EP2381900A1

EP2381900A1 - Insertion instrument for inserting socket inserts into the spherical recesses of hip sockets

Info

Publication number: EP2381900A1
Application number: EP09795968A
Authority: EP
Inventors: Roman Preuss; Michael Kuntz; Tobias Weiss; Ralph Autenrieth; Götz GRIESMAYR; Manuela Muhr-Schenk
Original assignee: Ceramtec GmbH
Current assignee: Ceramtec GmbH
Priority date: 2008-12-17
Filing date: 2009-12-15
Publication date: 2011-11-02
Also published as: CN102438557A; US9301855B2; KR101712030B1; JP5812865B2; WO2010069940A1; JP2012511982A; US20110245837A1; DE102009054633A1; KR20120006970A; CN102438557B

Abstract

The invention relates to an insertion instrument (9) for hip endoprosthetics for inserting socket inserts (17) into endoprosthetic hip sockets (18), having holding claws (2), which are connected to a substantially ring-shaped support element (12) through spring elements (16), wherein the insertion instrument (9) can be placed on the socket insert and can be connected to said socket insert through the holding claws (2). In order for the user to receive direct palpatory information about the events in the operation area and to not suffer a perceived loss of control, it is proposed that the support element (12) surround a freely accessible, substantially circular effective insertion area (11), the center point of which is located on the longitudinal axis of the insertion instrument.

Description

Insertion tool for inserting pan inserts into the domes of

acetabular

The invention relates to an insertion instrument for total hip arthroplasty for inserting socket inserts into endoprosthetic acetabular cups according to the preamble of claim 1.

There are a variety of prosthetic systems in the market for replacing the natural hip joint in the event of painful traumatic, arthrotic or other changes. In this case, so-called modular systems are generally used in which in a mostly made of a metal alloy Hüftpfanne a socket insert is used, which forms part of the artificial sliding bearing and which of a metal alloy, a ceramic material, a plastic or a composite of the aforementioned materials can exist. Frequently, the coupling between socket insert and acetabulum takes place via a so-called conical clamping, in which a conically shaped part of the outer geometry of the cup insert forms a frictional connection with a suitably conically shaped part of the inner geometry of the acetabulum, see FIG.

Figure 1 shows a sectional view of a hip pan (hatched) according to the prior art with inserted socket insert, which is coupled via a conical clamping with the acetabular cup.

One of the problems that can occur intraoperatively is the tilted insertion of the socket insert into the acetabular cup. Then, instead of the described conical clamping jamming of the socket insert between three contact points within the clamping cone of the acetabulum occur. Depending on the height, the force applied during jamming occur as a result of puπktuelleπ jamming on such high friction forces that the position of the socket insert intra-operatively can not be corrected, see Figure 2.

Figure 2 shows a sectional view of a Hϋftpfanne (hatched) according to the prior art with tilted inserted pan insert.

The consequences for the function of the hip joint prosthesis with tilted inserted insert significantly depend on the material of the socket insert and range from increased wear on corrosion to complete destruction of the socket insert. Thus, a tilted inserted socket insert can be the cause of a later complex, painful and expensive revision operation.

In order to avoid the tilted insertion of cup inserts, a number of insertion tools are available in the market. Their function is essentially based on the following three steps:

1. Gripping the socket insert at the upper outer edge.

2. Aligning the instrument with acetabular insert on the acetabulum so that the axes of symmetry of acetabulum and cup insert are parallel.

3. Jerky, fast sliding of the socket insert in the acetabulum, thereby lifting the handle and creating the clamp connection.

The gripping of the upper outer edge of the socket insert by the instrument is usually carried out via a so-called three-point recording. The instrument has to claw-shaped elements which protrude at least three points beyond the outer edge of the socket insert and each exert on a point-shaped point below the end face of the socket insert a normal force or friction force. The alignment of the instrument with Pfanneneinsatz is usually done by placing the instrument on the end face of the acetabular cup or on elements (eg recesses or elevations) near the end face, which in turn lie in a plane parallel to the end face.

