# US 5,702,471 A · Finger joint

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- Number: US 5,702,471 A
- Document ID: US5702471A
- Status: Granted
- Kind: A
- Application number: 08/617,231
- Filed: 1996-03-18
- Granted: 1997-12-30
- Earliest claimed: 1995-04-06
- Assignees: Eska Medical GmbH & Co.
- Inventors: Hans Grundei; Jurgen Rudigier; Christian Weber
- Web page: https://patentgrep.com/patent/US5702471A

## CPC

- A61F 2/4241: {for hands, e.g. fingers}
- A61F 2/30907: {Nets or sleeves applied to surface of prostheses or in cement}
- A61F 2/30767: {Special external or bone-contacting surface, e.g. coating for improving bone ingrowth}
- A61F 2002/30235: {tubular, e.g. sleeves}
- A61F 2002/30332: {Conically- or frustoconically-shaped protrusion and recess}
- A61F 2002/30354: {Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis}
- A61F 2002/3037: {Translation along the common longitudinal axis, e.g. piston}
- A61F 2002/30405: {made by screwing complementary threads machined on the parts themselves}
- A61F 2002/3055: {for adjusting length}
- A61F 2002/30589: {Sealing means}
- A61F 2002/30593: {hollow}
- A61F 2002/30594: {slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots}
- A61F 2002/30601: {telescopic}
- A61F 2002/30604: {modular}
- A61F 2002/30624: {Hinged joint, e.g. with transverse axle restricting the movement}
- A61F 2002/30632: {with rotation-limiting stops, e.g. projections or recesses}
- A61F 2002/30662: {with rotation-limiting means}
- A61F 2002/30777: {Oblong apertures}
- A61F 2002/30878: {with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts}
- A61F 2002/30909: {Nets}
- A61F 2002/30912: {made of expanded metal, e.g. diamond mesh or metal nets having lozenge-shaped apertures}
- A61F 2002/30934: {Special articulating surfaces}
- A61F 2002/4243: {for interphalangeal joints, i.e. IP joints}
- A61F 2002/4251: {for metacarpo-phalangeal joints, i.e. MCP or MP joints, e.g. knuckle joints}
- A61F 2220/0025: Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F 2220/0033: made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
- A61F 2230/0069: cylindrical
- A61F 2310/00011: Metals or alloys
- Y10T 403/32573: Ball stud passes through confining opening
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A finger joint has first and second hollow anchorage shafts (2, 3) which can be implanted in finger tubular bones with a hinge joint (4) arranged between them. The first hollow shaft (2) can be connected with a ball cage (5) of the hinge joint (4) in which a spherical part (6) is mounted, on which a protruding stem (7) is formed. This stem (7) passes through the ball cage (5), and indeed through a slit (8) provided therefor in the wall of the ball cage (5). The slit (8) in the ball cage (5) widens continuously from the point (P) at which the stem (7) passes through the ball cage (5) in the extended position of the joint (4) to the point (M) at which the stem (7) passes through the ball cage (5) in the flexed position of the joint. In this manner, additional play is allowed to the joint in the flexed position, which largely corresponds to the physiological coordinated movement of a finger joint.

## Claims

### Claim 1

A prosthetic finger joint (1) comprising a first and a second hollow anchorage shaft (2, 3) configured to be implanted in tubular finger bones, and a hinge joint (4) in a form of a ball-and-socket joint arranged between the shafts (2,3), the first hollow shaft (2) being connected with a ball cage (5) of the hinge joint (4), a spherical part (6) provided with a protruding stem (7) being mounted in the ball cage, the stem (7) passing through a slit (8) in the ball cage (5) and connecting with the second hollow shaft (3), the slit (8) in the ball cage (5) continuously widening from a point (P) at which the stem (7) passes through the ball cage (5) in an extended position of the joint (4) to a point (M) at which the stem (7) passes through the ball cage (5) in a flexed position of the joint (4).

### Claim 2 (depends on 1)

The prosthetic finger joint according to claim 1, wherein the ball cage (5) itself is a sphere, and the slit (8) penetrates through a wall of the spherical ball cage (5) on part of a meridian from a pole (P) up to approximately the equator.

### Claim 3 (depends on 1)

The prosthetic finger joint according to claim 1, wherein the spherical part (6) is constructed as one piece with the stem (7) and is provided with a polyethylene coating (9).

### Claim 4 (depends on 1)

The prosthetic finger joint according to claim 1, wherein a pole cap (10) of at least a diameter of the spherical part (6) is provided, whereby the pole cap (10) can be screwed onto the ball cage (5) as a cover to complete a spherical outer configuration of the ball cage (5).

### Claim 5 (depends on 1)

The prosthetic finger joint according to claim 1, wherein the stem (7) extends into a sliding sleeve (11) which is connected with the second hollow shaft (3) in such a way that the stem (7) can slide lengthwise to execute longitudinal compensatory movements in the sleeve (11).

### Claim 6 (depends on 5)

The prosthetic finger joint according to claim 5, wherein the sliding sleeve (11) comprises polyethylene.

### Claim 7 (depends on 5)

The prosthetic finger joint according to claim 5, wherein the sliding sleeve (11) has a collar (12) on its end facing the ball cage (5), the collar (12) lying on an exterior of the ball cage in an assembled stage of the joint.

### Claim 8 (depends on 7)

The prosthetic finger joint according to claim 7, wherein the collar (12) is constructed as a partial spherical segment corresponding to a spherical surface of the ball cage (5).