×

Apparatus for preventing screw backout in a bone plate fixation system

  • US 5,578,034 A
  • Filed: 06/07/1995
  • Issued: 11/26/1996
  • Est. Priority Date: 06/07/1995
  • Status: Expired due to Term
First Claim
Patent Images

1. A bone fixation apparatus comprising:

  • a bone fixation plate having a bottom surface adapted to engage a portion of the bone being fixated, an opposite top surface and a bore defined therethrough;

    a bone screw having an elongated shaft and an enlarged head portion engaging said bore at said top surface of said plate when said shaft extends therethrough, said shaft defining a first diameter non-threaded portion adjacent said head portion and bone engaging threads having a second larger diameter remote from said head portion; and

    an annular collar substantially surrounding said non-threaded portion of said bone screw shaft, said collar having an initial inner diameter greater than said second diameter, said collar being formed of a material such that said inner diameter shrinks in response to a change in temperature thereof to a final diameter smaller than said second diameter to thereby trap said collar between said head portion and said second diameter bone engaging threads of said bone screw.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×