use of cutting guides for saw blades can reduce buckling because the cutting guide is configured to hold the saw blade in place while making the required cuts. The use of cutting guides often requires the use of longer blades, which can result in additional skiving. Furthermore, most currently used cutting guides require the cutting guide to first be secured to the bone at the desired location, thereby increasing surgical time. Furthermore, currently available cutting guides are bulky, obstruct the surgeon's view, and cause inconvenience to the surgeon during the cutting procedure.

[0005] Finally, some cutting instruments use cutting guides that are monitored with an active control system that is part of the robotic cutting system.

[0006] This active control system denies the surgeon freedom of movement, and the repeated corrections of the control system can cause some delay, thus reducing both the ability to operate and the accuracy of the cutting procedure. Furthermore, active control systems require expensive automated equipment to guide the cutting blade. Also, the partially described system hides the blade, thereby reducing the operator's field of view.

[0007] One of the goals in robotic surgery is to increase cutting accuracy and reduce cutting time, but this can be difficult if the saw blade cannot cut at the desired location the first time and if the surgeon cannot clearly see the saw and the bone at the same time.

[0008] The present application aims to overcome these drawbacks. Summary of the Invention

[0009] Therefore, in order to overcome these drawbacks, the present invention provides: A surgical cutting instrument, such as an oscillating saw, cutting blades intended to cut the patient's anatomical elements according to the cutting plane; a casing surrounding a motor connected to the cutting blade; and Cutting guide The cutting guide comprises: a sliding mechanism connected to the casing; a sliding unit connected to the casing by a sliding mechanism, the sliding unit defining a sliding axis sensibly parallel to the cutting surface, the sliding unit cooperating by sliding with the sliding mechanism and intended to slide along the casing; a blade retaining element carried by the sliding unit, the blade retaining element being configured to cooperate with the cutting blade to maintain the cutting blade aligned with the sliding axis; abutment elements held by a sliding unit and intended to abut against abutting body parts of the patient; Equipped with the sliding mechanism and sliding unit are configured to be positioned below the cutting blade in an in-use configuration; and The sliding unit, blade retaining element and abutment element are associated with a surgical cutting instrument that remains stationary with respect to a patient's anatomical element when the cutting guide is actuated by pressure resulting from the surgical cutting instrument being pushed toward the patient's anatomical element.

[0010] When the surgical cutting instrument is held by the surgeon to perform a cut (i.e., in the use configuration), the sliding mechanism and sliding unit are advantageously positioned below the cutting blade so that the entire blade is visible to the surgeon during the cutting procedure. Thus, in the present invention, the smart positioning of the sliding mechanism and sliding unit of the present cutting guide avoids undesirable skiving (e.g., deviation from the intended cutting plane and / or deviation from the intended entry point) during the cutting process while allowing the entire cutting blade to be in full view of the surgeon.

[0011] According to one embodiment, the abutment element is configured to be positioned below the cutting blade in the use configuration.

[0012] According to one embodiment, the blade retaining element is also configured to be positioned completely below the cutting blade in the use configuration. In this configuration, all elements of the cutting guide are positioned completely below the cutting blade in the use configuration, which gives the surgeon a much freer field of view, all without losing precision due to undesired skiving. Indeed, even in this configuration, the blade is advantageously supported by the blade retaining element.

[0013] According to one embodiment, the sliding mechanism is a passive mechanism. This embodiment advantageously makes it possible to prevent the risk of delays and electronic failures. Due to the absence of any kind of complex electronics, the surgical cutting instrument according to the invention is lightweight, easy to handle, and does not reduce the smoothness of the cutting operation.

[0014] The surgical cutting instrument according to the present invention may comprise one or several of the following features shown in the following embodiments taken separately from each other or in combination with each other.

[0015] According to one embodiment, the cutting blade exhibits a front end and a rear end, the front end being the cutting end and the rear end being the end connected to the casing.

