Patent Abstract:
A screw assembly and method developed for the fixation of femoral neck fractures without interruption of the growth process is disclosed. The screw assembly includes a male component that is attached to the lateral cortex and a female component that is attached at the proximal epiphysis. Anchorage of the components is achieved through screw-type fixation. The screw has a built-in feature that allows for free extension of its length as the fracture site or the slipped capital physeal plate heals and normal patient growth continues. Stable fixation and rotational stability are created at the fracture (slip) site while avoiding compression forces, thus avoiding premature closure of the physeal plate.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present patent application claims the benefits of priority of U.S. patent application Ser. No. 13/750,881, entitled “CANNULATED TELESCOPIC FEMORAL NECK SCREW DEVICE AND RELATED FIXATION METHOD” and filed at the United States Patent and Trademark Office on Jan. 25, 2013. 
       FIELD 
       [0002]    The present document generally relates to a screw assembly system and method for the fixation of fractures along the femoral neck, and in particular to an improved cannulated bone screw assembly that enables the implant to be used for the fixation of bone fractures through the physeal plate (growth plate). 
       BACKGROUND 
       [0003]    Cannulated screws have been used for internal fracture fixation, and a single screw placement through the femoral neck has become the preferred treatment for fractures through the physeal plate. Fractures through the physeal plate are more commonly referred to as Slipped Capital Femoral Epiphysis. 
         [0004]    Generally, such a fixation device comprises a hollow shaft having a predetermined cross-section and provided with threaded sections beginning at the medial end of the device spanning a predetermined length of the shaft. The fixation device is placed parallel to the neck of the femur and secures the fracture with compressive force applied by the spherical lateral screw head at the lateral cortex. The prior art typically describes a variety of screw systems comprising different shaft diameters, shaft lengths, thread pitches and thread lengths in order to offer a fixation device for all possible locations and extents of the fracture sites. The general configuration of cannulated screws is well illustrated in U.S. Pat. No. 7,207,994. Such described screws are non self-adjustable in length and, therefore incapable of providing a surgical fixation to stabilize fractured bones during the healing process without disrupting the normal bone growth particularly in pediatric patients. 
         [0005]    In another example described in U.S. Published Patent Application No. 20070260248, an adjustable feature is incorporated into the screw allowing extension of the shaft length along a predetermined range. The screw has an outer member and an inner member connected together by a spring-like component. Once the shaft length is selected and the device is stabilized in said position, the device is inserted into the prepared canal of the femoral neck to fixate the bone segments, just as previously described for cannulated screws, in order to promote healing. 
         [0006]    Other prior art include an intramedullary nail described as an adjustable solution for long bone fixation in U.S. Pat. No. 6,524,313. However, no prior art device has shown adjustable screw solutions for this regard. Therefore, there is a need in the art for an extendable screw system for surgical fixation of femoral neck fractures in pediatric patients. 
         [0007]    Given the present design of cannulated screws used for the fixation of femoral neck fractures, including Slipped Capital Femoral Epiphysis, the compressive loads created by the medially threaded shafts and the lateral spherical screw heads inhibit the normal growth in young patients. Premature closure of the physeal plate is a reoccurring condition widely documented in the literature as a result of pinning and fixation via cannulated screws. Telescoping devices such as the Fassier-Duval Intramedullary Nail, whose fixation features do not thread into the physeal plate, have shown successful internal fixation of fractures and osteotomies in long bones without compromising the integrity of the physeal plate and thus allowing the continuation of normal patient growth. 
       SUMMARY 
       [0008]    In one aspect, a cannulated screw assembly is provided that is self-extendable in length for surgical fixation of fractured femoral necks or slipped femoral epiphysis in a young patient. 
         [0009]    In another aspect, a cannulated screw assembly is provided which requires minimally invasive instrumentation and a relatively straightforward surgical technique. 
         [0010]    Hence, in accordance with one aspect of the screw assembly, a screw assembly for fixation of femoral neck fractures may include a telescopic assembly having two opposed ends and including a male component and a female component. The interconnected components permit axial movement of each end relative to each other. Anchorage of the female and male components is achieved through screw-type fixation of each end of the telescoping screw to the lateral cortex of the femur and the head of the femur. The smooth shaft design and lack of compression element allow free longitudinal extension of the length of the screw so that the screw is extendable as the bone heals and normal patient growth occurs. 
