Implant sensors

Abstract

Exemplary orthopedic implants are disclosed. The orthopedic implants may include one or more sensors. Exemplary sensors include sensors to monitor bone growth, changes to the implant over time, and proper placement of the implant. The orthopedic implants may include a woven material. Sensor arrangements to detect a state of an item are disclosed. Exemplary states include folded, unfolded, and inflated. Exemplary items include an orthopedic implant and a parachute.

1 . An orthopedic implant for placement in a cavity formed in a bone, said cavity having a predetermined shape, said orthopedic implant comprising:
 a flexible body having an opening, said flexible body having an inflated state wherein said body has an outer shape generally corresponding to said predetermined shape formed in said bone and a non-inflated shape wherein said outer shape has a smaller envelope than said inflated state;   a plurality of sensors supported by said flexible body, said plurality of sensors providing an indication of whether said flexible body is in said inflated state or said non-inflated state; and   a filler, said filler being positioned in said flexible body and causing said flexible body to transition from said non-inflated state to said inflated state, wherein said plurality of sensors include a plurality of optical sensors.   
     
     
         2 . The orthopedic implant of  claim 1 , wherein said plurality of sensors include a plurality of optical sensors. 
     
     
         3 . The orthopedic implant of  claim 2 , wherein said plurality of optical sensors are in optical communication with an external detector through an optical fiber. 
     
     
         4 . The orthopedic implant of  claim 3 , wherein said plurality of optical sensors are a plurality of diffraction gratings disposed in said optical fiber, said optical fiber having a first shape indicating said presence of said fold wherein said plurality of diffraction gratings are in a first plurality of locations and a second shape indicating said absence of said fold wherein said plurality of diffraction gratings are in a second plurality of locations. 
     
     
         5 . A system for monitoring wear of orthopedic implant for placement proximate a bearing surface when installed in a body, said system comprising:
 an orthopedic implant body;   a plurality of sensors supported by said orthopedic implant body and arranged to be positioned proximate said bearing surface, each sensor corresponding to a location on said orthopedic implant; and   an interrogation system to interrogate said plurality of sensors subsequent to installation in said body, each sensor of said plurality of sensors providing a first indication in response to an interrogation signal in an absence of wear of said orthopedic implant at said location corresponding to said sensor and a second indication in response to said interrogation signal in a presence of wear of said orthopedic implant at said location corresponding to said sensor.   
     
     
         6 . The system of  claim 5 , wherein said first indication is a response signal and said second indication is the lack of said response signal. 
     
     
         7 . The system of  claim 6 , wherein each sensor includes a controller and said response signal includes a unique identifier. 
     
     
         8 . The system of  claim 6 , wherein each sensor is a resonant circuit and said response signal is at a unique frequency. 
     
     
         9 . The system of  claim 6 , wherein said body includes a three-dimensional woven component. 
     
     
         10 . The system of  claim 9 , wherein said three-dimensional woven component includes a plurality of materials which form a gradient woven material. 
     
     
         11 . A method of monitoring wear of an orthopedic implant placed proximate a bearing surface when installed in a body, said method comprising the steps of
 providing a body of said orthopedic implant;   providing a plurality of sensors supported by said orthopedic implant body and arranged to be positioned proximate said bearing surface, each sensor corresponding to a location on said orthopedic implant; and   interrogating said plurality of sensors to determine if said orthopedic implant has experienced wear.   
     
     
         12 . The method of  11 , wherein each sensor of said plurality of sensors provides a first indication in response to an interrogation signal in said absence of wear of said orthopedic implant at said location corresponding to said sensor and a second indication in response to said interrogation signal in said presence of wear of said orthopedic implant at said location corresponding to said sensor. 
     
     
         13 . The method of  claim 12 , wherein said step of interrogating said plurality of sensors to determine if said orthopedic implant has experienced wear includes the steps of:
 positioning an external interrogation system proximate to said orthopedic implant; and   for a respective sensor
 passing said interrogation signal through said body; 
 receiving from said respective sensor one of said first indication and said second indication. 
   
     
     
         14 . An orthopedic implant for positioning proximate a bone in a body, said orthopedic implant comprising:
 a first body portion including a three-dimensional woven material having a plurality of layers; and   a second body portion coupled to said three-dimensional woven material, wherein said three-dimensional woven material includes a first woven layer having a first plurality of weft fibers and a first plurality of in layer warp fibers, said first layer having a first stiffness; a second woven layer having a second plurality of weft fibers and a second plurality of in layer warp fibers, said second layer having a second stiffness generally less than said first stiffness; a third woven layer having a third plurality of weft fibers and a third plurality of in layer warp fibers, said third layer having a third stiffness generally less than said second stiffness; a first plurality of out of layer warp fibers which couple together said first layer and said second layer; and a second plurality of out of layer warp fibers which couple together said second layer and said third layer.   
     