[0016] According to one embodiment, the cutting guide is available in two configurations: a stationary arrangement in which the blade retaining element cooperates with the cutting blade near the leading end of the blade; The blade retaining element is configured to cooperate with the cutting blade near the rear end of the blade. indicates, The cutting guide changes from a static configuration to an active configuration when the cutting guide is actuated.

[0017] According to one embodiment, when the sliding mechanism is a passive mechanism, it comprises at least one spring element configured to cooperate with the sliding unit to enable the cutting guide to change from the operating configuration to the stationary configuration when the cutting guide stops operating.

[0018] According to one embodiment, the blade retaining element comprises a magnet intended to cooperate with the cutting blade by magnetization.

[0019] According to one embodiment, the blade retaining element comprises a slot intended to receive the cutting blade.

[0020] According to one embodiment, the blade retaining element is positioned below the cutting blade.

[0021] According to one embodiment, the abutment element is configured to block the cutting guide along an axis nominally perpendicular to the sliding axis.

[0022] According to one embodiment, the abutment element presents at least one spike intended to reversibly fix the cutting guide to the abutting body part of the patient.

[0023] According to one embodiment, the abutment element exhibits at least one lateral ridge intended to reversibly fix the cutting guide to the abutting body part of the patient along an axis direction that is nominally perpendicular to the sliding axis.

[0024] According to one embodiment, the abutment element presents a rounded shape intended to adapt to the natural curve of the abutting body part of the patient.

[0025] According to one embodiment, the abutment element exhibits an ergonomic shape configured to allow comfortable and safe positioning of the operator's hand.

[0026] According to one embodiment, the cutting guide is integrally formed with the casing.

[0027] According to one embodiment, the present invention relates to a cutting guide intended to be connected to a surgical cutting instrument, such as an oscillating saw, said instrument comprising a casing surrounding a motor, said motor being connected to a cutting blade, the cutting blade being intended to cut an anatomical element of a patient according to a cutting plane. a sliding mechanism connected to the casing; a sliding unit coupled to the casing by a sliding mechanism, the sliding unit being intended to slide along the casing and defining a sliding axis sensibly parallel to the cutting surface, and further cooperating by sliding with the sliding mechanism; a blade retaining element carried by the sliding unit, the blade retaining element being designed to cooperate with the cutting blade to maintain it aligned with the sliding axis; abutment elements held by a sliding unit and intended to abut against abutting body parts of the patient; Equipped with.

[0028] The sliding mechanism is a passive mechanism, in that the sliding unit, blade retaining element and abutment element remain static with respect to the patient's anatomy when the cutting guide is actuated by pressure generated from a cutting instrument being pushed towards the patient's anatomy.

[0029] Because the cutting guide of the present invention relies on a passive mechanism, there is no risk of delay or any risk of electronic failure. Because there is no complex electronic device of any kind, the cutting guide of the present invention is lightweight, easy to handle, and does not reduce the smoothness of the cutting procedure. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a perspective view of a surgical cutting instrument equipped with a cutting guide according to a first embodiment of the present invention. FIG. [Figure 2] 10 is an underside view of a surgical cutting instrument fitted with the same embodiment of a cutting guide according to the present invention. [Figure 3] 10 is a bottom view of a surgical cutting instrument equipped with a cutting guide according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a top view of a surgical instrument equipped with a cutting guide according to a second embodiment of the present invention. [Figure 5] 10A-10C are detailed perspective views of different embodiments of an abutment element according to the invention; [Figure 6] 10A-10C are detailed perspective views of different embodiments of an abutment element according to the invention; [Figure 7] 10A-10C are detailed perspective views of different embodiments of an abutment element according to the invention; [Figure 8] 10A-10C are detailed perspective views of different embodiments of an abutment element according to the invention; [Figure 9] FIG. 10 is a detailed perspective view of a retaining element according to another embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view of a surgical cutting instrument equipped with a cutting guide according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] As shown in FIGS. 1 and 10, the surgical cutting instrument 10 exhibits a generally elongated shape extending along an extension axis X, which defines a cutting direction. The surgical cutting instrument 10 includes a casing 12 extending along the extension axis X. The casing 12 encloses a motor (not shown) for actuating the surgical instrument 10. The casing 12 exhibits a front surface 12A, a rear surface 12B, an upper surface 12C along an axis Y generally perpendicular to the extension axis X, a lower surface 12D, and two side surfaces 12E along a transverse axis Z, all of which are joined together. In the example shown in FIGS. 1, 2, 3, and 10, the casing 12 exhibits a cylindrical shape approximately 150 mm long and 40 mm wide. The surgical cutting instrument 10 is intended to be handled by an operator, particularly a surgeon, using a handle 14 connected to the casing 12. In the example shown in FIGS. 1, 2, 3, and 10, the handle 14 extends from the lower surface 12D. In this case, when the surgical cutting instrument 10 is in use by an operator (i.e., in the use configuration), the lower surface 12D is outside their field of view.