         [0011]    According to one embodiment of the screw assembly with a beveled head design, the screw assembly is provided with an elongated tube having one end formed with an external self-tapping thread that has a diameter greater than the external diameter of the tube, and a cannulated rod having one end formed with an external self-tapping thread as large as the external diameter of the tube. The cannulated rod is adapted for insertion through a drilled canal into the bone until the self-tapping end is anchored in the medial end of bone (the epiphysis of the femoral head) and the rod spans the fracture site. The elongated tube is adapted for insertion into the bone, over the cannulated rod, until the external fixation thread at the lateral end of the tube is anchored within the lateral cortex of the bone. The screw assembly creates a stable fixation and inhibits radial displacements of the fractured segments of the bone while permitting longitudinal extendibility as the bone structures heals and normal patient growth occurs. 
         [0012]    This embodiment of the screw assembly provides a relatively easy method of implantation because anchorage of the screw assembly is as would be anchorage of a single cannulated screw, wherein the action is achieved through rotating the respective rod and tube components until the threads anchor in the bone structures with the use of detachable driving tools. The position of the screw assembly is final when beveled head is parallel to surface of the lateral cortex. 
         [0013]    According to another embodiment with a triblobe design, the screw assembly is provided with a male component with an elongated rod having one end formed with an external self-tapping thread that has a diameter greater than the external diameter of the tube, and a female component having one end formed with an external self-tapping thread that is the same diameter as the tube. The female component is adapted to be inserted through a drilled canal into the bone until the self-tapping end is anchored in the medial end of bone (the epiphysis of the femoral head) and the rod spans the fracture site. The male component is adapted to be inserted into the bone, inside the female component, until the external fixation thread at the lateral end of the rod is anchored within the lateral cortex of the bone. 
         [0014]    An additional characteristic of this embodiment is to provide a cannulated screw assembly for surgical fixation of fractures bones which prevents rotational instability of the femoral epiphysis by preventing the rotation of the male and female components along the central axis. Rotation is hindered by interlocking of a non-circular feature (e.g. one or more flat surfaces, trilobe, cloverleaf, etc.) on the outer surface of the male component and the inner surface of the female component. The male component must be placed into the female component according to the specific mating pattern dictated by the interlocking feature on the components of the assembly. The screw assembly inhibits both radial displacements of the fractured segments of the bone and axial rotation of the segments around the axis of the screw assembly, while permitting longitudinal extendibility as the bone structures heal and normal patient growth occurs. 
         [0015]    Moreover, the screw assembly provides a relatively easy method of implantation because the design allows anchorage of the screw assembly as would the anchorage of a single cannulated screw. The male and female components are assembled as per presented in the embodiment in order to screw in simultaneously both medial and lateral threading through a simple continuous rotation action with the use of a driving tool detachably connected to the male component, which in turn serves as the driving tool for the female component. Device position is final when all threads on tube have fully tapped into bone beyond the physeal plate within the femoral epiphysis. 
         [0016]    In all embodiments, the screw assembly has a unique feature of self-adjustment in length after its implantation to provide a stable fixation of the fractured bone segments without the use of compressive forces to promote healing without disrupting normal patient growth, which is particularly advantageous when the screw assembly is used in children. In addition, rotational stability can be achieved by the incorporation of a non-circular design feature to block rotation between male and female components. Furthermore, retrieval features incorporated into the lateral ends of the embodiments of the present invention allow retention of the screws during insertion and removal procedures. Finally, a cap-like component completes the screw assembly, which inserts into the proximal end of the screw assembly at the lateral cortex in order to prevent bone in-growth for eased retrieval of the screw assembly once the fracture site is healed or patient growth is complete. 
