Medical securement element with abrasive grains on thread surface

• US 4,177,524 A
• Filed: 05/10/1977
• Issued: 12/11/1979
• Est. Priority Date: 05/14/1976
• Status: Expired due to Term

• Current Assignee: Pfaudler, Inc. (GMM Pfaudler Ltd.)
• Original Assignee: Pfaudler-Werke AG
• Inventors: Scharbach, Heinz, Grell, Helmut
• Primary Examiner(s): Frinks, Ronald L.
• Application Number:
  US05/795,658
• Time in Patent Office: 945 Days
• Field of Search: 3/1.9-1.913, 128/92 C, 128/92 B, 128/92 CA, 128/92 BC, 32/10 A
• US Class Current: 606/86.00R
• CPC Class Codes: A61B 17/1655 for tapping
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61C 8/0012 characterised by the material or composition, e.g. ceramics, surface layer, metal alloy use of specific materials A61K6/00
• CPC Class Codes: A61C 8/0013 with a surface layer, coating
• CPC Class Codes: A61C 8/0022 Self-screwing A61C8/0028 takes precedence
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/3085 with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30858 Threads interrupted by grooves or sidewalls, e.g. flat sidewalls
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2310/0061 Coating made of silicon oxide or hydroxides
• CPC Class Codes: A61F 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00934 Coating made of enamel
• CPC Class Codes: A61L 27/30 Inorganic materials
• CPC Class Codes: A61L 27/32 Phosphorus-containing materials, e.g. apatite

Abstract

A medical securement element with a self-tapping screw thread is provided with biocompatible abrasive grains at the surface of the thread. The grains are preferably embedded in a layer of porcelain enamel on a metal substrate.

Claims

1. A medical securement element for engagement with a counterthread in a bone, comprising a self-tapping screw thread with biocompatible abrasive grains at the surface of the thread.

2. A securement element according to claim 1 wherein the abrasive grains comprise calcium hydroxyl apatite.

3. A securement element according to claim 1 wherein the abrasive grains comprise quartz sand.

4. A securement element according to claim 1 wherein the abrasive grains have a maximum grain size of 0.7 mm.

5. A securement element according to claim 4 wherein the abrasive grains have a grain size ranging from 0.2 to 0.4 mm.

6. A securement element according to claim 1 wherein the abrasive grains are embedded in an enamel layer.

7. A securement element according to claim 6 wherein the thread is covered with a layer comprising 20% to 60% by weight of said abrasive grains, the balance of said layer being enamel matrix.

8. A securement element according to claim 1 wherein the thread is subdivided by cut-out notches into thread segments and the thread segments in each row of segments are displaced circumferentially in relation to the thread segments of each adjacent row.

9. A securement element according to claim 8 wherein each thread segment is displaced circumferentially from thread segments in adjacent rows by one-half the distance between the midpoints of adjacent thread segments, whereby each thread segment is aligned with the cut-out notches in adjacent rows.

10. A securement element according to claim 8, having a conical thread, wherein the distance between the midpoints of adjacent thread segments increases from one thread segment to the next in the direction of increasing thread diameter.

11. A securement element according to claim 1 wherein the thread is subdivided by cut-out notches into thread segments and the ratio of the maximally stressed cross-sectional surface of each thread segment to the area enclosed by a first line along the apex of said thread segment, a second line along the apex of an axially adjacent thread segment, a third line extending through one end of said thread segment at right angles to said first line, and a fourth line extending through the other end of said thread segment at right angles to said first line is in the range from 1:

1 to 0.1;

1.