[0032] In this application, the term "perceptually" refers to the measurement error margin.

[0033] In this application, the terms "front" and "rear" with respect to various elements are defined relative to the cutting direction, with "front" being in the positive direction along the cutting direction and "rear" being in the negative direction along the cutting direction.

[0034] The surgical instrument 10 further comprises a cutting blade 16, which is intended to cut an anatomical element A, e.g., a bone, of a patient. This cutting occurs in a cutting plane P, as already mentioned in the introduction. The cutting blade 16 exhibits two ends: a leading end 16A and a trailing end 16B. The leading end 16A is the end intended to cut the anatomical element A, i.e., it is the cutting end. The trailing end 16B is the end connected to a motor inside the casing 12 and thus to the casing 12. In a known manner, the cutting blade 16 oscillates in the plane P about an axis of rotation that is substantially parallel to the Y axis and located near the front face 12A of the casing 12. The angular rotation of the cutting blade 16 is approximately 4 degrees. In the example of FIGS. 1, 2, 3, and 10, the cutting blade is made of biocompatible stainless steel and is approximately 110 mm long.

[0035] In accordance with the present invention, to prevent bending of the cutting blade 16 during the cutting procedure, the surgical instrument 10 exhibits a cutting guide 18. The cutting guide 18 may be a separate component that can be attached to or detached from the casing 12. In the embodiment shown in FIG. 10, the cutting guide 18 is attached to the surgical instrument 10 using a fastening system 17. The cutting guide 18 may also be integrally formed with or integrated within the casing 12, as shown in FIGS. 1, 2, and 3.

[0036] In accordance with the present invention, the cutting guide 18 comprises: a sliding mechanism 20 connected to the casing 12; a sliding unit 22 coupled to the casing 12 by a sliding mechanism 20; a blade retaining element 24 held by the sliding unit 22; abutment element 26 held by sliding unit 22 Equipped with.

[0037] The sliding unit 22 is intended to slide along the casing 12. The sliding unit 22 therefore defines a sliding axis X', which in the embodiment shown in FIGS. 1, 2, and 3 is tangentially aligned with the extension axis X of the surgical instrument 10. The sliding axis X' is further tangentially parallel to the cutting plane P. The sliding unit 22 exhibits a front end 22A and a rear end 22B. The rear end 22B of the sliding unit 22 cooperates with the sliding mechanism 20. More specifically, as shown in FIGS. 1, 2, and 3, the sliding unit 22 moves through the sliding mechanism 20.

[0038] In the embodiment shown in FIGS. 1 and 2, the sliding unit 22 comprises at least one sliding rod, in particular two sliding rods. Each sliding rod is parallel to the sliding axis X′ and extends along one side surface 12E of the casing 12. The presence of two sliding rods enhances stability and balance during surgery. In the embodiment shown in FIG. 3, the sliding unit 22 comprises a single sliding rod. In this embodiment, the sliding rod exhibits a general T-shape. This T-shape allows the rod to remain compact while exhibiting increased rigidity and further prevents the sliding rod from rotating about the axis X′. The single rod extends along the underside 12D of the casing 12 and is therefore invisible to the operator during surgery, as can be seen in FIG. 4.

