Patent Publication Number: US-2003225437-A1

Title: Device for retaining material

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority to U.S. Provisional Patent Application Serial No. 60/370,531, filed Apr. 4, 2002 and entitled “A Device for Retaining Material”, which is hereby incorporated by reference. 
    
    
     
       TECHNICAL FIELD  
       [0002] The present invention relates generally to surgical tools and more particularly to a stopple useful for retaining material within hollow needle/push rod assemblies.  
       BACKGROUND AND SUMMARY OF THE INVENTION  
       [0003] Radiation therapy has been useful for treating individuals afflicted with cancer since the early 20 th  century. Brachytherapy is an advanced form of radiation treatment that is used for treating prostate cancer. Typically, radioactive seeds or sources are placed within or near a tumor, giving a high radiation dose to the tumor while reducing the dose to surrounding healthy tissues in the body.  
       [0004] Hollow needle/push rod assemblies have become increasingly popular surgical tools for the delivery of seeds to tumors during Brachytherapy. Typically, the radioactive seeds are loaded into the hollow needle&#39;s cylindrical cavity, adjacent the push rod. The seeds are often interspersed between synthetic absorbable spacers. The spacers are of the same size and shape as the seeds, both typically being cylindrical with rounded ends. Once loaded, the needle/push road assembly is inserted into the tumor by a surgeon and the seeds are implanted by retracting the needle over the push rod, thereby ejecting the seeds from the hollow needle into the tumor. Alternatively, the seeds and spacers may be preloaded into a synthetic absorbable carrier, which is useful for retaining the seeds and spacers in a predefined location within living tissue. The carrier is then implanted in a tumor using a hollow needle/rod assembly as described above.  
       [0005] The use of hollow/needle push rod assemblies requires that the needle tip be unsealed so that the seeds can be easily loaded into the needle cavity. Furthermore, the seeds and spacers are designed to easily travel within the needle cavity so that they can be deployed quickly and efficiently into the desired tissue. Thus, the seeds and spacers are prone to being inadvertently ejected from the hollow needle tip during operation of the needle assembly. This poses a health risk to both the patient and others in proximity to surgical procedure, any one of whom might accidentally be exposed to radiation emitted by inadvertently ejected seeds. Therefore, it is desirable to improve the safety of Brachytherapy by preventing undesired seed ejection.  
       SUMMARY OF THE INVENTION  
       [0006] A stopple is provided for retaining material within a hollow needle/push rod assembly. The stopple is typically composed of a synthetic absorbable material and is configured to fit snugly within the hollow needle of the needle/push rod assembly. The stopple is typically circular in shape, having a diameter that is substantially similar to the inner diameter of the hollow needle. The stopple is further configured to prevent inadvertent ejection of material stored in the hollow needle/push rod assembly. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is an enlarged cross-sectional view of a circular stopple, shown adjacent to a Brachytherapy element, according to one embodiment of the present invention.  
     [0008]FIG. 2 is a partial cross-sectional view of a hollow needle/push rod assembly including seeds, spacers and a stopple located at the distal end of the needle, according one embodiment of the present invention.  
     [0009]FIG. 3 is a cross-sectional view of a carrier housing radioactive seeds, spacers, and a stopple, according to one embodiment of the present invention.  
     [0010]FIG. 4 is a partial cross-sectional view of a hollow needle/push rod assembly including the carrier shown in FIG. 3, according to one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0011] Referring initially to FIG. 1, one embodiment of a stopple useful for retaining material within a hollow needle/push rod assembly is generally shown at  10 . The stopple has a body  10  that is typically circular in shape, having a diameter  12  that is greater than diameter  14  of Brachytherapy element  16 . Body  10  is also referred to herein as the stopple. Brachytherapy element  16  is typically a radioactive seed or synthetic absorbable spacer useful in the treatment of prostate cancer. Typically, diameter  12  is approximately 0.1 mm to 100 mm, and is preferably 0.2 mm.  
