Patent Application
20090118713
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The present invention relates generally to a tissue cleaning apparatus and more particularly, to a powered rotating perforated basket assembly which is sequentially reversed in clockwise/counterclockwise cycles to clean human tissues.
Several hundred thousand tissue transplants are annually performed in the United States. The single most variable factor with respect to allographic transplantation is the preparation of such bone and tissue segments. Procedure and protocol of the some 400 tissue banks in North America are quite varied and has resulted in various technology with developed processes.
Allografts are vital for bone stock deficiencies that occur during orthopaedic trauma, joint reconstruction, or other reconstructive procedures. The main criteria for an orthopaedic allograft are the retention of strength, the retention of biologic factors, and the reduction of risk of disease transmission. The first two should not be affected by processing, while processing should eliminate the risk for disease transmission.
There is no known industry standard specifying levels of cleanliness for cleaning and preparing bone segments. The problems associated with this lack of standards interpret to poor process control, inadequate removal of tissue from the parent surface and to a large extent lack of sterility during the tissue recovery process.
Human bone obtained from cadaveric donors is typically procured under sterile conditions in an operating suite environment of local hospitals. The bone is stored frozen until it is further processed into small grafts under similar sterile conditions, or under clean-room conditions. Procurement and processing of human tissues is typically performed by groups certified by the American Association of Tissue Banks under standard operating procedures for the processing of each specific bone graft. Large bones such as the femur are thawed and debrided of excess tissue prior to being cut into smaller grafts. Processing of the smaller grafts includes cleaning of bone marrow from the cancellous bone spaces. Cleaning of bone marrow and tissue from small bone grafts has been described in the scientific literature and in brochures and documents made public by groups involved in the procurement and processing of human tissues.
The use of prior art procedures to clean bone tissue involves the use of a pressurized flow of solution as a rapidly moving stream which dislodges bone marrow by impact of the solvent on the bone graft. In U.S. Pat. No. 5,333,626 issued Aug. 2, 1994, a high pressure wash is used to clean bone. The bone is cleaned with a high pressure detergent solution such as TritonX-100 and Tween 80 preferably from 37° C. to 80° C. The bone may be further decontaminated by exposing it to 3% hydrogen peroxide solution from 5 to 120 minutes (preferably 5 to 60 minutes) after which the residual hydrogen peroxide is removed by washing with sterile water. After cleaning, the bone is finally decontaminated by contacting the bone with a global decontaminate for 30 to 60 minutes. Such procedures tend to generate aerosols of tissue and solvent which can be hazardous to processing personnel. The present invention virtually eliminates this hazard.
Ultrasonic cleaners are also used to clean bone tissue. Ultrasonic energy in liquid generated by piezoelectric or other types of transducers creates cavitation, which is the mechanism for ultrasonic cleaning. Cavitation consists of the formation and collapse of countless tiny cavities, or vacuum bubbles, in the liquid. The energy produces alternating high and low pressure waves within the liquid of a tank. The liquid is compressed during the high pressure phase of the wave cycle, then pulled apart during the low pressure phase. As the pressure in the liquid is reduced during the low pressure phase, cavities grow from microscopic nuclei to a maximum critical diameter. During the subsequent high pressure phase they are compressed and implode. The energy is powerful, but safe for parts because it is localized at the microscopic, i.e., cellular, scale. Factors affecting the strength of cavitation are temperature, surface tension, detergents or other agents which reduce surface tension are optimal, viscosity (medium vapor pressure is most conducive to ultrasound activity), and density (where high density creates intense cavitation with greater implosive force).
A number of prior art references have used ultrasonics together with detergents and other solutions to clean bone.
In U.S. Pat. No. 5,556,379 issued Sep. 17, 1996 and U.S. Pat. No. 5,976,104 issued Nov. 2, 1999, the processing of the smaller grafts including cleaning of bone marrow from the cancellous bone spaces using mechanical means, soaking, sonication, and/or lavage with pulsatile water flow under pressure is disclosed. This cleaning may use reduced or elevated temperatures, for example 4° C. to 65° C., and may also include the use of detergents, alcohol, organic solvents or similar solutes or combination of solutes designed to facilitate solubilization of the bone marrow.
