Patent Application
20070293788
Referring to
The distal end 6 may also comprise at least one aperture 7. It is preferred that the aperture 7 be elongated to align with fenestrations within a bone marrow aspirate cannula such as that described herein. It is also preferred that the aperture 7 be shaped so as to maintain the strength of the distal end of the cannula.
In other preferred embodiments, the outer cannula 2 may comprise graduated markings 32. These markings may be laser etched. It may be convenient for the gradations to be spaced 1 cm apart to allow for depth measurement within cancellous bone and body cavity spaces.
The proximal end of the outer cannula 2 may be secured in a first handle 4. The first handle 4 may be composed of a rigid medical grade plastic or any other rigid medical grade material, such as, for example, stainless steel. Preferably, the first handle 4 has a port 10, a port being defined as an opening through which other materials or objects may pass. Port 10 preferably serves for receiving the inner cannula or other such devices as described below.
A bone harvest system 1 also comprises an inner cannula 22 having a distal end 26 that is generally semicylindrical. As used herein, semicylindrical is defined as having the shape of a longitudinal half of a cylinder. In an exemplary embodiment of the present invention, the distal ends of the inner and outer cannulas have a semicircular circumference defined by an arc greater than about 180° for retaining harvested bone 60. In certain embodiments, the distal ends of the inner and outer cannulas are defined by an arc greater than about π radians. In an exemplary embodiment of the present invention, the circumference of the semicylindrical distal ends of the inner and outer cannulas is greater than about 50% of their total circumference. In another embodiment, the circumference of the distal end of the inner cannula is greater than the circumference of the distal end of the outer cannula. Preferably, the tip 28 of the distal end 26 is generally rounded or generally convex. The tip 28 of the distal end 26 may also be generally blunt. These generally rounded, generally convex, and generally blunt distal ends minimize the risk for accidental perforation of the cortical bone boundaries. Perforation of the cortical bone boundaries could result in damage to nerves, vessels, and/or soft tissue structures.
The distal end 26 may further comprise at least one cutting surface. It is preferred that each exposed edge 36 of the distal end 26 comprises a cutting surface.
In certain embodiments, distal ends 6 and 26 comprise proximal surfaces 5 and 25, shown in, for example,
In a preferred apparatus of the present invention, the inner surface of distal end 26 may comprise a plurality of furrows 38. As used herein, furrows are defined as ruts, grooves, indentations, depressions, or trenches that can retain harvested bone material. In some embodiments, the furrows 38 are aligned normal to the longitudinal axis of the inner cannula 22. In others, the furrows are canted with respect to the transverse plane of the inner cannula 22.
Alternatively, the inner surfaces of both the inner cannula 22 and/or the outer cannula 2 may comprise a plurality of furrows 38. In some embodiments, the furrows 38 are aligned normal to the longitudinal axes of the cannulas. In others, the furrows 38 form a generally threaded pattern in the inner surfaces of the cannulas.
Cannulas 2 and 22 may be composed of any biocompatible, sterilizable material. It is preferred that the cannulas are composed of any medical grade material that has the strength and rigidity to perforate through cortical bone and navigate within the marrow space. The cannulas are preferably composed of stainless steel or rigid plastic material. The cannulas may also be composed of other metals such as medical-grade titanium.
In some embodiments of the present invention, the proximal end of the inner cannula 22 is secured in a second handle 24. The second handle 24 may be composed of a rigid medical grade plastic or any other rigid medical grade material, such as, for example, stainless steel. The second handle 24 may also have a port such as 10, a port being defined as an opening through which other materials or objects may pass.
One way of assembling a bone harvest system of the present invention is to insert inner cannula 22 into a port 10 of the first handle 4 and coaxially insert the inner cannula into the outer cannula 2. Preferably, the diameter of the inner cannula 22 is less than the diameter of the outer cannula 2. More preferably, the diameter of the inner cannula 22 is such that the inner cannula may be slidable and rotatable within the outer cannula 2. Most preferably, the diameter of the inner cannula 22 is the largest diameter possible that will allow for the inner cannula to be slidable and rotatable within the outer cannula 2.
The lengths of the inner and outer cannulas may be such that the tip 8 of the outer cannula 2 and the tip 28 of the inner cannula 22 are generally aligned when the inner cannula 22 is fully inserted into the outer cannula 2. Furthermore, the angled chamfers 9 and 29 align along their circumferences when the assembly is in an open configuration, so as to direct the volume of cancellous bone into the interior of the inner cannula.
Preferably, the first handle 4 will be seated under the second handle 24 when the bone harvest system 1 is fully assembled. In an exemplary embodiment of the present invention, the first handle 4 and second handle 24 cooperate such that the second handle may be rotated with respect to the first handle so as to cause the inner cannula 22 to rotate within the outer cannula 2. More preferably, the first handle 4 and second handle 24 cooperate such that the second handle may be rotated with respect to the first handle so as to cause the inner cannula 22 to rotate within the outer cannula 2, resulting in the distal ends of the cannulas to substantially enclose a volume.
