Abstract:
An orthopedic device to register and retain an anatomical position. The device includes a plurality of independently deformable members or one or more support members forming a contact area adapted to contact the body and conform to the anatomical position when placed in contact with the body. One or more adjustment members permit alteration of the contact area either to conform to a neutral anatomical position or to set a desired anatomical position. A locking mechanism is included to lock the adjustment members to retain the shape of the contact area after the body is removed from the contact area. The desired anatomical position may be repeatably established by placing the body in contact with the contact area having the retained shape. A reproducible reference datum may be used to replicate the desired skeletal orientation interoperatively.

Description:
BACKGROUND  
       [0001]     Orthopedic procedures often require precise anatomical positioning. For instance, certain spinal surgical procedures require a fixed, known positioning of the spinal column. Surgeons often strive to place a patient&#39;s anatomy, such as the neck or back in a neutral position (e.g., having an appropriate lordosis or kyphosis) for better access during surgery and/or to place surgical devices or implants. Crude implements such as inflatable pads, saline bags, or rolled-up sections of material are sometimes used in an effort to accomplish this task.  
         [0002]     Other diagnostic and pre-operation procedures may also require a known anatomical positioning. Imaging procedures such as X-Ray, CT or MR imaging provide invaluable information and are often used as a reference during surgical procedures. Positioning markers that appear in the resultant images are sometimes used to help identify reference points. However, the position of these markers as well as the position of the patient&#39;s anatomy should be repeatably established for maximum reliability. The locating markers are more accurate if the anatomical position is the same as when the images were taken. The relevant anatomy should also be stabilized and near-motionless during imaging process to enhance the resultant image quality.  
         [0003]     Further, the relatively recent introduction of motion sparing devices as spinal implants entails a greater degree of positional precision as compared to that needed for fusion technology. Thus, the need for repeatable, accurate anatomical positioning has become even more crucial.  
         [0004]     Accordingly, some effort has been made to use a positioning device to capture a desired anatomical position prior to surgery, perhaps during a consultation visit, and then transfer that position to the operating room table for surgery. However, it is often difficult for surgeons to accomplish this feat because of the bulkiness and lack of repeatable accuracy and adjustability found in conventional devices.  
       SUMMARY  
       [0005]     Embodiments of the present invention are directed to orthopedic positioning devices adapted to capture or register a desired anatomical position. Numerous embodiments are provided, each employing various mechanisms for capturing the desired anatomical position. Embodiments may include a plurality of independently deformable members or one or more support members forming a contact area adapted to contact the body and conform to the anatomical position when placed in contact with the body. One or more adjustment members may be used to permit alteration of the contact area either to conform to a neutral anatomical position or to set a desired anatomical position. A locking mechanism may further be included to lock the adjustment members to retain the shape of the contact area after the body is removed from the contact area. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a profile view of an adult human showing a curvature of the spine that may be registered using one or more embodiments of the present invention;  
         [0007]      FIG. 2  is a schematic illustration of an orthopedic device according to one embodiment of the present invention approximately positioned for registering the head and cervical curvature anatomy of a human subject;  
         [0008]      FIG. 3  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0009]      FIG. 4  is a top view of an orthopedic device according to one embodiment of the present invention;  
         [0010]      FIG. 5  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0011]      FIG. 6  is a top view of an orthopedic device according to one embodiment of the present invention;  
         [0012]      FIG. 7  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0013]      FIG. 8  is a front view of an orthopedic device according to one embodiment of the present invention;  
         [0014]      FIG. 9  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0015]      FIG. 10  is a schematic illustration of an orthopedic device according to one embodiment of the present invention approximately positioned for registering the head and cervical curvature anatomy of a human subject;  
         [0016]      FIG. 11  is an isometric view of an orthopedic device according to one embodiment of the present invention;  