         [0017]    Additional objectives, advantages and novel features will be set forth in the description which follows or will become apparent to those skilled in the art upon examination of the drawings and detailed description which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of a first embodiment of a screw assembly having a trilobe configuration; 
           [0019]      FIG. 2  is a side view of the screw assembly; 
           [0020]      FIG. 3  is an exploded view of the screw assembly showing the female component, male component and cap; 
           [0021]      FIG. 3A  is an end view of the male component; 
           [0022]      FIG. 4  is partially exploded side view of the screw assembly with the male component, female component, and cap; 
           [0023]      FIG. 5  is a perspective view of the female component; 
           [0024]      FIG. 5A  is a cross-sectional view along line  5 A- 5 A of  FIG. 5 ; 
           [0025]      FIG. 6  is a side view of the female component; 
           [0026]      FIG. 7  is a perspective view of the male component 
           [0027]      FIG. 7A  is a cross-sectional view along line  7 A- 7 A of  FIG. 7 ; 
           [0028]      FIG. 8  is a side view of the male component; 
           [0029]      FIGS. 9A and 9B  are perspective views of the cap; 
           [0030]      FIG. 10  is a perspective view of a second embodiment of the screw assembly having a double flat configuration; 
           [0031]      FIG. 11  is a side view of the screw assembly shown in  FIG. 10 ; 
           [0032]      FIG. 12  is an exploded view of the screw assembly shown in  FIG. 10  illustrating the female component, male component and cap; 
           [0033]      FIG. 12A  is an end view of the male component shown in  FIG. 12 ; 
           [0034]      FIG. 13  is a partially exploded side view of the screw assembly shown in  FIG. 10  with the male component, female component, and cap; 
           [0035]      FIG. 14  is a perspective view of the female component shown in  FIG. 10 ; 
           [0036]      FIG. 14A  is a cross-sectional view taken along line  14 A- 14 A of  FIG. 14 . 
           [0037]      FIG. 15  is a side view of the female component shown in  FIG. 10 ; 
           [0038]      FIG. 16  is a perspective view of the male component shown in  FIG. 10 ; 
           [0039]      FIG. 16A  is a cross-sectional view of the male component along line  16 A- 16 A of  FIG. 16 ; 
           [0040]      FIG. 17  is a side view of the male component shown in  FIG. 10 ; 
           [0041]      FIG. 18  is a perspective of a third embodiment of the screw assembly having a beveled head configuration; 
           [0042]      FIG. 19  is a side view of the screw assembly shown in  FIG. 18 ; 
           [0043]      FIG. 20  is an exploded view of the screw assembly shown in FIG. 
           [0044]      FIG. 21  is a partially exploded side view of the screw assembly shown in  FIG. 18  with the male component and female component; 
           [0045]      FIG. 22  is a perspective view of the female component shown in  FIG. 18 ; 
           [0046]      FIG. 22A  is a cross-sectional view taken along line  22 A- 22 A of  FIG. 22 ; 
           [0047]      FIG. 23  is a side view of the female component shown in  FIG. 18 ; 
           [0048]      FIG. 24  is a perspective view of the male component shown in  FIG. 18 ; 
           [0049]      FIG. 24A  is a cross-sectional view taken along line  24 A- 24 A of  FIG. 24 ; and 
           [0050]      FIG. 25  is a side view of the male component shown in  FIG. 18 ; 
           [0051]      FIGS. 26A-26G  illustrate one method for using the screw assembly shown in  FIG. 1 . 
       
    
    
       [0052]    Corresponding reference characters indicate corresponding elements among the view of the drawings. The headings used in the figures should not be interpreted to limit the scope of the claims. 
       DETAILED DESCRIPTION 
       [0053]    Referring to the drawings, various embodiments of the screw assembly are illustrated and generally indicated as  100 ,  200  and  300  in  FIGS. 1-25 . 
         [0054]    In one embodiment shown in  FIGS. 1-9 , the screw assembly, designated  100 , may include a hollow female component  102  configured to receive a male component  104  with a cap  105  that engages one end of the male component  104 . Specifically, the male component  104  is freely slidable relative to female component  102  along longitudinal axis  900  ( FIG. 1 ), which allows the screw assembly  100  to lengthen over time along axis  900  and accommodate the natural growth of the growth plate as the fracture heals over a period of time. 
         [0055]    Referring to  FIGS. 1 and 4 , the female component  102  defines circular-shaped hollow shaft  107  that defines an elongated trilobe-shaped channel  118  therein configured to accommodate a trilobe-shaped shaft  106  of the male component  104  such that the trilobe-shaped shaft  106  of the male component  104  may freely slide relative to the elongated trilobe-shaped channel  118  of the female component  102 . 
