Abstract:
An apparatus for removing a solid object from a body canal or vessel includes a coil of wire configured to slidably receive a guide wire and a sack having a mouth and a closed bottom opposite the sack. A resilient frame is connected between the coil of wire and the sack for biasing the mouth of the sack open around the coil of wire. The resilient frame is positionable between a collapsed state where the mouth of the sack is closed against the bias of the resilient frame and a deployed state where the mouth of the sack is biased open by the resilient frame.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 12/423,576 filed Apr. 14, 2009 and which published on Sep. 10, 2009 as U.S. Patent Application Publication Number 2009-0228036. U.S. patent application Ser. No. 12/423,576 is a continuation of U.S. patent application Ser. No. 11/128,524 filed May 13, 2005 and which issued as U.S. Pat. No. 7,537,601. U.S. patent application Ser. No. 11/128,524 is a continuation of U.S. patent application Ser. No. 10/000,546 filed Oct. 21, 2001 and which issued as U.S. Pat. No. 6,893,451. U.S. patent application Ser. No. 10/000,546 claims priority from U.S. Provisional Patent Application Ser. No. 60/247,824, filed Nov. 9, 2000, and U.S. Provisional Patent Application Ser. No. 60/249,534, filed Nov. 17, 2000. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is directed to capturing objects beyond an operative site in any of a variety of medical procedures employed to treat any number of medical conditions in human and/or animal patients. 
         [0004]    2. Background Information 
         [0005]    In many medical procedures, objects are dislodged or otherwise freed by the surgeon during the surgical procedure, and it is useful and/or necessary to capture the dislodged and/or otherwise freed object. 
         [0006]    Although minimally invasive interventional medical therapies in general, and minimally invasive endovascular therapy in particular, are medical procedures where objects may be dislodged or otherwise freed during the procedure, each has enjoyed unprecedented expansion to treat patients because of the numerous medical benefits associated with not having to enter the body through more invasive surgical techniques. These benefits include, but are not limited to, less trauma and/or scarring for patients, less time to heal, less risk of infection and decreased hospital stays, to name but a few. 
         [0007]    More particularly, minimally invasive endovascular therapy is often used to treat diseased vessels, e.g., arteries and veins. With such therapy, small instruments are inserted into the vessels through a puncture or access opening made in one of the vessels at an entry site and are advanced through the circulatory system to an operative site where the vessel has become diseased, and the instruments are used to repair the diseased or operative site. 
         [0008]    Typically, the goal of such therapy is to dilate full or partial blockages of the diseased vessel. Such blockages may have developed over time or may have developed quickly, as for example, in response to an injury. One common source of such blockage is thromboemboli which has formed in the vessel. Thrombus is an aggregation of platelets, fibrin, clotting factors and cellular components of blood that spontaneously form and attach on the interior wall of a vein or artery, and thromboemboli are emboli of thrombus which operate to partially or completely occlude the interior or lumen of the blood or other vessel. 
         [0009]    Techniques to open and/or maintain the dilation of the partially or completely occluded lumen of blood or other vessels include positioning a balloon across an obstruction or partially occluded section of the vessel, inflating the balloon to compress the build up (balloon angioplasty) and/or temporarily or permanently inserting a tube-like support within the vessels to keep the vessel open (stenting). 
         [0010]    Minimally invasive endovascular therapy has the significant advantage that it is less invasive than traditional surgical techniques and causes less trauma to the patient. However, this therapy is complicated by the fact that it can undesirably dislodge or free particles/objects during the procedure as discussed above, and in that the tools or instruments and workspace, e.g., the interior of the vessels of the body, are in some cases extremely small and close, and reaching the operative site with the tools is very difficult in some instances due to the considerable branching of the circulatory system that may occur between the entry site into the blood vessel and the operative site. This therapy is further complicated by the fact that the entry site is often far from the operative site, as for example, where the entry site is in the thigh at the femoral artery and the operative site is located in the neck at the carotid artery. Even when the surgeon&#39;s instruments have been properly advanced to the operative site, manipulating the tools to perform their respective functions at the operative site is often difficult for the surgeon due to many factors including the close quarters at the operative site and the distance between the entry site and the operative site. 
