Method and apparatus for a radiolucent and MRI compatible cranial stabilization pin
A substantially radiolucent cranial stabilization pin is adapted for use with a fixture for immobilizing a patient's head during a medical procedure. The pin includes a tip and a body, which are secured together to form the pin. The tip and body are constructed from non-ferrous, non-magnetic materials that are biocompatible. The tip and body are safe for use with, and compatible with, imaging techniques including MR imaging and CT imaging. In some examples the tip is a titanium insert and the body is molded within and around at least a portion of the tip. In some versions, the tip includes a hollow portion and one or more openings providing access to the hollow portion. The molded body flows into and around portions of the tip creating a secure pin suitable to withstand torque and axial forces observed in use.
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This application claims priority from the disclosure of U.S. Provisional Patent Application Ser. No. 61/155,701, entitled “METHOD AND APPARATUS FOR A RADIOLUCENT CRANIAL STABILIZATION PIN,” filed Feb. 26, 2009, the disclosure of which is incorporated by reference herein.
BACKGROUNDDuring some surgical operations or other procedures, a portion of the body upon which surgery is being conducted may be substantially immobilized, such as, for example, a patient's head during head or neck surgery. Such immobilization of a patient's head, for example, may be accomplished with a fixture such as a skull clamp or other fixture, as disclosed in U.S. Patent Publication No. 2006/0084900, entitled METHOD AND APPARATUS FOR ATTACHING ACCESSORIES TO A SURGICAL FIXTURE, published Apr. 20, 2006, and in U.S. patent application Ser. No. 12/437,227, METHOD AND APPARATUS FOR USING A SURGICAL FIXTURE IN AN INTRA-OPERATIVE COMPUTED TOMOGRAPHY SCANNER, filed May 7, 2009, the disclosures of which are incorporated by reference herein. Other examples of cranial stabilization systems and components include any of the DORO products of pro med instruments GmbH of Freiburg, Germany. These and other devices may be used with cranial stabilization pins, also referred to as skull pins, which may be used to securely hold a patient's head within the skull clamp or other device.
It may be desirable to use such a cranial immobilization system or technique with a surgical procedure using intra-operative computed tomography (CT) scanning or other types of imaging (e.g., MRI, PEM, X-Ray, etc.). In some circumstances, it may be desirable and convenient for components of the cranial immobilization system to be compatible with the imaging technology, e.g. MRI, and further radiolucent. For example, it may be desirable that the skull pins be substantially or completely radiolucent and safe for use with MRI, yet still provide sufficient durability in use. While many surgical accessories and immobilization fixtures exist, it is believed that no one prior to the inventors has created or used the invention described herein.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown. In the drawings, like reference numerals refer to like elements in the several views. In the drawings:
The following description of certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, versions, and advantages of the invention will become apparent to those skilled in the art from the following description, which is by way of illustration, one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the descriptions should be regarded as illustrative in nature and not restrictive.
Referring to
Distal end (104) of pin (10) of the present example comprises annular collar (108) and a conical protrusion (110). Annular collar (108) provides first surface (112) that is configured to act as a stop by contacting a portion of a pin-holding component of a skull clamp or other device. Conical protrusion (110) extends distally from body (100), tapering from larger to smaller diameter as protrusion (110) extends distally. At a distal-most end, conical protrusion (110) is associated with tip (200). Of course, distal end (104) of pin (10) may have a variety of other types of features and configurations in addition to or in lieu of having annular collar (108) and/or conical protrusion (110).
Tip (200) is largely a hollow structure comprising shaft (202) and conical protrusion (204). Shaft (202) is located along proximal end (206) of tip (200), and conical protrusion (204) is located along distal end (208) of tip (200). Conical protrusion (204) extends distally from shaft (202), tapering to a point at its distal-most end. At its proximal-most end, conical protrusion (204) includes lip (210). Lip (210) has a diameter greater than shaft (202) such that lip (210) overhangs shaft (202). Shaft (202) comprises sidewall (212), and sidewall (212) is configured with one or more openings (214). For example, as shown in
In some versions, tip (200) is constructed from a non-magnetic metal, such as titanium. During fabrication, a solid piece of titanium is milled and/or turned to create the general shape as shown in
In some versions, body (100) is constructed from a plastic by an injection molding process. Suitable plastics may include polyether-etherketone (PEEK), duroplastic, and/or other thermoplastics or thermosetting plastics, all or any of which may include glass-fiber and/or carbon-fiber reinforcement. Moreover, in some versions, body (100) and tip (200) are securely joined via the injection molding process. For example, tip (200) is positioned within the injection mold as an insert, and body (100) is molded around and within tip (200). Where such a process is used, the molten plastic flows into void space (224) of tip (200) via open end (216) of shaft (202) and openings (214) in sidewall (212). The molten plastic fills void space (224) within tip (200) and overflows to encapsulate shaft (202). The shape of the mold is such that the molten plastic continues to form body (100) in the shape as shown in
Referring to
While body (100) has been described as being constructed of plastic, and by an injection molding process, other suitable materials and methods of construction will be apparent to those of ordinary skill in the art in view the teachings herein. For example, body (100) may be fabricated by machining by turning, milling, etc. instead of injection molding. Additionally, based on the teachings herein, other ways to securely join tip (200) and body (100) will be apparent to those of ordinary skill in the art. For example, tip (200) and body (100) may be securely joined with an adhesive.