     [0012] Stopple  10  is typically composed of at least One synthetic organic material such polylactic acid and/or its derivatives. In a preferred embodiment of the present invention, the composition of stopple  10  includes approximately 5-100% polyglycolic acid and 5-95% lactide. In a particularly preferred embodiment of the present invention, stopple  10  is composed of 90% polyglycolic acid and 10% lactide. In another preferred embodiment, stopple  10  is composed of 100% polyglycolic acid. In yet another preferred embodiment, stopple  10  is composed of 100% polydioxanone. Stopple  10  is typically manufactured in the same manner as the synthetic absorbable spacer described above using methods well known in the art.  
     [0013] Referring next to FIG. 2, a partial cross-sectional view of a hollow needle/push rod assembly is generally shown at  18 . Assembly  18  typically includes push rod  20  and hollow needle  22 , and is configured to deposit material in living tissue. Assembly  18  is also typically configured to retain at least one spacer  24  and at least one radioactive seed  26 , and may retain up to eight seeds, or seeds and spacers. Spacers  24  are typically made of a synthetic absorbable material. In a preferred embodiment of the present invention, spacers  24  and stopple  10  are composed of the same synthetic absorbable material. Seeds  26  are typically composed of iodine-125, which has a half-life of 60 days, and are typically of the same size and shape as spacers  24 . Spacers  26  and seeds  24  are typically arranged in a linear fashion within needle  22 , along their longitudinal axis. Assembly  18  is further configured to retain stopple  10  at the distal end  28  of hollow needle  22 .  
     [0014] Stopple  10  is typically configured to prevent inadvertent ejection of spacers  24  and/or seeds  26  from assembly  18 . Typically, diameter  12  of stopple  10  is greater than the diameter of both spacers  24  and seeds  26  and is substantially similar to inner diameter  30  of needle  22 . Frictional force applied by stopple  10  to inner surface  32  of needle  22  prevents stopple  10  from being dislodged from the needle, thus retaining the seeds and spacers. Typically stopple  10  resists applied forces of approximately 0.2 up to 4 lbs./in. 2 . In a preferred embodiment of the present invention, stopple  10  is configured to resist an applied force of up to 0.8 lbs./in. 2 . Exceeding the applied force is achieved by manually pushing push rod  20  along the longitudinal axis of needle  22 , towards the distal end of the needle. Upon exceeding the applied force stopple  10 , spacers  24  and seeds  26  are ejected from the needle.  
     [0015] Referring next to FIG. 3, a carrier housing a stopple according to one embodiment of the present invention is shown generally at  34 . Typically, carrier  34  is cylindrical in shape and has first and second ends  36  and  38 , respectively. Carrier  34  is typically configured to retain spacers  24 ′, seeds  26 ′, and at least one stopple  10 ′. Stopple  10 ′ is typically configured to have a diameter that is greater than the diameter of the seeds and spacers. In one embodiment of the present invention, stopple  10 ′ is configured such that its diameter is slightly greater than the diameter of carrier  34 , causing carrier  34  to be slightly deformed upon insertion of stopple  10 ′ into second end  38 . Stopple  10 ′ is typically configured to prevent spacers  24 ′ and seeds  26 ′ from inadvertently falling out of second end  38 .  
     [0016] Referring next to FIG. 4, a partial cross-sectional view of a hollow needle/push rod assembly according to another embodiment of the present invention is generally shown at  18 ′. Assembly  18 ′ typically includes push rod  20 ′ and hollow needle  22 ′, and is configured to retain carrier  34  (shown in FIG. 3). Similar to stopple  10  described above, stopple  10 ′ is configured to resist force applied along the longitudinal axis of needle  22 ′ that would otherwise dislodge spacers  24 ′ and seeds  26 ′. Carrier  34  is typically configured to be ejected from needle  22 ′ upon a force applied to push rod  20 ′ that is greater than the frictional force applied to inner surface  30 ′ by stopple  10 ′, as desired.  
     [0017] The above-described stopples  10 ,  10 ′ prevent inadvertent seed and spacer ejection during operation of needle/push rod assemblies for Brachytherapy and therefore reduce the health risks associated with handling radioactive seeds.  
     [0018] Although the invention has been disclosed in its preferred forms, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense, because numerous variations are possible. The subject matter of the invention includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions, and/or properties disclosed herein.