         [0011]    One method and apparatus commonly used by surgeons to ensure the tools reach the operative site is to first thread a simple guide wire to or beyond the operative site. Thereafter, various tools are threaded over the guide wire by the surgeon to reach the operative site. It is an important aspect of such guide wires that they must be easy to manipulate through the vessels, including in certain cases, through lesions or areas of blockage in the vessel by the surgeon. In addition to exhibiting sufficient resiliency so as to be pushable in the vessel, the guide wire must exhibit sufficient flexibility and maneuverability to enable the surgeon to traverse the many twists and turns of the circulatory (or other) system to reach the operative site. 
         [0012]    An aspect of the ability for a surgeon to manipulate the guide wire through the circulatory or other system is the guide wire&#39;s “torquability”. As defined herein, the term “torquability” means that as the surgeon rotates the proximal region of the guide wire that extends outside of the patient&#39;s body during the advancement of the guide wire through the patient&#39;s blood or other vessels to the operative site, the amount of rotation at the proximal region of the guide wire is transmitted to the distal end of the guide wire being inserted and advanced through the patient&#39;s blood or other vessels to the operative site. A lack of correlation between rotation at the proximal region of the guide wire and rotation at the distal end of the guide wire is referred to as reduced torquability and is undesirable. A high degree of correlation is referred to as a high degree of torquability and is desirable. As may be appreciated, it is most desirable for the guide wire to have an exact correlation or high torquability between the rotation applied proximally at the proximal region of the guide wire and the rotation developed distally in the guide wire, so that the surgeon can carefully control and direct the medical guide wire. With known devices, there is considerable difference between the amount of rotation applied at the proximal region of the guide wire and the amount of rotation developed at the distal end of the guide wire, making it very difficult for surgeons to maneuver the distal end of the guide wire. 
         [0013]    Even where the guide wire exhibits the desired torquability characteristics, and the tools have been properly threaded to the operative site and have been properly manipulated to perform their respective functions at the operative site, there remains the problem noted above, namely, that the process of dilating the occlusion and/or inserting the stent may dislodge or free small particles or objects, also known, among other things, as clots, fragments, plaque, emboli, thromboemboli, etc. More particularly, with respect to endovascular therapy, the term “embolic event” has come to be used to describe complications where thrombus or plaque is shed inadvertently from a lesion to migrate to smaller vessels beyond the operative site to create a full or partial occlusion of the lumen of the vessel or vessels. This is most undesirable and can lead to many complications. Complications depend upon the site in the body where such emboli lodge downstream of the operative site, but may include stroke, myocardial infarction, kidney failure, limb loss or even death. With increasing vigor, surgeons have expressed the need to reduce the likelihood of such complications so that protection against embolic events will become a standard component of endovascular therapy. 
         [0014]    Devices have been made in the art to capture objects, including emboli, downstream of an operative site in medical procedures, including endovascular therapy. Such devices generally employ a capture device, such as a bag or filter, which has a collapsed state and an expanded or deployed state. Typically, the capture device is maintained in its collapsed state within sheathing and is inserted into the blood or other vessel and is threaded beyond the operative site. It is then ejected from the sheathing whereupon it expands to its deployed state to capture the objects dislodged or otherwise freed during the medical procedure. 
         [0015]    One device for removing clot or filtering particles from blood is described in U.S. Pat. No. 4,723,549 to Wholey et al., which discloses a device for dilating occluded blood vessels. This device includes a collapsible filter device positioned between a dilating balloon and the distal end of the catheter. The filter comprises a plurality of resilient ribs secured to the catheter that extend axially toward the dilating balloon. Filter material is secured to the ribs. The filter deploys as a balloon is inflated to form a cup-shaped trap. An important limitation of the Wholey et al. device appears to be that the filter does not seal around the interior vessel wall. Thus, particles sought to be trapped in the filter can instead undesirably pass between the filter and the vessel wall and flow downstream in the circulatory system to produce a blockage. Another limitation is that the device also presents a large profile during positioning. Yet another limitation appears to be that the device is difficult to construct. 
