Patent Description:
More particularly, the present invention relates to a surgical tool for scraping and collecting bone particles, i.e. bone shavings or chips/flakes, which can be used in such tissue regeneration techniques.

In the past, tools were developed to harvest bone material from various areas of the skeletal structure with the aim of obtaining granules or particles of a size suitable for tissue biological regenerative needs.

These tools have made it possible to increase autologous bone harvesting techniques and treat the harvested bone material by obtaining bone granules adapted to be inserted into bone pockets to fill bone defects or to increase skeletal structures.

In recent years, harvest methods have been refined by the introduction on the market of tools for removing and collecting particles (chips or shavings), by scraping bones, which comprise a handle carrying a scraping blade at its front end, and a chamber for collecting the removed material.

Among said devices it is included the device disclosed in Patent No. <CIT> by the same Applicant.

Document <CIT> discloses an exemplary surgical tool for scraping and collecting bone particles.

A need perceived in the field is to make such devices increasingly effective and comfortable in scraping and collecting bone chips, as well as to make such devices easier and cheaper to produce, while enabling medical staff to save money.

An object of the present invention is to solve such needs of the prior art, with a simple, rational and cost-effective solution.

These objects are achieved by the features of the invention set forth in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

The invention, in particular, makes available a surgical tool for scraping and collecting bone particles, comprising:.

Thanks to this solution, the construction of the surgical tool, e.g. of the passage opening thereof, and its functionality is particularly improved compared to known surgical tools, as the collection chamber (i.e. the cannula that defines it) does not require any special processing or adaptation, but can be made simply and quickly.

For example, the distal end of the collection chamber can be planar and free from steps or notches, allowing faster, cheaper and more accurate manufacturing. Advantageously, the spacer can be rigidly attached to the blade and has a first face facing the blade and in contact with it, and a second face facing the distal end of the collection chamber and intended to contact it via a contact portion of the second face. Thanks to this solution, the coupling between the spacer and the blade (i.e. the stem supporting it) can be made in a simple, constructively rational and efficient way. According to an aspect of the invention, the spacer may have an annular shape comprising a central hole coaxial with the stem and an asymmetric outer perimeter having a circular portion configured to define a contact portion of the second face, wherein the contact portion is configured to contact the distal end of the collection chamber, and a recess adapted to be radially separated from the distal end of the collection chamber, wherein the passage opening is delimited, in an axial direction, by a portion of a scraping edge of the blade and by a circumferential portion of the distal end of the collection chamber and, in a circumferential direction, by the recess of the spacer.

Thanks to this solution, the spacer is shaped to fulfil in the best possible way its main functions and, at the same time, it can be made quickly and easily using forming techniques suitable for large-scale production.

Advantageously, the collection chamber may have a curved longitudinal extension along a curved line with a single curvature, the passage opening being arranged at an extrados area of the distal end of the collection chamber.

This makes the surgical tool more effective, as it facilitates bone scraping actions, especially in certain circumstances of use, efficient in the collection of bone chips separated from the scraped bone, and comfortable to be used by the personnel in charge of harvesting bone chips.

According to an advantageous aspect of the invention, the stem can be elastically flexible.

Alternatively or additionally, the stem can be elastically extendible, i.e. elongatable.

Thanks to this solution, the elastic reaction of the stem is such that it improves the (impulsive) cutting action of the blade on the bone chips, improving the detachment of the chips from the bone and collection thereof in the collection chamber, while reducing at the same time the side effects generated by the detachment of the chips on the scraped bone (such as lacerations, pain or trauma).

Preferably, the collection chamber and the stem are mutually movable sliding between a collection position of the collection chamber, wherein the second face of the spacer is in contact with the distal end of the collection chamber and the collection chamber is accessible only by the passage opening defined by the spacer, and a discharge position, wherein the second face of the spacer is distal from the distal end of the collection chamber releasing it.

This solution makes it possible to collect and discharge bone chips easily and safely for the staff.

Advantageously, the surgical tool may comprise a locking element configured to temporarily lock the stem and the collection chamber at least in their collection position.

Thanks to this solution, when the surgical tool is in the operative configuration, where the stem and the collection chamber are in their collection position, any accidental opening of the collection chamber is prevented, thus eliminating any risk of loss of the collected bone material or any contamination.