In the Simonds reference from the New England Journal of Medicine, page 726, Mar. 12, 1992, entitled TRANSMISSION OF HUMAN IMMUNODEFICIENCY VIRUS TYPE I FROM SERONEGATIVE ORGAN AND TISSUE DONOR, the bone was lyophilized and treated with ethanol. The lyophilized tissue has the soft tissue removed, followed by treatment with two antibiotics, irrigation with sterile water, packaging and refreezing and lyophilization to a residual moisture content of less than 5%. The ethanol treated tissue underwent ultrasonic cleaning in 30% ethanol, removal of marrow by water lavage and brief treatment in 100% ethanol.
U.S. Pat. No. 5,095,925 issued Mar. 17, 1992 is directed toward a bone cleaning device using ultrasonics which removes gross tissue from bone to prepare the same for transplant and use in surgery. The bone is subjected to a positive pressure stream of sterile water, ultrasonically cleaning the same in a detergent followed by rinsing and soaking and reintroduced to the ultrasonic process if necessary within a preferred working temperature range of 27° C. to 33° C.
U.S. Pat. No. 5,509,968 issued Apr. 26, 1996 is directed toward cleaning used orthopaedic implants which are decontaminated and made available for reuse by a three step process for removal of protein tissue, bone tissue and lipids using sonication.
The implant is suspended in an aqueous bath of detergent suitable for emulsifying lipids at elevated temperatures, such as 40° C. to 60° C., and is typically treated for about 1 to 45 minutes by the use of an ultrasonic cleaning system. The solution in the treating container is discarded and the container and implant are washed with clean water. A container is filled with a dilute acid capable of dissolving bone salts (e.g., calcium phosphate minerals that are deposited in the collagen matrix of the bone). The implant is added to the container, and subjected to ultrasonic treatment for approximately the same time. After treatment, the solution containing dissolved bone salts is discarded and the implant and container are again rinsed with clean water. The implant is then subjected to a bath of an aqueous solution sodium hypochlorite of a concentration as sold for general cleaning purposes, (household bleach). This step removes any remaining organic bone tissue as well as protein. An ultrasonic cleaning system is again used for the same time and temperature. When this step is completed, the solution is discarded and both the implant and container rinsed with water.
U.S. Pat. No. 5,797,871 issued Aug. 25, 1998 is also directed toward a bone cleaning process using ultrasonics in which the bone is sonicated in a solution of several detergents within a temperature range of 37° C. to 50° C. to produce bone grafts essentially free from bone marrow and detectable fungal and viral contamination.
A number of prior art patents show the cleaning of bones through agitation and centrifugation.
U.S. Pat. No. 5,513,662 issued May 7, 1996 discloses treating bone at less than ambient pressure and then agitated the same vigorously in an agitator. The U.S. Pat. No. 5,797,871 patent noted above also uses mild and vigorous agitation in connection with its bone cleaning sonication process.
U.S. Pat. No. 5,977,432 issued Nov. 2, 1999 is directed toward a process for removing essentially bone marrow from a cut bone graft. A large substantially intact bone is selected and excess cartilage and associated soft tissues are removed from the surface of the bone. The bone is left whole or may be cut into smaller pieces constituting cut grafts and bone marrow is removed from the cancellous bone spaces of the small cut grafts through the application of centrifugal force. Prior to and/or following the application of centrifugal force, the bone graft may optionally be pretreated with one or more decontaminating agents, and/or solubilizing agents
The above and other objects, feature and advantages of the present invention will be apparent in the following detailed description thereof when read in conjunction with the appended drawings wherein the same reference numerals denote the same or similar parts throughout the several views.
The present invention is a portable tissue cleaning apparatus constructed with a housing having a motor contained therein, the housing being provided with a base member, side walls mounted to the base member and a top cover mounted over the housing side walls. A switch assembly is mounted on the top cover for operation of the apparatus. A connector assembly connects the motor to a rotatable perforated basket assembly housing in a fluid container; which is rotated in sequential clockwise and counterclockwise cycles a set number of revolutions to clean bone tissue placed therein. Each sequential cycle is ramped up at the start and ramped down at the end of the cycle. The perforated basket is cylindrical with an impeller mounted on its bottom to direct cleaning fluid in a predetermined path, and the basket is divided into separate sections.