         [0016]    U.S. Pat. No. 4,873,978 to Ginsburg discloses a vascular catheter that includes a strainer device at its distal end. The device is inserted into a vessel downstream from the treatment site and advanced to a proximal downstream location. The filter is contained in a sheath when closed. When pushed from the sheath, the filter deploys such that its mouth spans the lumen of the vessel. Deployment is by expansion of resilient tines to which the strainer material is attached. Again, however, it appears that the filter does not seal around the interior vessel wall, thus undesirably allowing particles to bypass the filter by passing between the filter and the vessel wall. The position of the mouth relative to the sheath is also clinically limiting for the Ginsburg device. 
         [0017]    U.S. Pat. No. 5,695,519 to Summers et al. discloses a removable intravascular filter on a hollow guide wire for entrapping and retaining emboli. The filter is deployable by manipulation of an actuating wire that extends from the filter into and through the hollow tube and out the proximal end. One limitation with the Summers et al. device appears to be that its filter material is not fully constrained. Therefore, during positioning within a vessel, as the device is positioned through and past a clot, the filter material can snag clot material undesirably creating freely floating emboli. It is unclear if the actuating wire can close the filter, and it appears in any event that it will exert a pull force on the rim of the filter that could tear the wire from the rim. Another limitation appears to be that the device application is limited by the diameter of the tube needed to contain the actuating wire. 
         [0018]    U.S. Pat. No. 5,814,064 to Daniel et al. discloses an emboli capture device on a guide wire. The filter material is coupled to a distal portion of the guide wire and is expanded across the lumen of a vessel by a fluid activated expandable member in communication with a lumen running the length of the guide wire. One limitation of the device appears to be that during positioning, as the device is passed through and beyond the clot, filter material may interact with the clot so as to undesirably dislodge material and produce emboli. It is further believed that the device may also be difficult to manufacture. Another limitation is that it is difficult to determine the amount of fluid needed to expand the member. A lack of control can rupture and tear the smaller vessels. Thus, the Daniel et al. device would appear to be more compatible with use in the larger vessels only. 
         [0019]    PCT Publication No. WO 98/33443 discloses a removable vascular filter wherein the filter material is fixed to cables or spines mounted to a central guide wire. A movable core or fibers inside the guide wire can be utilized to transition the cables or spines from approximately parallel the guide wire to approximately perpendicular the guide wire. A limitation of this device appears to be that the filter does not seal around the interior vessel wall. Thus, particles, e.g., emboli-forming materials, can undesirably bypass the filter by passing between the filter and the vessel wall. Another limitation appears to be that this umbrella-type device is shallow when deployed so that, as it is being closed for removal, the particles it was able to ensnare could escape. Yet another limitation is that the frame is such that the introduction profile presents a risk of generating emboli as the device is passed through and beyond the clot, occlusion or stenosis. 
         [0020]    U.S. Pat. No. 5,769,816 to Barbut et al. discloses a device for filtering blood within a blood vessel. The device is delivered through a cannula and consists generally of a cone-shaped mesh with apex attached to a central support and open edge attached to an inflation seal that can be deflated or inflated. The seal is deflated during delivery and when delivery is complete, it is inflated to seal the filter around the lumen of the vessel. Limitations of this device include that it is complex to manufacture. Inflation and deflation of the seal adds additional operative steps thus prolonging the operation and introducing the issue again of control, e.g., of how much to inflate to obtain a seal without causing damage to the vessel or other material. While the device may be suitable for large vessels, such as the aorta, is would be most difficult to scale for smaller vessels, such as the carotid or the coronary arteries. 
         [0021]    U.S. Pat. No. 5,549,626 to Miller et al. discloses a coaxial filter device for removing particles from arteries and veins consisting of an outer catheter that can be inserted into a blood vessel and an inner catheter with a filter at its distal end. The filter is a radially expandable receptacle made of an elastic mesh structure of spring wires or plastic monofilaments. When pushed from the distal end of the catheter, the filter deploys across the vessel lumen. A syringe attached to the proximal end of the inner catheter aspirates particles entrapped in the filter. One limitation of this device appears to be that it is possible that some particles will remain in the filter after aspiration such that, when the filter is retracted into the outer catheter, particles not aspirated are undesirably released into the circulatory system. 
