The present invention relates to a device and a method for selecting at least one hip joint prosthetic element from a number of hip joint prosthetic elements in hip joint operations. More particularly, the invention relates to selecting the at least one hip joint prosthetic element based on a contour of the pelvis and/or the femur, wherein differences in the leg length and leg offset are taken into account and/or compensated.
In a known method for selecting at least one hip joint prosthetic element and/or a hip joint prosthetic, a surgeon, prior to the operation, produces a representation of the hip to be operated on based on x-ray recordings. From this representation, the model and size of the hip joint prosthetic are selected.
In a method for selecting at least one hip joint prosthetic element from a number of hip joint prosthetic elements, bone and/or cartilage contour data of the pelvis and/or the femur may be detected, wherein at least one hip joint prosthetic element can be selected based on the detected bone and/or cartilage contour data. In particular, the shape and/or contour of the pelvis and/or the femur can be detected, for example, using a computer-assisted navigation system, wherein the amount of removed bone and/or cartilage material can be measured. Before the bone and/or cartilage contour data are detected, markers, such as reference stars, for example, can be attached to the hip and/or the femur to register a bone and/or cartilage contour or a shape of the pelvis and/or the femur.
In the registering process, coordinate systems can be defined, for example, by sensing or scanning landmarks (e.g., characteristic positions or points of the hip and/or the femur), wherein the structure, shape or contour of the hip and/or the femur can be registered or defined. The coordinate system of the hip to which the contour of the bone and/or the cartilage of the pelvis may be registered or defined, can be defined by the front hip plane and the mid-sagittal plane, for example. The coordinate system of the femur can be defined such that the direction of the leg length and/or the direction of the leg offset can be registered or defined with respect to the femoral coordinate system. This enables a neutral position of the femur and in particular a neutral position of the femur relative to the hip to be virtually ascertained, for example, from the direction of the leg length and/or the direction of the leg offset.
At least one hip joint prosthetic element can be ascertained or selected before and/or during a hip joint operation, for example, from the detected shape or contour of the bones, cartilage of the pelvis, femur, and/or from the detected missing and/or removed bone and/or cartilage material, wherein the hip joint prosthetic element can be a prosthetic head, a prosthetic shaft and/or a prosthetic cavity. By taking into account the removed bone material, suitable hip joint prosthetics, which enable compensation for differences in the leg length and/or the leg offset, can be simply, quickly, automatically and exactly ascertained.
The bone and/or cartilage contour data can be detected using a pointer (e.g., the hip and/or the femur can be scanned with the pointer). Alternatively, the hip and/or the femur can be optically scanned before and/or during a hip joint operation, for example. Each technique can be used to obtain the contour or shape of the hip and/or the femur, which then can be registered with respect to particular coordinate systems.
The bone and/or cartilage contour data also can be detected and/or registered using a recording method such as a computer tomography method, a nuclear spin tomography method, an ultrasound method, a positron emission tomography method (PET) and/or a single photon emission computed tomography method (SPECT).
In particular, a first set of bone and/or cartilage contour data can be detected and/or registered before and/or during a hip joint operation to obtain a pre-operative or intra-operative shape or contour of the pelvis and/or the femur, for example. From the shape and/or contour, conclusions can be drawn regarding differences in the leg length and/or the leg offset, from which an amount of removed bone and/or cartilage material can be ascertained, for example. The detected bone and/or cartilage contour data can be provided to a navigation system (e.g., via direct input or via transmission by a network or other wired or wireless transmission method), wherein the navigation system can calculate a neutral standing position of a person from the detected and/or registered bone and/or cartilage contour data. In this way, the direction of the leg length of the femur can be aligned parallel to the front hip plane and/or to the mid-sagittal plane. This can provide a person in a standing position with legs running at least approximately parallel to each other, and/or the hip of the person lay at least approximately parallel to a standing surface of the person.
Data, such as an amount of bone and/or cartilage material that should be or has been removed, also could be input into the navigation system. Using this data, the navigation system, based on detected or registered bone and/or cartilage contour data, can navigate an instrument for removing the bone and/or cartilage material. While the bone and/or cartilage material of the hip and/or the femur is being removed and/or after it has been removed by means of an instrument navigated by the navigation system, for example, a second set of bone and/or cartilage contour data can be detected and/or registered.
For example, the second set of bone and/or cartilage contour data can be detected and/or registered using a pointer and/or an imaging method, wherein at least one hip joint prosthetic element, such as a prosthetic head, a prosthetic cavity or a prosthetic shaft, is selected based on the first set of bone and/or cartilage contour data obtained before and/or during the hip joint operation, and on the second set of bone and/or cartilage contour data ascertained during and/or after the hip joint operation.