         [0017]      FIG. 12  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0018]      FIG. 13  is an isometric view of an orthopedic device according to one embodiment of the present invention;  
         [0019]      FIG. 14  is a side view of an orthopedic device according to one embodiment of the present invention;  
         [0020]      FIG. 15  is a section view of an orthopedic device according to one embodiment of the present invention;  
         [0021]      FIG. 16  is a side view of an orthopedic device according to one embodiment of the present invention; and  
         [0022]      FIG. 17  is an isometric view of an orthopedic device according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0023]     The present invention is directed to embodiments of orthopedic devices and methods adapted to capture and retain a desired anatomical position. As a non-limiting example, the lordotic curvatures designated LC 1  (cervical) and LC 2  (lumbar) in  FIG. 1  may need to be set, determined, and repeatably transferred to various locations, such as an imaging lab or an operating room. For example, a surgeon may want to capture an existing curvature of an otherwise young, healthy patient. Conversely, the surgeon may wish to set a more “normal” curvature for a patient who is experiencing abnormal, possibly degenerative, curvature (lordotic or otherwise) of the spine. This procedure may be performed preoperatively, anywhere from immediately before to days in advance of surgery. Then, the patient may be placed in contact with the device at later times, such as during an operation, to reproduce the same anatomical position.  
         [0024]     In any case, the present embodiments and methods of using said embodiments are well suited for establishing and repeatably determining an appropriate vertebral spacing and alignment. The devices disclosed herein may also be suitable for capturing desired skeletal and anatomical positions for other parts of the body, including for example, arms, legs, elbows, and knees. Various embodiments of devices adapted to accomplish these functions will now be described with reference to the Figures where corresponding parts are referenced throughout this description by similar numbers.  
       Embodiment 1  
       [0025]     In one embodiment, the orthopedic device is designated generally by the number  10 , as shown in  FIGS. 2, 3  and  4 .  FIG. 2  shows a side view of the orthopedic device used in one particular application to capture or establish a desired cervical lordotic curve. The device  10  may be used to position the patient on the operating room table  11  during surgery to get the proper position for accessing and accurately placing instrumentation, surgical devices, or surgical implants. In addition, the device  10  may be used to register a patient&#39;s neutral head and/or neck position pre-operatively in the supine or standing position so that the desired anatomical position may be transferred into the operating room or imaging lab for the procedure. Advantageously, this device  10  may be a stand-alone item, an item that attaches to a wall, a bed, an operating room table or similar item. Alternatively, the device  10  may be an integral part of any of these items.  
         [0026]     As shown in  FIGS. 3 and 4 , the orthopedic device  10  is constructed as a multi-chambered support pad with a plurality of individual chambers  12 ,  14 ,  16  separated from one another by parting walls or seams  18 . The device  10  has a flexible outer skin that is compliant and adapted to conform to a patient&#39;s anatomy but may also be a semi-rigid material or material that requires the input or removal of a signal, field, or pulse to become compliant. Each of the plurality of individual chambers  12 ,  14 ,  16  is independent of one another and may be separately inflated or filled to achieve a desired shape. Each chamber  12 ,  14 ,  16  is inflatable with a filler substance such as a fluid, including gases or liquids. In one embodiment, the device  10  may include a fluid coupling  20  for connection to a liquid or compressed gas source (not shown), such as in an operating room. In one embodiment, the fluid coupling  20  may be coupled to a portable gas source, such as a refillable tank or disposable carbon dioxide cartridges.  
         [0027]     The end chambers  12 ,  16  are disposed at opposite ends of the device  10 , which is substantially rectangular as shown, but may also be round, oval, square, triangular, or other polygonal shapes. The end chambers  12 ,  16  form opposite ends of the device  10 . The end chambers  12 ,  16  are separated from one another by intermediate chamber  14 . The sides  30  of the device  10  are formed in part by each of the individual chambers  12 ,  14 ,  16 . In one embodiment, end chamber  16  is disposed at a superior end of the device  10  while end chamber  12  is disposed at an inferior end. In one embodiment, end chamber  12  has an interior volume that is slightly larger than end chamber  16 . In another embodiment, end chambers  12 ,  16  have substantially similar interior volumes. A central chamber  14  comprises a hammock section  26  that is suspended at opposite sides  30  of the device  10 . Two open sections  32  are bounded by the hammock section  26  and one of the end chambers  12 ,  16 .  
