A BONE FIXTURE FOR AN IMAGE GUIDED SURGERY
Publication Date: 2004-Dec-29
The IP.com Prior Art Database
In an embodiment, a bone fixture 100 for an image guided surgery comprises at least a pair of anti-rotation sleeves 12 configured insertable through a bone 10, at least a pair of screw rods 14 configured individually insertable into the sleeves 12, and a connecting member 16 configured to clamp the ends of the sleeves 12 and the screw rods 14.
FIELD OF THE INVENTION
 This invention relates generally to fixtures, and more particularly, to percutaneous bone fixtures for an image guided surgery.
BACKGROUND OF THE INVENTION
 Typically, in an image guided surgery, a reference frame is attached percutaneously to an anatomy e.g. a bone being operated upon. For example, this reference frame may be a field transmitter in an electromagnetic tracking system or an array of LEDs in an optical tracking system.
 A known device for attaching a reference frame to a bone includes an anti-rotation sleeve comprising a plurality of teeth at one end. The sleeve is configured insertable through a soft tissue such that the toothed end abuts the bone. During fixing, a bone screw is inserted through the sleeve and into the bone. The screw is tightened, causing that the sleeve to press the bone such that the teeth engage the surface of the bone. However, this device does not provide an anti-rotation device that would sufficiently hold the bone in desired stationary position.
 Another known device for fixing a reference frame to a bone comprises a spaced apart pair of thin threaded rods (typically with bone screw threads on one end) that are configured insertable into a bone, and a connector bar that is configured to rigidly clamp both the rods. Although this device exhibits rigid clamping property, there exists a likelihood of significant rotation of the connector bar.
 For example, If the threaded rods are able to rotate in the bone, then a torque applied to the connector bar around an axis parallel to the long axis of the threaded rods can cause both rods to rotate (in the same direction) at their interface with the bone. This rotation coupled with the flexibility of the rods, may allow the connector rod to rotate in response to the torque. However, the movement of the connecting bar and hence repositioning of the reference frame are undesirable and may lead to large errors during an image guided procedure.
 Thus, there exists a need in the art to have a fixture that has a significant anti-rotation property for rigidly fixing the reference frame to the bone.
SUMMARY OF THE INVENTION
 In an embodiment, a bone fixture for an image guided surgery comprises at least a pair of anti-rotation sleeves configured insertable through a bone, at least a pair of screw rods configured ind...