         [0056]    Referring to  FIGS. 5 and 5A , the circular-shaped hollow shaft  107  of the female component  102  further defines a proximal end opening  110  in communication with the elongated trilobe-shaped channel  118 . In addition, the female component  102  further include a medial threaded portion  108 , having a cancellous profile, that defines an axial opening  111  in communication with an interior cannulated section  114 . The other end of the interior cannulated section  114  is in communication with the far end of the elongated trilobe-shaped channel  118  such that fluid flow communication is established between the axial opening  111  and the proximal end opening  110 . In one embodiment, the inner diameter of the cannulated section  114  is less than the inner diameter of the elongated trilobe-shaped channel  118 . As shown, one embodiment of the medial threaded portion  108  may define a self-tapping cut-out feature  121  that facilitates entry of the female component  102  into the bone as shall be described in greater detail below. As further shown, an internal threaded portion  112  is defined adjacent to the proximal end opening  110  for engaging with a removal device (not shown) with matching thread. 
         [0057]    As shown in  FIGS. 7 ,  7 A and  8 , the male component  104  includes a trilobe-shaped shaft  106  having a substantially three-sided cross-sectional configuration sized and shaped to be disposed within the elongated trilobe-shaped channel  118  when the male component  104  is engaged to the female component  102 . The male component  104  defines a far end opening  113  along a trilobe-shaped end  136  of the elongated trilobe-shaped shaft  106  and a lateral threaded portion  116  at the opposite end of the elongated trilobe-shaped shaft  106 . The lateral threaded portion  116  features a flat head configuration at the free end thereof that positions the lateral threaded portion  116 , whose diameter is larger than the trilobe-shaped shaft  106 . In addition, the lateral threaded portion  116  defines a self-tapping feature  120  formed along the lateral threaded portion  116 . 
         [0058]    As shown in  FIG. 7A , the far end opening  113  is in communication with a cannulated section  119  which forms a channel along the length of the elongated trilobe-shaped shaft  106 . In addition, a drive feature  122  communicates with the opposite end of the cannulate section  119  through an internal threaded section  115  formed adjacent the drive feature  122 , whose combination is used to retain and drive the assembled male and female components simultaneously into the bone ( FIG. 26A ). 
         [0059]    Referring to  FIG. 3A , the trilobe-shaped shaft  106  includes a first trilobe portion  130 , a second trilobe portion  132 , and a third trilobe portion  134  that collectively form a non-cylindrical cross-sectional configuration that prevents rotation of the female component  102  relative to the male component  104 . As noted above, the trilobe-shaped shaped shaft  106  is freely slidable along longitudinal axis  900  of the screw assembly  100 , while the non-circular shape of the trilobe-shaped shaft  106  prevents rotational movement of the female component  102  relative to the male component  104  along rotational direction  902  (e.g. in either the clockwise or counter-clockwise rotational directions). Although the embodiment of the male component  104  shown in  FIGS. 1-8  defines a three-sided trilobe-shaped cross-sectional configuration, other types of non-cylindrical cross-sectional configurations may be used to define the shaft  106 , such as triangular, square, rectangular, or oblong-shaped cross-sectional configurations that allows sliding movement of the male component  104 , but prevents rotational movement of the female component  102  relative to the male component  104 . In this mating engagement between the female component  102  and the male component  104 , the drive mechanism  10  is able to drive both female and male components  102  and  104  into the bone. 
         [0060]    Referring to  FIGS. 9A and 9B , the cap  105  may be used to seal off the recessed drive feature  122  of the male component  104 . As shown, the cap  105  includes a semi-spherical shaped cap portion  126  that defines a recess  125  configured to connect with a drive and removal tool  11  with a matching profile. The cap portion  126  communicates with a cylindrical-shaped middle portion  128  with an external threaded portion  124  that extends axially from the middle portion  128 . As shown in  FIG. 4 , the external threaded portion  124  of the cap  105  is configured to engage and retain the proximal end internal threads  115  defined by the male component  104 . 
         [0061]    During manufacture, the following dimensions may be used for one embodiment of the screw assembly  100 , although other suitable dimensions may be used for other embodiments. Referring to  FIGS. 2 and 6 , the screw assembly  100  may have a length  500  of between 60 mm to 102 mm in 2 mm increments, while the female component  102  may have a length  502  of between 52 mm to 92 mm in 4 mm increments and a width  504  of 6.5 mm to 7.3 mm. As shown in  FIG. 8 , the male component  104  may have a length  506  of between 48 mm to 50 mm and a width  508  at the head  508  of between 8.0 mm to 9.0 mm. 
