DE102008062730A1 - Method for determining adaptability between adapter in joint ball and external cone of prosthesis shaft of modular joint prosthesis during revision operation of patient, involves determining whether adapter fits to cone of prosthesis - Google Patents

Abstract

The method involves attaching a test specimen (1) with different inner cones (3) to an external cone of a shaft of a joint prosthesis, where the test specimen is provided in the form of cut ball segments. The inner cones on adherence to preset minimum distance between front sides of the external cone of the shaft of the joint prosthesis and a predetermined insertion depth of the external cone of the shaft of the prosthesis are tested in the inner cone of the specimen. A determination is made to check whether an adapter fits to the external cone of the joint prosthesis based on test results. An independent claim is also included for a device for determining adaptability between an adapter in a joint ball and an external cone of a prosthesis shaft of a modular joint prosthesis during a revision operation.

Description

The The invention relates to a method for determining the passability between an adapter for use in a provided for replacement ball joint foreign design and an outer cone of one used in the femur Prosthetic socket of a modular joint prosthesis during a revision operation.

The The invention further relates to a device for determining the passability between an adapter for use in an exchange intended Joint ball of foreign design and an outer cone of a Femur inserted prosthetic socket of a modular joint prosthesis during a revision operation.

It It is known that there are a variety of modular in use Joint prosthesis systems of different manufacturers exist, in particular when replacing damaged or worn components a joint prosthesis, such as joint ball or adapter to problems in choosing the right prosthetic component during to lead the operation. Often this is due to that the manufacturer's production of the corresponding joint prosthesis or the manufacturer is no longer active in the market is. The surgeon must decide during the procedure in a short time, whether an adapter or a ball joint from another manufacturer to Outer cone of the prosthesis socket inserted into the femur fits or a completely new modular joint prosthesis system must be used.

The latter procedure extends the already relatively long-lasting procedure for the patient and is often associated with the transection of the femur ( US 5 100 407 A ). The selection of a suitable adapter on the outer cone of the femoral prosthesis stem from a set of adapters according to the Trial and Error method is tedious and ultimately unsatisfactory for the patient ( EP 0 767 638 B1 ).

task

at In this prior art, the object of the invention is to provide a method and apparatus for determining passability of an adapter to provide joint prosthesis, which make it possible modular components of a joint prosthesis from different manufacturers to combine with each other to simplify the revision operation and joint balls of ceramic or metal on an already lying Shaft to fit accurately.

These The object is achieved by a method and a device of the beginning said genus having the features of claims 1 or 6 solved.

advantageous Embodiments of the method according to the invention and the device are the dependent claims

The inventive solution is characterized made that the components of modular joint prostheses different Manufacturer through the use of an appropriately adapted adapter compatible and combinable with each other. This is with the extraordinary benefit for the patient, that the prosthesis socket used in the femur is not removed and only one to the existing geometric relationships the outer cone of the prosthesis stem adapted adapter must be used to ensure compatibility between to manufacture the new and existing components of the prosthesis.

The Combination of components of modular joint prostheses different Manufacturer succeeds by a determination of the passability between an inner cone of an adapter and an outer cone of the Shank of a joint prosthesis, wherein a mark and length measuring scale having Test specimen in the form of a visually observable spherical segment a set of specimens with different Innenkonen successively attached to the shaft of the joint prosthesis and then the fitting to the shaft of the joint prosthesis Adapter by testing the inner cones for compliance with a permissible minimum distance between the front of the outer cone of the Shank of the joint prosthesis and the inner cone and one as permissible predetermined insertion depth of the outer cone of the joint prosthesis is determined in the inner cone of the specimen.

