US20020099386A1 — Locking mechanism for a bone screw

Claim 1

Independent Claim 96 words

1 . A locking mechanism for a bone screw, comprising: a clamping element for stabilizing bone segments, having at least two snap catches protruding from a bone-contacting surface of said clamping element and spaced around an edge of a screw hole of the clamping element; and a bone screw having a circumferential groove located on a top portion thereof below a screw head, for receipt of said snap catches; wherein said snap catches interlock with said groove to secure said bone screw to said clamping element when said bone screw is inserted into said clamping element.

Claim 2

Dependent Claim 96 words

1 . A locking mechanism for a bone screw, comprising: a clamping element for stabilizing bone segments, having at least two snap catches protruding from a bone-contacting surface of said clamping element and spaced around an edge of a screw hole of the clamping element; and a bone screw having a circumferential groove located on a top portion thereof below a screw head, for receipt of said snap catches; wherein said snap catches interlock with said groove to secure said bone screw to said clamping element when said bone screw is inserted into said clamping element.

Claim 3

Dependent Claim 23 words

2 . A locking mechanism in accordance with claim 1 , wherein: said snap catches comprise spikes adapted to act as bone anchors.

Claim 4

Dependent Claim 37 words

3 . A locking mechanism in accordance with claim 2 , wherein: said spikes comprise elastic spring elements; and said elastic spring elements snap into said groove when said bone screw is inserted into said clamping element.

Claim 5

Dependent Claim 29 words

4 . A locking mechanism in accordance with claim 1 , wherein said bone screw is removable from said clamping element after said snap catches interlock with said groove.

Claim 6

Dependent Claim 37 words

5 . A locking mechanism in accordance with claim 4 , wherein a greater axial force is needed to remove said screw from said clamping element than is needed to insert said screw into said clamping element.

Claim 7

Dependent Claim 36 words

6 . A locking mechanism in accordance with claim 4 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i) said snap catches, or (ii) said groove.

Claim 8

Dependent Claim 29 words

7 . A locking mechanism in accordance with claim 1 , wherein: said screw comprises a shaft having a conical portion between said groove and threads of said shaft.

Claim 9

Dependent Claim 42 words

8 . A locking mechanism in accordance with claim 1 , wherein: said groove has a flat edge portion perpendicular to a shaft of said screw; and said snap catches have a square end portion for interlocking with said flat edge portion.

Claim 10

Dependent Claim 46 words

9 . A locking mechanism in accordance with claim 8 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i) said square end portion of said snap catches, or (ii) said flat edge portion of said groove.

Claim 11

Dependent Claim 39 words

10 . A locking mechanism in accordance with claim 1 , wherein: a targeting instrument is placed on said clamping element; and said screw is screwed through said clamping element and into said bone segment via said targeting instrument.

Claim 12

Dependent Claim 31 words

11 . A locking mechanism in accordance with claim 1 , wherein: said screw is a cannulated screw; and said screw is positioned on the bone segment via a Kirschner wire.

Claim 13

Dependent Claim 36 words

12 . A locking mechanism in accordance with claim 1 , wherein: said screw is rotatable after interlocking with said clamping element in order to achieve further pre-stress between said bone segment and said clamping element.

Claim 14

Dependent Claim 26 words

13 . A locking mechanism in accordance with claim 1 , wherein: said screw is a cannulated screw having internal threads in a cannulated portion thereof.

Claim 15

Dependent Claim 93 words

14 . A locking mechanism in accordance with claim 13 , wherein: said screw is removable from said clamping element using a removal device having (i) an externally threaded distal end for engagement with said internal threads of said cannulated portion of said screw, and (ii) a handle at a proximal end; said removal device is adapted to be inserted into said screw via a cannulated screwdriver; and removal of said screw is possible by unscrewing said screw from said bone segment using said cannulated screwdriver while simultaneously pulling on said removal device.

Claim 16

Dependent Claim 58 words

15 . A removal device for revision of an internally threaded cannulated bone screw, comprising: a wire body having threads at a distal end thereof for engagement with said corresponding threads of said screw; and a handle at a proximal end of the wire body for use in pulling the removal device after engagement with the cannulated screw.

Claim 17

Dependent Claim 58 words

15 . A removal device for revision of an internally threaded cannulated bone screw, comprising: a wire body having threads at a distal end thereof for engagement with said corresponding threads of said screw; and a handle at a proximal end of the wire body for use in pulling the removal device after engagement with the cannulated screw.

Claim 18

Dependent Claim 23 words

16 . A removal device in accordance with claim 15 , wherein: said removal device is adapted for insertion into a cannulated instrument.

Claim 19

Dependent Claim 23 words

17 . A removal device in accordance with claim 15 , wherein: said removal device is adapted for insertion into a cannulated screwdriver.

Claim 20

Dependent Claim 31 words

18 . A removal device in accordance with claim 15 , wherein the threads of the wire body are external threads and the corresponding threads of said screw are internal threads.

Claim 21

Dependent Claim 80 words

19 . A method for revision of an implanted cannulated bone screw, comprising the steps of: inserting a cannulated screwdriver into a screw head of said cannulated bone screw; introducing a removal device into said cannulated screwdriver; screwing a threaded distal end of said removal device into a corresponding threaded portion of said cannulated screw; and simultaneously unscrewing said screw using said cannulated screwdriver and pulling said screw using a handle located on a proximal end of said removal device.

Claim 22

Dependent Claim 80 words

19 . A method for revision of an implanted cannulated bone screw, comprising the steps of: inserting a cannulated screwdriver into a screw head of said cannulated bone screw; introducing a removal device into said cannulated screwdriver; screwing a threaded distal end of said removal device into a corresponding threaded portion of said cannulated screw; and simultaneously unscrewing said screw using said cannulated screwdriver and pulling said screw using a handle located on a proximal end of said removal device.

Claim 23

Dependent Claim 34 words

20 . A method in accordance with claim 19 , wherein the distal end of said removal device is externally threaded and the corresponding threaded portion of said screw is an internally threaded portion.

Claim 24

Dependent Claim 34 words

21 . A method in accordance with claim 19 , wherein: said bone screw secures a clamping element to a bone segment; and a locking mechanism secures said bone screw to said clamping element.

Claim 25

Dependent Claim 95 words

22 . A method in accordance with claim 21 , wherein said locking mechanism comprises: at least two snap catches protruding from a bone-contacting surface of said clamping element and spaced around an edge of a screw hole; and a circumferential groove located on a top portion of said screw below a screw head for receipt of said snap catches; wherein said snap catches interlock with said groove to secure said bone screw to said clamping element when said bone screw is screwed into said bone segment through said screw hole of said clamping element.

Claim 26

Dependent Claim 22 words

23 . A method in accordance with claim 22 , wherein: said snap catches comprise spikes adapted to function as bone anchors.

Claim 27

Dependent Claim 36 words

24 . A method in accordance with claim 23 , wherein: said spikes comprise elastic spring elements; and said elastic spring elements snap into said groove when said bone screw is inserted into said clamping element.

Claim 28

Dependent Claim 36 words

25 . A method in accordance with claim 22 , wherein a greater axial force is needed to remove said screw from said clamping element than is needed to insert said screw into said clamping element.

Claim 29

Dependent Claim 35 words

26 . A method in accordance with claim 22 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i) said snap catches, or (ii) said groove.

Claim 30

Dependent Claim 28 words

27 . A method in accordance with claim 22 , wherein: said screw comprises a shaft having a conical portion between said groove and threads of said shaft.

Claim 31

Dependent Claim 41 words

28 . A method in accordance with claim 22 , wherein: said groove has a flat edge portion perpendicular to a shaft of said screw; and said snap catches have a square end portion for interlocking with said flat edge portion.

Claim 32

Dependent Claim 44 words

29 . A method in accordance with claim 28 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i)said square end portion of said snap catches, or (ii) said flat edge portion of said groove.

Claim 33

Dependent Claim 35 words

30 . A method in accordance with claim 22 , wherein: said screw is rotatable after interlocking with said clamping element in order to achieve further pre-stress between said bone segment and said clamping element.

Claim 34

Dependent Claim 107 words

31 . A method for locking a bone screw to a clamping element, comprising the steps of: providing a clamping element for stabilizing bone segments, having at least two snap catches protruding from a bone-contacting surface of said clamping element and spaced around an edge of a screw hole; providing a bone screw having a circumferential groove located on a top portion thereof below a screw head, for receipt of said snap catches; and screwing said bone screw into said bone segment through said screw hole of said clamping element until the snap catches interlock with the groove to secure said bone screw to said clamping element.

Claim 35

Dependent Claim 107 words

31 . A method for locking a bone screw to a clamping element, comprising the steps of: providing a clamping element for stabilizing bone segments, having at least two snap catches protruding from a bone-contacting surface of said clamping element and spaced around an edge of a screw hole; providing a bone screw having a circumferential groove located on a top portion thereof below a screw head, for receipt of said snap catches; and screwing said bone screw into said bone segment through said screw hole of said clamping element until the snap catches interlock with the groove to secure said bone screw to said clamping element.

Claim 36

Dependent Claim 22 words

32 . A method in accordance with claim 31 , wherein: said snap catches comprise spikes adapted to function as bone anchors.

Claim 37

Dependent Claim 36 words

33 . A method in accordance with claim 32 , wherein: said spikes comprise elastic spring elements; and said elastic spring elements snap into said groove when said bone screw is inserted into said clamping element.

Claim 38

Dependent Claim 28 words

34 . A method in accordance with claim 31 , wherein said bone screw is removable from said clamping element after said snap catches interlock with said groove.

Claim 39

Dependent Claim 36 words

35 . A method in accordance with claim 34 , wherein a greater axial force is needed to remove said screw from said clamping element than is needed to insert said screw into said clamping element.

Claim 40

Dependent Claim 35 words

36 . A method in accordance with claim 34 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i) said snap catches, or (ii) said groove.

Claim 41

Dependent Claim 28 words

37 . A method in accordance with claim 31 , wherein: said screw comprises a shaft having a conical portion between said groove and threads of said shaft.

Claim 42

Dependent Claim 41 words

38 . A method in accordance with claim 31 , wherein: said groove has a flat edge portion perpendicular to a shaft of said screw; and said snap catches have a square end portion for interlocking with said flat edge portion.

Claim 43

Dependent Claim 44 words

39 . A method in accordance with claim 38 , wherein: removal of said screw from said clamping element results in deformation of at least one of (i)said square end portion of said snap catches, or (ii) said flat edge portion of said groove.

Claim 44

Dependent Claim 38 words

40 . A method in accordance with claim 31 , wherein: a targeting instrument is placed on said clamping element; and said screw is screwed through said clamping element and into said bone segment via said targeting instrument.

Claim 45

Dependent Claim 30 words

41 . A method in accordance with claim 31 , wherein: said screw is a cannulated screw; and said screw is positioned on the bone segment via a Kirschner wire.

Claim 46

Dependent Claim 35 words

42 . A method in accordance with claim 31 , wherein: said screw is rotatable after interlocking with said clamping element in order to achieve further pre-stress between said bone segment and said clamping element.

Claim 47

Dependent Claim 25 words

43 . A method in accordance with claim 31 , wherein: said screw is a cannulated screw having internal threads in a cannulated portion thereof.

Locking mechanism for a bone screw

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