         [0062]    In a second embodiment shown in  FIGS. 10-17 , the screw assembly, designated  200 , may include a hollow female component  202  configured to receive a male component  204  with a cap  205  that engages the male component  204  in similar fashion as cap  105 . As shown in  FIG. 12A , the male component  204  includes a double flat shaped shaft  206  having opposing sides  232  and  236  as well as opposing sides  230  and  234  that collectively define either a generally squared-shaped or rectangular-shaped cross sectional configuration. Similar to screw assembly  100 , the non-cylindrical shape of the double flat shaped shaft  206  for the male component  204  functions in a similar manner as the trilobe-shaped shaft  106  of male component  104  to prevent rotational movement  906  of the female component  202  relative to the male component  204  while allowing free sliding movement along longitudinal axis  904  of the screw assembly  200 . 
         [0063]    Referring to  FIGS. 14 and 15 , the female component  202  includes a cylindrically-shaped elongated hollow body  207  having a proximal end opening  210  at one end and an external threaded portion  208  at the opposite end thereof. In one embodiment, the external threaded portion  208  may have a cancellous-shaped profile having a diameter substantially equivalent to the diameter of the cylindrically-shaped elongated hollow body  207  for providing increased mechanical properties under weight bearing conditions. In addition, the external threaded portion  208  includes a self-tapping feature  221  that facilitates entry of the female component  102  into the bone and an axial opening  211 . 
         [0064]    As shown in  FIG. 13 , the axial opening  211  is in communication with a cannulated section  214  formed through the external threaded portion  208  of the female component  202 . In addition, the cannulated section  214  is in communication with an elongated channel  218  formed through the cylindrically-shaped elongated hollow body  207  that is configured to receive the male component  204  therein. In one embodiment, the elongated channel  218  defines a double-sided cross sectional configuration having the same cross sectional configuration as the double sided-shaped shaft  206 . As further shown, a left handed internal threaded section  212  is formed proximate the proximal end opening  210  and is configured to mate with a removal instrument (not shown) for ease of retrieval of the female component  202 . 
         [0065]    Referring to  FIGS. 13 ,  16 ,  16 A and  17 , the male component  204  defines a medial threaded portion  216  having a flat head with a self tapping feature  220  formed along the medial threaded portion  216 . In one embodiment, a drive feature  222  forms a hexagonal-shaped recess in communication with a proximal end internal threaded portion  215  configured to engage an external threaded portion  224  of the cap  205  when the cap  205  is engaged into the male component  204 . The combination of the drive feature  222  and the internal threaded portion  215  is used to retain and drive the assembled male and female components  202  and  204  into the bone ( FIG. 26A ). In addition, the male component  204  includes an axial opening  213  in communication with cannulated section  219  that forms an elongated channel between the axial opening and the drive feature  222 . As shown, the cap  205  is similar in construction as cap  105  having a middle portion  228  in communication with a cap portion  226  having a recess  225 . 
         [0066]    During manufacture, the following dimensions may be used for one embodiment of the screw assembly  200 , although other suitable dimensions may be used for other embodiments. Referring to  FIG. 11 , the screw assembly  200  may have a length  700  of between 60 mm to 102 mm in 2 mm increments. As shown in  FIG. 15 , the female component  202  may have a length  702  of between 50 mm to 90 mm in 4 mm increments and a width  704  of between 6.5 mm and 7.3 mm. As shown in  FIG. 17 , the male component  204  may have a length  706  of between 48 mm to 50 mm and a width  708  of between 8.0 mm to 9.0 mm 
         [0067]    In a third embodiment shown in  FIGS. 18-25 , the screw assembly, designated  300 , may include a hollow female component  302  configured to receive a male component  304 . As shown in  FIGS. 22 ,  22 A, and  23 , the female component  302  defines a hollow cylindrical shaft portion  306  having a far end opening  310  formed at one end and a lateral beveled end portion  308  at the opposite end thereof. The hollow cylindrical shaft portion  306  allows for ease of insertion of the screw assembly  300  into the bone and eliminates disruption of the physeal plate as not sharp features are inserted into the physeal plate. The far end opening  310  is in communication with an elongated channel  320  formed along the cylindrical shaft portion  306 . 
