Patent Publication Number: US-2005124919-A1

Title: Measuring device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      Not Applicable  
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT  
      Not Applicable  
     BACKGROUND OF THE INVENTION  
      The present invention relates to a measuring device for measuring a body part of a patient, more particularly a measuring device which can be used to create a computer model of the body part useful in the manufacture of a custom-made brace or the diagnosis of a bodily condition.  
      Surgery, injury or disease to joints and other parts of the body may require the support provided by a brace or similar device. Braces of varying designs may be used to support a patient&#39;s knee, elbow, shoulder, ankle, lower back, neck or other part of the body.  
      Off-the-shelf products are often the quickest and most cost-effective to obtain. Off-the-shelf braces may be available in different sizes and typically are adjustable to obtain an acceptable fit.  
      Custom-made braces manufactured to the individual measurements of a particular patient may offer a better fit than off-the-shelf products. A plaster or fiberglass mold of the joint or body part is sometimes used in building a custom-made brace. However, creating a mold is often a lengthy and messy procedure. In addition, the manufacturer of the custom-made brace must have physical access to the mold.  
      Measurements of the joint or body part are sometimes used in building a custom-made brace. However, most body parts are not regular in shape, thus compounding the problem of making repeatable or meaningful measurements. These measurements also often lack context, or information as to how the measurements relate to each other or a physical landmark.  
      As described below, the present invention is directed to a measuring device which can provide data sufficient to create a three-dimensional model of a body part without the need for making a mold or making several disparate measurements. These and other objects and advantages of the invention will be described below in connection with the appended drawings illustrating the preferred embodiments of the invention.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is directed towards a measuring device, in one embodiment comprising: a reference component capable of being secured to a body part of a patient and providing a reference point; an articulated measurement arm movably coupled to the reference component, the articulated measurement arm having a plurality of sections, each section having a measurement point; and a plurality of sensors associated with the measurement points, the sensors capable of providing a plurality of data sufficient to allow determination of a position of each measurement point relative to the reference point.  
      In another embodiment measuring device comprises: a femoral component capable of being secured to a leg of a patient and providing a reference point; a tibial component movably coupled to the femoral component, the tibial component capable of being secured to the leg, the tibial component having a first sensor capable of providing data sufficient to determine a position and an orientation of the tibial component with respect to the femoral component; a first measurement arm movably coupled to the femoral component, the measurement arm having a first measurement point capable of being brought into contact with the leg, the first measurement arm having a second sensor capable of providing a plurality of data sufficient to determine a position of the first measurement point with respect to the femoral component; and a second measurement arm movably coupled to the tibial component, the second measurement arm having a second measurement point capable of being brought into contact with the leg, the second measurement arm having a third sensor capable of providing a plurality of data sufficient to determine a position of the second measurement point with respect to the tibial component; wherein the first measurement point and the second measurement point are capable of being in contact with the leg simultaneously.  
      A method for generating a three-dimensional model of a body part, comprising: establishing a reference point associated with a physical landmark of the body part; bringing a plurality of measurement points into contact with the body part, wherein each of the measurement points is in contact with the body part simultaneously, wherein each of the measurement points is mechanically coupled to the reference point; using a computer to collect data from a plurality of sensors associated with the measurement points, wherein the plurality of sensors are capable of providing a plurality of data sufficient to determine the positions of each measurement point with respect to the reference point; determining the position of each measurement point in three-dimensional space with respect to the reference point to generate the three-dimensional model of the body part. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an isometric view of one embodiment of the measuring device of the present invention.  
       FIGS. 2A-2D  show four different views of the measuring device.  
       FIGS. 3A-3B  shows the measuring device with its measurement arms configured to measure a thinner leg and a thicker leg, respectively.  
       FIG. 4  shows the measuring device in use around the leg of a patient. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  shows one embodiment of a measuring device  100  of the present invention. Measuring device  100  includes a femoral component  110  and a tibial component  120 , both movably coupled to a femoral-tibial component  130 . Femoral component  110  includes a reference point  110 ′.  
      Femoral component  110  and tibial component  120  each have a surface which allows stable placement on the leg of the patient. Femoral-tibial component  130  is curved to clear the knee of the patient. Femoral component  110 , tibial component  120  and femoral-tibial component  130  may be manufactured in different shapes and sizes.  
      Femoral component  110  and tibial component  120  may include straps or other devices for securely attaching femoral component  110  and tibial component  120  to the leg of the patient. Femoral component  110  and tibial component  120  may also be secured to the leg of the patient using tape, bandages or other non-permanent methods.  