         [0028]     The device  10  includes a fluid pressure regulating system  22  consisting of individual control valves  34 ,  36 ,  38  for controlling the flow of fluid from the fluid coupling  20  to the individual chambers  12 ,  14 , and  16 , respectively. The control valves  34 ,  36 ,  38  may be actuated to allow pressurized gas or liquid to flow from the fluid source (via coupling  20 ) into the respective chambers  12 ,  14 ,  16 . Further, the same control valves  34 ,  36 ,  38  may also be actuated to release pressurized gas/liquid from the chambers  12 ,  14 ,  16  to the atmosphere or to a scavenging or collection mechanism. In this manner, the control valves  34 ,  36 ,  38  may be used to adjust the size, shape, rigidity and compliance of the individual chambers  12 ,  14 ,  16 . Thus, as shown in  FIG. 2 , end chamber  12  may be inflated to a greater degree than medial chamber  14  or end chamber  16  to capture or impart a desired cervical lordotic curvature and head position in the subject patient. In a similar manner, the anterior or posterior rotation of a limb or head may be controlled by controlling the inflation of the individual chambers  12 ,  14 ,  16 . All control valves  34 ,  36 ,  38  may then be closed to seal the contents of the chambers and retain the desired anatomical position.  
       Embodiment 2  
       [0029]     In another embodiment, an orthopedic device similar to that described in Embodiment 1 is designated generally by the number  40 , as shown in  FIGS. 5 and 6 . The device  40  includes the previously described end chambers  12 ,  16  and sides  30 . However, two intermediate chambers  42 ,  44 , each comprising the aforementioned hammock section  26 , are incorporated into the device. Consequently, three open sections  32  are formed in the device  40 . Naturally, any number of intermediate chambers may be incorporated into the orthopedic devices  10 ,  40 . A corresponding number of hammock sections  26  and open sections  32  will vary as the number of intermediate chambers vary.  
         [0030]     Each of the individual chambers  12 ,  16 ,  42 ,  44  of device  40  includes an inlet port  46  that may be used as a one-time fill port or as an inlet-outlet adjustment port. Further, each of the individual chambers  12 ,  16 ,  42 ,  44  may be filled with a common fluid, gas, or liquid or some combination thereof. In one embodiment, the individual chambers  12 , 16 ,  42 ,  44  may be filled, at the time when the patient&#39;s anatomy is to be captured or set, with a solidifying fluid such as a quick setting polyurethane or polystyrene foam. Thus, the device may be placed adjacent the patient&#39;s anatomy and a suitable amount of the solidifying fluid can be injected into the individual chambers. Once the contents of the chambers  12 ,  16 ,  42 ,  44  harden and cure, the desired anatomy will be advantageously captured. Alternatively, the individual chambers  12 ,  16 ,  42 ,  44  may also be pre-filled or lined with a thermoplastic or thermoplastic elastomer substance, which allows the device  40  to conform to the patient&#39;s anatomy when heated to a predetermined temperature, but which also hardens to retain the desired shape once cooled.  
         [0031]     In the aforementioned embodiments and in the embodiments described below, a reference datum may be used in conjunction with the orthopedic device  10 ,  40  to establish the desired anatomical position. The reference datum may then be used during subsequent anatomical re-positioning as a verification that the desired anatomy is in fact replicated. Those skilled in the art will comprehend that a variety of different measuring reference tools may be used. For instance, a linear measurement to a data point or between surfaces may be taken. To that end, a datum feature  15  may be included on the device  10  as shown in  FIGS. 2, 3 , and  4 . A linear measurement between the datum feature  15  and table  11  may be taken and subsequently verified. Alternatively, a probe may be used to mechanically determine the height of the datum feature. Electrical, acoustical, or optical measuring devices may also be used.  
