Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 C.F.R. ยง 1.57.
The present invention relates to a shoulder prosthesis component for a patient. The invention also relates to a method for producing a shoulder prosthesis component for a patient.
In a healthy human shoulder, the head of the humerus, which is generally ball-shaped, and the glenoid cavity of the scapula articulate with each other and form a ball-and-socket joint. Total shoulder arthroplasty is a common treatment for shoulder pain resulting from arthritis or injury and leads to replace the ball-and-socket joint by a shoulder orthopedic prosthesis.
Such a shoulder prosthesis generally includes both a glenoid component to be fixedly implanted on the glenoid of the scapula and a humeral component to be fixedly implanted on the humerus, the glenoid component and the humeral component being provided to articulate directly with each other.
Over the last few years, it is proposed to design the humeral and glenoid components specifically to the patient to be treated. For this purpose, images of the humerus and of the glenoid are first acquired and the side of the humeral or glenoid component, intended to be applied directly on the humerus or glenoid is then designed to match accurate bone anatomy of the humerus or glenoid of the patient: in other words, the aforesaid side of the shoulder prosthesis component is the negative image of the humerus or glenoid. In that way, the shoulder prosthesis component is implanted without removing bone material from the humerus or glenoid, which enables to optimize preservation of the osseous capital for the patient in question. However, the geometrical congruence between the shoulder prosthesis component and the humerus or glenoid may lead to devitalize at least some parts of the bone material covered by the component because of insufficient mechanical stress on these parts. In other words, this technique based on the negative image of the humerus or glenoid may induce osteolysis for the humerus or glenoid. Besides, some securement problems may also occur when the bone material that is complementary covered by the component has a poor quality.
One of the goals of the invention is to propose an improved shoulder prosthesis component for a patient, which in particular is lifelong and stable on the humerus or glenoid after implantation.
To this end, one object of the invention is a shoulder prosthesis component for a patient, comprising an implantation body, which defines an implantation axis and which is designed to be received within a bone of the patient that includes a cortical bone external layer and a cancellous bone internal layer, and to compact therein the cancellous bone internal layer in a planned manner that is differentiated along and around the implantation axis depending on preoperative local bone density and quantity of the cancellous bone internal layer.
Another object of the invention is a method for producing a shoulder prosthesis component for a patient, especially for producing the shoulder prosthesis component as defined above, this method comprising:
a data providing step, in which a bone of the patient that includes a cortical bone external layer and a cancellous bone internal layer is characterized by patient bone data representative of preoperative local bone density and quantity of the cancellous bone internal layer,
a design step, in which an implantation body of the shoulder prosthesis component to be produced is designed from the patient bone data so that the bone as prosthesized with the shoulder prosthesis component to be produced receives inwardly the implantation body and has its cancellous bone internal layer that is compacted in a planned manner that is differentiated along and around an implantation axis of the implantation body depending on preoperative local bone density and quantity of the cancellous bone internal layer, and
a manufacturing step, in which the implantation body designed at the design step is manufactured.
After implantation of the shoulder prosthesis component according to the invention on a bone of a patient, especially on a humerus or a glenoid of the patient, the cancellous bone internal layer of this bone is compacted within the bone by the implantation body of the component in a manner that is differentiated along and around a longitudinal axis of the bone. Furthermore, the manner according to which the cancellous bone internal layer is compacted is planned in function of preoperative local bone density and quantity of the cancellous bone internal layer. In that way, the implantation body of the component according to the invention is designed to compact, in other words is designed to deform the cancellous bone internal layer so as to produce a predicted result for the compaction of the bone material in the bone when the component is inserted into this bone. Thanks to the invention, an appropriate mechanical stress having a predetermined value that is both non zero and not too high can be applied by the implantation body of the component on the bone material in the bone, being noted that the predetermined value of this mechanical stress may be differentiated along and/or around the longitudinal axis of the bone according to the aforesaid planned manner: this mechanical stress stimulates the bone material in the bone and thus avoids any devitalization or even osteolysis. Furthermore, even if the cancellous bone internal layer has a poor quality, the invention enables to take this into account for designing the implantation body of the component, especially by adjusting the localization and amount of the compression performed by the implantation body, and thus to avoid any lack of securement for the implantation body into the bone.
According to additional advantageous features for the shoulder prosthesis component according to the invention:
The implantation body includes a peripheral part that is shaped and structured to compact the cancellous bone internal layer in said planned manner.
The peripheral part is also shaped and structured to be deformed while compacting the cancellous bone internal layer in said planned manner.
The peripheral part comprises a porous structure which has a porosity that is varied along and around the implantation axis depending on preoperative local bone density and quantity of the cancellous bone internal layer.
The implantation body further includes a central core that is more rigid than the peripheral part.
The peripheral part comprises an elastic shell, which is supported by the central core by means of spacers and which has a deformation capability that is varied along and around the implantation axis depending on preoperative local bone density and quantity of the cancellous bone internal layer.