Further features and advantages of the invention will be more apparent after reading the following description provided by way of non-limiting example, with the aid of the accompanying drawings.

With particular reference to these figures, a surgical tool for scraping and collecting, e.g. manually, bone particles, i.e. shavings or chips/flakes of bone, is globally referred to as <NUM>.

In this disclosure, the terms "lower" and "upper" are used in this description referring to the position of the surgical tool <NUM> in use configuration, wherein "lower" means facing the bone to be scraped and "upper" means facing the part opposite the bone to be scraped.

Furthermore, the terms "front or "distal" and "back" or proximal" have been used in the present description referring to the position of the surgical tool <NUM> with respect to the hand holding the tool, wherein "front" or "distal" means in a position furthest from the palm of the user's hand and "back" or "proximal" means in a position closest to the palm of the user's hand.

The surgical tool <NUM> comprises a handle <NUM> that can be held (at the back) by an operator.

The handle <NUM> has an elongated body provided with a longitudinal axis A.

For example, the opposite axial ends of the handle <NUM> are open.

The handle <NUM> comprises, at the back, a handgrip <NUM> adapted to be held by one hand of the operator and an opposite distal end is free.

A proximal end of the handgrip <NUM> defines the proximal end of the handle <NUM>.

The handle <NUM> also comprises a cannula <NUM>, which is attached at the front to the handgrip <NUM>.

The cannula <NUM> axially extends the handgrip <NUM> (in the front direction).

A distal end of the handgrip <NUM> defines the distal end of the handle <NUM>.

The cannula <NUM>, in particular, has a proximal end fixed, for example snap-fitted or screwed or welded or otherwise, to the distal end of the handgrip <NUM> and a free opposite distal end.

The cannula <NUM>, for example, has a constant transversal section (orthogonal to the longitudinal axis A) throughout its longitudinal extension.

For example, the cannula <NUM> has an inner chamber <NUM>, which is substantially cylindrical (the term "cylindrical" meaning that its transversal section may be circular, as in the preferred example shown, or of any other shape).

The inner chamber <NUM> of the cannula <NUM> is axially prolonged in a backward direction from an inner cavity <NUM> of the handgrip <NUM>, for example having the same shape and size as the inner chamber <NUM> of the cannula <NUM>.

In practice, the handle <NUM> defines as a whole a hollow body having an axial cavity formed by the inner cavity <NUM> of the handgrip <NUM> and the inner chamber <NUM> of the cannula <NUM> joining.

In the example shown, the cannula <NUM> and the handgrip <NUM> are made of two separate bodies, but it is not excluded that they can be made as a single body.

In a first embodiment shown in <FIG> and <FIG>, the cannula <NUM> has a rectilinear portion, proximal to the proximal end (and ending at the back therewith) of the cannula itself, which has a rectilinear (coaxial) longitudinal axis, and a curved portion, proximal to the distal end of the cannula <NUM> (at a non-zero distance from it), which has a curved longitudinal axis (e.g. according to an arc of a circumference).

In such a first embodiment, the cannula <NUM> also has a further rectilinear portion, proximal to the distal end of the cannula itself (and terminating at the front therewith), which has a rectilinear (coaxial) longitudinal axis, tilted (at the top) with respect to the longitudinal axis of the rectilinear portion by an angle substantially between <NUM>° and <NUM>°, for example equal to <NUM>°.

In practice, the curved portion of the cannula <NUM> is axially interposed between the rectilinear portion and the further rectilinear portion.

For example, the curvature of the cannula <NUM> is such that it curves at the top the distal end of cannula <NUM>, i.e. it has an upper intrados and a lower extrados.

In a second embodiment shown in <FIG> and <FIG>, the cannula <NUM> has a (totally) rectilinear longitudinal axis.

The distal end of the cannula <NUM>, i.e. of the handle <NUM>, is (completely) planar (and free from steps or notches).

The cannula <NUM> internally delimits a collection chamber <NUM>, which is defined near the distal end thereof.

In particular, the distal end of the cannula <NUM> coincides with the distal end of the collection chamber <NUM>.

The collection chamber <NUM> is defined internally by a distal portion of the inner chamber <NUM> of the cannula <NUM>, i.e. it is delimited perimetrically by the (perimeter wall of) the cannula <NUM> and at the front by the distal end of the cannula <NUM> itself.

The collection chamber <NUM> has, as will be better described hereinafter, a variable volume, e.g. it has a proximal end which is (axially) movable with respect to the distal end. The surgical tool <NUM> further comprises a stem <NUM>, which is housed, at least partially, inside the handle <NUM>, i.e. the handgrip <NUM> and/or the cannula <NUM>.

The stem <NUM> is defined by an elongated body along a longitudinal axis B and is axially inserted inside the handle <NUM> (i.e. of the handgrip <NUM> and/or the cannula <NUM>).

The stem <NUM> has a back end <NUM>, which - for example - protrudes from the proximal (open) end of the handle <NUM>, i.e. of the handgrip <NUM>, and an opposite front end <NUM> arranged near the distal end of the handle, i.e. of the cannula <NUM>.

The stem <NUM> comprises at least one front end tract, provided with the front end <NUM> thereof, which is adapted to be contained within the collection chamber <NUM>, with abundant radial clearance.

The collection chamber <NUM>, in practice, is defined by a radial portion of the inner chamber <NUM> of the cannula <NUM> interposed between the (inner wall of the) cannula <NUM> and (the outer wall of the front end tract of) the stem <NUM>.

The stem <NUM>, furthermore, has an enlarged rear tract, which terminates at the back with a grip portion (again) defined externally at the back of (the handgrip <NUM> of) the handle <NUM> and provided with the back end <NUM>.

The grip portion of the stem <NUM> is, for example, ergonomically shaped to be easily gripped by the user.

The back enlarged tract of the stem <NUM> is exactly radially received in the inner cavity <NUM> of the handgrip <NUM> (and/or at least one axial tract of the inner chamber <NUM> of the cannula <NUM>).

On the front end tract of the stem <NUM> there is a shutter disc <NUM>, which is exactly housed inside the inner chamber <NUM> of the cannula <NUM>, so as to occlude (at the back) the collection chamber <NUM>.

In practice, the collection chamber <NUM> is delimited perimetrically/radially by the (inner wall of the) cannula <NUM> and at the back by the shutter disc <NUM> of the stem <NUM>, while it is open at the front at the distal end of the cannula <NUM> (i.e. of the handle <NUM>).

The stem <NUM>, e.g. at least or only its front end tract (except for the shutter disc <NUM>), is elastically flexible (resilient), i.e. it is configured to be bendingly deformed, without being plastically deformed, and independently return elastically to its undeformed configuration.

For example, the stem <NUM>, i.e. only the front end tract (except for the shutter disc <NUM>) thereof, has a flexural rigidity (bending modulus) between <NUM> MPa and <NUM> MPa, preferably <NUM> MPa.

Again, the stem <NUM>, e.g. at least or only its front end tract (except for the shutter disc <NUM>), is elastically extensible (preferably elongatable), i.e. it is configured to be tensile deformed, without being plastically deformed, and independently return elastically in its undeformed configuration.

For example, the stem <NUM>, i.e. only the front end tract (except for the shutter disc <NUM>) thereof, has an elastic (tensile) modulus, also called Young's modulus, of between <NUM> MPa and <NUM> MPa, preferably <NUM> MPa.

The stem <NUM> (preferably in a single piece) is for example made of a plastic material. The surgical tool <NUM> further comprises a blade <NUM> configured to scrape bone particles, e.g. in the form of bone shavings or chips/flakes.

The blade <NUM> is supported by the stem <NUM>, near the front end <NUM> thereof.

The blade <NUM> has a rigidity (which is high, i.e. greater than the rigidity of the bone) such that it does not resonate during the scraping operation it is subjected to.

The blade <NUM> is generally made of metal, preferably stainless steel.

For example, the blade <NUM> is attached, preferably unseparatedly, to the front end <NUM> of the stem <NUM>.

The blade <NUM> is arranged outside the handle <NUM> (i.e. the cannula <NUM> thereof).

In practice, the blade <NUM> is arranged at the front of the distal end (of the cannula <NUM>) of the handle <NUM>.

The blade <NUM> protrudes radially from the stem <NUM>, for example by a radial tract having substantially the same width as the width of the collection chamber <NUM>.

The blade <NUM> comprises a cap <NUM> provided with a sharpened (radial) scraping edge <NUM>, for example facing downwards.

The scraping edge <NUM> (globally) has a circumferential longitudinal extension.

The scraping edge <NUM> is a free edge (in use) of the blade <NUM>, i.e. protruding from the handle <NUM> (either axially or radially) or otherwise not in contact with it or with other elements of the surgical tool <NUM>, preferably facing downwards with respect to the handle <NUM>.

In the embodiment shown in <FIG> and <FIG>, the scraping edge <NUM> is arranged radially outwards from the extrados part of the curvature assumed by the cannula <NUM>.

The blade <NUM> comprises a rear (or scraping) face <NUM>, substantially planar, facing backwards (i.e., towards the distal end of the handle <NUM> and/or the cannula <NUM>).

The rear face <NUM> is substantially orthogonal to the longitudinal axis B of the stem <NUM>, or at least of a tract thereof proximal to its front end to which the blade <NUM> is attached. The blade <NUM> further comprises a fastening tang <NUM>, for example cylindrical or prismatic, which is derived from the cap <NUM> (in a single piece with it), for example from the rear face <NUM> thereof, with its axis orthogonal to the rear face <NUM>.

The fastening tang <NUM> is configured to be firmly and rigidly fastened to the front end of the stem <NUM>, for example by remaining firmly engaged thereon without any possibility of movement.

For example, the stem <NUM> includes a fastening tube <NUM> having a back end fitted on the front end of the stem <NUM> and fastened thereon, for example by crimping, and a front end fitted on the fastening tang <NUM> and fastened thereon, for example by crimping.

The surgical tool <NUM> further comprises a spacer <NUM>, which is configured to be interposed between the rear face <NUM> of the blade <NUM> and the distal end of the collection chamber <NUM> (i.e. of the cannula <NUM>).

The spacer <NUM> is made in a body separated from the blade <NUM> and the cannula <NUM> (and/or from the collection chamber <NUM>).

Preferably, but not limited to, the spacer <NUM> is rigidly fastened to the stem <NUM> (and/or the blade <NUM>).

In the example shown, the spacer <NUM> is rigidly fastened to the blade <NUM>, for example fitted on the fastening tang <NUM> (with the interposition of the fastening tube <NUM> and/or of an end portion of the stem <NUM>).

The spacer <NUM>, globally, is such that it partially occludes the distal end of the collection chamber <NUM> leaving (open only) a lower passage opening <NUM> for introducing the bone particles scraped by the blade <NUM> into the collection chamber <NUM>.

Such passage opening <NUM> is obtained by keeping at a distance, for at least a lower circumferential tract of the spacer <NUM>, the lower portion of the rear face <NUM> of the blade <NUM> (provided with the scraping edge <NUM>) from the (lower portion of) distal end of the collection chamber <NUM>.

The spacer <NUM> is provided with a first (front) face <NUM> facing the blade <NUM> and in contact with the rear face <NUM> thereof and an opposite second face <NUM> facing the distal end of the collection chamber <NUM> (and the cannula <NUM>), of which an upper circumferential contact portion <NUM> (lower than its entire circumferential perimeter) is intended to contact it.

In practice, the contact portion <NUM> is configured to contact the distal end of the collection chamber <NUM> by closing (at the top) the latter (as will be better described hereinafter).

The spacer <NUM> is basically shaped like a collar.

Preferably, the spacer <NUM> - as shown schematically in <FIG> - has an annular shape comprising a central hole <NUM> coaxial with the stem and/or the fastening tang <NUM> of the blade <NUM> and an asymmetrical outer perimeter provided with an upper circular portion <NUM> configured to define at the back the aforesaid contact portion <NUM> of the second face <NUM>.

The outer perimeter of the spacer <NUM>, moreover, is provided with a (lower) recess <NUM>, having a radial dimension smaller than the radial dimension of the circular portion <NUM>, which is adapted to be radially separated from the distal end of the collection chamber <NUM> (when the contact portion <NUM> defined in the circular portion <NUM> is in contact with the distal end of the collection chamber <NUM> itself).

The passage opening <NUM> is, in practice, delimited:.

The axial width of the passage opening <NUM> is, substantially, equal to the axial thickness of the spacer <NUM> (at the circular portion <NUM>, i.e. of the contact portion <NUM> thereof).

The circumferential width of the passage opening <NUM> is substantially equal to the (angular) width of the recess <NUM>.