The hip joint prosthetic element can be selected from the difference between the first and second set of bone and/or cartilage contour data, e.g., from the difference in the contour of the pelvis and/or the femur before and after the hip joint operation, such that the selected hip joint prosthetic element compensates for the difference between the pelvis and/or the femur before and after the operation, wherein the difference may be created by the removed bone and/or cartilage material. Preferably, the hip joint prosthetic element can be selected such that it compensates for or obtains a leg offset prior to the operation or differences in the leg length prior to the operation, or such that the pre-operative data are taken into account when selecting the hip joint prosthetic element, in addition to the bone and/or cartilage material removed by the navigated instrument.
The amount of the bone and/or cartilage material removed by the navigated instrument also can be ascertained during the removal process, for example, by detecting the positional data of the instrument and processing the data using a computational unit to determine the amount of bone and/or cartilage material that has been removed. Preferably, the hip joint prosthetic element can be selected such that the leg length and/or the leg offset, which may be predetermined or known before the hip joint operation, is obtained based on a difference in the leg length prior to the operation, an existing leg offset and/or removed or missing bone and/or cartilage material when selecting the at least one hip joint prosthetic element.
Furthermore, the invention provides a computer program which, when it is loaded onto a computer or is running on a computer, performs a method as described above. The invention further provides a program storage medium or a computer program product comprising such a program.
In order to select at least one hip joint prosthetic element from a number of hip joint prosthetic elements, a device for selecting the at least one hip joint prosthetic element preferably includes: a data detection apparatus for detecting bone and/or cartilage contour data, such as the shape, contour or outer structure of the pelvis and/or the femur; a computational unit connected to the data detection system, wherein the computational unit processes the detected bone and/or cartilage contour data transmitted from the data detection system to the computational unit (e.g., via a wire connection such as via a LAN network and/or wirelessly, for example by means of Bluetooth, WLAN or HIPERLAN); and a database or database memory or memory system such as a bulk memory, in which characteristic data of a number of hip joint prosthetic elements can be stored. The computational unit can select at least one hip joint prosthetic element from the database or memory in accordance with detected bone and/or cartilage contour data, for example, by comparing the detected bone and/or cartilage contour data, such as the contour of the pelvis and/or the femur, with a number of data for hip joint prosthetic elements available in the database or memory, such as the contour or shape of various hip joint prosthetic elements. The computational unit can select at least one hip joint prosthetic element from the database or memory that has the greatest match or similarly to the detected bone and/or cartilage contour data, for example.
The data detection system preferably can comprise at least one pointer provided with markers, and at least one camera, such as an infrared camera, and/or infrared lamps, wherein the markers can be active markers emitting infrared radiation or passive markers reflecting infrared radiation. The emitted or reflected infrared radiation can be detected by the at least one camera, such that the position of the pointer and therefore the contour of the pelvis and/or the femur can be deduced. The data detection system also can comprise an instrument provided with markers such that the instrument can be detected by the cameras, wherein the instrument can remove bone and/or cartilage material, wherein the amount of the removed bone and/or cartilage material can be deduced based on the position of the instrument. The contour or the shape of the pelvis and/or the femur also can be detected or registered using a computer tomograph, a nuclear spin tomograph, an ultrasound tomograph, a positron emission tomograph and/or a SPECT tomograph, each of which can form part of the data detection system.
The device for selecting at least one hip joint prosthetic element from a number of hip joint prosthetic elements preferably comprises a data output device, such as a screen or the like, which can graphically output the bone and/or cartilage contour data (e.g., as numerical values), and/or the selected hip joint prosthetic element (e.g., a number identifying the respective hip joint prosthetic element or the hip joint prosthetic element itself). A data input device, such as, for example, a keyboard and/or a scanner (e.g., a 3D scanner) also can be provided and can be connected to the computational unit, the database and/or memory. Using the data input device, data such as data for various known hip joint prosthetic elements can be input, or known hip joint prosthetic elements themselves can be scanned in and stored in the database or memory, for example. Further, data such as detected bone and/or cartilage contour data can be input that can be processed in the computational unit and then can be compared with known data from the database.
The device can comprise a navigation system that can be connected to the computational unit and, for example, can navigate a trackable instrument (e.g., an instrument that includes trackable markers) for removing bone and/or cartilage material. The instrument can be navigated based on the detected bone and/or cartilage contour data and the detected shape or contour of the pelvis and/or the femur, for example, by ascertaining how the instrument should be navigated, to what positions the instrument should be guided, or what movements the instrument should perform, in order to remove the desired amount of bone and/or cartilage material.
In a preferred embodiment, the selected hip joint prosthetic element, via the device, can be automatically positioned at a point, such as on the pelvis or on or in the femur, for example.