The peripheral part comprises:
The shoulder prosthesis component further comprises an articulation member, which is provided with an articulation surface and which is provided to be coupled with the implantation body.
The shoulder prosthesis component is a humeral component, the implantation body being designed for the humerus of the patient.
The shoulder prosthesis component is a glenoid component, the implantation body being designed for the glenoid of the patient.
According to additional advantageous features for the producing method according to the invention:
The design step includes:
The data providing step includes performing a CT scan of the bone and segmenting CT images of the CT scan into the patient bone data.
The manufacturing step includes using an additive manufacturing process.
The method further comprises coupling the implantation body manufactured at the manufacturing step with an articulation member of the shoulder prosthesis component, the articulation member being provided with an articulation surface.
Embodiments of the invention will be better understood from reading the description which will follow, which is given solely by way of example and with reference to the drawings, in which:
The
an external bone layer H1 that is made of hard bone and that corresponds to a cortical bone layer, and
an internal bone layer H2 that is made of soft bone and that corresponds to a cancellous or spongious bone layer.
The cortical bone external layer H1 forms an outer sleeve for the humerus H, especially for the diaphyseal and metaphyseal parts of the humerus, and is internally covered by the cancellous bone internal layer H2 which in turn internally defines a free volume that corresponds to a medullary canal of the humerus H. It is important to note that the accurate shape of the cortical bone external layer H1 and the accurate shape of the cancellous bone internal layer H2 are specific to the patient to be treated. In particular, the cancellous bone internal layer H2 has bone density and quantity which vary both along and around a longitudinal axis of the humerus H, the corresponding local variations of bone density and quantity of the cancellous bone internal layer H2 being specific to the patient in question. For example, the cancellous internal bone layer H2 may include a first portion, which is located both at a first level along the longitudinal axis of the humerus H and at a first angle around this longitudinal axis and which has a bone density and a bone quantity, i.e. a bone thickness, that are different from the bone density and thickness of a second portion of the cancellous bone internal layer H2, which is located both at a second level along the longitudinal axis of the humerus and at a second angle around this longitudinal axis, the second level being different from the first level and/or the second angle being different from the first angle, it being understood that the first and second levels and the first and second angles have any respective values depending on the patient.
In view of producing a humeral component to be implanted at the humerus H of the patient in question, the local bone density and quantity of the cancellous bone internal layer H2 of the humerus H are quantified, especially for the diaphyseal part and for the metaphyseal part of the humerus. As the head of the humerus H is intended to be at least partly removed during surgery, the bone anatomy of this head has not be characterized, which explains why the head of the humerus H is drawn only in dotted lines in
In some embodiments, these patient bone data result from segmenting CT images of a CT scan performed on the humerus H. As indicated above, an example of such a CT image is shown in
In some embodiments, other imaging techniques may be used as an alternative or supplement to a CT scan in order to provide the aforesaid patient bone data. For example, X-ray images and/or MRI images may be performed on the humerus H and analyzed, typically by computer, in order to provide the aforesaid patient bone data. In any case, these data are preoperative, that is to say representative of the bone anatomy of the humerus H of the patient before this humerus is surgically treated in view of receiving a humeral component.
Also before surgically treating the humerus H, the aforesaid patient bone data are used to design an implantation body of a humeral component that is to be produced and intended to be implanted at the humerus during a future surgery. As explained later in reference to the
In practice, one possibility is to use rules to design this implantation body, these rules being based on the patient bone data and relating preoperative local bone density and quantity of the cancellous bone internal layer H2 to a desired compacted condition for this cancellous bone internal layer of the humerus H as prosthesized with the humeral component to be produced. The particulars of such rules are not limitative. For example, one of these rules is to plan that a portion of the cancellous bone internal layer H2, having a low density and a high thickness has to be compacted with a high rate of compaction, for example around 50%. Another rule may be to plan that a portion of this cancellous internal bone layer H2, having a low bone density and a small thickness has to be compacted with a low rate of compaction, for example less than 50%, such as around 25%. Other rules may be contemplated. Besides, instead of using rules with compaction rates, the rules may be with compaction values.
Other possibilities for operating the design of the implantation body on the basis of the aforesaid patient bone data may be considered. More generally, it is important to understand that the implantation body is designed to apply stresses on the cancellous bone internal layer H2 and thus to deform and compact this layer H2 so as to produce a predicted result for the compaction of the various portions of that bone material in the humerus H when in the future this implantation body is inserted into the humerus. In some embodiments, designing the implantation body provides to design a peripheral part of this implantation body so that this peripheral part is shaped and structured in order to compact the cancellous internal bone layer H2 in the aforesaid planned manner. In some embodiments, the compaction effect provided by such a peripheral part of the implantation body may also take into account the fact that this peripheral part is deformed while compacting the cancellous bone internal layer H2 in the aforesaid planned manner, the implantation body being designed so that its peripheral part is shaped and structured accordingly.
Once the design of the implantation body of the humeral component to be produced is established, a following step is to manufacture this designed implantation body. The manufacturing techniques which can be used are not limitative. In some embodiments, an additive manufacturing process may be used.