         [0022]    U.S. Pat. No. 6,027,520 to Tsugita et al. discloses a method and system for embolic protection consisting of a filter on a guide wire coupled with a separate stent catheter deployed over the guide wire. One limitation of the Tsugita et al. device is that the many filter designs summarized in the patent generally lack a controllable, conformable circumferential support in the mouth of the filters to ensure they seal around the inside of a blood vessel. Without such a seal, it is again possible for particulate material to evade the filter by undesirably passing between the filter and the vessel wall, whereupon the particulate material may flow downstream of the operative or other site to produce full or partial blockage of the vessels. Many of the Tsugita et al. filter expansion devices utilize multiple struts to open the filter. These are not desirable as they increase the profile of the device when crossing a lesion, in turn, reducing the range of clinical cases on which they can be used. Further, such designs add stiffness to the region of the undeployed filter which can impede the surgeon&#39;s ability to direct the guide wire through the complex twists and turns of the circulatory system to the operative site, e.g., making it difficult to direct the device into a branching vessel. Also, the Tsugita et al. design is burdened by its use of a long deployment sheath to hold the filter in a collapsed state and direct it to the operative site. The Tsugita et al. sheath extends from a hemostatic seal at the site of entry into the blood or other vessel to the operative site (see column 7, lines 56-58. and also column 8, lines 19-30 of the Tsugita et al. patent). This long sheath, necessary in the Tsugita et al. design, significantly impairs the ability to direct the guide wire through the circulatory system to the operative site. Not only is such a sheath an impairment to directing the guide wire around the twists and turns of the circulatory system, but such a sheath also “loads” the guide wire, which operates to significantly reduce the Tsugita et al. system&#39;s torquability, greatly reducing the ability of the surgeon to control the guide wire and guide it through tight lesions. 
         [0023]    At column 7, lines 28-32, Tsugita et al. states that its stent may comprise a tube, sheet, wire, mesh or spring, and goes on to state that such a stent can cover the plaque and substantially permanently trap it between the stent and the wall of the vessel. (see column 9, lines 55-58 of the Tsugita et al. patent) However, this is not accurate, and depending upon the type of stent, not only will it not trap such plaque, but plaque can reform through the interstices of the mesh whereupon the vessel can again become fully or partially occluded. 
         [0024]    These shortcomings are present whether the stent is mechanically expandable or self expanding. Relative to mechanically expandable stents, they are delivered with a stent catheter. See U.S. Pat. Nos. 5,507,768; 5,158,548 and 5,242,399 to Lau et al. incorporated herein by reference. The catheter has an inflatable balloon at or near the distal end on which the stent is mounted. An inflation lumen runs the length of the catheter to the balloon. Generally, the stent is a tubular mesh sleeve. See U.S. Pat. No. 4,733,665 to Palmaz incorporated herein by reference. A self-expanding stent is typically made of Nitinol. It is compressed within a catheter until deployment. It is pushed from the catheter to deploy it. Both types of stents tend to create embolic particles. Also, both allow stenotic material to build up through the interstices of the wire mesh that could again occlude the artery. 
         [0025]    Permanent filters for the vena cava are well-established clinical devices. These open filters capture large emboli passing from a surgical site to the lungs. U.S. Pat. No. 3,952,747 to Kimmell, Jr. et al. discloses the Kimray-Greenfield filter. It is a permanent filter typically placed in the vena cava and consists of a plurality of convergent legs in a generally conical array Each leg has a hook at its end to impale the interior wall of the vena cava. U.S. Pat. Nos. that are joined at their convergent ends to an apical hub. U.S. Pat. Nos. 4,425,908 to Simon; 4,688,553 to Metals; and 4,727,873 to Mobin-Uddin are also illustrative of such devices. 
         [0026]    U.S. Pat. Nos. 5,669,933 and 5,836,968 to Simon et al. are illustrative of removable blood clot filters suitable for the venous system, specifically the vena cava. 