         [0032]     Another non-limiting example of a reference feature is an inclinometer  35  as shown in  FIGS. 5 and 6 . Whereas the datum feature  15  (shown on device  10 ) may be used to measure linear distances, the inclinometer  35  may be used to determine angular displacements. The inclinometer  35  may be a mechanical, optical, electrical, or fluid filled device. An angular position of a head or limb may therefore be repeatably established by reading the inclinometer  35  output pre-operatively or during an imaging procedure. The patient is then repositioned at a later time (inter-operatively or otherwise) to achieve the same or similar inclinometer  35  output.  
       Embodiment 3  
       [0033]     In one embodiment, the orthopedic device is designated generally by the number  50 , as shown in  FIGS. 7 and 8 . The device  50  comprises a flexible sheet  52  anchored at opposite ends  54 ,  56 . The flexible sheet may be constructed of a flexible polymer or other flexible materials, such as a monomer, a metal, or natural material such as leather. The length of the flexible sheet  52  between the ends  54 ,  56  is generally greater than the straight-line distance between the ends  54 ,  56  so that the flexible sheet  52  buckles upward in a substantially curved configuration. The curvature of the flexible sheet  52  is adjustable via a rack and pinion gear assembly comprising a substantially stationary rack  58  mounted to a rail  62  and an adjustable pinion gear (not specifically shown) operatively coupled to an adjustment knob  60 . The adjustment knob  60  may be rotated in either a clockwise or counter-clockwise direction as indicated by the arrows labeled R. Rotation of the knob  60  causes the knob  60  to move between extended and retracted positions, thereby changing the curvature of the flexible sheet  52 .  
         [0034]     One end  54  (the fixed end) of the flexible sheet  52  is fixedly attached to the rail  62  using a pin, screw, rivet or other suitable attachment means  64 . The opposite end  56  (the free end) of the flexible sheet  52  is coupled, directly or indirectly, to the moveable adjustment knob  60 . The adjustment knob  60  and its integral pinion gear move toward or away from the fixed end  54  as the knob  60  is rotated. The adjustment knob  60  may be locked in place to retain the curvature of the flexible sheet  52  using a dedicated locking device (not specifically shown). Alternatively, the knob  60  may be frictionally locked by the presence of an interference between the rack  58  and pinion gears.  
         [0035]     As shown in  FIG. 8 , the device  50  may include two adjustment knobs  60  disposed at opposite sides of the device  50 . The two adjustment knobs  60  may be tied together such that rotation of one imparts rotation on the other. Thus, either knob  60  may be used to adjust the position of the entire free end  56  of the flexible sheet  52 . Alternatively, the knobs may be tied to separate rack and pinion gear assemblies mounted on separate side rails  62  so as to allow independent adjustment of the sides of the free end  56  of the flexible sheet  52 .  
         [0036]     The device  50  may also include a set of linear bearings  66  that couple the rail  62  to a base plate  68 , which may be mounted onto a table or wall (not shown). Alternatively, the rails  62  may be coupled to a table or wall using the linear bearings  66 . Alternatively, the rails  62  may be coupled directly to a table or wall without any linear bearings  66 . The bearings  66  allow adjustment of the position of the device  50  as a whole. Thus, the device  50  may be repositioned as needed to accommodate patients having a different height or different anatomy.  