In some embodiments, the first and second handle may comprise mechanical means for locking the handles in a fixed position so as to prevent undesired movement of the inner cannula within the outer cannula when in an open assemble for insertion into cancellous bone. One mechanical means for locking, shown in
It is preferred that when the handles are in a locked position, the distal ends of the cannulas are in an “open” position, wherein the distal ends generally overlap (see
In some embodiments, the first and second handle may further comprise mechanical means for restricting rotation of the inner cannula when assembled in the outer cannula. These mechanical means may comprise any device, such as a tab or catch, such that a rotation of greater than approximately 180° from the locked position is prevented. For example, such mechanical means may comprise tabs 17 and 15, shown in
Referring to
The proximal end of the fenestrated cannula 52 may be secured in a third handle 54. The third handle 54 may be composed of a rigid medical grade plastic or any other rigid medical grade material, such as, for example, stainless steel. A standardized Luer 40 is inset within the third handle 54 to allow attachment of a surgical syringe for bone marrow aspiration.
In one method of using the system of the present invention, the cannulas of the assembled system 1 are aligned such that the distal ends of the cannulas generally overlap in an “open” position (
In one method of accessing the cancellous bone space, a cortical drilling device is used to create a hole within the cortex of a bone. Cortical drilling devices are known in the art, per se, and are not a part of the present invention. Once the hole is created, the cortical drilling device is removed and an assembled system 1, wherein the system is in an “open” position, is inserted into the cortical hole.
In preferred methods of inserting the device assembly 1 into the cancellous bone space, a bone marrow aspiration needle assembly comprising an outer cannula and a needle stylet, such as that described in pending U.S. patent application Ser. No. 11/223,085, assigned to the assignee of the present invention, filed on Sep. 9, 2005 and incorporated herein by reference in its entirety, may be used to access the cancellous bone space. Other devices known in the art may also be used. The needle assembly can be used to pierce the cortical wall at the site where bone and bone marrow is to be harvested. After piercing the cortical wall, the needle stylet is withdrawn from the outer cannula. Preferably, a guide wire, for example a Kirschner wire, is inserted through the outer cannula into the cancellous space. The outer cannula is withdrawn and a second cannula is advanced over the guide wire until contact with the distal cortical shell is made. Preferably, the proximal end of the second cannula has an outer diameter greater than the outer diameter of the outer cannula. More preferably, the proximal end of the second cannula has an outer diameter substantially greater than the outer diameter of the outer cannula. In preferred embodiments, the distal end of the second cannula is tapered, such that the outer diameter is substantially equal to the outer diameter of the outer cannula, allowing the distal end of the second cannula to be inserted into the opening in the cortical bone created by the needle assembly. A trephine, or similar instrument, is then advanced over the second cannula to the site where the bone and bone marrow is to be harvested. The trephine is used to create a hole in the cortex of the bone using techniques known in the art. Preferably, with the guide wire in place, the trephine and second cannula are withdrawn and the assembled device of the present invention (1) is advanced over the guide wire and inserted into the pre-formed cortical hole.
Preferably, the entire length of the distal ends of the cannulas is submerged within the cancellous bone. The graduated markings 32 may assist in determining the depth of the system into the cortical hole. The generally blunt, generally rounded, or generally convex ends of the cannulas deflect off of dense, cortical bone walls which surround the softer cancellous bone regions, thus re-directing the assembly within the cancellous bone space. This minimizes the risk for accidental perforation of the cortical bone boundaries, which could result in damage to nerves, vessels, or soft tissue structures.
The mechanical means for locking may be released to unlock the handles, consequently unlocking the distal ends of the cannulas. In some embodiments, pin 12 may be removed from aperture 14 to unlock the handles. The second handle 24 can be rotated around the first handle 4 to cause the inner cannula 22 to rotate within the outer cannula 2 so as to encapsulate a volume of cancellous bone 60 within the distal ends of the cannulas. The cutting surfaces on the distal end of the inner cannula and the rotation of the inner cannula within the outer cannula severs the bone. Angled chamfers 9 and 29 direct the volume of cancellous bone into the interior of the inner cannula. Furrows 38 aid in retaining harvested bone 60 within the cannulas. Preferably, the second handle 24 is rotated approximately 180° relative to the first handle 4 to encapsulate and retrieve a bone sample. In some embodiments, mechanical means such as, for example, 15 and 17, may be used to restrict rotation of the inner cannula when assembled in the outer cannula. In this configuration, the assembly is in a substantially closed configuration to encapsulate a volume of cancellous bone.
The inner cannula 22 may be slidably removed from the outer cannula 2 using the second handle 24. The furrows 38 prevent the volume of cancellous bone 60 from being prematurely dislodged from the inner cannula 22. Once the inner cannula has been removed from the outer cannula, the volume of cancellous bone may be expelled from the inner cannula by tapping the distal end of the inner cannula over a basin 70. Alternatively, the volume of cancellous bone may be expelled by insertion of a plunging device, for example, plunger 50, through a port of the second handle, and into the inner cannula. (See
In certain embodiments, once a sample of cancellous bone has been harvested, the inner cannula 22 may be re-inserted into outer cannula 2 and the handles locked such that the distal ends of the cannulas are in the open position. The cannulas can be moved as a unit further into the bone to harvest additional cancellous bone samples, using the methods as previously described. These procedures can be repeated as necessary, until sufficient quantities of material have been removed.
Turning to
Thus, there have been described presently preferred embodiments of devices and kits for harvesting bone and bone marrow. While the present invention has been particularly shown and described with reference to the presently preferred embodiments thereof, it is understood that the invention is not limited to the embodiments specifically disclosed herein. Numerous changes and modifications may be made to the preferred embodiments of the invention, and such changes and modifications may be made without departing from the spirit of the invention. It is therefore intended that the appended claims cover all such equivalent variations as they fall within the true spirit and scope of the invention.