         [0027]    However, the presently available capture devices all suffer from the limitation that they are not easily manipulated in the patient&#39;s body. They usually include tube-like sheathing material which extends all along the length of the guide wire used to insert the capture device into the vessel, generally extending from the entry site into the body, also known as an access port or access opening to the operative site, which sheathing operates to contain the capture device until its desired deployment in the vessel beyond the operative site. Such sheathing material operates to reduce torquability of the guide wire used to insert the capture device and operates to significantly reduce the flexibility of wire within the circulatory or other system as noted above. Removal without causing excessive movement of the deployed filter is also a problem. As the sheath is pulled from the access port during removal, the surgeon must continually reposition his hand to hold the wire used to insert the capture device, that is, as the sheath is pulled through the access port, the surgeon must release the wire and then re-grasp further down from the access port. As the surgeon&#39;s hand grasps the wire further from the access port, the more difficult it becomes to steady the guide wire as the sheath is withdrawn. As such, the capture device may move back and forth, and as it is generally at this point in its expanded state, the constant rubbing of the wall of the blood or other vessel or canal by the capturing device may irritate or injure the wall of the blood or other vessel or canal. 
         [0028]    Another complication is that several capture devices include bulky or complex deployment mechanisms, and further, when deployed, fail to fully seal around the interior of the vessel or other wall or fail to prevent unwanted release of captured particles, fragments, objects, emboli, etc., whereupon such particles, fragments, objects, emboli, etc. can undesirably escape and travel beyond the capture device. 
         [0029]    Thus, there is a need in the art for a capture device and methods of constructing and using such device, which is easily threaded through the vessels or canals of humans and/or animals to reach an operative site, which exhibits excellent torquability, flexibility and maneuverability, which is easily removable along with its captured objects once the medical procedure has been completed without injuring or irritating the wall of the vessel or canal, and which forms a seal with the wall of the vessel or canal or otherwise prevents the undesirable escape of particles, fragments, objects, emboli, etc. beyond the capture device during surgery. There also is a need in the art for a system of associating surgical tools with such a capture device to provide protection downstream of an operative site for the capture of objects dislodged and/or freed during the medical procedure. 
       SUMMARY OF THE INVENTION 
       [0030]    The various embodiments and examples of the present invention as presented herein are understood to be illustrative of the present invention and not restrictive thereof and are non-limiting with respect to the scope of the invention. 
         [0031]    According to one non-limiting embodiment of the present invention, a continuous pour concrete slip dowel is disclosed configured for use across a joint between adjacent concrete slabs. The continuous pour concrete slip dowel of the invention includes a slip sleeve configured to be positioned within a first concrete slab, and a main dowel rod having i) a first rod end portion configured to be received within the slip sleeve, ii) a second opposed rod end configured to be received within a second concrete slab which is adjacent the first slab and spaced from the first slab by a intervening joint, and iii) an intermediate coupling rod portion connecting the first rod end with the second rod end, wherein the coupling rod portion defines an offset therein whereby the coupling rod portion is configured to extend around the joint. 
         [0032]    These and other advantages of the present invention will be clarified in the description of the preferred embodiments taken together with the attached figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is a schematic perspective view of a concrete slip dowel in position across a frame member with an expansion joint forming member in accordance with one non-limiting embodiment of the present invention; 
           [0034]      FIG. 2  is a schematic perspective view of the concrete slip dowel of  FIG. 1 ; 
           [0035]      FIG. 3  is a schematic cross sectional view of the concrete slip dowel of  FIG. 1 ; 
           [0036]      FIG. 4  is a schematic cross sectional view of the concrete slip dowel of  FIG. 1  following a continuous pour of adjacent slabs in accordance with the present invention; 
           [0037]      FIG. 5  is a schematic cross sectional view of the concrete slip dowel of  FIG. 1  following a continuous pour of adjacent slabs in accordance with the present invention; 
           [0038]      FIG. 6  is a schematic cross sectional view of the concrete slip dowel of a second embodiment of the present invention following a continuous pour of adjacent slabs in accordance with the present invention; 
           [0039]      FIG. 7  is a schematic perspective view of the concrete slip dowel of  FIG. 6 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    In summary, the present invention relates to a continuous pour concrete slip dowel  10  which is disclosed configured for use across a joint, such as an expansion joint having an expansion member  16  between adjacent concrete slabs  18  and  20 . The construction of the expansion member is known in the art, but generally is formed of a rubber or other elastomeric material to accommodate slab expansion. The continuous pour concrete slip dowel  10  of the invention includes a slip sleeve  12  configured to be positioned within a first concrete slab  18 , and a main dowel rod  10  having i) a first rod end portion configured to be received within the slip sleeve  12 , ii) a second opposed rod end configured to be received within a second concrete slab  20  which is adjacent the first slab  18  and spaced from the first slab  18  by a intervening joint that may include an expansion member  16  or the like, and iii) an intermediate coupling rod portion connecting the first rod end with the second rod end, wherein the coupling rod portion defines an offset, such as through a U-Shaped configuration, therein whereby the coupling rod portion is configured to extend around the joint and around expansion member  16 , if any, via extension into the stone base. As the rod  10  makes up the main component of the entire slip dowel arrangement, the term rod and dowel will be used effectively interchangeably throughout this application. The dowel  10  assembly is inclusive of the slip sleeve  12 . 
