Plastic double nut mechanism enabling rigid orthopedic distraction
US5968043A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1998 |
| Grant date | Oct 19, 1999 |
| Priority date | — |
| Expiry date | Feb 10, 2018 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B17/66
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A distraction apparatus for an external fixation device used to rigidly immobilize bone fragments during bone lengthening and angular deformity correction includes distractor mechanisms and pivotable spacers for connecting frame members of an external fixator, and wire and half pin fasteners. The interconnected distractor mechanisms, pivotable spacers and frame members form a rigid structure with rigidity which is maintained during adjustment of the distraction. For linear distraction, the distraction mechanism is a single screw assembly with a single-threaded rod and dual plastic nuts disposed either side of a metallic adjustment surface. After tightening down, the nuts may be synchronously co-rotated, advantageously using a tool such as a double wrench engaging on aligned faces of the nuts. This synchronous co-rotation causes linear displacement along the threaded rod, thereby enabling distraction. Further, the metal-to-plastic inter-face between the nuts and the adjustment surface facilitates this synchronous co-rotating without causing loosening of the nuts, thereby minimizing the introduction of play in the mechanism during distraction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.