Improved milling cutter for orthopaedic use, in particular knee, pelvis or ankle surgery

Abstract

The present invention relates to an orthopaedic surgical instrument, in particular a milling cutter, comprising: an internal stem (2) extending along a longitudinal axis (X-X) of its own and provided with an attachment end (7) attached to a motorized member; a tubular envelope (5) surrounding the internal stem (2); an operating head (15) at a stem end (8) opposite the attachment end (7); a universal joint (10) between the stem end (8) and a tool (9) of the operating head, so that the tool (9) extends along an angled axis (Y-Y) with respect to the longitudinal axis (X-X). The milling cutter according to the invention improves the implementation precision of the position of the hole in any surgical procedure with difficult-to-access anatomies, such as in the knee, the pelvis and the ankle.

Description

TECHNICAL FIELD

[0001] The present invention relates to an orthopaedic surgical instrument, and more particularly to an improved milling cutter usable in knee, pelvic or ankle surgery, and the description is made with reference to these particular applications in order to simplify its presentation, but it must not represent a limitation on the Applicant's rights.

[0002] More particularly, the invention relates to an instrument for treating the human tibia and for performing an osteotomy or milling which prepares other surgical phases to be performed on a predetermined portion of the tibia with very limited access. However, the instrument of the present disclosure can be used in other types of surgical operations, such as for example on the acetabular cup of the pelvis or for the treatment of the ankle. BACKGROUND

[0003] It is known that the articular surfaces of the knee can deteriorate and develop pathologies due to ageing, disease or sporting activities.

[0004] Likewise, other bones can deform over time, or develop pathologies which must be treated surgically with appropriate instruments.

[0005] For example, in the case of the knee, it has become common to perform surgery by removing the condyle and replacing these bone structures with a prosthetic implant. It is also possible to replace the articular surface of the patella, without touching or cutting the tendons connected to it, with great care.

[0006] According to some surgical strategies in this technical field, a relatively common surgery is the replacement of the posterior or medial side of the patella adjacent to the femoral condyle by implanting a prosthesis. For this purpose, the posterior surface of the patella is resected to create a flat surface on which the prosthesis can be mounted.

[0007] Figure 1 A lateral view of a unicompartmental surgery (for example milling) is shown schematically, which involves the joint of the knee and in which the distal portion of the femur and the proximal portion of the tibia can be seen.

[0008] The figure shows schematically the position of the femur and tibia which can be reached during a unicompartmental surgery, and it can be understood that the femur covers a portion of the tibia, making access particularly difficult. Basically, the incision area is much smaller than the incision area that can be used for a total prosthetic surgery.

[0009] In addition, the ligaments and soft tissues are generally in better condition, but this involves the fact that the femur cannot move so much and indeed much less than in a total prosthetic surgery, due to the maintenance of the cruciate ligaments (anterior and posterior) and the knee bone not dislocated.

[0010] All this specifically means that the preparation of the proximal part of the tibia cannot be performed from above, due to the proximity of the distal part of the femur, but must be performed in frontal superior mode, i.e. with the positioning of the instrument in an uncomfortable position.

[0011] The preparation of the tibia for the implant of a stability element, such as a unicompartmental plate, or a pin, etc., is usually performed with a milling cutter tip arranged in an oblique manner; however, this involves a greater removal of bone, which is filled with cement.

[0012] Figure 2 A schematic is shown which illustrates this case, in which a 9 mm milling cutter tip is used to create a seat for a stability element with only 6.2 mm diameter.

[0013] This solution has two evident drawbacks:

[0014] - increased removal of bone tissue;

[0015] - surprisingly lower compactness of the cement, since the compactness of the cement is optimal with a limited thickness of about 1 mm around the pin. On the contrary, the distribution of the cement is not uniform and a smaller adhesion is created with a thickness in the range of 0.5 mm to 2.5 mm.

[0016] There are also technical solutions in which the milling cutter tip is mounted on a universal joint at one end of the surgical instrument to allow the action axis of the milling cutter to be angled, for example as described in European applications n° EP 1 410 763 A1 or n° EP 2 954 860 A2. However, these solutions are structurally complex and not suitable for knee surgery.

[0017] The aim of the present invention is to envisage an orthopaedic surgical instrument, in particular an improved milling cutter, having structural and functional characteristics in order to overcome the drawbacks reported with reference to the solutions of the prior art.

[0018] Another aim of the present invention is to envisage an instrument which allows the preparation of the surgical seat on the knee along an axis with an anterior passage, to avoid interference with the distal part of the femur.

[0019] A further aim of the present invention is to prevent the surgeon from having to manipulate the instrument only with his manual and visual skills, but to allow him to operate in a comfortable and practical way due to the construction of the instrument itself.

[0020] Still another aim of the present invention is to provide an instrument which is easy to handle and use by the orthopaedic surgeon and which does not hinder the surgeon's view during the operation.