[0039] As previously mentioned, the sliding unit 22 carries the blade retaining element 24 and the abutment element 26. More specifically, as shown in Figures 1, 2 and 3, the blade retaining element 24 and the abutment element 26 are carried by the front end 22A of the sliding unit 22.

[0040] The blade retaining element 24 is designed to cooperate with the cutting blade 16 to maintain the cutting blade 16 aligned with the sliding axis X'. During surgery, cooperation between the cutting blade 16 and the retaining element 24 keeps the cutting blade 16 aligned within the cutting plane P. More specifically, the blade retaining element 24 positions the cutting blade 16 so that it contacts the retaining element 24 when both the cutting guide 18 and the cutting blade 16 are attached to the casing 12. The blade retaining element 24 thus serves to align the cutting blade 16 with the sliding unit 22, thereby guiding the cutting blade 16 during the cutting procedure. Thus, during surgery, forces applied to the axis Y are supported by the sliding unit 22, thereby preventing the blade from bending.

[0041] In the embodiment shown in Figures 1, 2 and 3, the blade retaining element 24 exhibits a rectangular shape and comprises on its upper surface a magnet 28 intended to cooperate with the cutting blade 16 by magnetization. In this embodiment, the upper surface (along axis Y) of the blade retaining element 24 cooperates with the lower surface (along axis Y) of the cutting blade 16. More specifically, the magnet 28 is intended to hold the cutting blade 16 by magnetization. In the particular case of the embodiment shown in Figure 1, the magnet 28 is located in a recess, which prevents the cutting blade 16 from rubbing on the magnet 28 and the resulting wear. In another embodiment shown in Figure 9, the blade retaining element 24 comprises a slot 29 intended to receive the cutting blade 16.

[0042] In one advantageous embodiment, to facilitate use of the surgical cutting instrument 10, the blade retaining element 24 is preferably positioned (along the Y-axis) below the cutting blade 16. In this manner, the blade retaining element 24 is out of the operator's field of view and does not interfere with the cutting procedure.

[0043] The abutment element 26 is intended to abut against a patient's abutting body part. This abutting body part may or may not be the patient's anatomical element A to be cut. The abutment element 26 exhibits a leading end 26A and a trailing end 26B. In the embodiment shown in Figures 1, 5, 6, 7, and 9, the trailing end 26B of the abutment element 26 is attached to the blade retaining element 24. The abutment element 26 can be formed integrally with the blade retaining element 24, so that the two elements 24, 26 are part of the same component. If the abutting body part of the patient is a hard part of the body, such as a bone, the abutment element 26 may exhibit at least one spike intended to reversibly secure the cutting guide 18 thereto. Preferably, the leading end 26A of the abutment element 26 includes a series of regularly positioned spikes, as shown in Figure 5. In another embodiment shown in FIGS. 6, 7, and 8, the abutment element 26 exhibits at least one lateral ridge extending along a Z-axis, which is essentially perpendicular to the extension axes X and Y. This ridge is intended to reversibly secure the cutting guide 18 to a hard or soft part of the patient's body along the Y-axis. The front end 26A of the abutment element 26 may also exhibit at least one lateral ridge to prevent movement of the cutting guide (and thus the surgical instrument 10) along the Y-axis. Preferably, as shown in FIGS. 6, 7, and 8, the front end 26A of the abutment element 26 exhibits a series of lateral ridges that prevent the cutting guide 18 from moving along the Y-axis and allow only flat movement aligned with the cutting plane P. The ridges are shaped to avoid damaging the patient's body part. The abutment element 26 may have a rounded shape intended to fit the natural curves of the body part, as shown in FIG. 7. The abutment element 26 thus provides a controlled contact interface between the cutting guide 18 and the anatomical element A of the patient to be cut.