The jerky pushing out of the socket insert from the gripping elements, creating a jamming between socket insert and acetabular cup, takes place i.d.R. by an additional plunger on the insertion instrument or using a so-called Impaktorinstrumentes.

Such insertion instruments are e.g. in EP 1 076 537 B1 and DE 299 22 792 U 1.

Disadvantages of the existing solutions are:

> Inserting the socket insert into the acetabulum and generating the initial clamping is done by a pestle or an impactor instrument. Both result in the handling surgeon no longer having finger contact with the socket insert and thus losing some of the control over the movement of the component. This is usually perceived as very unpleasant by surgeons who palpate a substantial portion of their information about their surgical field, and results in low acceptance (= use) of the insertion instruments. > The use of an insertion instrument is in most cases an additional step, which results in low acceptance of the insertion instruments due to the pressure to increase the effectiveness in the operating room. - A -

Insertion instruments, which rest on the entire end face of the acetabulum for aligning the acetabulum insert, can be supported by bone and bone

Soft tissue, which protrudes from the outside over the acetabular rim

Aligning be disturbed, so that no tilt-free insertion of the socket insert with the instrument is possible - or the risk of tipping is increased again.

> The insertion instrument is often an additional instrument in the surgeon's instrument set, which adds expense to the provision of surgical instruments. > Insertion instruments, which are not an additional instrument in the instrument set, but are intended for single use, are either supplied as separate products (= additional packaging necessitates additional unpacking time and additional waste) or require a specific design of the pan insert packaging to also accommodate the insertion instrument therein ,

A solution of the problems described is achieved by an inventive insertion according to the features of claim 1.

The insertion of acetabular inserts in endoprosthetic acetabular cups and anchoring there via a conical clamping, carried out with an insertion instrument according to the invention, which is placed on the end face of the socket insert and clamped to this by means of retaining claws for insertion of the socket insert with attached insertion tool in the endoprosthetic hip socket without used and positioned on both sides. Then slid by pressure on the socket insert or on the dome of the socket insert with sufficient joining force of the socket insert from the retaining jaws of the insertion and goes with the acetabulum a frictional contact. The insertion instrument is used only for gripping and accurately positioning the socket insert in the acetabular cup. The pressure on the inner cup of the socket insert to the sufficient joining force takes place without pressure transmission devices directly and exclusively by the user's fingers. As a result, the described disadvantages are eliminated and the surgeon or the user receives direct palpatohsche information about what is happening in the surgical field and suffers no perceived loss of control.

The insertion instrument according to the invention is characterized in that the support member encloses a freely accessible substantially circular effective through-hole, the center of which is located on the longitudinal axis of the Einsetzinstrumentes. The substantially circular effective penetration area must be large enough that a finger of the user or surgeon is push-through. The penetration area must be so small that the insertion instrument has sufficient stability and on the other hand must not be so small that fingers of the user are not durchsteckbar.

In a preferred embodiment, the effective diameter of the through-hole area is greater than or equal to 2.0 cm, more preferably greater than or equal to 2.5 cm.

With effective diameter is meant in a support element which surrounds a circle as a through-hole (see Figure 3), the diameter of the circle. However, if the support element encloses a penetration area other than a circle, as shown in FIGS. 7a, 7b and 8, the effective diameter is the diameter of the inscribed circle (see FIG. 7a, reference numeral 20). By effective diameter is meant the diameter of the user's finger rather than the area (see Figure 7a, reference numeral 21) of the through-hole, which is essentially irrelevant to the insertion of the finger.

In an inventive embodiment, the spring elements and the support element are combined to form a one-piece support spring element and the retaining claws are arranged on the support spring element. In this embodiment, the insertion instrument is in one piece and is easy to manufacture.

Preferably, the support spring element is an elastically yielding ring, wherein the retaining claws are arranged on the outer circumference of the ring. For placing on the outer edge of the socket insert, the retaining claws must be pushed only by a radial clamping over the outer edge of the socket insert, that is, the support spring element is deformed and acts on the retaining claws a spring force. Thus, each retaining surface of the retaining claws exerts a compressive force on the socket insert, which is the magnitude and direction of the spring force on the respective retaining claw.