       Embodiment 4  
       [0037]     In another embodiment, an orthopedic device similar to that described in Embodiment  3  is designated generally by the number  65 , as shown in  FIG. 9 . In contrast to device  40 , device  65  includes a flexible sheet  52  having two free ends. That is, both ends of the flexible sheet  52  are coupled to adjustment knobs  60 ,  69 . As above, each adjustment knob  60 ,  69  includes an integral pinion gear (not explicitly shown) that mates with a rack  58  mounted on a rail  62 . Thus, rotation of either adjustment knob  60 ,  69  results in a change in the shape of the curved, flexible sheet  52 . This device  65  may advantageously permit fine adjustment of the curvature and position of the flexible sheet  52  without having to move the entire device  65  relative to the item (e.g., table or wall) on which the device  65  is mounted. However, as with device  50 , device  65  may include linear bearings  66  or other adjustment means allowing for gross position adjustment.  
       Embodiment 5  
       [0038]     In one embodiment, the orthopedic device is designated generally by the number  70 , as shown in  FIGS. 10, 11 , and  12 . The device  70  comprises a flexible sheet  72  anchored at opposite ends  74 ,  76  to a base  75  (see  FIG. 12  in particular). The flexible sheet  72  covers a plurality of laterally extending rollers  78 , each of which are supported by independent adjustment mechanisms  80 . Thus, as shown by the Cartesian coordinate system labeled X-Y-Z in  FIG. 11 , each of the rollers  78  is independently adjustable in either the Y-direction or the Z-direction. In general, the rollers extend substantially in the X-direction parallel to the base  75 , which resides substantially in the X-Z plane. The flexible sheet  72  is comprised of a pliable material that is thick enough to supportably follow the contours of the rollers  78  beneath the flexible sheet  72  as well as the contours of a patient&#39;s anatomy above the flexible sheet  72 . Plastic or polymer materials may be suitable for such a purpose.  
         [0039]     The individual adjustment mechanisms  80  include extending or telescoping support members  82  that move the rollers  78  in the Y-direction. The support members  82  extend between the rollers  78  and a base member  84 . The support members  82  may be threaded, pneumatic, or spring biased to impart motion to the rollers  82  in the Y-direction. The position of each individual roller  82  in the Y-direction is set by manipulating an actuator  86  that serves to control the appropriate translation mechanism (e.g., threads, air pressure, spring-bias lock, etc. . . . ). Similarly, the position of each adjustment mechanism  80  in the Z-direction is set by manipulating an actuator  88  that serves to control that appropriate translation mechanism, which may also comprise pneumatic, spring biased, or threaded mechanisms. The actuators  86 ,  88  may inherently function as locking members, but dedicated locking mechanisms (not shown) may be appropriate and perhaps even desirable for added stability. Appropriate locking mechanisms will vary according to the translation mechanism implemented and are known by those skilled in the art. Some non-limiting examples include friction locks, gear locks, pins, clamps, seals (in the case of pneumatic devices), and the like.  
         [0040]     In practice, this device  70  may be mounted to a wall or mounted or laid to rest on a table. The subject anatomy is then brought into contact with the flexible sheet  72  and the actuators  86 ,  88  are then manipulated to adjust the position of the individual rollers  78 , and consequently the flexible sheet  72 , to closely match the anatomy. Alternatively, the rollers  78  may be adjusted to impart a desired position different than the existing neutral position for the subject anatomy.  
       Embodiment 6  
       [0041]     In one embodiment, the orthopedic device is designated generally by the number  90 , as shown in FIGS.  13 , 14 , 15 , and  16 . The device  90  resembles a pillow and comprises a flexible sheet  92  that covers an array of blunted or rounded pins  96 . Initially, the pins  96  are held in place in an extended first position by a perforated base  98 , as shown in  FIGS. 14 and 15 . However, each pin  96  is moveable or retractable through the perforated base  98  into a second position in the suspension base  100  (see  FIG. 16 ). The suspension base  100  provides space into which the pins  96  may retract under the influence of pressure applied to the flexible sheet  92 . The fit between the individual pins  96  and the perforated base  98  is advantageously sufficiently tight to allow the pins  96  to move, but simultaneously offers enough resistance to require a pressure to move the pins  96 .  
