1. Field of the Invention
This invention pertains generally to generating passageways through tissue, and more particularly to creating curved paths in bone.
2. Description of Related Art
Recently, the technique of accessing the vertebral body through minimally invasive means has been developed through the surgical techniques used in vertebroplasty and kyphoplasty. Although accessing the vertebral segments of the spine through the pedicle and into the lateral/anterior section of the body of the vertebra is the primary method of placing a treatment device (e.g. a bone cement delivery device and/or an RF probe) into the vertebra, it is difficult to place a probe in the posterior midline section of the vertebra. Furthermore, accessing the posterior midline section of the S1 segment of the spine is difficult with a straight linear access route. A probe preferably needs to be capable of navigating to the posterior section of the S1 vertebral body as well as the same target area within a lumbar vertebral segment. In addition, it is contemplated that spinal segments in the cervical and thoracic spine may also be targeted.
In order to accurately and predictably place a treatment device in the posterior midline section of a lumbar vertebral body or S1 vertebral body, the device or probe needs to navigate to said area through varying densities of bone. However due to the varying densities of bone, it is difficult to navigate a probe in bone and ensure its positioning will be in the posterior midline section of the vertebral body.
Current techniques for tissue aspirations require a coaxial needle system that allows taking several aspirates through a guide needle without repositioning the guide needle. However the problem with this system is that after the first pass of the inner needle in to the lesion, subsequent passes tend of follow the same path within the mass, yielding only blood not diagnostic cells.
A scientific paper written by Kopecky et al., entitled “Side-Exiting Coaxial Needle for Aspiration Biopsy,” describes the use of a side exiting coaxial needle to allow for several aspiration biopsies. The guide needle has a side hole 1 cm from the distal tip. When a smaller needle is advanced through this new guide needle, the smaller needle is deflected by a ramp inside the guide, causing the smaller needle to exit through the side hole. Although this side exiting needle is able to deflect a bone aspiration needle, it does not guarantee that the needle exits the side hole in a linear direction into the tissue site. Once the tissue aspiration needle exits the needle, it will deviate from a linear path depending on the density of the tissue and inherent material strength of the needle. This is an inherent problem the device is unable to overcome.
Accordingly, an object of the present invention is a system and method for generating a path in bone that predictably follows a predetermined curved path.