• a) Feststellen des tatsächlichen Abstandes zwischen Stirnseite des Außenkonus des Schaftes der Gelenkprothese und dem Dach des Innenkonus des Prüfkörpers,
• b) Vergleich des tatsächlichen Abstandes gemäß Schritt a) mit der Markierung am Prüfkörper als Maß für den minimal zulässigen Abstand zwischen Stirnseite des Außenkonus des Schaftes der Gelenkprothese und dem Dach des Innenkonus des Prüfkörpers,
• c) Abziehen des aufgesetzten Prüfkörpers vom Außenkonus des Schaftes der Gelenkprothese sobald im Schritt b) ermittelt wird, dass der zulässige Abstand unterschritten wird und Aufstecken eines weiteren Prüfkörpers aus dem Satz der Prüfkörper mit einem anderen Innenkonus,
• d) Fortführen der Schritte a) bis c) solange bis der tatsächlich festgestellte Abstand mit der Markierung exakt übereinstimmt oder diese überschreitet,
• e) Beurteilen der Rotationsfestigkeit und der Kippneigung durch Drehen des Prüfkörpers auf dem Außenkonus und bei Feststellen eines spürbaren Gleitreibungswiderstandes ohne Kippneigung,
• f) Ermitteln der tatsächlichen Einstecktiefe des Außenkonus des Schaftes der Gelenkprothese in den Innenkonus des Prüfkörpers als ein Maß für den sicheren Sitz des Innenkonus auf dem Außenkonus des Schaftes der Gelenkprothese durch ein Ablesen der Längen-Messskala am Prüfkörper,
• g) Ausschließen des gewählten Innenkonus des Prüfkörpers sobald im Schritt f) ermittelt wird, dass die tatsächliche Einstecktiefe die minimal zulässige Einstecktiefe unterschreitet und Abziehen des Prüfkörpers,
• h) Aufstecken eines weiteren Prüfkörpers und Fortführen der Schritte a) bis d) solange bis die tatsächlich ermittelte Einstecktiefe größer ist als die minimal zulässige Einstecktiefe unter Einhaltung des minimal zulässigen Abstands,
• i) Auswahl eines bevorrateten Adapters mit dem gemäß Schritt h) ermittelten Innenkonus zum Einsetzen in die Gelenkkugel.

The solution according to the invention ensures that the surgeon can safely select the adapter suitable for use in accordance with the geometrical conditions actually existing on the outer cone of the shaft of the joint prosthesis during the operation with the following partial steps:

• a) determining the actual distance between the end face of the outer cone of the shaft of the joint prosthesis and the roof of the inner cone of the test specimen,
• b) comparison of the actual distance according to step a) with the marking on the test specimen as a measure of the minimum permissible distance between the end face of the outer cone of the shaft of the joint prosthesis and the roof of the inner cone of the specimen,
• c) Removing the attached test specimen from the outer cone of the shaft of the joint prosthesis as soon as it is determined in step b) that the allowable distance is exceeded and attaching a further specimen from the set of Test specimen with another inner cone,
• d) continuing steps a) to c) until the actually determined distance exactly matches or exceeds the marking,
• e) evaluating the rotational strength and the tendency to tilt by rotating the test specimen on the outer cone and detecting a noticeable sliding friction resistance without tipping tendency,
• f) determining the actual insertion depth of the outer cone of the shaft of the joint prosthesis in the inner cone of the test specimen as a measure of the secure fit of the inner cone on the outer cone of the shaft of the joint prosthesis by reading the length measuring scale on the specimen,
• g) exclusion of the selected inner cone of the specimen as soon as it is determined in step f) that the actual insertion depth falls below the minimum permissible insertion depth and removal of the specimen,
• h) attaching a further test specimen and continuing steps a) to d) until the actually determined insertion depth is greater than the minimum permissible insertion depth while maintaining the minimum permissible distance,
• i) Selection of a stored adapter with the inner cone determined according to step h) for insertion into the joint ball.

From A particular advantage is that the measure of minimal permissible distance from the tolerances of the corresponding Diameter and angle of the inner cone of the test specimens and the outer cone of the shaft of the joint prosthesis determined so that it becomes possible, geometrically unsuitable Safe and fast exclude adapters and a wobble and a rotation of the adapter on the outer cone of the shaft prevent the joint prosthesis.

It It has been shown that the measure of the minimal permissible insertion depth of the outer cone of the shank the joint prosthesis in the inner cone of the specimen from the length of the overlap of the two cones depends and is sufficient if the insertion depth at least 7 mm.

The Device according to the invention has a simple and manageable construction, especially for fast and safe determination of the right adapter is suitable.

The Device comprises a set of test specimens in shape of cut ball segments, each with different Inside cones, with a marker to determine the minimum allowable distance between an end face of the outer cone of the shank of Joint prosthesis and a roof of the inner cone of the specimen is provided near the roof at a cutting edge of the inner cone, and that at the cutting edge of the inner cone a length measuring scale for determining the insertion depth of the outer cone of the shank arranged in the inner cone of the respective test specimen is.

With The surgeon can use these two measuring devices during the Operation quickly the minimum allowable distance between the end face of the outer cone of the shaft of the joint prosthesis and the insertion depth of the outer cone of the shaft in the Visually inspect the inner cone of the test specimen and Immediately make a decision as to whether the selected inner cone suitable for adaptation or unsuitable.

Further Advantages and details will become apparent from the following description with reference to the accompanying drawings.

embodiment

The Invention will hereinafter be an embodiment be explained in more detail.

It shows

1 a front view of the test piece of the device according to the invention with marking for determining the minimum allowable distance and length measuring scale for determining the insertion depth,

2 a side view according to 1 .

3 a schematic view of the device according to the invention in the attached to the outer cone of the shaft of the joint prosthesis state for determining the minimum allowable distance,

4 a schematic of the device according to the invention in the attached to the outer cone of the shaft of the joint prosthesis state for determining the insertion depth,

5 a schematic representation of the sequence of the method according to the invention.

