Self-aligning cap nut for use with a spinal rod anchor
US6443953B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 2000 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | Mar 6, 2020 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B17/7032
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A spinal implant system is provided having a stabilization rod, a plurality of bone anchors which could be either hooks or screws and which have an internal recess that defines a rod-receiving channel. Sidewalls of the anchor project beyond the recess, and are threaded on the outside. These external threads cooperate with the internal threads of a locking member, or cap nut, which has a top surface with a cavity that includes an internal hexagon. The internal threads are on the inside of the cylindrical sidewalls of the cap nut. Further, on the bottom side of the top surface, the cap nut has a guide member in the form of a cylindrical boss, which has a smaller diameter than that of the recess within the anchor. The boss helps to prevent cross threading and to prevent collapse of the anchor sidewalls under high forces. An annular ridge on the bottom of the boss further helps to retain the rod relative to the anchor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.