Bicentric polyaxial locking screw and coupling element
US5647873A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1995 |
| Grant date | Jul 15, 1997 |
| Priority date | — |
| Expiry date | Nov 13, 2015 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61F2310/00023
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A polyaxial orthopedic device for use with rod implant apparatus includes a screw having a curvate head, a bicentric locking shell disposed therearound, and a coupling element having a curvate tapered socket into which both the screw and the shell nest. The bicentric shell is slotted and has a semi-spherical interior volume into which the screw head is initially polyaxially held. The coupling element has an axial bore through which the screw and shell may be inserted, and a curvate bottom having a smaller radius of curvature than the shell, which provides a radially inward force on the locking shell when forced thereinto. This radially inward force causes the shell to crush lock against the head of the screw, therein locking the two at the instant angulation. In an initial disposition, however, the screw and the shell head remain polyaxially free with respect to each other, and to the coupling element. The coupling element also includes a transverse channel in which a rod may be disposed. In a first embodiment the channel is formed between a pair of upwardly extending members, and in a second embodiment, the channel is formed in the side of the element. In either case, a rod which …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.