[0044] During surgery, cooperation between the abutment element 26 and the blade retaining element 24 allows for greater reliability and strength during the cutting procedure. That is, the abutment element 26 rests against a body part and thus guides the cutting instrument 10 relative to the patient's body, while the blade retaining element 24 supports and guides the cutting blade 16 relative to the cutting instrument 10. This cooperation therefore provides better stability and better accuracy during the cutting procedure.

[0045] 8, the rear end 26B of the abutment element 26 exhibits an ergonomic, easy-to-grip shape, which allows the operator to position their free hand H (meaning the hand not holding the handle 14) on the abutment element 26 in a safe and comfortable way, resulting in better tactile sensation during the cutting procedure, and in particular a better sense of any changes in the anatomical element A being cut, such as the transition from the hard cortical tissue of the bone to the softer intramedullary inner part.

[0046] As previously mentioned, the sliding unit 22 cooperates by sliding with the sliding mechanism 20. Thus, the only degree of freedom allowed between the cutting guide 18 and the surgical cutting instrument 10 is translation along the sliding axis X'.

[0047] The sliding mechanism 20 is a passive mechanism, which means that the cutting guide 18 is only manually actuated by pressure applied by the operator against the patient's anatomical element A and / or an abutting body part of the patient using the abutment element 26 during the cutting procedure. More specifically, it means that during the cutting procedure the sliding unit 22, blade retaining element 24, and abutment element 26 remain static with respect to the patient's anatomical element A when the cutting guide 18 is actuated by pressure resulting from the surgical cutting instrument 10 being pushed towards said patient's anatomical element A.

[0048] As shown in Figures 10 and 3, the sliding mechanism 20 may be external or internal to the casing 12. The sliding mechanism 20 includes at least one hollow shaft 30, each opening at the front end 12A of the casing 12 and configured to receive a sliding rod of the sliding unit 22. In the embodiment shown in Figures 1 and 2, the sliding mechanism includes two hollow shafts 30, each extending along one side surface 12E of the casing 12. In the embodiment shown in Figures 3 and 4, the hollow shafts 30 extend along the underside 12D of the casing 12 and are therefore not visible to the operator during the amputation procedure.

[0049] The sliding mechanism 20 is configured such that the cutting guide 18 has two configurations, i.e. a stationary configuration in which the blade retaining element 24 cooperates with the cutting blade 16 near the leading end 16A of the blade 16; The blade retaining element 24 is configured to cooperate with the cutting blade 16 near the rear end 16B of the blade 16. This allows you to show the following.

[0050] When the cutting guide 18 is actuated (meaning when the operator applies pressure to the cutting instrument 10 and cutting guide 18 using the abutment element 26 against the patient's anatomical element A and / or an abutting body part of the patient), the cutting guide 18 changes from its resting configuration to its operating configuration.

[0051] 1 and 2, in some embodiments, the sliding mechanism 20 includes at least one spring element 34. The spring element 34 may be a mechanical spring or, alternatively, a gas spring. Each spring element 34 is embedded at the rear end of the sliding mechanism within each hollow shaft 30 or bore 32. Each spring element 34 is configured to cooperate with the rear end of the sliding unit 22, and more particularly, each spring element 34 is configured to cooperate with the rear end of each sliding rod of the sliding unit 22. This cooperation allows the cutting guide 18 to change from its operating configuration to its resting configuration when the cutting guide 18 is deactivated.

[0052] As shown in Figures 1-10, the sliding mechanism 20 and sliding unit 22 are configured to be positioned under the cutting blade 16 when the surgical cutting instrument is in the use configuration (i.e., the head is being held by the surgeon to perform the cut). By virtue of this design, the sliding mechanism 20 enables the blade retention element 24 to always support the cutting blade 16 near the patient's anatomy A. This ensures optimal stress distribution between the cutting guide 18 and the blade 16 and avoids buckling of the blade 16, while minimizing visual obstruction so that the surgeon maintains a clear view of the blade and the surgical site. The present invention therefore reduces buckling of the blade 16 by providing it with additional support points as close as possible to the patient's anatomy A.