         [0068]    As shown in  FIG. 22A , an internal drive feature  322  is formed at the proximal end inside the lateral beveled end portion  308  and forms a hexagon-shaped recess. The drive feature  322  is configured to receive a portion of the drive mechanism  10  ( FIG. 26A ) for insertion through a bone. As further shown, a left-handed internal threaded portion  324  is formed between the drive feature  322  and a cannulated section  326 . The left-handed internal threaded portion  324  facilitates retention of the screw assembly  300  for ease of removal, while the cannulated section  326  for guided insertion of the component into the bone using a cannulated rod (not shown). The lateral beveled end portion  308  has a diameter larger than the hollow shaft portion  306  for better retention of the screw assembly  300  in the bone. 
         [0069]    Referring to  FIG. 19 , the lateral beveled end portion  308  defines a beveled profile that positions the cortical profiled threads of the lateral beveled end portion  308  fully within the lateral cortex, flush against the bone surface, thereby eliminating exposure of the threads outside the bone. 
         [0070]    As shown in  FIGS. 20 ,  24 ,  24 A, and  25 , the male component  304  defines a hollow cylindrical shaft portion  307  with a medial threaded portion  316  having a cancellous profile formed at one end of the shaft portion  307  and an external drive feature  312  formed at the opposite end thereof. The medial threaded portion  316  defines a self-tapping feature  318  that facilitates entry of the male component  304  into the bone. In some embodiments, the medial threaded portion  316  has a diameter larger than the diameter of the cylindrical shaft  307 . As shown, an axial opening  313  is formed proximate the medial threaded portion  316  and is in communication with an elongated channel  325  at one end thereof. The external drive feature  312  forms an opening  315  that communicates with the opposite end of the elongated channel  325 . As such, the male component  304  is fully cannulated to insert over a standard guide wire (not shown). In addition, the hollow cylindrical shaft portion  307  defines a left-handed retrieval threaded section  314  formed proximate the external drive feature  312 . 
         [0071]    As shown in  FIG. 20 , the male component  304  may freely slide relative to the female component  302 . In this embodiment, no cap is required to be engaged to the male component  304 . 
         [0072]    During manufacture, the following dimensions may be used for one embodiment of the screw assembly  300 , although other suitable dimensions may be used for other embodiments. Referring to  FIG. 19 , the screw assembly  300  may have a length  800  of between 60 mm to 100 mm in 2 mm increments. As shown in  FIG. 23 , the female component  302  may have a length  802  of between 50 mm to 80 mm in 4 mm increments and a width  804  at the shaft of between 8.0 mm to 9.0 mm. As shown in  FIG. 25 , the male component  304  may have a length  806  of 50 mm, a width  808  at the shaft of between 5.0 mm and 5.8 mm and a width  808  at the head of between 6.5 mm to 7.3 mm. 
         [0073]    Referring to  FIGS. 26A-26G , one method of using the screw assemblies  100  and  200  is illustrated. However, for ease of description only the use of screw assembly  100  will be described herein since the method of use is the same for both embodiments. Referring to  FIGS. 26A-26C , the male component  104  received within the female component  102  is inserted through the physeal plate using a drive mechanism  10  until the lateral threaded portion  116  of the male component  104  is fully disposed within the lateral cortex. In this arrangement, the male component  104  is fully received within the female component  102  such that the cylindrical shaft  106  is fully disposed within the female component  102 . As shown in  FIGS. 26D-26F , the cap  105  is attached to the lateral threaded portion  116  using the driving mechanism  11  which seals off both the male component  104  and female component  102  within the lateral cortex. As shown in  FIG. 26G , the free sliding engagement between the female component  102  and the male component  104  allows the cylindrical shaft  106  to gradually extend from the female component  102  as the physeal plate grows over time as the fracture heals. 
         [0074]    It should be understood from the foregoing that, while particular embodiments have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the invention as will be apparent to those skilled in the art. Such changes and modifications are within the scope and teachings of this invention as defined in the claims appended hereto.

Technology Classification (CPC): 0