As an alternative to the foregoing, it is possible to provide that the spacer is arc-shaped having two opposite circumferential ends mutually placed at a non-zero predetermined circumferential distance and lower than the diameter of the portion of the stem <NUM> (and/or fastening tang <NUM> and/or fastening tube <NUM>) that they embrace, wherein the passage opening <NUM> is delimited in the axial direction by a lower portion of the scraping edge <NUM> of the blade <NUM> (at the front) and by a circumferential portion of the distal end of the collection chamber <NUM> facing the scraping edge <NUM> (backwards) and in the circumferential direction by the circumferential ends of the spacer <NUM>.

The spacer <NUM> further comprises an inner tang <NUM> axially protruding from the second face <NUM> thereof, which is configured to embrace, at least partially (i.e. preferably only in the upper portion), an (upper) portion of the fastening tang <NUM> and/or the fastening tube <NUM> and/or the stem <NUM>.

The maximum radial dimension of the inner tang <NUM> is (abundantly) smaller than the inner diameter of the collection chamber <NUM>, so as to be inserted therein (with abundant radial clearance) inside the collection chamber <NUM>, when the second face <NUM> of the spacer <NUM> is in contact (by its contact portion <NUM>) with the distal end of the collection chamber <NUM> itself.

The inner tang <NUM>, for example, has a radial thickness increasing from the free back end to the back end that joins to the second face <NUM>, defining a guide ramp.

For example, the spacer <NUM> is substantially rigid (non-deformable), e.g. made of plastic or metal.

Preferably, the collection chamber <NUM>, i.e. the handle <NUM>, and the stem <NUM> are mutually movable in axial sliding, alternatively between:.

Preferably, the stem <NUM> is slidably movable within the handle <NUM>, by means of a prismatic-type connection (i.e. without possibility of axial rotation).

As mentioned above, the collection chamber <NUM> has a variable volume, i.e. it has a maximum volume when the stem <NUM> and the collection chamber <NUM> are in the collection position and has a minimum volume when the stem <NUM> and the collection chamber <NUM> are in the discharge position.

In fact, when the stem <NUM> and the collection chamber <NUM> are in the collection position, the shutter disc <NUM> is placed at a maximum non-zero distance from the distal end of the collection chamber <NUM>, for example greater (even twofold or threefold) than the inner diameter of the cannula <NUM>, and when the stem <NUM> and the collection chamber <NUM> are in the discharge position, the shutter disc <NUM> is placed at a minimum distance (lower than the maximum distance) from the distal end of the collection chamber <NUM>, wherein for example such minimum distance is substantially zero or in any case lower than the inner diameter of the cannula <NUM>.

In practice, the shutter disc <NUM> (defining the proximal end of the collection chamber <NUM>) is such as to act as a plunger for discharging the bone chips collected in the collection chamber when the stem <NUM> and the collection chamber <NUM> are brought from the collection position to the discharge position, operating a back pushing action on the bone chips towards the distal end of the collection chamber <NUM> (released from the closure operated by the blade <NUM>) from which they exit.

When the stem <NUM> and the collection chamber <NUM> are brought from their discharge position to the collection position, the inner tang <NUM> of the spacer <NUM>, especially in the embodiment shown in <FIG> and <FIG>, acts as a guide ramp (creeping against the distal end of the collection chamber) to take the spacer <NUM> to its correct position, wherein the second face <NUM> of the spacer <NUM> is in contact (with its contact portion <NUM>) with the distal end of the collection chamber <NUM> leaving only the passage opening <NUM> open.

The surgical tool <NUM> further comprises a locking element <NUM>, which is configured to temporarily and/or removably mutually lock the stem <NUM> and the collection chamber <NUM> at least in their collection position.

It is not excluded that the locking element <NUM> may be configured to mutually lock the stem <NUM> and the collection chamber <NUM> selectively in the collection position and discharge position.

The locking element <NUM> comprises, for example, a harpoon (rotatably) associated with the back end <NUM> of the stem <NUM>, which is movable between an engagement position of a seat made at (the rear end <NUM> of) the stem <NUM> and a disengagement position thereof. When the stem <NUM> and the collection chamber <NUM> are in their collection position, the seat is arranged outside (at the back of) the handle <NUM> and is engageable or disengageable by the locking element <NUM>.

When the locking element <NUM> is in the engaged position (and the stem <NUM> and the collection chamber <NUM> are in their collection position), the locking element <NUM> prevents any sliding movement between the stem <NUM> and the collection chamber <NUM> (abutting against the back end of the handle <NUM>).