Turning now to
The humeral component 10 comprises an implantation body 11 that is designed as described above. The implantation body 11 defines an implantation axis X11 intended to be aligned with the longitudinal axis of the humerus H upon implantation of the humeral component 10 at the humerus H. As discussed above in connection with designing an implantation body on the basis of the aforesaid patient bone data representative of preoperative local bone density and quantity of the cancellous bone internal layer H2, the implantation body 11 of the humeral component 10 is designed to be received within the humerus H and to compact therein the cancellous bone internal layer H2 in a planned manner that is differentiated along and around the implantation axis X11 depending on preoperative local bone density and quantity of this cancellous bone internal layer H2: as shown in
In some embodiments as the one shown in
In some embodiments as the one shown in
Turing now to
The humeral component 20 comprises an implantation body 21 and an articulation head 24, which are functionally similar to the implantation body 11 and the articulation head 14 of the humeral component 10 respectively. The implantation body 21 defines an implantation axis X21 that is similar to the implantation axis X11 for the implantation body 12 of the humeral component 10. Moreover, the implantation body 21 includes a peripheral part 22 and a central core 23, which are functionally similar to the peripheral part 12 and the central core 13 of the implantation body 11 respectively.
The peripheral part 22 of the implantation body 21 is distinguished by its structure, in the sense that the peripheral part 22 comprises or even consists of an elastic shell 22A and spacers 22B that mechanically connect the elastic shell 22A to the central core 23. The elastic shell 22A has a deformation capability that is varied along and around the implantation axis X21 depending on preoperative local bone density and quantity of the cancellous bone internal layer H2 of the humerus H. Upon implantation of the implantation body 21 in the humerus H, the elastic shell 22A applies on the cancellous bone internal layer H2 stresses resulting at least from the elastic material, the shape and the thickness of the elastic shell 22A and from the action of the spacers 22B on the elastic shell 22A, so that the peripheral part 22 can compact this layer H2 with a predicted compaction rate and/or value that is varied along and around the implantation axis X21 in accordance with the aforesaid planned manner with which the various portions of this layer H2 are desired to be compacted, as explained previously.
In practice, the peripheral part 22 may be manufactured by additive manufacturing processes.
Turning now to
The humeral component 30 comprises an implantation body 31 and an articulation head 34, which are functionally similar to the implantation body 11 and the articulation head 14 of the humeral component 10 respectively. The implantation body 31 defines an implantation axis X31 that is similar to the implantation axis X11 for the implantation body 12 of the humeral component 10. Moreover, the implantation body 31 includes a peripheral part 32 and a central core 33, which are functionally similar to the peripheral part 12 and the central core 13 of the implantation body 11 respectively.
The peripheral part 32 is distinguished by its structure, in the sense that the peripheral part 32 comprises or even consists in an intermediate, soft undercoat 32A, which covers the central core 33, and an external, frangible coating 32B, which overlays the undercoat 32. Both undercoat 32A and coating 32B have a shape adaptability, that is to say that they can each adapt their shape upon implantation of the humeral component 30, the shape adaptability for each of the undercoat 32A and the coating 32B being varied along and around the implantation axis X31 depending on preoperative local bone density and quantity of the cancellous bone internal layer H2. However, these two shape adaptabilities are implemented by two different basic mechanisms: the undercoat 32A is conformable by elastic deformation whereas the coating 32B is conformable by surface breaking, on the understanding that the material of the coating 32B is bioabsorbable so that the detached particles from the coating 32B are absorbed by the tissues of the patient. This bioabsorbable material may be ceramic type and is for example a mixture of hydroxyapatite and tricalciumphosphate, or any brittle biological bone substitute. Thanks to the respective shape adaptability of the undercoat 32A and of the coating 32B, the peripheral part 32 of the implantation body 31 applies on the cancellous bone internal layer H2 some predetermined stresses upon implantation of the implantation body 31 in the humerus H, so that this peripheral part 32 can compact this layer H2 with a predicted compaction rate and/or value that is varied along and around the implantation axis X31 in accordance with the aforesaid planned manner with which the various portions of this layer H2 are desired to be compacted as explained previously.
All of the above considerations relevant to the humerus of a patient and to producing a humeral component for this humerus are applicable to the glenoid of a patient and to produce a glenoid component for this glenoid. For example,
As for the implantation bodies 11, 21 and 31 of the humeral components 10, 20 and 30, the implantation body 41 may include a peripheral part 42 that is intended to be in contact with the cancellous bone internal layer G2, being able to apply stresses on this layer G2 by compacting the latter with a predicted compaction rate and/or value that is varied along and around the implantation axis X41 in accordance with the aforesaid planned manner with which the various portions of the layer G2 are desired to be compacted. Various embodiments for the implantation body 41 and for its peripheral part 42 may be considered. In
In the embodiment of
The embodiment shown in
Number | Date | Country | Kind |
---|---|---|---|
17306747.1 | Dec 2017 | EP | regional |