      A femoral elevation joint  112  and a femoral azimuth joint  122  couple femoral-tibial component  130  to femoral component  110 . A tibial elevation joint  132  and a tibial azimuth joint  142  couple femoral-tibial component  130  to tibial component  120 . Femoral elevation joint  112  and femoral azimuth joint  122  have axes of rotation which are substantially perpendicular. Tibial elevation joint  132  and tibial azimuth joint  142  also have axes of rotation which are substantially perpendicular. Femoral elevation joint  112 , femoral azimuth joint  122 , tibial elevation joint  132  and tibial azimuth joint  142  may allow the force required to move femoral component  110  and tibial component  120  to be fixed or adjustable. Femoral elevation joint  112 , femoral azimuth joint  122 , tibial elevation joint  132  and tibial azimuth joint  142  are hinges, but may be universal joints, ball-and-socket joints, or any other suitable coupling devices.  
      A femoral elevation sensor  113  and a femoral azimuth sensor  123  are coupled to femoral elevation joint  112  and femoral azimuth joint  122 , respectively. Femoral elevation sensor  113  and femoral azimuth sensor  123  are capable of detecting an elevation angle and an azimuth angle, respectively, of femoral-tibial component  130  with respect to femoral component  110 . A tibial elevation sensor  133  and a tibial azimuth sensor  143  are coupled to tibial elevation joint  132  and tibial azimuth joint  142 , respectively. Tibial elevation sensor  133  and tibial azimuth sensor  143  are capable of detecting an elevation angle and an azimuth angle, respectively, of femoral-tibial component  130  with respect to tibial component  120 . Femoral elevation sensor  113 , femoral azimuth sensor  123 , tibial elevation sensor  133  and tibial azimuth sensor  143  are angular potentiometers, but may also be any suitable sensor or group of sensors capable of providing sufficient data to allow the positions and orientations femoral component  110 , tibial component  120  and femoral-tibial component  130  to be determined with respect to reference point  110 ′.  
      Femoral component  110 , tibial component  120  and femoral-tibial component  130  are rigid and have known geometries. Data from femoral elevation sensor  113 , femoral azimuth sensor  123 , tibial elevation sensor  133  and tibial azimuth sensor  143  are used with these known geometries to calculate the positions and orientations of femoral component  110 , tibial component  120  and femoral-tibial component  130  with respect to reference point  110 ′.  
      Measurement arms  111  are movably coupled to femoral component  110  and tibial component  120 . Measurement arms  111  are articulated, each having an inner section  155  and an outer section  165 . Inner section  155  and outer section  165  are curved to accommodate a wide range of patients, but may also be made in any suitable shape or size. Four measurement arms  111  are coupled to each of femoral component  110  and tibial component  120 , but any number of measurement arms  111  may be coupled to femoral component  110  and tibial component  120 . Measurement arms  111  are coupled to femoral component  110  and tibial component  120  at substantially right angles, but may also be coupled at any angle or each at different angles. Each measurement arm  111  may also have a single section or articulated into any number of sections. Each measurement arm  111  may also be of a telescoping design.  
      An inner section joint  152  movably couples inner section  155  to femoral component  110  or tibial component  120 . An outer section joint  162  movably couples outer section  165  to inner section  155 . Inner section joint  152  and outer section joint  162  may allow the force required to move inner section  155  and outer section  165  to be fixed or adjustable. Inner section joint  152  and outer section joint  162  are hinges which limit the motion of inner section  155  and outer section  165  to one axis, but may also be universal joints, ball-and-socket joints or any other suitable coupling devices.  
      An inner section sensor  153  and an outer section sensor  163  are coupled to inner section joint  152  and outer section joint  162 , respectively. Inner section sensor  153  is capable of detecting an angle between inner section  155  and femoral component  110  or tibial component  120 . Outer section sensor  163  is capable of detecting an angle between outer section  165  and inner section  155 . Inner section sensor  153  and outer section sensor  163  are angular potentiometers, but may also be any suitable sensor or group of sensors capable of providing sufficient data to allow the positions and orientations of inner section  155  and outer section  165  with respect to femoral component  110  or tibial component  120  to be determined.  
      An inner section measurement point  159  and an outer section measurement point  169  are located at the ends of inner section  155  and outer section  165 , respectively. Each inner section measurement point  159  and each outer section measurement point  169  are capable of being in contact with the leg of the patient simultaneously with all other measurement points. Inner section measurement point  159  and outer section measurement point  169  may also be attached anywhere along inner section  155  and outer section  165  respectively. Inner section  155  and outer section  165  may also have multiple measurement points.  
