Tools and methods for fitting orthoses
An orthosis is fitted to a body joint, in a preferred embodiment the equine fetlock, by locating the center of rotation (COR) of the joint; measuring the bones comprising the joint at points located with respect to the COR; selecting the appropriate orthosis from a selection of models thereof; and custom-fitting the orthosis to the individual by heating it to soften a layer of thermoformable foam on the interior of the orthosis and clamping the orthosis in place over the body joint. A kit of tools for performing the measurements is disclosed, as are a method for location of the COR of the body joint by palpation and a preferred heater.
1. A method for fitting an orthosis to a body joint comprising first and second bones, said orthosis comprising proximal and distal cuffs Joined to one another by a pivot structure, said cuffs each comprising an outer shell, a first layer of molded foam contoured to fit the body joint, and a second layer of thermoformable foam, said method comprising the steps of:
locating the center of rotation of the body joint;
measuring said first and second bones at predetermined points located with respect to the center of rotation of the body joint;
responsive to said measurement step, selecting an orthosis from a plurality of models thereof;
heating the orthosis; and
clamping the orthosis over the body joint so that the thermoformable foam conforms permanently to the first and second bones.
2. The method of claim 1 , wherein said body joint is an equine fetlock, made up of cannon and pastern bones, and wherein said measurement step comprises (1) measuring the width of the cannon bone and the depth at which its maximum width is disposed from a forward surface of the cannon bone, (2) measuring the circumference of the pastern bone, and (3) measuring the width of the fetlock.
3. The method of claim 2 , wherein said step (1) is performed using a cannon tool for simultaneously measuring the maximum width of the cannon bone and the depth at which its maximum width is disposed from a forward surface of the cannon bone.
4. The method of claim 3 , wherein said cannon tool comprises an elongated beam, a first anvil fixed to one end of said beam, and a second anvil sliding along said beam, whereby said first and second anvils are brought into contact with opposed side surfaces of said cannon bone to determine its width.
5. The method of claim 4 , wherein said sliding anvil is provided with markings for convenient identification of the depth at which the maximum width of the cannon bone is disposed from a forward surface thereof.
6. The method of claim 5 , wherein the sliding anvil is provided with a plurality of spring-biased pins extending out of the surface of the anvil in contact with an outer side surface of the cannon bone, such that one of the pins protrudes out an opposite surface of the anvil at a position corresponding to the maximum width of the cannon bone.
7. The method of claim 2 , wherein said step of measuring the width of the cannon bone and the depth at which its maximum width is disposed from a forward surface of the cannon bone is performed at a plurality of locations along the axial extent of the cannon bone, measured from the center of rotation of the fetlock.
8. The method of claim 7 , wherein said plurality of locations along the axial extent of the cannon bone are located by disposing an alignment tape on the surface of the cannon bone, with a reference point on the alignment tape located at the center of rotation of the fetlock and plural measurement locations indicated on the alignment tape.
9. The method of claim 2 , wherein said step (2) of measuring the circumference of the pastern bone is performed by disposing a pastern tool comprising a head member, disposed over the center of rotation of the fetlock, a tongue member defining a predetermined distance from the center of rotation of the fetlock, and a measurement ribbon, said ribbon being passed around the pastern to measure its circumference at said predetermined distance from the center of rotation of the fetlock.
10. The method of claim 9 , wherein said ribbon is provided with colored sections employed for measuring the circumference of the pastern.
11. The method of claim 4 , wherein said elongated beam is provided with colored sections disposed along its length, and said sliding anvil comprises a reference mark for comparison to said colored sections for determining the spacing of the sliding anvil from the first fixed anvil in order to measure the width of the cannon and of the fetlock.
12. The method of claim 1 wherein the center of rotation of the joint is located by palpation.
13. The method of claim 12 , wherein the joint is an equine fetlock, and the location of its center of rotation is performed by:
locating a depression between a palmar process of the first phalanx and a base of a proximal sesamoid bone;
identifying a joint margin, and marking this point as point A;
identifying a prominence of an intercondylar ridge on a cranial aspect of a cannon bone near the fetlock, and marking a point B where the intercondylar ridge merges with a flat cranial surface of the distal cannon bone;
marking a point C at the same level as point B with respect to the horizontal, but on the forward-most part of a lateral surface of the cannon bone; and
marking a point D midway between points A and C, which is the center of rotation of the fetlock.
14. A tool for measuring dimensions of an equine fetlock, made up of cannon and pastern bones, and wherein said dimensions include the width of the cannon bone and the depth at which its maximum width is disposed from a forward surface of the cannon bone, and the width of the fetlock, said tool comprising:
an elongated beam;
a first anvil fixed to one end of said beam; and
a second anvil sliding along said beam, whereby said first and second anvils are brought into contact with opposed side surfaces of said cannon bone to determine its width; and
wherein one of said anvils is provided with markings for convenient identification of the depth at which the maximum width of the cannon bone is disposed from a forward surface thereof.
15. The tool of claim 14 , wherein the sliding anvil is provided with a plurality of spring-biased pins extending out of the surface of the anvil in contact with an outer side surface of the cannon bone, such that one of the pins protrudes out an opposite surface of the anvil at a position corresponding to the maximum width of the cannon bone.
16. The tool of claim 14 , further comprising a bubble level for ensuring that the tool is correctly aligned with respect to the cannon bone.
17. The tool of claim 14 , wherein said beam is provided with dimensional information, and said sliding anvil is provided with an indicating line for comparison with said dimensional information.
18. The tool of claim 17 , wherein said dimensional information comprises a series of colored markings on said beam.