     
         15 . The orthopedic implant of  claim 14 , further comprising a plurality of sensors supported by said three-dimensional woven material, said plurality of sensors positioned proximate said bone and configured to provide an indication of a presence of bone in-growth into said three-dimensional woven material. 
     
     
         16 . The orthopedic implant of  claim 14 , further comprising a plurality of sensors supported by said three-dimensional woven material, said plurality of sensors positioned proximate said bone and configured to provide an indication of a strain experience by said three-dimensional woven material. 
     
     
         17 . An orthopedic implant for positioning proximate a bone in a body, said orthopedic implant comprising:
 a body portion including a three-dimensional woven material having a plurality of layers; and   a plurality of sensors supported by said three-dimensional woven material, said plurality of sensors positioned proximate said bone and configured to provide an indication of a presence of bone in-growth into said three-dimensional woven material.   
     
     
         18 . The orthopedic implant of  claim 17 , wherein said plurality of sensors each include a capacitive element having a first dielectric value, said presence of said bone in-growth into said three-dimensional woven material changing said first dielectric value. 
     
     
         19 . The orthopedic implant of  claim 18 , wherein said capacitive element is operatively coupled to an antenna which broadcasts a signal having a frequency based at least in part on said first dielectric value, said antenna broadcasting at a first frequency in said absence of bone in-growth into said three-dimensional woven material and at a second frequency in said presence of bone in-growth into said three-dimensional woven material. 
     
     
         20 . An orthopedic implant for positioning proximate a bone in a body, said orthopedic implant comprising:
 a body portion including a three-dimensional woven material having a plurality of layers; and   sensing means supported by said three-dimensional woven material, said sensing means being passive.   
     
     
         21 . A method of measuring bone in-growth into an orthopedic implant placed proximate a bone when installed in a body, said method comprising the steps of:
 providing a body of said orthopedic implant, said body including a woven material;   providing a sensor supported by said woven material and arranged to be positioned proximate said bone; and   interrogating said sensor to determine if said bone has grown into said woven material, said sensor providing a first indication if bone in-growth is present.   
     
     
         22 . The method of  claim 21 , wherein said sensor in response to interrogation provides a signal of a first frequency in said absence of said presence of bone in-growth and a signal of a second, different frequency in said presence of bone in-growth, said second, different frequency being said first indication. 
     
     
         23 . A method of measuring strain experienced by an orthopedic implant placed proximate a bone when installed in a body, said method comprising the steps of:
 providing a body of said orthopedic implant, said body including a woven material;   providing a sensor supported by said woven material and arranged to be positioned proximate said bone; and   interrogating said sensor to determine an amount of strain experienced by said orthopedic implant.   
     
     
         24 . The method of  claim 23 , wherein said sensor in response to interrogation provides a signal of a first frequency in said absence of strain and a signal of a second, different frequency in said presence of strain, said second, different frequency being said first indication, 
     
     
         25 . An assembly, comprising:
 a flexible body having a folded state and an unfolded state; and   a plurality of sensors supported by said flexible body, said plurality of sensors providing an indication of whether said flexible body is in said folded state or said unfolded state.   
     
     
         26 . The assembly of  claim 25 , wherein said flexible body is a portion of an orthopedic implant. 
     
     
         27 . The assembly of  claim 25 , wherein said fold is detected base(on a relative position of a first sensor, to a second sensor. 
     
     
         28 . The assembly of  claim 27 , wherein said first sensor and said second sensor are passive sensors interrogated by an external device. 
     
     
         29 . The assembly of  claim 28 , wherein said first sensor and said second sensor are each resonant circuits which provide said indication based on a separation between said first sensor and said second sensor. 
     
     
         30 . The assembly of  claim 29 , wherein when said first sensor and said second sensor are spaced a first distance apart said first sensor resonates in response to a first frequency from said external device and said second sensor resonates in response to a second frequency from said external device and when said first sensor and said second sensor are spaced less than said first distance apart said first sensor and said second sensor resonate together in response to a third frequency from said external device. 
     
     
         31 . The assembly of  claim 30 , wherein said external device interrogates said plurality of sensors through a frequency range including said first frequency, said second frequency, and said third frequency. 
     
     
         32 . An assembly, comprising:
 a flexible body having a folded state and an unfolded state; and   means for sensing whether said flexible body is in said folded state or said unfolded state.   
     
     
         33 . The assembly of  claim 32 , wherein said means for sensing said shape of said flexible body is a passive sensing means. 
     
     
         34 . The assembly of  claim 32 , wherein said means for sensing said shape of said flexible body is an active sensing means.