[0021] Finally, the instrument of the present invention should be easy to remove and reassemble, to ensure a clean, hygienic handling and reuse of the instrument. SUMMARY

[0022] The solution idea of the present invention consists in designing a milling cutter having an angled operating head with respect to the longitudinal axis of the instrument, but having a particularly simple and functionally comprehensive structure.

[0023] The above listed objects are achieved by means of an orthopaedic surgical instrument, and more particularly, by means of an improved milling cutter, comprising:

[0024] - an internal rod extending along its longitudinal axis (X-X) and provided with an attachment end attached to a motorized member;

[0025] - a tubular envelope surrounding the internal rod;

[0026] - an operating head at the rod end opposite the attachment end;

[0027] - a universal joint between the rod end and a tool of said operating head, so that said tool extends along an angled axis (Y-Y) with respect to said longitudinal axis (X-X).

[0028] Advantageously, the tubular envelope is configured with two superimposed half-shells covered by a handle.

[0029] Furthermore, the internal rod is free-running with respect to the tubular envelope, so that it can be rotated under the action of the motorized member when the surgeon holds the instrument.

[0030] At least one pair of bushings mounted in free-running manner on opposite portions of said internal rod is provided for supporting the tubular envelope.

[0031] The bushings are made of a low-friction synthetic material, such as PEEK.

[0032] Furthermore, the end of one of the two half-shells comprises a housing seat for accommodating the universal joint of the operating head. This housing seat has an annular portion having an axis corresponding to the above-mentioned angled axis (Y-Y).

[0033] Any anti-rotation element (for example, an anti-rotation protruding notch) is provided on at least one of the two half-shells for retaining the handle of the two half-shells surrounding the tubular envelope.

[0034] Finally, it should be noted that the universal joint has a portion corresponding to the rod end of the operating head and another portion, for example a perforation or a milling tip.

[0035] A selected embodiment will now be described in detail with reference to the accompanying drawings. From the present disclosure, it will be clear to the person skilled in the art of orthopaedic surgery that the following description of a preferred embodiment is provided for illustrative purposes only and is not intended to limit the present application as defined by the appended claims.

[0036] The accompanying drawings

[0037] Figure 1 shows a partial lateral view of a joint involved in an orthopaedic surgical operation of an orthopaedic surgical instrument manufactured according to the prior art;

[0038] Figure 2 shows a lateral partial view of the surgical end of an orthopaedic surgical instrument still according to the prior art Figure 1

[0039] Figure 3 shows a schematic perspective view of an orthopaedic surgical instrument manufactured according to the present application;

[0040] Figure 4 shows another schematic perspective view of the instrument of Figure 2 , showing the main components of the instrument;

[0041] Figure 5 shows a lateral schematic view of a component of the instrument of Figure 3

[0042] Figure 6 shows a lateral schematic view of another component of the instrument of Figure 3

[0043] Figure 7 shows a schematic lateral sectional view on a vertical plane of a portion of a component of Figure 6

[0044] Figure 8 shows a schematic perspective view of an orthopaedic surgical instrument of the present application in an assembled condition;

[0045] Figure 9 shows a partial lateral view of a joint involved in an orthopaedic surgical operation of an orthopaedic surgical instrument manufactured according to the present application;

[0046] Figure 10 shows a lateral schematic view of an example of another embodiment of the instrument according to the present application, in particular for use in the hip region;

[0047] Figure 11 shows a schematic lateral sectional view on the line A-A of the instrument according to Figure 10

[0048] Figure 12 and​​​​​Figure 13 a corresponding schematic section view on a vertical plane of an example of application of the instrument according to the present application in the surgical treatment of the ankle joint is shown. DETAILED DESCRIPTION

[0049] With reference to the drawings, a surgical instrument for orthopaedics and more particularly an improved milling cutter, useful for knee, pelvic and ankle surgery, is shown as a whole and schematically with 1. The following description is made with reference to these specific application fields, whose purpose is merely to simplify its presentation, without this representing a limitation to the Applicant's rights.

[0050] The milling cutter 1 comprises an elongated body with an internal stem 2, covered by a tubular, preferably cylindrical, envelope 5, formed by a first half-shell 3 and a second half-shell 6, and a handle 4 which surrounds most of the tubular envelope 5.

[0051] The two half-shells 3, 6 are coupled to each other as two valves for forming the tubular envelope 5.

[0052] The handle 4 overlaps the tubular body 5 for at least two thirds of the extension of the latter.

[0053] The internal stem 2 extends along a main longitudinal axis X-X and has an end 7 shaped and configured as a quick coupling attachment device for a main shaft (not shown) of a motorized member, such as a drill bit.