The 1 shows the basic structure of the device according to the invention for determining the fit between an adapter for use in a provided for replacement joint ball of a foreign design and an outer cone of a prosthesis stem used in the femur of a modular joint prosthesis.

The device according to the invention comprises at least one spherical segment-like test piece 1 with a measuring room 2 of one sheath open inner cone 3 and a roof 4 is limited. The roof 4 forms the upper end of the measuring space 2 , In the roof 4 is centric one in the measuring room 2 leading bore 5 introduced, which serves for receiving or inserting a not further described separation instrument.

The inner cone 2 has in his coat M an opening 6 formed by a section along a plane SE of the spherical segment-like Prüfköpers 1 arises, causing the opening 6 through parallel axis A of the specimen 1 extending surfaces F is limited (see 2 ). In these areas F is near the roof 4 a mark 7 and a length measurement scale 8th introduced, the mark 7 at the same time the starting point of the length measuring scale 8th is. The opening 6 is positioned so that both the mark 7 , and the length measurement scale 8th readable by the surgeon and the front side 9 the outer cone 10 of the shaft 11 the joint prosthesis is recognizable.

A device according to the invention includes at least one set of test specimens 1 with cone angles α and diameters graded differently from test piece to test piece D.

The 3 shows the test specimen 1 im on the outer cone 10 a shaft 11 a joint prosthesis plugged state for determining the distance AM between the front side 9 the outer cone 10 and the roof 4 of the test piece 1 , In the example shown, the mark is correct 7 almost with the location of the front 9 the outer cone 10 of the shaft 11 the joint prosthesis match. The location of the mark 7 on the surface F results for each test specimen 1 individually from the known tolerances of the corresponding diameter and angle of the inner cone 3 of the test piece 1 and the outer cone 10 of the shaft 11 the joint prosthesis and a specified safety factor. The minimum allowable distance AM is then maintained when between the location of the mark 7 and the front side 9 the outer cone 10 Match exists. If the distance AM is too small, it may come to rest on the surfaces, whereby a wobbling, rotation and wear can not be excluded. The absence of coincidence between marking 7 and the location of the front side 9 indicates, therefore, that the distance AM is too small and therefore to exclude the selected inner cone 3 leads.

The 4 shows the determination of the insertion depth ET of the outer cone 10 in the inner cone 3 of the test piece 1 , The insertion depth ET determines the secure hold of the inner cone 3 on the outer cone 10 and depends essentially on the length of the overlap of the two cone surfaces.

It It has been proven that a secure hold then guaranteed is when the insertion depth ET is at least 7 mm.

The 5 shows schematically the course of the method according to the invention.

The test piece 1 a set of test specimens each with different inner cones 2 is on the outer cone 10 of the shaft 10 attached to the joint prosthesis and the actual distance AM between the front side 9 the outer cone 10 and the roof 4 the inner cone 3 determined (step a). This is the location of the front page 9 with the mark 7 on the surface F of the specimen 1 compared. If the comparison shows that there is an undershoot of the distance AM, the test specimen becomes 1 from the outer cone 10 of the shaft 11 subtracted and a new specimen 1 selected from the set of test specimens with, for example, a larger cone diameter D or a larger cone angle α. This new test specimen 1 will then turn on the outer cone 10 of the shaft 11 the joint prosthesis attached. This is followed by the determination of the distance AM. If it is determined that the distance AM is maintained or exceeded by the actual distance, an assessment is made of the rotational strength and the tilt tendency of the test specimen 1 on the outer cone 10 of the shaft 11 (Step e) by rotating the specimen 1 on the outer cone 10 , If no tilting tendency is determined and a noticeable sliding friction is to be overcome during rotation, the actual insertion depth ET of the outer cone is determined 10 of the shaft 11 in the inner cone 3 of the test piece 1 (Step f). If there is no appreciable sliding friction without tilting tendency, the test specimen becomes 1 subtracted and a new specimen 1 from the set of test specimens with again changed cone diameter D and cone angle α on the outer cone 10 attached. The testing process starts again with step a).

If, during the determination of the insertion depth ET, it is determined that the actual insertion depth exceeds a minimum permissible insertion depth prescribed as a function of the cone length, the conditions for the passability of the inner cone to be adhered to for selection must be met 3 of the present specimen before and the correspondingly suitable adapter for the joint component can be selected from a stockpiled for this purpose.

The Invention is limited in its execution not on the aforementioned embodiments Rather, much more Variants are conceivable, which of the illustrated solution even with fundamentally different types may differ.