Referring to
Pin (20) comprises body (300) and tip (400). Tip (400) is largely a hollow structure comprising shaft (402), conical protrusion (404), and collar (405). Collar (405) is located along proximal end (406) of tip (400), and conical protrusion (404) is located along distal end (408) of tip (400). Shaft (402) extends between collar (405) and conical protrusion (404). Conical protrusion (404) extends distally from shaft (402), tapering to a point at its distal-most end. At its proximal-most end, conical protrusion (404) includes lip (410). Lip (410) has a diameter greater than shaft (402) such that lip (410) overhangs shaft (402). As shown in
In some versions, tip (400) is constructed from a non-magnetic metal, such as titanium. During fabrication, a solid piece of titanium is milled and/or turned to create the general shape as shown in
In some versions, body (300) is constructed from a plastic by an injection molding process. Suitable plastics may include polyether-etherketone (PEEK), duroplastic, and/or other thermoplastics or thermosetting plastics, all or any of which may include glass-fiber and/or carbon-fiber reinforcement. Moreover, in some versions, body (300) and tip (400) are securely joined via the injection molding process. For example, tip (400) is positioned within the injection mold as an insert, and body (300) is molded around and within tip (400). Where such a process is used, the molten plastic flows into void space (424) of tip (400) via open end (416) of collar (405). The molten plastic fills void space (424) within tip (400) and also surrounds shaft (402) and collar (405). The molten plastic further fills the space (426) of collar (405) between fins (420, 422). The shape of the mold is such that the molten plastic continues to form body (300) in the shape as shown in
Referring to
While body (300) has been described as being constructed of plastic, and by an injection molding process, other suitable materials of construction and processes by which to construct body (300) will be apparent to those of ordinary skill in the art in view of the teachings herein. For example, body (300) may be fabricated by machining by turning, milling, etc. instead of injection molding. Additionally, other ways to securely join tip (400) and body (300) will be apparent to those of ordinary skill in the art in view of the teachings herein. For example, tip (400) and body (300) may be securely joined with an adhesive.
Referring now to
Openings (606) of sidewall (604) provide surface area for bonding tip (600) to body (500) while reducing the mass of tip (600). As mentioned above, the reduction in mass of tip (600) minimizes the appearance of artifacts in the output of imaging scans when pin (30) is used with various imaging technologies. Openings (606) have a triangular shape as shown in
Tip (600) may be manufactured in a variety of ways. For example, fabricating tip (600) may involve metal production processes including casting, forging, flow forming, rolling, extrusion, sintering, metalworking, machining, milling, turning, bending, folding, or combinations of the above. Tip (600) may comprise a single piece or be made from a plurality of pieces securely joined together. In some versions, a single piece of material is folded and the ends of the piece joined together to form tip (600). Where a joining process is used in manufacturing tip (600), the joining processes may include welding, brazing, soldering, or combinations thereof. Still in other versions, a single piece of material is drilled to create inner cavity (602) of tip (600). Tip (600) is then milled and/or turned to create the outer cone or pointed shape. Sidewall (604) of tip (600) is then drilled or cut to create openings (606).
Body (500) comprises proximal end (502) and distal end (504). Distal end (504) is associated with tip (600) of pin (30). Proximal end (502) is associated with other cranial stabilization components. Body (500) is generally comparable to body (100) and body (300) described above. For example, body (500) incorporates annular recess (506), annular collar (508), and first surface (512) of annular collar (508) as described above with reference to body (100) and body (300). A difference between body (500) and the bodies (100, 300) described previously is that conical protrusion (510) of body (500) takes on a different shape to securely fit with tip (600) as will be described further below.
Referring now to the association of tip (600) to body (500), in some versions, body (500) and tip (600) are associated using an injection molding process. In some such versions, body (500) is formed entirely by injection molding while tip (600) is an insert to the injection mold. When molding occurs, the molded material bonds to tip (600) to produce a unitary structure. During the injection molding process, the molten material, e.g. plastic, fills inner cavity (602) of tip (600), bonding with interior surface (610) of inner cavity (602) as well as with the surface areas provided by edges (612) of openings (606) in sidewall (604) of tip (600). In such versions, sidewall (604) of tip (600) remains exposed.
In some versions, tip (600) may incorporate other features, alternatively or in addition to openings (606), to enhance bonding of tip (600) to body (500). For example, interior surface (610) of tip (600) may be configured with grooves or threads to increase the bonded surface area between body (500) and tip (600). Still in other versions, the injection molding material may encapsulate tip (600) so the final appearance of pin (30) is a single injection molded piece, although pin (30) comprises dual components of tip (600) and body (500). In such versions, the injection molding material will also bond with the outer surface, or sidewall (604), of tip (600), thereby increasing the bonded surface area. Based on the teachings herein, other techniques and features to incorporate to produce a pin having a tip that can withstand the torque and axial forces typical with a cranial stabilization procedure while having a low mass tip such that artifacts are minimal in imaging scan outputs will be apparent to those of ordinary skill in the art.
