# US 2008/0306604 A1 · Orthopaedic Device and Procedure to Realize Such a Device

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- Number: US 2008/0306604 A1
- Document ID: US20080306604A1
- Status: Published application
- Kind: A1
- Application number: 12/159,474
- Filed: 2006-12-28
- Published: 2008-12-11
- Earliest claimed: 2005-12-28
- Assignees: Alma Mater Studiorum - Università di Bologna
- Inventors: Vincenzo Parenti Castelli
- Web page: https://patentgrep.com/patent/US20080306604A1

## CPC

- A61F 2/38: for elbows or knees
- A61F 2/08: Muscles; Tendons; Ligaments
- A61F 2/3804: {for elbows}
- A61F 2/40: for shoulders
- A61F 2/4202: {for ankles}
- A61F 2002/30639: {having rolling elements between both articulating surfaces}
- A61F 2002/30934: {Special articulating surfaces}
- A61F 2002/30943: {using mathematical models}
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

An orthopaedic device (1) for the mobile connection of a first and a second bony segment (4, 5) of an organic device for cooperating with or substituting a natural articulation comprising a first working surface (9) related to the first cooperating segment (4) with a second working surface (10) related to the second bony segment (5) in order to constrain (guide) the relative motion between the said bony segments (4, 5); the first and the second working surface (9, 10) are respectively practically shaped as the axodes of the relative motion of a first and a second link of a linkage practically equivalent to the natural articulation; in particular the first and the second link are corresponding, in the linkage, to the first and the second bony segment (4, 5).

## Claims

### Claim 1

Orthopaedic device for the mobile connection of a first and a second bony segment (4, 5) of an organic apparatus for substituting or cooperating with a natural articulation (2), the said device comprising a first working surface (9) associated to the said first bony segment (4) and a second working surface (10) associated with a said second bony segment (5), the said first and second surfaces (9, 10) collaborating in order to guide the relative motion between the said bony segments (4, 5), the said device being characterized by the fact that the said first and second working surfaces (9, 10) are suitable to roll one over the other one.

### Claim 2 (depends on 1)

Device according to the claim 1, characterized by the fact that the said first and second working surfaces (9, 10) are respectively defined as portions of a first and a second ruled surface with curvilinear directrix, the said first and second ruled surface having as directrices the centrodes (σ1, σ2) of a planar or spherical motion which represents an approximation of the real spatial motion of the said natural articulation (2).

### Claim 3 (depends on 1)

Device according to the claim 1, characterized by the fact that the said first and second working surfaces (9, 10) are respectively defined as portions of a first and a second ruled surface with curvilinear directrix, the said first and second ruled surface having as directrices the centrodes (σ1, σ2) of the relative motion of a first link (4′) and a second link (5′) of a linkage (13) substantially equivalent to the said natural articulation (2), the said first and second links (4′, 5′) being in particular corresponding in the said linkage (13) to the said first and second bony segment (4, 5).

### Claim 4 (depends on 1)

Device according to claim 1, characterized by the fact to comprise connecting elements (8) operatively active between the said first working surface (9) and the said working surface (10).

### Claim 5 (depends on 4)

Device according to the claim 4, characterized by the fact that the said connecting elements (8) comprise a number of elastic elements (14, 15, 16).

### Claim 6 (depends on 4)

Device according to the claim 4, characterized by the fact that the said connecting elements (8) comprise a first and a second flexible element (14, 15), the said first flexible element (14) being associated, in a substantial correspondence with its own first extremity (14a), to a said second bony segment (5), and in a substantial correspondence with its own second extremity (14b), to the said first bony segment (4), the said second flexible element (15) being fixed in a substantial correspondence with its own first extremity (15a) to the said second bony segment (5) and in a substantial correspondence with one of its own second extremity (15b) to a said first bony segment (4).

### Claim 7 (depends on 6)

Device according to the claim 6, characterized by the fact that the said first flexible element (14) in part wraps itself about the said first working surface (9) and in part about the said second working surface (10).

### Claim 8 (depends on 6)

Device according to claim 6, characterized by the fact that the said second flexible element (15) in part wraps itself about the said first working surface (9) and in part about the said second working surface (10).

### Claim 9 (depends on 6)

Device according to claim 6, characterized by the fact that the said connecting elements (8) comprise a third associated flexible element (16), in a substantial correspondence with one of its own extremity (16a), to a said second bony segment (5), and in a substantial correspondence with its own second extremity (16b), in a substantial correspondence with its own second extremity (16a) to the said first bony segment (4).

### Claim 10 (depends on 9)

Device according to the claim 9, characterized by the fact that the said third flexible element (16) is located symmetrically with respect to the said first flexible element (14) with respect to the said second flexible element (15).

### Claim 11 (depends on 3)

Device according to claim 3, characterized by the fact that the said first and second ruled surfaces are cylindrical surfaces, the said linkage (13) being in particular a planar linkage.

### Claim 12 (depends on 3)

Device according to claim 3, characterized by the fact that the said first and second ruled surfaces are conic surfaces, the said linkage being in particular a spatial linkage for which the said first and second links move according to a spherical motion.

### Claim 13 (depends on 1)

Device according to claim 1, characterized by the fact to comprise operationally active means (17, 18, S1, S2) for the transmission of forces between the said first and second bony segment (4, 5), the said first and second working surfaces (9, 10) preferably suitable to guide the relative motion between the said first and second bony segment (4, 5).

### Claim 14 (depends on 13)

Device according to claim 13, characterized by the fact that the said means (17, 18, S1, S2) for the transmission of forces comprise a working surface (17) associated to the said first bony segment (4) and a second working surface (18) associated to the said second bony segment (5), the said first and the said second working surfaces (17, 18) being conjugate surfaces.

### Claim 15 (depends on 14)

Device according to claim 14, characterized by the fact that the conjugate profiles (S1, S2) respectively corresponding to the said first surface (17) and to the said second conjugate surface (18) between them conjugated, are obtained as a function of the said centrodes (σ1, σ2) of motion.

### Claim 16 (depends on 1)

Device according to claim 1, characterized by the fact that the said first and second bony segments (4, 5) are defined respectively, in a knee (3), by the femur (4) and the tibia (5).

### Claim 17 (depends on 1)

Device according to claim 1, characterized by the fact to define an internal prosthesis for the said natural articulation (2).

### Claim 18 (depends on 1)

Device according to claim 1, characterized by the fact to define an external prosthesis for the said natural articulation (2).

### Claim 19 (depends on 1)

Device according to claim 1, characterized by the fact to define an orthosis for the said natural articulation (2).

### Claim 20

Procedure to realize an orthopaedic device (1) for the movable connection of a first and a second bony segment (4, 5) of an organic apparatus to substitute or to cooperate with a natural articulation (2), characterized by the fact to comprise the phases of:
finding experimentally the axodes of the real spatial motion of the said articulation (2);
finding the centrodes (σ1, σ2) of a planar relative motion or the axodes of a spherical relative motion which represent an approximation of the said real spatial motion;
associating a first working surface (9), defined as a portion of a first ruled surface with a curvilinear directrix, to a said first bony segment (4);
associating a second working surface (10), defined as a portion of a second ruled surface with a curvilinear directrix, to a said second bony segment (5); the directrices of the said first and second ruled surface being the said centrodes of motion;
constraining the said first and second working surfaces (9, 10) by means of connecting elements (8) to allow the said first surface (9) and the said second surface (10) to roll one over the other.

### Claim 21

Procedure to realize an orthopaedic device (1) for the mobile connection of a first and a second bony segment (4, 5) belonging to an organic apparatus for replacing or collaborating with a natural articulation (2), characterized by the fact to comprise the phases of:
simulating the said natural articulation (2) by a linkage (13) substantially equivalent to the said natural articulation (2);
finding the centrode (σ1, σ2) of the relative motion of a first link (4′) and a second link (5′) of the said linkage (13), called first link (4′) being the corresponding of the said first bony segment (4) of the said linkage (13) and called second link (5′) being the corresponding of the said second bony segment (5) of the said linkage (13);
relating a first working surface (9), defined as a portion of a first ruled surface with a curvilinear directrix, to the said first bony segment (4);
relating a second working surface (10), defined as a portion of a second ruled surface with a curvilinear directrix, to the said second bony segment (5); the directrices of the said first and second ruled surfaces being the centrodes (σ1, σ2) of motion;
constraining the said first and second working surfaces (9, 10) by means of connecting elements (8) to allow the above said first surface (9) and the above said second surface (10) to roll one over the other.

### Claim 22 (depends on 20)

Procedure according to claim 20, characterized by the fact to comprise the phases for associating at least one first and a second loading surface (17, 18) respectively to the said first and second bony segment, the said loading surfaces (17, 18) being conjugated.

### Claim 23 (depends on 22)

Procedure according to the claim 22, characterized by the fact to comprise the phase of realizing the said first and second loading surfaces (17, 18) starting from the corresponding conjugate profiles (S1, S2).

### Claim 24 (depends on 23)

Procedure according to the claim 23, characterized by the fact to comprise the phase of determining the said conjugate profiles (S1, S2) as a function of the said centrodes (σ1, σ2) of motion.