         [0041]    The dowel rod  10  can be formed of any suitable material such as from a rebar rod that is bent into the U shape as shown, generally consisting of four ninety degree bends. The U-Shape as shown provides several advantages for manufacturing and for operation. First the U-shape allows for a sufficiently large radius in the bends, such as about 1 inch diameter to the inner surface of the rod in the bent portion, that conventional bending table, bending rolls, or bending presses can be used on a conventional rebar member, from about ¼ inch to 1 inch diameter rebar, to form the rod  10 , without further heat treatment of the bent rod  10 . Obviously, the rod  10  can be made in other methods, such as casting the rod  10  in a desired shape, or by hot working a bar or other known methods; however cold working a rebar member on conventional bending equipment is believed to provide certain cost advantages to the present invention. 
         [0042]    A further advantage of the general U-shape as shown is the minimized contact with the frame member  14  and the expansion member  16 . The minimal contact with these components allows the frame member  14  to be more easily removed after the pour. 
         [0043]    As described above the rod  10  is easily formed by bending or cold working a rebar member of the appropriate length. It can be formed as follows. A ½ inch diameter steel rebar member of the desired length is inserted into a mechanical table bender with about 9-12 inches of the rebar member that will form one end of the rod  10  extending beyond a first bending pin, which may be a two inch diameter pin. The rebar member is bent around the first pin to about ninety degrees, thus forming one end of the rod  12  and the first bend of the U shaped intermediate coupling rod portion. A second pin, such as a two inch diameter pin, is provided on the table and the rebar member is bent around the second pin for 180 degrees (or two 90 degree bends) to form the bottom of the U shaped intermediate coupling rod. A third pin of the same diameter as the first pin is provided on the table and the rebar member is bent around the third pin to form the final upper bend of the U shaped intermediate coupling rod with about 9-12 inches beyond the bend to form the opposed end of the rod. 
         [0044]    A two inch diameter pin for forming the inside of the U shaped intermediate coupling rod allows the rod  10  to easily accommodate a 2×4 wooden frame member  14  and expansion member  16  as it is well known that 2×4 wooden members are, in actuality, less than 2 inches thick. The position of the second pin is such that the height (vertical distance) of the rod  12  from the lower end of the U shaped intermediate coupling rod to the upper side of the end of the rod is about 4 inches to about 6 inches. 
         [0045]    Each end of the rod will extend approximately 9 inch to 12 inches and the ends will preferably be co-axial and about the same length. The co-axial arrangement of the ends of the rod  10  allows the ends to be placed in the middle of the respective slabs  18  and  20 . An overall height of the rod  10  of 4-6 inches allows the rod  10  to be used with most conventional concrete slab thicknesses. The ends of the rod  10  should be extending substantially in the middle of the slab  18  and  20  and perpendicular to the joint. 