[0054] An opposite end 8 of the stem 2 is cinematically coupled and articulated to an operating head 15 of the milling cutter 1, which carries, for example, a perforating tool tip 9.

[0055] Advantageously, the internal stem 2 is idle with respect to the tubular envelope 5 and the handle 4. In other words, the stem 2 can be rotated by coupling with a motorized member, while the handle intended for the orthopaedic surgeon is firmly held by the surgeon's hand.

[0056] At least one pair of bushings 11, 12 is provided, mounted on opposite portions of the internal stem 2, so as to allow the half-shells 3 and 6 to be juxtaposed and mounted, forming the tubular envelope 5 which is then covered by the handle 4.

[0057] A first bushing 11, to be defined as proximal, is located on the portion of the shaped end 7; it is free to move along the stem 2 up to a predetermined distance from the end 7, defined by a spacer 13.

[0058] The other bushing 12, to be defined as distal, is always located on the same stem 2 in the vicinity of the end 8 coupled to the operating head 15.

[0059] The bushings slide freely along the stem 2 until the envelope 5 comprises the two half-shells 3 and 6; at this point, the bushings are housed in the respective shaped seats 20, 21 of the envelope 5.

[0060] In a preferred, but not exclusive, embodiment, the two proximal and distal bushings 11 and 12 are made of a synthetic material, for example PEEK, in order to reduce the friction when the stem 2 rotates and to ensure the normal operation of the cutter.

[0061] All the components described above that make up the milling cutter 1 are easily removable and dismountable from each other in order to be easily cleaned.

[0062] Advantageously, according to the present application, the universal joint 10 is provided between the stem end 8 and the tool 9 of the operating head 15, so that the tool 9 can extend along an angled axis Y-Y with respect to the longitudinal axis X-X of the milling cutter 1.

[0063] Furthermore, a hosting seat 18 is provided for housing the universal joint 10 of the operating head 15.

[0064] This hosting seat 18 is substantially an open-guide-capsule angled body that houses the portion of the universal joint 10, for example the joint, so that the axis Y-Y of the tool tip 9 is oriented at a predetermined angular range "a" with respect to the axis of extension X-X of the stem 2 of the milling cutter 1.

[0065] This hosting seat 18 is integrally formed at the distal end of only one of the two half-shells 3, 6 of the tubular envelope 5 that covers the stem 2. More particularly, as Figure 6 and 7 shown, the hosting seat 18 that houses the universal joint 10 is present at the end of the half-shell 6.

[0066] The hosting seat 18 has an annular portion 19 having an axis corresponding to said angled axis Y-Y and equivalent to a guide device for the angular orientation of the tool tip 9. The diameter of this annular portion is slightly higher than the diameter of the tool tip 9.

[0067] Therefore, this single half-shell alternative allows the inclination of the angle "a" between the orientation of the two axes X-X of the stem 2 and Y-Y of the tool tip 9 to be varied.

[0068] Always at the distal end of this half-shell 6, integral with the hosting seat 18, the final configuration of the shielding appendix 17 and of the distal end of the tubular envelope 5 is obtained.

[0069] The other half-shell 3 has a distal end 16 that partially points towards and is shaped to cooperate with the appendix 17 of the other half-shell.

[0070] At least one of the half-shells 3, 6 also comprises an anti-rotation element, for example a flange 14 projecting outwards, to perform an anti-rotation function and to keep the handle 4 in place once it is mounted around the two half-shells 3, 6 of the tubular envelope 5. The flange 14 is preferably present on the half-shell 6, which also has the housing seat 18 formed in one piece and is intended to be inserted in a corresponding slot inside the handle 4.

[0071] The recesses 20, 21, which house the relative bushing portions 11 or 12, are provided in each half-shell 3, 6.

[0072] Finally, it should be noted that the universal joint 10, which connects the stem 2 with the tip 9, has a portion corresponding to the end 8 of the stem 2 and another portion coupled to the tool 9. The portion associated with the end 8 of the stem 2 can be formed in one piece with this end, while the other portion can have a thread or a quick-attachment device for removable mounting of the tool tip 9.

[0073] The milling cutter 1 according to the present application achieves the predetermined purpose and various advantages, the first of which is given by the fact that it makes it possible to implement a hole with a tip axis inclined at an angle with respect to the transmission axis of the motorized stem 2.

[0074] This angle "a" of the tool tip is particularly advantageous in the operating room in order to easily access the surgical area and to avoid possible contact areas between the instrument and the anatomical area.

[0075] The milling cutter according to the present application improves the implementation precision of the position of the hole in surgical operations with anatomical structures that are difficult to access, for example the guide instrument 21 visible in Figure 9 which can be used with or without the guide instrument 21.

[0076] The angled body of the housing seat 18 determines the angle of inclination between the tip 9 and the axis X-X of the stem 2. This angle "a" can be changed by replacing the component 18, i.e. by replacing all the half-shells 6 of the envelope 5 that form it.