In another inventive embodiment, the support spring element has a triangular or n-corner shape. Also a concertina-shaped form may be advantageous. It is always important to ensure that the effective penetration area is large enough that a finger is push-through. By designing the shape of the support spring element, the spring force can be adjusted.

In an alternative embodiment, the support element and the spring elements are separate components and the retaining claws are connected via the spring elements to the support element. By suitable selection of the spring elements, the spring forces can be adjusted individually. In one embodiment, the spring elements have a concertina-shaped form, which are preferably arranged perpendicular to the plane of the retaining claws. Alternatively, the support spring element or the support elements between the holding claws to produce more rigid and flexurally soft zones in its height and width varying cross-section.

The support spring element or the support elements can also have a change in cross-sectional geometry between the retaining claws to produce more rigid and flexurally soft zones.

The invention will be further explained with reference to figures.

Referring to Figures 1 and 2, which show the prior art, reference is made to the introduction to the description.

FIG. 3 shows an insertion aid according to the invention consisting of an annular, resilient support-spring element 12 with retaining claws 2.

The insertion instrument consists in this embodiment of a resilient, annular support spring element 12, which is followed by three retaining claws 2. The design of the Einsetzinstrumentes takes place in manufacturing technology advantageous as a monolithic component, which can be produced for example by injection molding. The flexibility of the support spring element 12 causes the retaining claws 2 can be moved radially. With increasing radial displacement of the retaining claws 2 thereby increases the spring force to be overcome. The force-displacement characteristic of the retaining claws 2 can be influenced by appropriate geometric design of the annular support spring element 12. The retaining claws 2 each have a retaining surface 3 (see FIG. 4). The retaining claws 2 lie with their lower end 6 (see FIG. 6) in the assembled state on an outer surface of the socket insert 17. In the assembled state, the support spring element 12 is in the cap 5 of the socket insert 17 and the retaining claws 2 engage over the end face and outer edge of the socket insert 17. However, embodiments are also conceivable in which the support spring element 12 and the retaining claws 2 in a plane lie above the cap 5 of the socket insert 17.

FIG. 4 shows an insertion aid according to the invention with a visible holding surface 3.

According to the insertion instrument is dimensioned so that the retaining claws 2 can be pushed over the outer edge of the socket insert 17 only by a radial clamping. That is, the support spring member 12 is deformed and on the retaining claws 2 acts a spring force. Thus, each support surface 3 exerts a compressive force on the socket insert 17, which is the spring force on the respective holding claw 2 amount and the same direction. Due to the pressure forces acting frictional forces between the holding surfaces 3 and the outer surface of the socket insert 17, which counteract a removal of the insertion of the pan insert 17. This is essential for the function of the Einsetzinstrumentes.

FIG. 5 shows a socket insert 17 with an insertion instrument according to the invention in the mounted state.

If the socket insert 17 is pushed with mounted insertion instrument in a acetabulum 18, the retaining claws 2 come at its lower end 6 in contact with the end face of the acetabulum 18. Since the retaining claws 2 all have the same extent down, the contact points form a plane which both to the end face of the acetabular cup 18 and to the end face of the cup insert 17th is parallel. Thus, this also results in an orientation of the two end faces, so that they are parallel to each other. A possible tilting of the socket insert 17 is counteracted. By still existing at this time, lateral gap between socket insert 17 and acetabulum 18 a slight displacement of the socket insert 17 in the acetabulum 18 is possible. By multiple back and forth of the socket insert 17 in the acetabulum 18 - each to light impact - with the finger 7 - it is possible for the user to check the correct position of the socket insert 17 in the acetabulum 18. Just the presence of easy displaceability and striking the components provides the user with very good palpatory feedback on the correct position of the socket insert 17 in the cup 18.

