Bi-fed offset pitch bone screw
AssigneeDepuy Acromed, Inc.
InventorsFrank S. Bono, Mark A. Fenton
Life of this patent
Estimating the term…
Abstract
A bone screw annd assembly are described wherein the bone screw has a dual lead thread that is provided as an offset thread. The bone screw has two leads starting less than 180.degree. apart. Because the leads start less than 180.degree. apart, the leads appear to spiral together along the shaft of the bone screw, creating a large groove and a small groove. The offset dual lead thread of the present invention provides enhanced pullout resistance by overcoming machining limitations to produce a bone screw with increased thread depth while maintaining or decreasing thread pitch. The bone screw may also be provided together with a bone plate to comprise a bone fixation assembly.
Claims23
A bone screw comprising:
- a head, a tip, and a shaft extending between the head and the tip, the shaft including a dual lead threaded section, the dual lead threaded section having a first lead and a second lead each in the form of helix, wherein the second lead starts between about 90.degree. and 150.degree. after the first lead.
A bone fixation assembly comprising:
- a bone plate having a plurality of apertures, and
- a bone screw including a head, a tip, and a shaft extending between the head and the tip along an axis,
- the shaft having a dual lead threaded section adjacent the tip, the dual lead threaded section having a dual lead thread disposed around the shaft along the axis, the dual lead thread having first lead and a second lead, wherein the second lead starts less than 180.degree. after the first lead, and the shaft having a second threaded section extending between the dual lead threaded section and the head.
A bone fixation assembly comprising:
- an implantable medical device and
- a bone screw having a head, a tip, and a shaft extending between the head and the tip, the shaft having a first section adjacent to the tip and a second section extending between the first section and the head, the first section having a dual lead thread disposed about the shaft, the dual lead thread having a first lead and a second lead, wherein the second lead starts less than 180.degree. from the first lead, and the second section is designed to engage the implantable medical device.
A bone screw comprising:
- a head, a tip, and a shaft extending between the head and the tip, the shaft including a dual lead threaded section, the dual lead threaded section having a first lead and a second lead each in the form of a helix, wherein the second lead starts about 120.degree. after the first lead.
Dependencies are inferred from the claim text.