The present invention addresses the needs and deficiencies noted above. It provides an apparatus with a temperature sensor to determine the temperature of the bone cleaning solution.
It is an object of the invention to provide a simple but efficient way of cleaning bones by uniformly cleaning same.
It is another object of the invention that it operates to effectively remove lipids and bone marrow form the cut bone pieces.
It is still another object of the invention that to provide a portable cleaning device which can be easily moved to a desired area.
It is another object of the invention to provide a device that can be simply operated with a minimum of training of personnel.
It is yet another object of the invention that the device can be easily broken apart for sterilization and cleaning.
The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein.
a is an enlarged side elevation view of the basket mounting taken from Circle A of
The preferred embodiment and best mode of the invention is shown in
The present invention generally refers to a portable tissue cleaning apparatus 20 constructed with a drive and control housing 30 having a basket assembly 100 mounted thereon. The basket assembly 100 is mounted on the bearing assembly 94 of the servo motor by three mounting bracket assemblies 140 positioned equal distant around the circumference of bearing assembly 94 and basket bearing housing 103 of the basket assembly 100. Each mounting bracket assembly 140 is constructed with a mounting bracket 142, a 5/16×0.875 inch screw 144 and a 5/16 inch rosette thumb screw knob 146 which fits over the head 145 of the screw 144 as is shown in
The housing 30 as shown in exploded view in
The front section 44 has a plurality of holes cut therein in a linear alignment to receive a number of controls to operate the cleaning apparatus. As can be seen in
A servo motor mount assembly 80 is mounted on the top section 46 and is connected to the basket bearing assembly 103 for driving the basket assembly 100. The servo motor mount assembly 80 is constructed with a 1⅛ inch buna-n u-cup 82, a junction box assembly 84, and a servo mount base 86 defining a central aperture 87. A coupling member 88 is mounted in central aperture 87 of the servo mount base 86 and an o ring 90 is placed around the periphery of the servo mount base 86 to provide a seal with the servo mount bearing housing 94. The coupling has a solid square shaped distal drive end 89. A double sealed ball bearing race 92 is seated over coupling member 88 and is held in place by a second ⅝ inch buna-n u-cup 93. A servo motor mount bearing housing 94 is mounted to the coupling member 88. The servo mount bearing housing 94 is provided with a hub 96 which receives the basket assembly 100. The bearing housing 94 is mounted to the coupling member 88.
The basket assembly 100 which is shown in exploded view in
In operation the bone tissue to be cleaned is placed into perforated basket 100 that has fin dividers 114 and 116. As the basket spins, the tissue is forced to spin in the same rate as the basket 100. The basket 100 has an impeller 120 at the bottom which forces cleaning solution up through the basket 100 and promotes fluid circulation over the tissue. Two liters of cleaning solution such as 0.1% Triton X-100 or 0.1% Tween 80 is used per cycle. The basket 100 has a ramped acceleration and deceleration which prevents the tissue from being damaged. The basket spins at a speed of 1000 rpm for 420 revolutions, then stops and spins in the opposite direction for 420 revolutions (equal to 25 seconds CW, 25 seconds CCW). The CW/CCW cycle continues until the operator stops the machine or until the cleaning solution reaches a temperature of 104° F. The inherent temperature rise of the cleaning solution at current setting (1000 rpm, 420 revolutions in the CW and CCW directions) is 0.6° F. per minute. The temperature of the cleaning solution is monitored to ensure that the machine shuts down if 104° F. is reached to prevent temperature damage of the BMP's and growth factors of the tissue. The number of revolutions that the basket 100 turns in each direction is programmable. The direction is reversed to reposition the tissue to ensure even cleaning of all tissue and helps eliminate the possibility that the tissue and cleaning solution reach the same speed. If the tissue and cleaning solution travel at the same speed and in the same direction, there will not be a washing effect as it would be more of a soaking effect. The basket 100 is removable from the cylindrical container and the tissue is removed from the basket for further processing. The basket 100 is autoclaved between each donor tissue usage to ensure sterility and donor separation.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention should not be construed as limited to the particular embodiments which have been described above. Instead, the embodiments described here should be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the scope of the present invention as defined by the following claims:
