Abstract:
An apparatus ( 10 ) having a hoop ( 20 ) housed within a sheath ( 14 ) operable to be extended therefrom using a plunger ( 22 ) for placement about a joint ( 12 ) to obtain a measurement associated with the joint ( 12 ). The hoop ( 20 ) is of a resilient material and configured for insertion into a patient using a minimally-invasive surgical technique so as to obtain a precise measurement of the joint ( 12 ) while minimizing trauma to the patient.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Embodiments of the present invention relate to apparatus and methods of sizing a body part in a surgical environment. More particularly, embodiments of the present invention present a hoop that is, upon extension from a sheath and arthroscopic insertion into a body, extendable about an outer or inner perimeter of a bone to yield a measurement of the bone for sizing a subsequently-installed implant. 
         [0003]    2. Related Art 
         [0004]    The human body contains a large number of joints with varying complexity. The hip and knee joints are two of the most complex joints in the body. Because these joints are weight bearing, they are highly susceptible to damage. The ends of bones associated with the hip and knee joints, as well as many other joints, are coated with articular cartilage, which is smooth and hard, so as to provide the associated bones with a slick surface during normal movement. The articular cartilage has a very low coefficient of friction and can also receive large compressive loads, which makes it vital to ensure ease of movement of the joints and prevent bone on bone contact therebetween. Normal articular cartilage is about 50 times slicker than ice. 
         [0005]    Over time, the articular cartilage on bones wears and degenerates, such that it thins or in some joints is completely lost. This is particularly problematic for weight-bearing joints such as the hip and knee. Upon wear of the articular cartilage, the slick, low friction surfaces from the cartilage are lost, and the ends of bones are exposed. Without any protecting articular cartilage, the bones contact each other. This bone on bone contact is painful and is often the end result of osteoarthritis. Additionally, bones can also become hard and sclerotic over time with associated loss of articular cartilage, which further increases the pain. 
         [0006]    Many methods have been developed to either replace worn cartilage or otherwise minimize the pain associated with the loss of the articular cartilage. The methods have varying degrees of success but are often accompanied by very extensive and invasive surgery. All invasive methods are costly, often requiring implanting nonbiologic parts within the knee, or, in some instances, human cadaver parts. These methods of treatment also require lengthy rehabilitation, which often leaves the patient in considerable pain. 
         [0007]    One method of treatment that has been used is implantation of cadaver menisci. This method has had only limited success and multiple failures. A second method is chondroplasty, or removal of and thinning out the existing damaged cartilage. This method is used to smooth the cartilage to reduce the friction between the bones and remove the flaps of cartilage that have delaminated from the bone. The success of this procedure is limited by the amount of cartilage remaining, and doctors guard against removal of too much of the articular cartilage so as to prevent exposure of the subchondral bone. For older patients or patients with traumatic arthritis of their knees, chondroplasty has only limited application because of the lack of healthy articular cartilage. 
         [0008]    If the articular cartilage loss is small, an osteochondral autograft transplant (known as an OATS procedure) can be performed. The OATS procedure requires removing a dowel shaped portion of bone and replacing it with a commensurate dowel shaped portion of articular cartilage from another area of the joint or even a cadaver. The OATS procedure is relatively invasive, has a fairly lengthy rehabilitation time, and has only limited success. 
         [0009]    An even further alternative to repairing articular cartilage damage is growing the patient&#39;s own cartilage in tissue cultures and placing the newly grown cartilage in the areas of cartilage loss. This is an expensive and often unsuccessful method of treatment. 
         [0010]    In the most extreme cases of arthritis, the joint may be artificially resurfaced or even replaced. In artificial joint replacement, the ends of the bones are capped with plastic or metal pieces that are cemented to the ends of the bone. Alternatively, the ends of the bones can be replaced with a biologic ingrowth coating of the metal used, which removes the need for the cement. This procedure is presently the standard approach to treating severe osteoarthritis of the knee. 
         [0011]    In most of these procedures, it is desirable to measure one or more of the bones associated with the joint to, for instance, correctly size an implant for use therewith. The standard approach to obtaining such a measurement is utilizing calipers to measure a diameter of the bone. Given that bones are generally not perfectly round, it is necessary to make a number of measurements about a surface of the bone using the calipers and, thereafter, reduce such measurements to a single estimated measurement of the bone. This process of measuring the bone is imprecise, which may result in installation of an implant that is improperly sized with respect to the bone. If the implant is too small, the implant may, for instance, be incapable of absorbing weight transferred from bones associated with the joint and the lifespan of the implant may be shortened by premature failure of the implant. If the implant is too large, the implant may, for instance, interfere with soft tissue adjacent to the implant, which subjects the patient to undue pain. Additionally, this process of measuring the bone is quite invasive and requires an excessive amount of time, which increases trauma to the patient and extends rehabilitation time. 
         [0012]    Accordingly, there is a need for a relatively more precise, more efficient, and less invasive apparatus and method for measuring a human bone. The present invention solves the above-described problems and provides a distinct advantage in the art of medical treatments associated with joints. More particularly the present invention provides a new apparatus and method to precisely measure a human bone, body part, footprint, or other area in a manner that is minimally invasive with minimal trauma so that an implant may be appropriately sized prior to deployment of the implant within the patient. 
       SUMMARY 
       [0013]    The following brief summary is provided to indicate the nature of the subject matter disclosed herein. While certain aspects of the present invention are described below, the summary is not intended to limit the scope of the present invention. Embodiments of the present invention provide an irrigation system and method that does not suffer from the problems and limitations of conventional irrigation systems such as those set forth above. 
         [0014]    Embodiments of the present invention provide an apparatus having a sheath, a hoop housed in a sheath, and a plunger coupled with the sheath and operable to extend the hoop about a joint to obtain a measurement associated with the joint. 
         [0015]    In more detail, embodiments of the present invention provide a housing structure that defines a chamber, a selectively configurable hoop housed within the chamber and operable to be extended from the chamber, and a controller connected to the hoop, wherein the controller is operable to cause the hoop to be extended from and retracted into the chamber. A position of the controller relative to the housing structure indicates a measurement of at least a portion of a perimeter of the bone. 
         [0016]    The hoop may be selectively configurable between a stored configuration in which a majority or an entirety of the hoop is retracted into the chamber and a use configuration in which the hoop is at least partially extended out of the chamber. The hoop may have a configuration defined by a degree of extension of the hoop from the chamber. The hoop may have a circumference defined by the position of the controller relative to the housing structure. A size of the hoop may be determined by how far the hoop is extended from the chamber. The hoop may be of a resilient material such that, when the hoop is at least partially extended out of the chamber, an extended portion of the hoop is generally circular in shape. 
         [0017]    The controller may include an elongated rod extending from a first end of the housing structure. The rod may be operable to extend and retract the hoop out of and into a second end of the housing structure. The rod may include indicia thereon operable to indicate the measurement based on the position of the controller relative to the housing structure. 
         [0018]    The apparatus may further include a closure on the first end of the housing structure to form a seal therebetween. The closure may include a slit therethrough that is sized and shaped to slidably receive a portion of the rod to permit connection of the rod to the hoop within the chamber of the housing structure. 
         [0019]    Embodiments of the present invention also provide a method of measuring a bone including the steps of providing an apparatus having a housing structure, a chamber within the housing structure, and a hoop housed within the chamber in a first configuration; positioning the apparatus adjacent to a bone; manipulating a controller secured to the housing structure to cause the hoop to be at least partially extended from the chamber and toward the bone so that the hoop assumes a second configuration; and observing indicia on the apparatus based on a position of the controller relative to the housing structure to obtain a measurement of the bone. 
         [0020]    The first configuration of the hoop may be a compressed configuration in which a majority or an entirety of the hoop is retracted into the chamber and the second configuration of the hoop may be a use configuration in which at least a portion of the hoop is extended out of the chamber and the portion of the hoop has a decompressed configuration. The decompressed configuration of the portion of the hoop may have a generally circular shape. 
         [0021]    The method may further include the step of calibrating the indicia based on whether an interior perimeter or an exterior perimeter of the hoop is to be used to measure the bone. The second configuration of the hoop may include a relationship to the bone that is one of (i) about an outer circumference of the bone, (ii) about an inner circumference of the bone, and (iii) substantially aligned with a footprint of the bone. The second configuration of the hoop may have a variable metric that is defined by a degree of extension of the hoop from the chamber. The variable metric may be a circumference or diameter of the hoop. The controller may include an elongated rod extending from a first end of the housing structure. The rod may be operable to extend and retract the hoop out of and into a second end of the housing structure. The housing structure may include a closure at a first end of the housing with a slit through the first end of the housing. The slit may be sized and shaped to slidably receive a portion of the rod to permit connection of the rod to the hoop within the chamber of the housing structure. 
         [0022]    Additional aspects, advantages, and utilities of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein: 
           [0024]      FIG. 1  is an elevated side view of an apparatus having a hoop extended from a sheath and engaged with a detracted or dislocated femur head of a hip joint, in accordance with an exemplary embodiment of the present invention, with the apparatus in phantom in a disengaged orientation; 
           [0025]      FIG. 2  is a top left rear side perspective view of the apparatus illustrated in  FIG. 1  with the hoop substantially extended; 
           [0026]      FIG. 3  is a top left front side perspective view of the apparatus illustrated in  FIG. 1  with the hoop substantially retracted; 
           [0027]      FIG. 4  is a bottom right front side perspective view of the apparatus illustrated in  FIG. 1  with the hoop substantially retracted; 
           [0028]      FIG. 5  is a top left front side perspective view of the apparatus illustrated in  FIG. 1  with the hoop extended about the joint; 
           [0029]      FIG. 6  is a bottom right front side perspective view of the apparatus illustrated in  FIG. 1  with the hoop partially extended; 
           [0030]      FIG. 7  is a top plan view of the apparatus illustrated in  FIG. 1  with the sheath in cross-section and the hoop substantially retracted therein; 
           [0031]      FIG. 8  is a top plan view of the apparatus illustrated in  FIG. 1  with the sheath in cross-section and the hoop partially extended therefrom; and 
           [0032]      FIG. 9  is a top left rear side perspective view of the apparatus illustrated in  FIG. 1  with a sleeve exploded from the sheath. 
       
    
    
       [0033]    The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. 
       DETAILED DESCRIPTION 
       [0034]    Turning now to the drawing figures, and particularly  FIG. 1 , a sizing apparatus  10  for a bone constructed in accordance with embodiments of the present invention is illustrated. The apparatus  10  is configured to be utilized with any bone, e.g., bones associated with a knee or hip joint. The apparatus  10  is operable to measure an exterior surface of the bone, e.g., an outer perimeter or circumference of the bone, an interior surface of the bone, e.g., an inner perimeter, concavity, or socket of the bone, or an area related to the bone, e.g., a footprint of the bone or space between bones. In this manner, the apparatus  10  provides precise sizing for an implant to be subsequently installed on or otherwise utilized with the bone. Embodiments of the present invention will be discussed in use with respect to a detracted or dislocated femur head of a hip joint  12 , although it is to be understood that the present invention is equally useable with other joints. 
         [0035]    The apparatus  10  of the exemplary embodiment of the present invention broadly includes a sheath  14  within a sleeve  16  that cooperatively defines a patient or distal end  18  of the apparatus  10 , and a band or hoop  20  that is selectively extendable from the sheath  14  via a telescoping controller or plunger  22 . The plunger  22  extends from a surgeon or proximal end  24  of the apparatus  10  to permit manipulation of such by a user or surgeon. In this manner, the surgeon may introduce the hoop  18  into a patient via arthroscopic insertion and maneuver the hoop  18  to measure the actual joint  12  and/or an area related to the joint  12 . A size of the hoop  18 , particularly a circumference or diameter of the hoop  18 , may be varied by expanding and retracting the hoop  18  via the plunger  22  to perform the measurement. For instance, the hoop  18  may be cinched tightly around the joint  12  via the plunger  22  to yield an outer circumferential measurement of the joint  12 . 
         [0036]    Turning to  FIGS. 2-8 , the sheath  14  includes an elongated cylindrical sheath wall  26  having interior and exterior surfaces  28 ,  30 . The sheath wall  26  defines a sheath chamber  32  that is sized and shaped to house a majority and preferably an entirety of the hoop  20 . It is foreseen, however, that the chamber  32  may house any portion of the hoop  20  without deviating from the scope of the present invention. 
         [0037]    The chamber  32  has an open end  34  at an end of the sheath  14  adjacent to the patient end  18  of the apparatus  10 , and a closed end  36  at an end of the sheath  14  adjacent to the surgeon end  24 . In the exemplary embodiment, the sheath  14  is made of stainless steel. It is foreseen, however, that the sheath  14  may be made of any like material that is durable and easily sterilized without deviating from the scope of the present invention. 
         [0038]    The closed end  36  of the sheath  14  is closed by a cap or closure  38  to form a seal therebetween. The closure  38  includes a top wall  40  with upper and lower surfaces  42 ,  44 , and a circumferential edge  46  thereabout. Extending through the upper and lower surfaces  42 ,  44  is a slit  48  that will be discussed hereafter. In the exemplary embodiment, the closure  38  is formed integrally with the sheath  14  using the same material as the sheath  14 , that is, stainless steel. It is foreseen, however, that the closure  38  may be selectively removable from the sheath  14  to, for example, permit access to the sheath chamber  32  without deviating from the scope of the present invention. It is further foreseen, however, that the sheath  14  may be made of any like material that is durable and easily sterilized without deviating from the scope of the present invention. 
         [0039]    The sleeve  16  includes an elongated cylindrical sleeve wall  52  having interior and exterior surfaces  54 ,  56 , as illustrated by  FIG. 9 . The sleeve wall  52  defines a sleeve chamber  58  that is sized and shaped to slidably receive the sheath  14  therein. The sleeve chamber  58  has a first open end  60  at an end of the sleeve  16  adjacent to the patient end  18  of the apparatus  10 , and a second open end  62  at an end of the sleeve  16  adjacent to the surgeon end  24 . When fitting the sleeve  16  over the sheath  14 , the interior surface  54  of the sleeve  16  is configured to slide along the exterior surface  30  of the sheath  14  until the cylindrical sleeve wall  52  abuts the lower surface  44  of the closure  38 . In this manner, the sleeve  16  is both removably and slidably secured to the sheath  14 . 
         [0040]    The sheath  14  and sleeve  16  are similarly sized and shaped and, in the exemplary embodiment, are generally oval in shape across a width of the sheath  14  and sleeve  16  and are preferably approximately six inches long and a half inch wide. It is foreseen, however, that sheath  14  and sleeve  16  may be sized and/or shaped differently, such as but not limited to circular or rectangular, without deviating from the scope of the present invention. 
         [0041]    The hoop  20  is a cable having first and second connecting ends  80 ,  82 . Each of the ends  80 ,  82  are secured together at a common end  84  of the plunger  22  via welding or the like. In this manner, the hoop  20  forms an enclosed area  86  and includes an outermost perimeter  88  and an innermost perimeter  90 , as best illustrated in top-plan view  FIG. 8 . The hoop  20  is manufactured from woven stainless steel or the like having two millimeter diameter and a degree of resiliency that causes the hoop  20  to assume a configuration depending on a position of the hoop  20  in relation to the sheath chamber  32 . In this manner, the hoop  20  is selectively configurable between a first stored configuration and a second use configuration using the plunger  22 . 
         [0042]    In the stored configuration, the hoop  20  is completely retracted into the sheath chamber  32  with the interior surface  28  of the sheath chamber  32  abutting the outer perimeter  88  of the hoop  20  so that the hoop  20  is compressed by the sheath  14  into a generally oval shape. In the use configuration, the hoop  20  is at least partially extended from the sheath chamber  32 . The resiliency of the hoop  20  causes an extended portion of the hoop  20  to decompress and assume a generally circular shape while a retracted portion of the hoop  20  remains compressed by the sheath chamber  32 , as respectively illustrated in  FIGS. 7 and 8 . 
         [0043]    The extended portion of the hoop  20 , and particularly the enclosed area  86  thereof, has a variable circumference that may be increased and decreased by respectively extending or retracting the hoop  20  with respect to the sheath chamber  32  to accommodate a wide variety of variously-sized joints. It is foreseen that the hoop  20  may be replaced, in its entirety, with longer or shorter hoops, so that apparatus  10  may be used with body parts. For instance, the hoop  20  is of an ideal length for use with the hip joint  12  while a relatively shorter hoop may be better suited for use with a knee joint. 
         [0044]    The length of the sheath  14  is determined based on the length of the hoop  20 , to enable the sheath chamber  32  to house the hoop  20  in its entirety when fully retracted therein by the plunger  22 . The hoop  20  to sheath  14  ratio is preferably 1:2, and more preferably approximately 1:1.75. 
         [0045]    The connecting ends  80 ,  82  of the hoop  20  are secured to the end  84  of the plunger  22 , and particularly to an elongated rod  96  of the plunger  22 . The rod  96  extends through the slit  48  in the closure  38  and is joined with the ends  80 ,  82  of the hoop  20  within the sheath chamber  32 . The rod  96  extends longitudinally from the sheath chamber  32 , through the slit  48 , and to another end  98  of the plunger  22 . The rod  96  includes opposing side surfaces  100 ,  102  and opposing top and bottom surfaces  104 ,  106 . In the exemplary embodiment, the side surface  100  and the top surface  104  has measurement indicia  108 , which includes one or more hatch marks  110  and one or more corresponding numerals  112  that relate to centimeters and/or millimeters. It is foreseen, however, that any one or more of the surfaces  100 ,  102 ,  104 ,  106  may include measurement indicia  108  having marks  110  or numerals  112 , or both without deviating from the scope of the present invention. 
         [0046]    The slit  48  and rod  96  are sized and shaped to tightly yet slidably mate with each other so as to not compromise the integrity of the seal between the sheath  14  and the closure  38 . The rod  96  is slidable with respect to the slit  48  along an entire length of the rod  96  between a maximum degree of extension, in which the rod  96  is almost entirely extended from the sheath  14  and substantially exposed from the sheath  14 , and a minimum degree of extension, in which the rod  96  is entirely extended into the sheath  14  and substantially concealed within the sheath  14 . 
         [0047]    The minimum degree of extension is defined by a handle  114  at the end  98  of the plunger  22 . The handle  114  defines the surgeon end  24  of the apparatus  10 , and includes upper and lower surfaces  116 ,  118  with a common perimeter  120 . The lower surface  118  of the handle  116  includes a connecting surface  122  that connects to the rod  96 . The upper and lower surfaces  116 ,  118  have a common contour. On either side of the connecting surface  122  are lower inward bends  124 ,  126 , that each translate to outward bends  128 ,  130  on the upper surface  116 , respectively. Between the outward bends  128 ,  130  on the upper surface is a depressed level surface  132  that is opposite to the connecting surface  122 . 
         [0048]    The handle  114 , and particularly the lower surface  126  thereof, is operable to abut the closure  38 , and particularly the upper surface  42  thereof, when the rod  96  is entirely extended into the sheath  14  and substantially concealed therein. In this manner, the handle  114  provides a backstop, thereby preventing the rod  96  from extending completely into the sheath  14 . The maximum degree of extension is defined by the hoop  20 , which has a circumference greater than a width of the slit  48 . In this manner, the hoop  20  provides a backstop, thereby preventing the rod  96  and hoop  20  from extending completely out of the sheath  14 . 
         [0049]    An exemplary use of the apparatus  10  during arthroscopic surgery of joint  12  will now be described. With the plunger  22  fully extended and the hoop  20  fully retracted into the sheath chamber  32 , the surgeon aligns the patient end  18  with a small incision made on a skin surface of the patient adjacent to the joint  12 . Preferably, the sleeve  16  is secured to a receiver that stabilizes the apparatus  10  with respect to the patient and allows a tip of the sleeve  16  to extend slightly through the incision into the patient. The apparatus  10  may be disconnected from the sleeve  16  to facilitate connection of the sleeve  16  with the receiver and subsequently reconnected therewith post connection. 
