Medical substituting element for hard tissues and artificial joint

• US 5,879,389 A
• Filed: 04/01/1996
• Issued: 03/09/1999
• Est. Priority Date: 04/07/1995
• Status: Expired due to Term

• Current Assignee: Tomihisa Koshino
• Original Assignee: Tomihisa Koshino
• Inventors: Koshino, Tomihisa
• Primary Examiner(s): Milano, Michael J.
• Application Number:
  US08/625,899
• Time in Patent Office: 1,072 Days
• Field of Search: 623/17, 623/20, 411/271, 411/352, 411/353, 411/379, 411/380, 411/381, 411/382, 411/109
• US Class Current: 623/20.11
• CPC Class Codes: A61B 17/8042 the additional component being a cover over the screw head
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone
• CPC Class Codes: A61B 17/8695 Washers surrounding screw head in plate hole A61B17/8047, between bone plate and bone A61B17/8028
• CPC Class Codes: A61B 2017/8655 with special features for locking in the bone
• CPC Class Codes: A61F 2/30721 Accessories
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30326 differing in height or in length
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30484 Mechanically expandable devices located on the first prosthetic part for locking into or onto the second prosthetic part
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30708 Means for distinguishing between left-sided and right-sided devices, Sets comprising both left-sided and right-sided prosthetic parts
• CPC Class Codes: A61F 2002/30774 internally-threaded
• CPC Class Codes: A61F 2002/3079 Stepped or enlarged apertures, e.g. having discrete diameter changes
• CPC Class Codes: A61F 2002/30795 : Blind bores, e.g. of circular cross-section
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/3895 : unicompartimental
• CPC Class Codes: A61F 2002/4631 : the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2002/4638 : Tools for performing screwing, e.g. nut or screwdrivers, or particular adaptations therefor
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2250/0037 : differing in height or in length
• CPC Class Codes: A61F 2250/0084 : Means for distinguishing between left-sided and right-sided devices; Sets comprising both left-sided and right-sided prosthetic parts
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00329 : Glasses, e.g. bioglass

Abstract

The invention solves a problem associated with a conventional medical substituting element for hard tissues that loosening is likely to occur after the substituting element is mounted on hard tissues, by providing the medical substituting element for hard tissues with: one or a plurality of through hole units into which fixation screws are inserted; a screw stopper for stopping the fixation screw inserted into the through hole unit at the position where the head of the fixation screw becomes lower than the upper end of the through hole unit; and a slip-off prevention member engaging unit formed in the inner wall of the through hole unit at the position higher than the screw stopper, wherein after the fixation screw inserted into the through hole unit is threaded into the hard tissues, a slip-off prevention member engages with the slip-prevention member engaging unit to ensure a slip-off prevention of the fixation screw.

Claims

1. A medical substituting element for hard tissues comprising;

one or a plurality of through hole units into which fixation screws are inserted;

a screw stopper for stopping said fixation screw inserted into said through hole unit at a position where a head of said fixation screw becomes lower than an upper end of said through hole unit;

a female thread portion formed in an inner wall of said through hole unit at a position higher than said screw stopper; and

a screw adapted for threaded engagement with said female thread;

wherein after said fixation screw inserted into said through hole unit is threaded into hard tissues, said screw is threaded into said female thread portion to ensure a slip-off prevention of said fixation screw;

and further wherein said has a threading direction opposite to that of said fixation screw.

2. A medical substituting element for hard tissues according to claim 1, wherein said female thread portion is so formed that when said screw as said slip-off prevention member is meshed with said female thread portion as said, slip-off prevention member engaging unit, the head of said, screw is substantially flush with, or lower than, the upper end of said through hole unit.

3. An artificial joint having a first constituent member mounted on a ground surface formed on one bone constituting a joint and a second constituent member mounted on a ground surface formed on the other bone constituting the joint, said first and second constituent members abutting against each other directly or via a slide member, or being coupled together by a member with an open/close mechanism, wherein

said first or second constituent member comprises;

one or a plurality of through hole units into which fixation screws are inserted;

a screw stopper for stopping said fixation screw inserted into said through hole unit at the position where the head of said fixation screw becomes lower than the upper end of said through hole unit; and

a female thread portion formed in an inner wall of said through hole unit at a position higher than said screw stopper; and

a screw adapted for threaded engagement with said female thread;

wherein after said fixation screw inserted into said through hole unit is threaded into hard tissues, said screw is threaded into said female thread portion to ensure a slip-off prevention of said fixation screw;

and further wherein said screw has a threading direction opposite to that of said fixation screw.

4. An artificial joint according to claim 3, wherein said female thread portion is so formed that when said screw as said slip-off prevention member is meshed with said female thread portion as said slip-off prevention member engaging unit, the head of said screw is substantially flush with, or lower than, the upper end of said through hole unit.

5. An artificial joint having a first constituent member mounted on a ground surface formed on one bone constituting a joint and a second constituent member mounted on a ground surface formed on the other bone constituting the joint, said first and second constituent members abutting against each other directly or via a slide member, or being coupled together by a member with an open/close mechanism, wherein

said first or second constituent member comprises:

one or a plurality of through hole units into which fixation screws are inserted;

a screw stopper for stopping said fixation screw inserted into said through hole unit at the position where the head of said fixation screw becomes lower than the upper end of said through hole unit; and

a slip-off prevention member engaging unit formed in the inner wall of said through hole unit at the position higher than said screw stopper; and

a slip-off prevention member;

wherein after said fixation screw inserted into said through hole unit is threaded into hard tissues said slip-off prevention member is engaged with said slip-off prevention member engaging unit to ensure slip-off prevention of said fixation screw, and further

wherein said slip-off prevention member engaging unit is a ring groove formed in the inner circumference of said inner wall of said through hole unit, and said slip-off prevention member is a stopper ring.

6. An artificial joint having a first constituent member mounted on a ground surface formed on one bone constituting a joint and a second constituent member mounted on a ground surface formed on the other bone constituting the joint, said first and second constituent members abutting against each other directly or via a slide member, or being coupled together by a member with an open/close mechanism, wherein

said first or second constituent member comprises:

one or a plurality of through hole units into which fixation screws are inserted;

a screw stopper for stopping said fixation screw inserted into said through hole unit at the position where the head of said fixation screw becomes lower than the upper end of said through hole unit; and

a slip-off prevention member engaging unit formed in the inner wall of said through hole unit at the position higher than said screw stopper,

wherein after said fixation screw inserted into said through hole unit is threaded into hard tissues, a slip-off prevention member engages with said slip-off prevention member engaging unit to ensure a slip-off prevention of said fixation screw;

and further wherein said slip-off prevent member engaging unit is a ring groove formed in the inner circumference of the inner wall of said through hole unit or a recess formed in the inner wall of said through hole unit, and said slip-off prevention member is a caulking projection formed on the head of said fixation screw.