POLYAXIAL MECHANISM FOR USE WITH ORTHOPAEDIC IMPLANT DEVICES
 Inventors: James D. Ralph. Oakland; Steven Tatar. Montville. both of N.J.
 Assignee: Third Millennium Engineering, LLC.
 Appl. No.: 799,721
 Filed: Feb. 12,1997
 Int. Cl.6 A61B 17/70
 U.S. Cl 606/61; 606/72; 606/73;
 Field of Search 606/61,60,72.
606/73. 69. 70. 71, 76. 77. 78; 623/17
 References Cited
U.S. PATENT DOCUMENTS
5,476,464 12/1995 Metz-Stravenhagen et al 606/61
5,591,166 1/1997 Berahardtetal 606/61
5,609,594 3/1997 Enico et al 606/61
5,628,740 5/1997 Mullane 606/61
5,662,653 9/1997 Songer et al 606/61
Primary Examiner—Guy V. Tucker
Attorney, Agent, or Firm—Joseph P. Enico. Esq.
A polyaxial orthopedic device for use with rod implant apparatus includes a hook or a screw having a recess which includes a lower portion and an upper portion, the up per portion is curvate. A rod receiving head having a channel formed therein, and a central bore which is curvately tapered at the inside bottom, and equivalently curvately tapered on the exterior surface, is polyaxially seated in the upper portion of the recess while a post element is inserted down through the head into the lower portion of the recess. The upper portion of the post is widened and curvate so that it seats in the curved lower interior of the bore of the head. The insertion of a rod into the head, onto the top of the post and the subsequent application of a downward force thereon by a nut causes the assembly to lock together, independent of the polyaxial angle of the head to the post and hook, or screw. The post may be held in the recess by means of a transverse dowel positioned in a co-linear transverse hole formed in the recess or post or by sweat locking the post into the recess; the process of sweat locking meaning the insertion of the post into the recess when there is a relative temperature differential being maintained between the two elements such that the post can be inserted into the hole, and the subsequent expansion of the post and contraction of the recess sweat locks the two elements together.
10 Claims, 6 Drawing Sheets