To push the socket insert ultimately until the frictional contact of the two conical surfaces - on the socket insert 17 outside and on the acetabular cup 18 inside - in the acetabular cup 18, the frictional forces between the holding surfaces 3 of the Einsetzinstrumentes and the outer surface of the cup insert 18 must be overcome. This is done by continuous or preferably by a sudden increase in the axial joining force by the finger 7 of the user. The socket insert 17 slides the remaining short distance in the acetabular cup 18, with no appreciable tilting of the cup insert 17 is more possible. Possible slight tilting is compensated and corrected by the self-centering effect of the conical clamping connection

FIG. 6 shows a socket insert 17 with an insertion instrument according to the invention in the assembled state when inserting the socket insert 17 into the acetabular cup 18.

As soon as the retaining claws 2 have detached from the socket insert 17, the spring element or the supporting spring element 12 returns to its original shape. By this quick return movement, the insertion instrument is further pressed off the end face of the acetabulum 18 and slides a few inches along the finger 7 of the user until the movement of the Einsetzinstrumentes comes to a standstill. If the user wears rubber gloves, as is the case during surgery, the inserter will stick to the user's finger through the glove. As a result, the user will inevitably remove the insertion instrument from the surgical field as he removes his hand from the surgical field.

The advantages of the embodiment according to the invention consist in:

> the direct handling of the socket insert 17 when inserted with the fingers 7 of the user (surgeon), so that the user receives direct palpatory information about the events in the surgical field and suffers no perceived loss of control.

> The three-point support on the retaining claws 2 on the end face of the acetabulum 18, which is achieved by the use of three retaining claws 2 and thus leads to static certainty in the alignment of the components to each other. If parts of the end face of the acetabulum 18 be covered by superior tissue, but it is also sufficient to search by turning the socket insert 17 with the insertion a position in which all three retaining claws 2 have contact with the acetabulum end face. The tissue freedom of the spaces between the jaws 2 is not necessary. > The low height of the Einsetzinstrumentes, so that this only slightly surmounted the end face of the socket insert 17 and thus can be packed in existing sterile packaging for pan inserts 17, without a change in geometry of the packaging is required. r of the monolithic and simple design of the Einsetzinstrumentes that allows cost-effective production, handling and sterilization and allows a one-way use.

Other embodiments arise from shape variation of the annular compliant element, i. Here, once the basic shape of the support spring element 12 in the top view, according to Figure 3, can be varied. Furthermore, the variation of the shape of the cross section of the annular element is conceivable or a combination of both variation measures.

For example, triangular or n-angular geometries are also conceivable, see FIG. 7.

Figure 7 shows two different insertion instruments in the view from above. A variation of the geometry of the annular compliant element may be e.g. by a triangle (Figure 7a) or n-corner shape (Figure 7b) happen.

Furthermore, it is possible to form the direct connecting paths between the three retaining claws 2 by means of yielding track elements. If, for example, a concertina-shaped design of the connecting sections 13 (see FIG. 8), this results in a deformability of the section element when a force acts, which leads to the radial displacement of the retaining claws 2. On the number and design of Zieharmonika arches, a specific design of the force-displacement characteristic of the retaining claws 2 is also possible in this case.

Furthermore, it is conceivable not to arrange the accordion-shaped configuration in a plane parallel to the plane of the retaining claws, but perpendicularly thereto, see FIG. 9, in order to enable integration into existing packaging, too. are usefully moved the Zieharmonika bows constructive in the region of the cap 5 of the socket insert 17.

Figure 8 shows an inventive insertion in the top view with a direct connection of the three retaining claws 2 by accordion-shaped spring elements or support spring elements 12 or connecting lines 13 between the jaws. 2

FIG. 9 shows an insertion instrument according to the invention in a top view (FIG. 9a) and in a sectional view (FIG. 9b). The connection of the three retaining claws 2 takes place with a central ring or support element 15 by zieharmomka-shaped spring elements 16, which are arranged perpendicular to the plane of the three retaining claws 2. At these spring elements 16, the retaining claws 2 are attached.