When the locking element <NUM> is in the engaged position, the locking element <NUM> allows the sliding movement between the stem <NUM> and the collection chamber <NUM>, allowing them to reach their discharge position.

In light of the above, the operation of the surgical tool <NUM> is as follows.

The surgical tool <NUM>, with the stem <NUM> and the collection chamber <NUM> in their collection position, is configured to be used to obtain bone particles (in the form of chips or shavings) and collect them, once separated from the bone to which they belong, within the collection chamber <NUM>.

In order to carry out this operation, it is sufficient to hold the handgrip <NUM> of the surgical tool <NUM> and lead the scraping edge <NUM> of the blade <NUM> into contact with a bone surface. As the surgical tool <NUM> has a curved cannula <NUM>, as illustrated in the embodiment shown in <FIG> and <FIG>, the relative position between the handgrip <NUM> and the bone further facilitates reaching the scraping area and the scraping operations themselves.

In order to scrape a bone particle it is sufficient to scrape with the scraping edge <NUM> of the blade in contact with the surface of a bone to be scraped, in the backward (rectilinear) direction, i.e. orthogonal to the rear face <NUM> of the blade <NUM> in the direction from the blade <NUM> towards the handgrip <NUM>.

The bone particle produced by the blade <NUM> is pushed (from the rear face <NUM> of the blade itself) into the collection chamber <NUM> through the passage opening <NUM> defined by the spacer <NUM>.

During this scraping action, moreover, the stem <NUM> is stressed in bending (by the constraint reaction exerted by the bone), and bends (in contrast to the flexural elasticity of the stem <NUM>) upwards (such bending is however limited, for example by the feedback exerted by the inner wall of the cannula <NUM> against the inner tang <NUM>).

As an alternative or in addition, during such a scraping action, the stem <NUM> is tensile stressed (by the restraint reaction exerted by the bone), and extends (in contrast to the axial elasticity of the stem itself) axially (tending to detach the second face <NUM> of the spacer <NUM> from the distal end of the collection chamber <NUM>).

When the constraint reaction of the bone is overcome by the tensile action exerted by the operator and/or the elastic reaction (flexural and/or axial) exerted by the stem <NUM>, the bone particle separates from the bone, for example by a shearing action (exerted by the scraping edge <NUM> of the blade <NUM>), and is forced to enter the collection chamber <NUM> where it is stored.

In practice, it has been observed that the flexural and/or axial elasticity of the stem <NUM> is such as to produce an impulsive shear force that allows (the scraping edge <NUM> of) the blade <NUM> to enhance the detachment of the bone particles from the scraped bone.

Once the desired amount of bone particles has been collected, for example by several consecutive scraping actions - as described above -, the operator may discharge the collected bone particles into the collection chamber <NUM>, for example into a suitable collection container.

To do so, it is sufficient to bring the stem <NUM> and the collection chamber <NUM> to their discharge position and to let the collected bone particles pass through the distal end of the collection chamber <NUM> which is disengaged from the blade <NUM>.

The invention thus conceived is susceptible to several modifications and variations, all falling within the scope of the inventive concept.

Claim 1:
A surgical tool (<NUM>) for scraping and collecting bone particles, comprising:
- a handle (<NUM>) provided with a handgrip (<NUM>);
- a collection chamber (<NUM>) having an end proximal to the handgrip (<NUM>) and a free distal end;
- a stem (<NUM>) at least partially arranged inside the collection chamber (<NUM>);
- a blade (<NUM>) fixed to a front end (<NUM>) of the stem (<NUM>), wherein the blade (<NUM>) protrudes radially from the stem (<NUM>) and is axially arranged outside the collection chamber (<NUM>) near the distal end thereof;
characterised in that the surgical tool (<NUM>) further comprises
- a spacer (<NUM>) interposed between a rear face (<NUM>) of the blade (<NUM>) and the distal end of the collection chamber (<NUM>), wherein the spacer (<NUM>) defines a passage opening (<NUM>) for introducing the bone particles scraped by the blade (<NUM>) into the collection chamber (<NUM>), maintaining at a predetermined non-zero axial distance, for at least a circumferential tract thereof, the rear face (<NUM>) of the blade (<NUM>) from the distal end of the collection chamber (<NUM>).