The selected hip joint prosthetic element, which can be both a prosthetic cavity and a prosthetic head or a prosthetic head connected to a prosthetic shaft, comprises a partially spherical surface element. The surface element can be at least approximately hemispherical, can be a spherical segment, a spherical sector and/or can be described as a spherical segment or spherical sector of a hollow sphere. An outer contour and an inner contour of the surface element can be partially spherical or at least approximately hemispherical. By inserting an additional element, for example, into the inner contour of the prosthetic head or onto the outer contour of the prosthetic cavity, the diameter and/or radius of the inner contour or outer contour of the hip joint prosthetic element can be varied. If the additional element is inserted into the inner contour of the prosthetic head, then the diameter of the convex inner contour of the prosthetic head is reduced by twice the thickness of the additional element and/or the radius of the inner contour of the prosthetic head is reduced by the thickness of the additional element. The additional element also can be placed on the outer contour of the prosthetic cavity, such that the diameter of the concave outer contour of the prosthetic cavity is increased by an amount corresponding to twice the thickness of the additional element.
The additional element also can be a removable element which may be removed from the hip joint prosthetic element or the inner or outer contour of the hip joint prosthetic element, wherein the diameter of the outer and/or inner contour of the hip joint prosthetic element can be varied by removing the additional element. The additional element, for example, can be removed from the inner contour of the prosthetic head, such that the diameter of the inner contour of the prosthetic head is increased by twice the thickness of the additional element which has been removed. The additional element also can be removed from the outer contour or the surface of the prosthetic cavity, such that the diameter of the outer contour of the prosthetic cavity is reduced by twice the thickness of the additional element. The additional element can exhibit various thicknesses, e.g., it can be one, three or five mm thick, or it can be up to 20 mm thick.
By inserting or removing the additional element, compensations can be made for differences in the leg length or the leg offset. Using the method described herein, a hip joint prosthetic element can be selected that may be provided with an additional element to compensate for or establish an existing, ascertained or desired difference in the leg length or leg offset.
The additional element also can be inserted into or attached to the prosthetic shaft, which can be connected to the prosthetic head, for example, or the additional element can be removed from the prosthetic shaft, wherein the length of the prosthetic shaft can be altered by removing or adding the additional element. The additional element can be placed on the prosthetic shaft or inserted into the prosthetic shaft, for example, such that adding the additional element increases the length of the prosthetic shaft by the length of the additional element, or the additional element can be removed from the prosthetic shaft, such that the length of the prosthetic shaft can be reduced by the length of the additional element. The additional element can be any length up to 20 mm, e.g., one, three, five or more mm in length.
The forgoing and other embodiments of the invention are hereinafter discussed with reference to the drawings.
The differences DF and DA, for example, can be transmitted via a wired or wireless connection from the data detection system (e.g., the cameras 16 and pointer 11) to the computational unit and/or to the navigation system 14. The data can be further processed and compared in the computational unit and/or navigation system 14 with known bone and/or cartilage contour data, such as known differences DF and DA, which can be stored in the database 15, for example, to enable selection of at least one suitable hip joint prosthetic element from the database 15. In said comparison, for example, hip joint prosthetic elements can be selected that replace, approximate or imitate the removed bone and/or cartilage material. In particular, a prosthetic cavity 19 as shown in
The computational unit and/or the navigation system 14 can select at least one hip joint prosthetic element, such as a prosthetic head 20, a prosthetic shaft 21 and/or a prosthetic cavity 19, from a number of hip joint prosthetic elements stored in the database 15, for example. The selection can be performed by comparing the detected bone and/or cartilage contour data and ascertaining the most suitable prosthetic element, such that the thickness DC of the prosthetic cavity 19 approximately corresponds to the difference DA between the old and the new contour of the hip joint cavity and/or such that the thickness DH of the prosthetic head 20 approximately corresponds to the difference DF between the old and the new contour of the femoral head. The selected hip joint prosthetic element or hip joint prosthetic elements then can be output on the display 14b, for example. Exemplary hip joint prosthetic elements are shown in
The prosthetic also can include three or more parts, such as a prosthetic cavity 19, which can be mounted in the hip joint cavity and connected to the prosthetic head 20. The prosthetic head 20 in turn can be connected to an anchoring element, such as a prosthetic shaft 21, which, for example, can be inserted and cemented into the femur 3.
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The actual code for performing the functions described herein can be easily programmed by a person having ordinary skill in the art of computer programming in any of a number of conventional programming languages based on the disclosure herein. Consequently, further detail as to the particular code itself has been omitted for sake of brevity.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
Number | Date | Country | Kind |
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04026471.5 | Nov 2004 | EP | regional |
This application claims priority of U.S. Provisional Application No. 60/645,149 filed on Jan. 19, 2005, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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60645149 | Jan 2005 | US |