Claims

1. A surgical cutting instrument (10), such as an oscillating saw, comprising: a cutting blade (16) intended to cut the patient's anatomical element (A) according to a cutting plane (P); a casing (12) surrounding a motor connected to said cutting blade (16); and A cutting guide (18), a sliding mechanism (20) connected to the casing (12); a sliding unit (22) connected to the casing (12) by the sliding mechanism (20), defining a sliding axis (X') sensibly parallel to the cutting plane (P), cooperating by sliding with the sliding mechanism (20) and intended to slide along the casing (12); a blade retaining element (24) carried by said sliding unit (22), said blade retaining element (24) being configured to cooperate with said cutting blade (16) to maintain said cutting blade (16) aligned with said sliding axis (X'); an abutment element (26) held by said sliding unit (22), said abutment element (26) intended to abut against a body part of the patient that is to be abutted; A cutting guide (18) comprising: A surgical cutting instrument (10) comprising: the sliding mechanism (20) and the sliding unit (22) are configured to be positioned below the cutting blade (16) in a use configuration; and The surgical cutting instrument (10) wherein the sliding unit (22), the blade retaining element (24) and the abutment element (26) remain stationary with respect to the patient's anatomical element (A) when the cutting guide (18) is actuated by pressure resulting from the surgical cutting instrument (10) being pushed toward the patient's anatomical element (A).

2. The cutting blade (16) exhibits a front end (16A) and a rear end (16B), the front end (16A) being the cutting end and the rear end (16B) being the end connected to the casing (12), and the cutting guide (18) has two configurations, namely a stationary configuration in which the blade retaining element (24) cooperates with the cutting blade (16) near the leading end (16A) of the blade; an operating configuration in which the blade retaining element (24) cooperates with the cutting blade (16) near the rear end (16B) of the blade (16); indicates, The surgical cutting instrument (10) of claim 1, wherein the cutting guide (18) changes from the resting configuration to the operating configuration when the cutting guide (18) is actuated.

3. 3. The surgical cutting instrument of claim 2, wherein the sliding mechanism comprises at least one spring element configured to cooperate with the sliding unit to enable the cutting guide to change from the operating configuration to the stationary configuration when the cutting guide stops actuating.

4. The surgical cutting instrument (10) of any one of claims 1 to 3, wherein the sliding mechanism (20) is a passive mechanism.

5. The surgical cutting instrument (10) of any one of claims 1 to 4, wherein the blade retaining element (24) comprises a magnet (28) intended to cooperate with the cutting blade (16) by magnetization.

6. The surgical cutting instrument (10) of any one of claims 1 to 4, wherein the blade retaining element (24) comprises a slot (29) intended to receive the cutting blade (16).

7. 7. The surgical cutting instrument (10) of claim 1, wherein the abutment element (24) is configured to block the cutting guide (18) along an axis (Y) that is nominally perpendicular to the sliding axis (X').

8. 8. The surgical cutting instrument (10) of any one of claims 1 to 7, wherein the abutment element (24) exhibits at least one spike intended to reversibly fix the cutting guide (18) to an abutting body part of the patient.

9. 9. The surgical cutting instrument (10) of claim 1, wherein the abutment element (24) exhibits at least one lateral ridge intended to reversibly fix the cutting guide (18) to an abutting body part of the patient along the direction of the axis (Y) that is nominally perpendicular to the sliding axis (X').

10. 10. The surgical cutting instrument (10) of any one of claims 1 to 9, wherein the abutment element (24) exhibits a rounded shape intended to fit the natural curve of the abutting body part of the patient.

11. 11. The surgical cutting instrument (10) of any one of claims 1 to 10, wherein the abutment element (24) exhibits an ergonomic shape configured to allow comfortable and safe positioning of an operator's hand.

12. The surgical cutting instrument (10) of any one of claims 1 to 11, wherein the cutting guide (18) is integrally formed with the casing (12).

13. The surgical cutting instrument (10) of any one of claims 1 to 12, wherein the sliding unit (22) is configured to be positioned below the cutting blade (16).

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