1

specimen

2

measuring room

3

inner cone

4

top, roof

5

drilling

6

opening

7

mark

8th

Length measuring scale

9

front

10

Außenkonus0

11

shaft

A

Axis of 1

AT THE

distance Front side-roof

D

diameter cone

ET

insertion

F

area of 1

M

Coat of 3

SE

level

α

cone angle

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 5100407 A [0004]
• - EP 0767638 B1 [0004]

Claims (11)

Method for determining the passability between an adapter for use in an intended for replacement ball joint foreign design and an outer cone of one used in the femur Prosthetic socket of a modular joint prosthesis during a revision operation in which a mark and a length measurement scale having test specimen in the form of a cut Ball segment of a set of specimens with different Innenkonen on the outer cone of the shaft the joint prosthesis attached and then the on the outer cone of the joint prosthesis fitting adapter a successive testing of Innenkonen on compliance with a permissible minimum distance between the end faces of the outer cone the shaft of the joint prosthesis and the inner cone and a as permissible specified insertion depth of the outer cone of the shaft of the joint prosthesis determined in the inner cone of the specimen becomes. Method according to claim 1, characterized in that that the following sub-steps are carried out: a) Determine the actual distance between front side of the conical Shaft of the joint prosthesis and the roof of the inner cone of the specimen, b) Comparison of the actual distance according to step a) with a marking on the specimen as a measure of the minimum permissible distance between front side of the Outer cone of the shaft of the joint prosthesis and the roof the inner cone of the specimen, c) remove of the attached test specimen from the outer cone of the stem of the joint prosthesis as soon as it is determined in step b), that the permissible distance is fallen below and plugging another test piece from the set of test specimens with another inner cone, d) Continue the steps a) to c) until the actually determined distance exactly matches or exceeds the mark, e) Evaluate the rotation resistance by rotating the test specimen and the tilt tendency on the outer cone of the shaft and upon detection of a noticeable sliding friction resistance without tilting tendency, f) Determining the actual insertion depth the outer cone of the shaft in the inner cone of the specimen as a measure of the secure fit of the inner cone on the outer cone of the shaft of the joint prosthesis a reading of the length measuring scale on the test specimen, G) Excluding the selected inner cone of the test specimen as soon as it is determined in step f) that the actual Insertion depth is below the permissible insertion depth and removing the test specimen, h) Plug on another test piece with modified Diameter and angle and continue the steps a) to d) until the actually determined insertion depth greater than the permissible insertion depth in compliance with the minimum permissible distance, i) Selection of a stocked adapter with the according to step h) determined inner cone for insertion into the joint ball. Method according to claim 1, characterized in that that is the measure of minimum allowable distance the tolerances of the corresponding diameter and angle of the inner cone the test specimen and the outer cone of the Shank of the joint prosthesis is determined. Method according to claim 1, characterized in that that the measure of the permissible insertion depth the outer cone of the shaft of the joint prosthesis in the inner cone of the test specimen according to the length of the inner cone of the specimen is determined. Method according to claims 1 and 4, characterized that the permissible insertion depth is set to at least 7 mm becomes. Device for determining the fit between an adapter for use in a foreign-provided joint ball and an outer cone of a prosthetic socket of a modular joint prosthesis during a revision operation for carrying out the method according to claim 1, characterized in that the device comprises a set of test specimens ( 1 ) in the form of cut-off spherical segments, each with different inner cones ( 3 ), where a marker ( 7 ) for determining the minimum permissible distance (AM) between an end face ( 9 ) of the outer cone ( 10 ) of the shaft ( 11 ) of the joint prosthesis and a roof ( 4 ) of the inner cone ( 3 ) of the test specimen near the roof ( 4 ) on a surface (F) of the inner cone ( 3 ) is provided, and that on the surface (F) of the inner cone ( 3 ) a length measuring scale ( 8th ) for determining the insertion depth (ET) of the outer cone ( 10 ) of the shaft ( 11 ) in the inner cone ( 3 ) of the respective test body ( 1 ) is arranged. Device according to claim 6, characterized in that the inner cones ( 3 ) of the test piece ( 1 ) of the set of test specimens have different angles (α) and diameter (D). Device according to claims 6 and 7, characterized that the minimum allowable distance (AM) is the tolerances the corresponding diameter and angle of the inner cone of the specimens and the outer cone of the shaft of the joint prosthesis considered. Apparatus according to claim 6, characterized in that the permissible insertion depth (ET) of the outer cone ( 10 ) Shank ( 11 ) in the inner cone ( 3 ) of the test specimen to the length of the inner cone ( 3 ) of the specimen is tuned. Device according to claim 9, characterized that the permissible insertion depth (ET) is at least 7 mm. Apparatus according to claim 6, characterized in that the set of test specimens ( 1 ) is associated with a set adapter for inserting or adjusting the joint ball.