A variation of the cross section of the annular, resilient element, or of the supporting spring element 12 can take place in cyclic form over the circumference of the annular, resilient element or supporting spring element 12. Thus, the force-displacement characteristic of the retaining claws 2 and the shape of the annular, resilient element or the supporting spring element 12 can be influenced during the deformation. Likewise, possible torsions of the annular element during the deformation can be deliberately suppressed or influenced, for example if an undesired tilting of the retaining claws 2 on the edge of the socket insert 17 or the acetabulum 18 could occur due to torsions.

The variation of the cross section can be done by changing its height and width, so that bending soft and rigid zones arise, for example, rigid zones in the region of the retaining claws 2 and flexible zones in the area between the retaining claws 2, see Figure 10. FIG. 10 shows an insertion instrument according to the invention (cutout between two retaining claws) with varying ring cross-section - variation of height and width of the cross section for producing more rigid and more bendable zones.

Furthermore, complete changes in cross-sectional geometry over the circumference are also conceivable, e.g. rectangular cross section in the region of the retaining claws towards a circular cross section exactly on the center of the ring between two retaining claws 2, see Figure 1 1.

FIG. 11 shows an insertion instrument according to the invention (section between two retaining claws 2) with a varying annular cross-section. Variation of the cross-sectional geometry from a rectangular shape to a circular shape and back to a rectangular shape.

Likewise, continuous optimization of the cross-sectional geometry by means of finite element simulations and using so-called adaptation algorithms is conceivable. The resulting geometry can deviate arbitrarily from the initial cross-section (for example, rectangular or circular shape) of the optimization, but lies within the correspondingly prescribed dimensional limits.

According to the invention, the insertion instrument thus consists of retaining claws 2, which abut retaining surfaces 3 (see FIG. 4) on the outside of the socket insert 1 (see FIG. 9). The retaining claws 2 are connected to spring elements 16 which hold the retaining claws 2 to the interior of the socket insert 17 Applying Force The spring elements 16 can at the same time also form the connection between the retaining claws 2 with one another (see FIGS. 3, 4, 5, 6, 7, 8, 10, 11) and / or be connected to a support spring element 12

Claims

claims

An eggπsetzinstrument (9) for total hip arthroplasty for inserting socket inserts (17) in endoprosthetic acetabular cups (18), with retaining claws

(2), which are connected via spring elements (16) with a substantially annular support member (12), wherein the insertion instrument (9) placed on the socket insert and with this on the retaining claws (2) is clampingly connectable, characterized in that the Carrying member (12) a freely accessible substantially circular effective

Penetration surface (11) encloses whose center is located on the longitudinal axis of the Einsetzinstrumentes.

2. insertion instrument according to claim 1, characterized in that the effective diameter of the through-hole (11) is greater than or equal to 2.0 cm, more preferably greater than or equal to 2.5 cm.

3. insertion instrument according to claim 2, characterized in that the diameter of the through-hole (11) is 2.5 cm.

4. insertion instrument according to one of claims 1 to 3, characterized in that the spring elements (16) and the support element (12) are combined to form a one-piece support spring element (12) and the retaining claws (2) on the support spring element (12) are arranged.

5. insertion instrument according to claim 4, characterized in that the supporting spring element (12) is an elastically yielding ring.

6. insertion instrument according to claim 4, characterized in that the supporting spring element (12) has a triangular or n-corner shape.

7. insertion instrument according to claim 4, characterized in that the support spring element (12) has a zieharmonikaförmige form aulweist.

8. insertion instrument according to one of claims 1 to 3, characterized in that the support element (1) and the spring elements (16) are separate components and the retaining claws (2) via the spring elements (16) are connected to the support element (1).

9. insertion instrument according to claim 8, characterized in that the spring elements (16) have a zieharmonikaförmige shape, which are preferably arranged perpendicular to the plane of the retaining claws (2).

10. insertion instrument according to one of claims 1 to 9, characterized in that the supporting spring element (12) or the support elements (1) between the retaining claws (2), to produce more rigid and flexurally soft zones, a varying in height and width cross-section exhibit.

1 1. Insertion instrument according to one of claims 1 to 10, characterized in that the support-spring element (12) or the support elements (1) between the holding claws (2) for generating more rigid and flexurally soft zones have a change in cross-sectional geometry.