      Inner section  155  and outer section  165  are rigid and have known geometries. Data from inner section sensor  153  and outer section sensor  163  are used with these known geometries to calculate the positions of inner section measurement point  159  and outer section measurement point  169  with respect to femoral component  110  or tibial component  120 .  
      Knee measurement arms  175  are movably coupled to femoral-tibial component  130 . Knee measurement arms  175  are curved to accommodate a wide range of patients, but may also be made in any suitable shape or size. Two knee measurement arms  175  are coupled to femoral-tibial component  130 , but any number of knee measurement arms  175  may be coupled to femoral-tibial component  130 . Knee measurement arms  175  are coupled to femoral-tibial component  130  at substantially right angles, but may also be coupled at any angle or each at different angles. Knee measurement arms  175  may also be articulated into two or more sections. Knee measurement arms  175  may also be of a telescoping design.  
      A knee measurement arm joint  172  movably couples each knee measurement arm  175  to femoral-tibial component  130 . Knee measurement arm joint  172  may allow the force required to move knee measurement arm  175  to be fixed or adjustable. Knee measurement joint  172  is a hinge which limits the motion of knee measurement arm  175  to one axis, but may also be a universal joint, ball-and-socket joint or any other suitable coupling device.  
      A knee measurement arm sensor  173  is coupled to knee measurement arm joint  172 . Knee measurement arm sensor  173  is capable of detecting an angle between knee measurement arm  175  and femoral-tibial component  130 . Knee measurement arm sensor  173  is an angular potentiometer, but may also be any suitable sensor or group of sensors capable of providing sufficient data to allow the position and orientation of knee measurement arm  175  to be determined with respect to femoral-tibial component  130 .  
      A knee measurement point  179  is located at the end of each knee measurement arm  175 . Each knee measurement point  179  is capable of being in contact with the leg of the patient simultaneously with all other measurement points. Knee measurement point  179  is a cup designed to locate a condyle of the patient, but may also be any other suitable shape. Knee measurement point  179  is movably coupled to knee measurement arm  175  with a swivel  178 , but may also be fixed. Knee measurement point  179  may also be located anywhere along knee measurement arm  175 . Knee measurement arm  175  may also have multiple measurement points.  
      Knee measurement arm  175  is rigid and has a known geometry. Data from knee measurement arm sensor  173  is used with this known geometry to calculate the position and orientation of knee measurement point  179  with respect to femoral-tibial component  130 .  
      Measuring device  100  may be calibrated by first using it on a cylinder of known diameter. Measuring device  100  may then be secured to the leg of the patient and adjusted so that all measurement points are in contact with the leg of the patient at the same time. Data from all sensors is obtained substantially simultaneously by a computer connected to the sensors.  
      The positions of all inner section measurement points  159  and outer section measurement points  169  with respect to femoral component  110  and tibial component  120  are known. The positions of all knee measurement points  179  with respect to femoral-tibial component  130  are known. The positions and orientations of femoral component  110 , tibial component  120  and femoral-tibial component  130  with respect to reference point  110 ′ are known. As a result, the positions of all inner section measurement points  159 , outer section measurement points  169  and knee measurement points  179  with respect to reference point  110 ′ may be calculated.  
      The reference point may be used as an origin in a three-dimensional space, and the positions of each of the measurement points with respect to the reference point, as well as the positions and orientations of femoral component  110  and tibial component  120 , used as coordinate data to generate a three-dimensional computer model of the leg of the patient. This model may be transmitted to the brace manufacturer to aid in the manufacture a custom-made knee brace. This model may also be used to diagnose varus and valgus knees.  
       FIGS. 2A-2D  show four different views of measuring device  100 .  FIG. 2A  is an isometric view from above.  FIG. 2B  is an isometric view from below.  FIG. 2C  is a view from directly above.  FIG. 2D  is a view from head-on.  
       FIGS. 3A-3B  shows measuring device  100  with its measurement arms  111  adjusted as if to measure a thinner leg and a thicker leg, respectively.  
       FIG. 4  shows measuring device  100  in use around a leg  200  of a patient. Typically, measuring device  100  is used with the knee in a straight and locked. However, measuring device  100  may also be used to make measurements of a bent knee.  
      The basic design of measuring device  100  may be used for measuring devices for other parts of the body. For example, a measuring device for the neck may be simplified, having only a reference component and one or more articulated measurement arms movably coupled to the reference component, and suitable sensors for detecting the positions of the measurement arms with respect to the reference component.  
      Although for purposes of illustration, certain materials, components, and structural embodiments have been depicted, those skilled in the art will recognize that various modifications to the same can be made without departing from the spirit of the present invention, and such modifications are clearly contemplated herein.