Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1995-09-20
2001-05-08
Mancene, Gene (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06228088
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an intramedullary catheter. More specifically, the present invention is directed toward an improved device and method for allowing repetitive delivery or withdrawal of fluids to or from the vascular system of bone marrow through a catheter device placed within a patient's bone.
Repetitive delivery of fluid into a patient's vascular system often entails an intravenous device. When a patient requires fluid during each of numerous treatment sessions, an intravenous device must be inserted into the patient's vein. Each time the device is inserted, the physician runs the risk of missing the vein and injecting fluid outside the vein. Moreover, physicians often find it difficult to find a vein, or once they do so, numerous injections into that vein may cause its rapid deterioration. In an effort to solve the above problems, numerous devices are commercially available which comprise a catheter commonly inserted into a large vein and having a self-sealing septum through which repetitive injections can be made into the catheter. Thus, instead of repetitively placing a needle into a vein, the needle can be repetitively placed through a septum and into a port attached to a conduit placed within the vein.
Intravenous catheters represent substantial improvements in the art, however, when used over a long period of time, they can cause infection and clotting in the vein near the area where the catheter is placed into the vein. Recently, a device and method were developed for repetitively placing fluid into the vascular system via bone marrow. Such a device incorporated herein as U.S. Pat. No. 4,772,261 comprises an intramedullary catheter placed into a tapped bore within the patient's bone and into the bone marrow. This device allows placement under the skin and the closing of the skin over the device such that the portion of the catheter extending outside the bone remains hidden under the skin. Although catheters placed into a patient's bone marrow represent improvements in the art, they are often difficult to place, and once in place, are difficult to find. It is important, when placing a bone catheter, that the head or outer-most member of the catheter be large enough to be easily detectable (or palpable) by the physician so that he or she can target the injection needle into the septum of the catheter. Furthermore, it is important that once a catheter is in place, it be securely held within the bone marrow and will not cause pain during normal patient movement. It is also important that the catheter-bone interface be secure or tight enough so as not to leak fluid outside the bone and into the surrounding tissue. However, the base of the catheter must be designed or shaped not to cause necrosis of the underlying periosteum resulting in a nidus for infection. Still further, it is important that a device be provided for repetitive harvesting or withdrawing of fluid from bone marrow as well as repetitive delivery of fluid to bone marrow.
SUMMARY OF THE INVENTION
Accordingly, it is desirable to produce an improved intra-medullary catheter which can be rapidly placed and securely held in a patient's bone. The improved catheter of the present invention can either be implanted underneath the patient's skin or can reside partially above the skin in a percutaneous embodiment. If implanted, the catheter is placed within a bore made through the patient's bone and into underlying bone marrow. A physician can feel for the catheter residing underneath the patient's skin and thereby insert a needle through the skin and into the catheter for delivery or withdrawal of fluid to or from the patient's vascular system. If the device is not implanted, but is placed percutaneous, the physician can simply visually detect the head of the catheter and gain access to the vascular system above the patient's skin.
The present invention includes a conduit having threads extending along the length of the catheter from a conically shaped head to a distal end that, when placed, resides within the patient's bone marrow. The threads act to securely hold the device within bone as the patient is undergoing normal activity. The improved device is securely held in the bone with a conically shaped head extending either inside (implanted) or outside (percutaneous) the patient's skin. If implanted, the conically shaped head allows sealing engagement with the bone adjacent the bore to prevent infection from entering the bone marrow and to prevent fluid from leaking outside the bone into the surrounding tissue.
In accordance with one embodiment of the present invention, a novel device is provided which can be implanted underneath a patient's skin. The implanted device is adapted to allow repetitive passing of fluid to a patient's vascular system via bone marrow. The implanted device comprises a tubular conduit with threads extending along the length of the conduit from a head placed at one end to the tip at the other end. By drilling a bore into the bone, the threaded conduit can be screwed into the bore by rotational movement of a tool placed over the head. When fully implanted into the bone, the tip of the conduit resides within the bone marrow of the bone and the head sealingly abuts the outer surface of the bone. A seal means is provided and adapted to retain a sealing membrane on the head of the device. The seal means includes a silicon elastomer which permits repetitive insertion and withdrawal of a needle without exposing bone marrow to infection. The head is generally conically-shaped having interior walls defining a saucer-shaped cavity covered by the seal means. The cavity is of sufficient size to receive a needle tip and allow a fluid access reservoir between the needle tip and the conduit (and subsequently the bone marrow). The seal means, or port to the septum, is of sufficient size to be easily detected by the physician when placing the needle in the implanted head. Although a physician cannot see the implanted device, he or she can target the needle by feeling for the underlying head and sealing membrane. The sealing membrane is dome shaped to aid the physician in palpably detecting the target area.
In accordance with another embodiment of the present invention, there is provided a device which is only partially implanted. The head portion of the device remains outside the patient's skin in a percutaneous embodiment. The percutaneous device is similar to the implanted device in that it has threads on the outside of a conduit extending from a conically shaped head to the distal tip. However, unlike the implanted device, the percutaneous device can be inserted directly into the bone without having to first drill a bore into the bone. The percutaneous conduit having cutting threads placed along the outer surface of the conduit and a cutting tip at the distal tip of the threads. The threaded conduit is screwed into bone by rotating a tool placed over the head of the device. As the device is being screwed into the bone, cutting tip and cutting threads form a bore simultaneous with the insertion of the device. Thus, the percutaneous device can be placed directly into the bone without having to pre-drill a bore as in the implanted embodiment. Placement of the percutaneous device is therefore quickly performed to allow emergency delivery or withdrawal of fluid to or from the patient's bone marrow.
In either the implanted or percutaneous embodiments, sealing engagement is made with the bone to prevent infection from entering the bone marrow and to prevent fluid from leaking from the bore. If implanted, the conically shaped portion of the head sealingly abuts the bone surface adjacent the bore. Thus, infection is prevented from entering the bore between the head and the bone surface. Conversely, if the head is configured above the patient's skin as in the percutaneous embodiment, a butting member or protrusion sealing abuts the bone surface to prevent infection from entering the bore.
Miller Larry J.
Zamorano-Gamez Ruben
Board of Regents , The University of Texas System
Fulbright & Jaworski L.L.P.
Mancene Gene
Robert Eduardo C.
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