         [0042]     A dedicated locking mechanism may be employed (as shown in  FIG. 16 ) to secure the pins in their relative positions. In one embodiment, the locking mechanism is a magnetic brake or other suitable lock, such as a friction lock or clamp that is activated by an actuator  102 . Alternatively, the suspension base  100  may be filled with a curable liquid  104  such as a quick-set epoxy or light-curable liquid to maintain the position of the pins  96 . Where a dedicated locking mechanism is used, it may be desirable to bias the individual pins  96  toward the flexible sheet  92  to facilitate the registration process. Thus, as a patient settles the target anatomy into the desired position against the device  90 , the pins  96  are pushed against the anatomy even after unintentional inward deflections of the pins  96 .  
         [0043]     As with other embodiments described above, the orthopedic device  90  may be used to capture or register a desired anatomical position. The patient (standing or lying) is brought into contact with the device  90  with the desired anatomy in the desired position. The desired position may be a natural or neutral position or a target position. As the patient contacts the device  90 , the pins  96  retract into the suspension base  100 . Then, once the pins are secured in position with the appropriate locking mechanism (e.g., actuator  102 , curing material  104 ), the patient may simply lift the desired anatomy off the device  90 . At this point, the flexible sheet  92 , which follows the contour formed by the top of the pins  92 , forms a negative of the desired anatomical position. In one embodiment, the pins directly contact the patient and there is no flexible sheet  92 .  
       Embodiment 7  
       [0044]     In one embodiment, the orthopedic device is designated generally by the number  110 , as shown in  FIG. 17 . The device  110  comprises a flexible, compliant bladder  112  filled with a Magneto-Rheological (MR) Fluid  118 , which is a suspension of micron-sized, magnetizable particles in a carrier fluid. Normally, MR fluids are free-flowing liquids having a consistency similar to that of motor oil. However, when a magnetic field is applied, their rheology changes to a consistency similar to putty. MR fluids having properties suitable for this application are available from Lord Corporation in Cary, N. C. The bladder  112  is contained within a frame  114 , which advantageously holds the bladder  112  in place while providing an opening  116  into which the desired anatomy may be positioned. Clearly, different frame  114  and bladder  112  configurations may be used for different anatomy parts, adults, children, and so on.  
         [0045]     The device  110  further comprises a control box  120  from which positive (+)  122  and negative (−)  124  leads are electrically coupled to magnetizing terminals  126  positioned on the frame  114 . The controlling function may also be implemented in a controller (not shown) implemented directly on or attached to the frame  114 . The magnetizing terminals  126  may comprise plates that are opposed to one another so that the presence of an energy source provided by the control box  120  via the leads  122 , 124  creates a magnetic field between the terminals  126 . The resulting magnetic field is advantageously strong enough to cause the MR fluid  118  to solidify in its present shape.  
         [0046]     In practice, the desired anatomy is placed in the desired position on or against the bladder  112  and the uncharged MR fluid  118  flows to conform to the desired anatomy. Once the appropriate position is achieved, the control box  120  is activated to impart a magnetic field on the MR fluid  118  to retain the desired shape. Rechargeable battery sources (not shown) may be coupled to the control box  120  (and hence, the magnetic terminals  126 ) to retain the desired shape for an extended period of time at least until the desired contour is no longer needed. Furthermore, the use of rechargeable batteries enhance the portability of the overall device  110 .  
         [0047]     In each of the above embodiments, suitable materials for the orthopedic devices  10 ,  40 ,  50 ,  65 ,  70 ,  90 , and  100  may include aluminum, plastic resin, or some other radiolucent materials. Alternatively, to create a distinctively different object during imaging processes, radio-opaque materials may be used to distinguish the subject anatomy.  
         [0048]     The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. For example, while the various embodiments have been described as discrete entities, the characteristics of each embodiment may be combined to form even more embodiments. For instance, the MR fluid may also be suitably implemented in the multi-chamber devices discussed above. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.