         [0046]    In operation the slip dowel  10  of the present invention operates as follows. The dowel  10  is appropriate for use whenever there is a joint between adjacent slabs  18  and  20  to be poured. The concrete contractor will place a plurality of the slip dowels along the line where the joint is to be formed, with the dowels  10  lying on their sides in the stone base  22 . The slip dowels  10  will be aligned with their ends extending parallel to the ends of adjacent slip dowels  10  and perpendicular to the joint. The slip sleeves  12  are loosely on at least one end of each slip dowel  10  rod. 
         [0047]    The frame member  14  with expansion member  16  is placed in position to complete the form. The remaining portions of the frame are not shown but their construction is well known in the art. The frame member  14  and expansion member  16  are placed to effectively extend across the base of the U shaped intermediate coupling rod of each rod  10 . Each rod  10  is then pivoted up about the base of the U shaped intermediate coupling rod to position the frame member  14  and expansion member  16  within the U shaped intermediate coupling rod as shown in the figures, wherein the ends are positioned at a height roughly ½ of the height of the associated slab  18  or  20  to be poured. A pin can be used to secure the dowel rod  10  in the desired position, with the pin driven into the ground and further supporting the frame member  14 , or driven into the frame member  14 . Alternatively the rods  10  can be supported via a concrete chair, which is a small generally plastic support member resting on the bed  22  that will be encased in the respective slab  18  or  20 . At this point each of the dowels  10  should be in a final position with their ends parallel to each other and perpendicular to the joint and about mid-height of the respective slabs  18  or  20 . It should be apparent that the same size dowel can be used for a range of concrete thicknesses as the rotation placement step can adjust the height throughout an entire range of heights up to the full height of the individual dowel rods  10 . 
         [0048]    The next step is to pour the first slab  18  to the expansion member  16  and to continue to pour the adjacent slab  20  in a single continuous pour leaving the frame member  14  in position. The frame member  14  can be removed after the concrete slabs  18  and  20  have begun to firm up or set and the frame member  14  back filled and finished in conventional concrete working fashion. The dowel rods  10  will be encased and secured to one slab  20  and allowed to move relative to the other slab due to the sleeve  12 . 
         [0049]    It should be noted that the leg of the U shaped intermediate coupling rod that is on the side of the sleeve  12  in slab  18  will not be sufficiently secured to the slab  18  to prevent relative motion due to expansion and relative lateral motion of slab  20  to which the rod  10  is secured. This is mainly because the leg of the U shaped intermediate coupling rod is effectively at the edge of the slab  18  and the expansion member  16 , by design, accommodates the associated lateral motion. The U shape is also believed to assist in the relative lateral motion. These factors allow the sleeve  12  to be formed as shown in  FIGS. 1-5 , which is a simple plastic tubular configuration that is currently commercially available. 
         [0050]    An alternative sleeve  12  design is shown in  FIGS. 6-7 , which is designed to assure that the rod  10  can slide in and out of the sleeve  12 . In this modification the end of the sleeve is enlarged to accommodate portions of the U shaped intermediate coupling rod, and will prevent concrete forming slab  18  from attaching to any portion of the rod. The slip dowel  10  of  FIGS. 6-7  operates in the same manner as the dowel of  FIGS. 1-5 , other than the construction of the “wide mouth” sleeve  12 . The modified sleeve of  FIGS. 5-6  could be formed as a one piece molded structure or, alternatively, as a two piece construction. The two piece modified “wide mouth” sleeve  12  construction allows a conventional sleeve  12  to be used with a second add on member forming the “wide mouth” end that receives the U shaped intermediate coupling rod, with the add on portion snapped, glued or otherwise affixed to the first sleeve portion. 
         [0051]    A further addition is that the ends of the rod need not be parallel to each other. The end of the rod opposite from the sleeve could be a zig-zag pattern or the like to facilitate bonding to the concrete slab  20 , if desired. Such a non-linear pattern should be minimal and generally aligned with the axis of the other end to maintain the structure in the middle of the slab  20 . This alternative is only identified to show the range of the present invention, but is not generally believed to be worth the additional fabrication costs. The design as shown in  FIGS. 1-5  represents the most cost effective, simple solution of the present invention. 
         [0052]    Whereas particular embodiments of the invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the spirit and scope of the present invention.