As mentioned above, another exemplary version for a skull pin, pin (40), is shown in
Referring now to
Referring now to
Referring now to
Referring now to
While above exemplary pins have been described as having a molded body bonded to a tip, other connection methods for securing a tip to a body will be apparent to those of ordinary skill in the art in view of the teachings herein. For example, body could be molded separately from tip and tip may be secured to body with a suitable fastener. In some versions, tip may snap-fit to body. In other versions tip may be screwed to body. Still in some other versions tip may be glued or chemically adhered to body. Also, any of the bodies described may be constructed by machining, e.g. milling, turning, etc., instead of or in addition to molding.
Based on the teachings herein, it will be appreciated by those of ordinary skill in the art that in any of the described examples, and examples not explicitly described but within the scope of the claims, the sizes and proportions of the tip and body may be altered. For example, the tip may be sized such that the portion of the tip extending from the body is small such that the output of an imaging scan shows a minimal artifact. Furthermore, the tip may be sized such that the portion of the tip extending from the body is generally equivalent to the portion of the tip that would penetrate the patient's skull during a stabilization procedure. In such an example, the exposed portion of the tip when not in use would be covered by bone when in use. With such a design, artifacts in the output of imaging scans may be minimized with the tip not exposed when in use.
Having shown and described various versions of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, versions, geometrics, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not required. Accordingly, the scope of the present invention should be considered in terms of whatever claims recite the invention, and is understood not to be limited to the details of structure and operation shown and described in the description.
Claims
1. A skull pin for use with a stabilizing device, wherein the pin comprises: a. a tip, wherein the tip is configured to contact a patient's skull, wherein the tip comprises a conical member, wherein the conical member comprises: i. a point at a distal end of the tip, wherein the point is configured to contact the patient's skull, ii. a substantially thin sidewall, wherein the substantially thin sidewall comprises an exterior surface and an interior surface, wherein the interior surface defines an inner cavity of the tip, iii. one or more protrusions formed in the interior surface of the sidewall, wherein the one or more protrusions comprise a threaded configuration; and b. a body, wherein the body comprises a proximal end and a distal end, wherein the proximal end of the body is dimensioned to fit in an opening of a skull clamp arm, wherein the distal end of the body is secured to the tip, wherein the distal end of the body extends within the inner cavity of the tip and contacts the one or more protrusions, wherein the body is a molded piece, wherein the tip is an insert piece and bonded to the body during molding.
2. The pin of claim 1, wherein the one or more protrusions comprise one or more ridges, wherein the one or more ridges define one or more gaps between the ridges, wherein the distal end of the body extends within the inner cavity of the tip and fills the one or more gaps defined by the ridges.
3. The device of claim 1, wherein the conical portion of the tip is substantially hollow.
4. The pin of claim 1, wherein the device is substantially radiolucent.
5. The pin of claim 1, wherein the tip is comprised of titanium and the body is comprised of plastic.
6. A skull pin for use with a stabilizing device, wherein the pin comprises: a. a tip, wherein the tip is configured to contact a patient's skull, wherein the tip comprises: i. a conical portion, ii. a point at a distal end of the conical potion, wherein the point is configured to contact the patient's skull, iii. a substantially thin sidewall, wherein the substantially thin sidewall comprises an exterior surface and an interior surface, wherein the interior surface defines an inner cavity of the tip, iii. one or more protrusions formed in the sidewall of the tip, wherein the one or more protrusions comprise a threaded configuration; and b. a body, wherein the body comprises a proximal end and a distal end, wherein the proximal end of the body is configured to be selectively retained within a skull clamp, wherein the distal end of the body is secured to the tip, wherein the distal end of the body extends within the inner cavity of the tip and contacts the one or more protrusions, wherein the body is a molded piece, wherein the tip is an insert piece and bonded to the body during molding.
7. A device for use with a head stabilizing device, wherein the device comprises a tip configured to contact a patient's skull, wherein the tip comprises: a. a point at a distal end, wherein the point is configured to contact the patient's skull; b. a sidewall, wherein the sidewall comprises an exterior surface and an interior surface, wherein the interior surface defines an inner cavity; and c. one or more protrusions formed in the sidewall, wherein the one or more protrusions comprise a threaded configuration configured to engage a body that is selectively securable to the head stabilizing device, wherein the body is a molded piece, wherein the tip is an insert piece and bonded to the body during molding.
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Type: Grant
Filed: Feb 25, 2010
Date of Patent: Dec 10, 2013
Patent Publication Number: 20100217280
Assignee: pro med instruments GmbH (Freiburg im Breisgau)
Inventors: Matthias E. Schuele (Freiburg), Matthias E. Schuele (Freiburg), Christian P. Schuele (Freiburg), Thomas C. Schuele (Munich)
Primary Examiner: Sameh Boles
Application Number: 12/712,716
International Classification: A61B 17/04 (20060101); A61B 17/84 (20060101); A61B 17/86 (20060101); A61F 2/08 (20060101);