[0077] In order to use the milling cutter 1 according to the present application, it is sufficient to mount the angled end 7 of the milling cutter 1 on the main shaft of a motorized member, for example a drill.

[0078] The surgeon can firmly hold the handle present on the drill and the handle 4 of the angled milling cutter 1. The hole can be made with or without a guide element.

[0079] Reference is made to Figure 10 and Figure 11, showing an example of another embodiment of the instrument according to the present application, configured for use in the hip region, in particular for making holes for bone screws. Such screws usually have an angle with respect to the access path of the surgeon, which requires an angled or flexible instrument to achieve the desired direction for the screw.

[0080] Figure 10 and Figure 11 The instrument is indicated with the reference 1'and, for this, the details and the cooperating parts, having the same structure and function as the previous embodiment, are indicated with the same reference numerals.

[0081] In the drawings, a cup or test cup is shown, coupled to the instrument which is the object of the present application. The arrangement of the holes 26 of the cup 25 is such that the access is particularly difficult. Thanks to the instrument 1'having the universal joint 10, which allows the tip 9 to be tilted along an axis Y-Y which is angled with respect to the axis X-X of the instrument 1 ', it is possible to reach and aim all the holes of the cup 25 with the tip 9.

[0082] Figure 12 and 13 Further examples of application of the instrument 1 of the present application are shown, in the ankle joint, in particular in the end portion of the tibia and on the talus.

[0083] Also in these cases, as in the example of Figure 11 The specific guide element 27 is used for the hole formed by the mill 1, which will be used for the subsequent insertion of the bone pin.

[0084] As is evident from these drawings, the configuration of the angled mill 1 allows easier access to the areas to be milled, thus greatly reducing the time of the operation or the time for the preparation of subsequent orthopaedic surgical procedures.

[0085] In understanding the scope of the present application, the term "comprising" and its derivatives, as used herein, are intended to be open-ended terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, but do not exclude the presence of one or more additional features, elements, components, groups, integers, and / or steps. The foregoing also applies to other descriptive terms such as "comprising," "having," "including," and their derivatives, as well as to the term, "consisting of." In addition, the term "a" or "an" when used in conjunction with the term "comprising" or "including" in the context of this specification and the claims is intended to mean one or more than one unless specifically indicated otherwise. Further, the term "another" when used in conjunction with the term "comprising" or "including" in the context of this specification and the claims is intended to mean one or more than one unless specifically indicated otherwise.

[0086] It should also be understood that, although the terms "first" and "second" or "one" and "the other" can be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another.

[0087] While only selected embodiments have been chosen to illustrate the present application, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made and that other embodiments can be used without departing from the scope of the application as defined by the appended claims.

Claims

1. An orthopaedic surgical instrument comprising: - an inner rod (2) extending along a longitudinal axis (X-X) of itself and provided with an attachment end (7) attached to a motorized member; - a tubular envelope (5) surrounding the inner rod (2); - an operating head (15) at a rod end (8) opposite the attachment end (7); - a universal joint (10) between the rod end (8) and a tool (9) of the operating head, so that the tool (9) extends along an angled axis (Y-Y) with respect to the longitudinal axis (X-X), characterized in that the tubular envelope (5) is configured with two superimposed half-shells (3, 6) covered by a handle (4), and at least one (6) of the half-shells comprises an anti-rotation element for holding the handle (4) surrounding the two half-shells (3, 6).

2. The surgical instrument of Claim 1, wherein, The inner rod (2) is operated empty with respect to the tubular envelope (5).

3. The surgical instrument according to claim 1, comprising at least one pair of bushings (11, 12) mounted in an empty working manner on opposite portions of the inner rod (2) for supporting the tubular envelope (5).

4. The surgical instrument of Claim 3, wherein, The bushings (11, 12) are made of a low-friction synthetic material.

5. The surgical instrument of Claim 1, wherein, The tubular envelope (5) is configured with two half-shells (3, 6), one (6) of which is provided at one end with a housing seat (18) for housing the universal joint (10) of the operating head (15).

6. The surgical instrument of claim 5, wherein, The housing seat (18) has an annular portion (19) having an axis corresponding to the angled axis (Y-Y).

7. The surgical instrument of Claim 1, wherein, The anti-rotation element is an anti-rotation protruding notch (14) for holding the handle (4) surrounding the two half-shells (3, 6) of the tubular envelope (5).

8. The surgical instrument of Claim 1, wherein, The universal joint (10) has one portion corresponding to the rod end (8) and another portion removably coupled with the tool (9).

9. The surgical instrument of Claim 1, wherein, The attachment end (7) is shaped as a quick coupling attachment device for a spindle of the motorized member.

10. The surgical instrument of claim 4, wherein, The bushings (11, 12) are made of PEEK.

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