# US 5,702,479 A · Shaft component for a joint endoprosthesis

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- Number: US 5,702,479 A
- Document ID: US5702479A
- Status: Granted
- Kind: A
- Application number: 08/318,866
- Filed: 1995-03-20
- Granted: 1997-12-30
- Earliest claimed: 1993-02-18
- Inventors: Peter Schawalder
- Web page: https://patentgrep.com/patent/US5702479A

## CPC

- A61F 2/3609: {Femoral heads or necks; Connections of endoprosthetic heads or necks to endoprosthetic femoral shafts (A61F2/3601 takes precedence)}
- A61F 2/36: Femoral heads {; Femoral endoprostheses}
- A61B 17/8695: {Washers (surrounding screw head in plate hole A61B17/8047, between bone plate and bone A61B17/8028)}
- A61F 2/30767: {Special external or bone-contacting surface, e.g. coating for improving bone ingrowth}
- A61F 2/30771: {applied in original prostheses, e.g. holes or grooves}
- A61F 2/3607: {including proximal or total replacement of the femur}
- A61F 2/367: {Proximal or metaphyseal parts of shafts (trochanteric devices connected to said proximal parts A61F2/30739)}
- A61F 2/3672: {Intermediate parts of shafts}
- A61F 2/3676: {Distal or diaphyseal parts of shafts}
- A61F 2/38: for elbows or knees
- A61F 2002/30233: {Stepped cylinders, i.e. having discrete diameter changes}
- A61F 2002/30235: {tubular, e.g. sleeves}
- A61F 2002/30426: {Bayonet coupling}
- A61F 2002/30433: {using additional screws, bolts, dowels, rivets or washers e.g. connecting screws}
- A61F 2002/30494: {Cooperating protrusions and recesses, e.g. radial serrations, located on abutting end surfaces of a longitudinal connection}
- A61F 2002/305: {Snap connection}
- A61F 2002/3054: {about a connection axis or implantation axis for selecting any one of a plurality of radial orientations between two modular parts, e.g. Morse taper connections, at discrete positions, angular positions or continuous positions}
- A61F 2002/30593: {hollow}
- A61F 2002/30785: {parallel}
- A61F 2002/30787: {inclined obliquely with respect to each other}
- A61F 2002/30789: {perpendicular with respect to each other}
- A61F 2002/3085: {with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface}
- A61F 2002/3631: {with an integral complete or partial peripheral collar or bearing shoulder at its base}
- A61F 2002/368: {with lateral apertures, bores, holes or openings, e.g. for reducing the mass, for receiving fixation screws or for communicating with the inside of a hollow shaft}
- A61F 2002/369: {Stepped shaft, i.e. having discrete diameter changes}
- A61F 2002/3694: {with longitudinal bores}
- A61F 2220/0025: Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F 2220/0041: using additional screws, bolts, dowels or rivets, e.g. connecting screws
- A61F 2230/0069: cylindrical
- 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)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

The shank unit of a joint endoprosthesis to be implanted in a tubular bone has a hollow, cylindrical, rotationally symmetrical anchoring sub-assembly (2) with a longitudinal axis (1) and an articulating sub-assembly (3). The articulating subassembly (3) is separate and detachably fixed to the anchoring sub-assembly (2). The articulating sub-assembly (3) comprises a rotationally symmetrical base element (31), an axis of rotation (32) and a neck extension (33) mounted eccentrically relative to the base element (31) and subtending an angle .alpha. of 70.degree. to the axis of rotation (32) to receive a joint ball (36). The base element of the articulating sub-assembly (3) can be mounted on the anchoring sub-assembly (2) in such a way that its axis of rotation (32) coincides with the longitudinal axis (1) and be detachably fixed to sub-assembly (2) at any angular position relative to the longitudinal axis (1), as a result of which the radial direction of the neck extension (33) is selectively variable to adjust the anterior torsion relative to the anchoring sub-assembly (2).

## Claims

### Claim 1

A shank unit for an endo joint prosthesis to be implanted in a tubular bone and comprising
a hollow, cylindrical anchoring sub-assembly (2) having a longitudinal axis (1) and being substantially rotationally symmetrical,
said anchoring sub-assembly comprising a plurality of coaxial, hollow cylindrical segments enlarging toward an upper end of said sub-assembly, said segments having perforated outer surfaces;
an articulating sub-assembly (3) detachably connectable to said upper end of said anchoring sub-assembly (2), said articulating sub-assembly including
a substantially rotationally symmetrical base element (31),
an axis of rotation (32), and
a neck extension (33) mounted eccentrically on said base element and subtending an angle of less than 90.degree. with said axis of rotation (32) for receiving a joint ball (36);
said base element of said articulating sub-assembly being detachably mountable on said on said anchoring sub-assembly (2) with the axes of said anchoring and articulated sub-assemblies coincident and with said articulated subassembly in any selected rotational angular position relative to said anchoring subassembly such that a radial position of said neck extension can be selected to adjust anterior torsion to a desired level.

### Claim 2 (depends on 1)

A shank unit according to claim 1 and including a screw (4) for detachably mounting said articulating sub-assembly to said articulating sub-assembly.

### Claim 3 (depends on 2)

A shank unit according to claim 2 wherein said anchoring sub-assembly includes exterior threads whereby said sub-assembly is self-tapping into the bone.

### Claim 4 (depends on 2)

A shank unit according to claim 2 wherein said anchoring sub-assembly includes a central, axial borehole having an inner thread of substantially constant diameter for receiving said screw.

### Claim 5 (depends on 2)

A shank unit according to claim 2 wherein said base element (31) comprises a central borehole having an enlarged portion to receive a head of said screw.

### Claim 6 (depends on 1)

A shank unit according to claim 1 wherein said upper end of said anchoring sub-assembly comprises an upper serrated surface lying in a plane substantially perpendicular to said longitudinal axis, and wherein said base element comprises a lower serrated surface to engage said upper serrated surface.

### Claim 7 (depends on 6)

A shank unit according to claim 6 wherein serrations of said upper and lower surfaces have the same angular spacings as each other.

### Claim 8 (depends on 1)

A shank unit according to claim 1 and further comprising a second base element between said first-mentioned base element of said articulating sub-assembly and said upper end of said anchoring sub-assembly, said second base element being substantially rotationally symmetrical about an axis of rotation and having upper and lower structured surfaces, said upper end of said anchoring sub-assembly and a lower surface of said first base element comprising surfaces structured to mate with said second base element.

### Claim 9 (depends on 8)

A shank unit according to claim 8 and further comprising a cylindrical case segment (53) eccentrically mounted on said second base element, and wherein said mating structured surfaces are serrated.

### Claim 10 (depends on 1)

A shank unit according to claim 1 wherein said neck extension subtends an angle of between 60.degree. and 80.degree. with said axis of rotation.

### Claim 11 (depends on 10)

A shank unit according to claim 10 wherein said neck extension subtends an angle of between 65.degree. and 75.degree. with said axis of rotation.

### Claim 12 (depends on 1)

A shank unit according to claim 1 wherein a lower end of said anchoring sub-assembly comprises a borehole having an internal thread for receiving an additional prosthesis or fastener.