Patent Application
20090222011
The present invention relates generally to the field of surgery and medical implants, and more particularly, to surgical tools and methods for use in positioning an intervertebral device between vertebral members of a patient.
The human spine is a biomechanical structure with thirty-three vertebral members, and is responsible for protecting the spinal cord, nerve roots and internal organs of the thorax and abdomen. The spine also provides structure support for the body while permitting flexibility of motion. A significant portion of the population will experience back pain at some point in their lives resulting from a spinal condition. The pain may range from general discomfort to disabling pain that immobilizes the individual. Back pain may result from a trauma to the spine, be caused by the natural aging process, or may be the result of a degenerative disease or condition.
Procedures to remedy back problems sometimes require correcting the distance between vertebral members by inserting an intervertebral device (e.g., spacer) between the members. The spacer, which is carefully positioned within the disc space and aligned relative to the vertebral members, is sized to position the vertebral members in a manner to alleviate the patient's back pain.
Further, the intervertebral device is preferably designed to facilitate insertion into a patient. That is, the shape and size of the device are designed to provide for minimal intrusion to a patient during insertion, but still be effective post-insertion to alleviate the pain and provide maximum mobility to the patient.
Major blood vessels are located at an anterior aspect of the spine and often the intervertebral device is designed to be inserted in the spinal cavity at the mid-line of the spine from an anterior aspect. Such an approach requires particular care relative to the blood vessels and/or other sensitive objects located at the spine mid-line when approaching the spinal cavity from the anterior direction.
Thus, a need exists for instruments and methods for inserting an intervertebral device into a spinal cavity which minimizes the opportunities for injuring blood vessels and/or other sensitive bodies in the vicinity of a mid-line of a spine.
The present invention provides, in an aspect, a targeting surgical instrument for use in spinal disc replacement which includes a first arm, a second arm, and a body portion. The first arm is configured to be longitudinally aligned with a mid-line of a spine and to be at least partially received on an endplate of a lower vertebra of spinal cavity. The spinal cavity is defined by the lower vertebra and upper vertebra of the spinal cavity. The second arm is positioned at an angle relative to the first arm. The second arm defines an insertion angle. The body portion connects the first arm and the second arm. The body portion includes a plurality of radiopaque markers, which may be located to allow alignment of the first arm on the mid-line of the spine.
The present invention provides, in another aspect, a method for use in spinal disc replacement which includes aligning a first arm of a targeting instrument with a mid-line of a spine and placing the first arm on an endplate of a lower vertebra of a spinal cavity. The spinal cavity is defined by the lower vertebra and an upper vertebra of the spinal cavity. The targeting instrument includes a second arm aligned at an angle relative to the first arm and a body portion connecting the first arm and the second arm. The second arm defines an insertion angle for a spinal implant. The body portion includes a plurality of radiopaque markers, which may be located to allow alignment of the first arm on the mid-line of the spine.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings in which:
In accordance with the principles of the present invention, a targeting surgical instrument for use in spinal disc replacement, and methods for use in implanting a prosthetic disc in a spinal cavity, are provided.
As depicted in
Tool 10 includes a first arm 200 and a second arm 300, which may be separated from, and positioned at an angle 320 relative to, each other. Angle 320 may be an acute angle, for example, an angle between about 10 degrees and about 45 degrees, such as about 35 degrees. First arm 200 and second arm 300 may be connected at a connecting body 250. Connecting body 250 may be rounded except for portions of an outer radial portion where first arm 200 and second arm 300 intersect connecting body 250 as depicted in
After a disc (not shown) has been removed from a spine of a patient to form spinal cavity 120, first arm 200 may be aligned with a mid-line 310 of a spine or endplate (e.g., endplate 110) thereof as depicted in
Mid-line 310 of the spine may be identified intra-operatively using an anterior-posterior X-ray image. Mid-line pin 130 then may be attached (e.g, via impaction) to an outer surface 105 of lower vertebra 100. Also, a lateral X-ray image may be taken of the spinal cavity with tool 10 inserted therein (i.e., after first arm 200 is attached to mid-line pin 130). The lateral X-ray image may allow markers 260 and probe 270 to be visible relative to the remainder of tool 10. Thus, a distal extent of probe 270 may be adjusted by the user (e.g., a surgeon) such that probe 270 extends to, or near, a distal end 103 of endplate 100 without extending past such distal end. Markers 260 may be aligned such that an imaginary line connecting them is substantially orthogonal to mid-line 310 of the spinal column and contained in the plane defined by the two arms of the tool 10. More particularly, the markers may be aligned with one another (i.e., one behind the other) when viewed via the lateral X-ray image of the spinal cavity with tool 10 inserted therein. Such alignment may thereby locate longitudinal axis 225 of first arm 200 on mid-line 310 of the spine.
In another example, probe 270 may include a hook 280 extending distally from connecting body 250 and being curved to a position substantially orthogonal to a longitudinal axis of first arm 200 as depicted in
After longitudinal axis 225 of first arm 200 is aligned on the mid-line 310 of the spinal column, as depicted in
The channels may be aligned relative to a longitudinal axis of first arm 200 and therefore the mid-line 310 of the spine such that a central rotation point of an implant is located at the mid-line 310 of the spine, and at a location defined by radial center 255 of contacting body 250 of tool 10, when the implant is inserted in spinal cavity 120 with top and bottom protruding portions (not shown) of the implant being received in the channels (not shown) previously cut and a leading edge of the implant reaches the posterior wall (e.g., a radial end or edge of endplate 110) of the vertebra. As noted above, the insertion of the implant along the direction defined by targeting pin 400 and second arm 300 allows the implant and the tools used to facilitate the preparation of spinal cavity 120 for the implant to avoid contacting and/or damaging sensitive blood vessels 600 (
As will be understood by one skilled in the art, a surgical targeting instrument (e.g., tool 10) could be formed of a variety of materials and formed in a variety of shapes which are configured to be received in a spinal cavity and be aligned with a mid-line of a spine and provide an arm at an off set angle relative to the mid-line of the spine, which may provide a entry angle for a variety of surgical instruments which avoid contacting blood vessels 600 (
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