         [0050]    Upon stabilization of the apparatus  10 , the surgeon manipulates the plunger  22  using the handle  114  to cause the hoop  20  to be arthroscopically inserted into the patient and in closer proximity to the joint  12 . During insertion, the hoop  20  remains compressed by the sheath chamber  32  until the hoop  20  passes through the incision and out of the sheath chamber  32 , at which point, the resilient material of the hoop  20  allows it to decompress into a generally circular shape. It is foreseen that friction reducing lubricant or fluid may be utilized to facilitate insertion of the hoop  20  via a fluid line attached to the apparatus  10 . Alternatively, the fluid may be inserted into the patient prior to use of the apparatus  10 . The seal between the sheath  14  and closure  38  is operable to prevent escape of any such fluid as well as any bodily fluid of the patient. 
         [0051]    The contours of the handle  114 , and particularly the bends  124 ,  126  and surface  132  of the handle  114 , facilitate secure grasping of the handle  114  by the surgeon with one hand while the other hand grasps the sleeve  16  and the closure  38 . To observe movement of the hoop  20 , the surgeon may utilize a small fiberoptic camera or arthroscope inserted into another small incision in the patient. 
         [0052]    In the exemplary embodiment, the hoop  20  is maneuvered to fit around an outer circumference of joint  12 . While maneuvering the hoop  20 , it may be necessary to further extend or retract the hoop  20  using the plunger  22  to adjust the size of the enclosed area  86  in view of the outer circumference of the joint  12 . Additionally, it may be necessary to pivot the apparatus  10 , as illustrated in  FIG. 1 , to lasso the joint  12 . Once the joint  12  is within the enclosed area  86  and the hoop  20  surrounds the joint  12 , the hoop  20  is cinched around the joint  12  by extending the plunger  22  away from the sheath  14 . The surgeon, after ensuring that the hoop  20  is sufficiently cinched around the joint  12  via the arthroscope, may then observe the indicia  108  on the rod  96  to learn the precise measurement of the joint  12 . For instance, if the numeral  112  of the indicia  108  most approximate to the closure  38  is fourteen, as illustrated in  FIG. 2 , then it is known that the circumference or diameter of the joint  12  is fourteen centimeters or millimeters. For more precise measurements, the marks  110  may be used in combination with the numerals  112 . 
         [0053]    The measurement of the joint  12  may then be recorded and the hoop  20  and apparatus  10  removed from the patient so that an appropriately-sized implant may be matched for use with the joint  12  and installed in the patient. The sleeve  16  may be disconnected from the apparatus  10  and remain attached to the receiver for use with subsequent procedures. 
         [0054]    The surgeon may perform additional measurements on adjacent portions of the joint  12 . For instance, the hoop  20  may be utilized to measure the inner circumference of an acetabulum, that is, a concave surface of a pelvis that receives the joint  12 . It is foreseen that other measurements may be used in lieu of or in addition to measurement of an outer circumference. For instance, the measurement of the inner circumference as well as measurement of a footprint of a joint, for instance, in knee surgery. Particularly, U.S. Pat. No. 7,976,578 to Marvel, the disclosure of which is incorporated herein by reference in its entirety, discloses a buffer for placement in a human knee between the femur and tibia. The present invention may be utilized to measure the area between the femur and tibia prior to insertion of the buffer, so that an appropriately-sized buffer may be placed therebetween. 
         [0055]    It is foreseen that it may be necessary to calibrate the apparatus  10  depending on the manner in which the hoop  20  is used to measure objects. For instance, measurements of inner and outer circumferences may require a slight adjustment of the indicia  108  to account for the width of the hoop  20 . The indicia  108  may include additional marks  110  and/or numerals  112  to account for the manner in which the hoop  20  is used to measure objects. For instance, additional marks  110  and/or numerals  112  that account for the width of the hoop  20  may be placed on any one or more of the used or unused surfaces  100 ,  102 ,  104 ,  106  without deviating from the scope of the present invention. 
         [0056]    In this manner, the present invention provides an efficient method to precisely measure a bone, body part, footprint, or other area in a manner that is minimally invasive with minimal trauma so that an implant may be appropriate sized prior to deployment of the implant within the patient. Although the present invention has been described with reference to the preferred embodiment illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the present invention as recited in the claims. 
         [0057]    Having thus described the preferred embodiment of the present invention, what is claimed as new and desired to be protected by Letters Patent includes the following: