Extension deceleration orthosis

Abstract

An extension deceleration orthotic fulcrum for knee and elbow braces, which simulates performance of the function of those ligaments that control joint motion and provide provides anteroposterior joint stability, comprising a lightweight, external spring assembly, upper and lower elongated arms, and a centric or polycentric fulcrum, which is adjustable for its range of motion, adaptable for use on many different style orthoses, and whose strength can be varied to suit corrective, preventive, anthropomorphic, environmental, and usage requirements, including means both for mechanically dampening the limb's angular velocity on extension to prevent hyperextension and for accelerating the limb's angular velocity on flexion to enable quicker, smoother, less stressful motion. In one embodiment spring rods are assembled medially and laterally to conventional pairs of elongated orthotic brace arms to span the joint fulcrum point by serpentinely engaging novel roller posts, the assemblage thus serving to decelerate the limb during the last 15 to 20 degrees of extension, to help prevent the striking of a stop with its attendant risk of hyperextension, and thus serving to use the stored energy of the spring to facilitate flexion of the limb.

We claim:  
     
       1. An anatomical brace for applying a force for resisting extension having a hinge comprising: 
       a. a pair of elongated arms, of equal thickness, with geared ends engaging each other adjacently, said geared ends provided with stopping means to limit the range of motion of the arms on extension, said arms connected by inner and outer plates, said plates overlapping the geared ends, said plates and arms fastened together by at least one screw, said at least one screw passing through busings, which act as hinge pivot points,  
       b. a lock screw which simultaneously clamps both the said plate fastening screws into position so as to permit free extension and flexion of the hinge, the improvement comprising:  
       c. a lightweight spring rod, which is assembled to said outer plate with a pivot screw, said pivot screw having a shoulder, said shoulder clamping the spring rod to the plate, with said spring rod serpentinely engaging on one side said pivot screw, and engaging on said rod's opposite side said at least one fastening screw,  
       d. said pivot screw being assembled to the outer plate on a line tangential to the pitch diameter of the geared elongated arm ends by passing through first roller means which serve as a pivot center for the spring rod,  
       e. means for controlling the application of said force for resisting extension comprising a friction reducing roller post selectively positioned on each arm, each of said posts being engaged by said spring rod on said one side as the arms are extended so that said spring rod biases the post toward flexion and therefore the arms toward flexion until the arms are in a preselected flexed positioned wherein further bending of the arms results in no force being applied by the rod against the posts;  
       f. the said friction reduction roller posts each comprising a screw fastened to the said elongated arm and a bushing through which said screw passes and which serves as second roller means to reduce friction when engaged by the spring rod during extension and flexion.  
     
     
       2. In an anatomical brace for applying a force for resisting extension having a hinge comprising: 
       
         a. a pair of elongated arms, of equal thickness, with geared ends engaging each other adjacently, said geared ends being provided with stopping means to limit the range of motion of the arms on extension, said arms being connected by inner and outer plates, said plates overlapping the geared ends, said plates and said arms being fastened together by at least one screw, said at least one screw passing through bushings, which act as hinge pivot points, and  
       
       
         b. a lock screw which simultaneously clamps both the said plate fastening screws into position so as to permit free extension and flexion of the hinge, the improvement comprising:  
       
       
         c. a lightweight spring road, which is assembled to said outer plate with a pivot screw, said pivot screw having a shoulder, said shoulder clamping the spring rod to the plate, with said spring rod serpentinely engaging on one side said pivot screw, and engaging on said rod's opposite side said at least one fastening screw,  
       
       
         d. said pivot screw being assembled to the outer plate on a line tangential to the pitch diameter of the geared elongated arm ends by passing through first roller means which serves as a pivot center for the spring rod,  
       
       
         e. means for controlling the application of said force for resisting extension comprising a friction reduction roller post selectively positioned on each arm, each of said posts being engaged by said spring rod on said one side as the arms are extended so that said spring rod biases the post toward flexion and therefore the arms toward flexion until the arms are in a preselected flexed position wherein further bending of the arms results in no force being applied by the rod against the posts, and  
       
       
         f. the said friction reduction roller posts each comprising a screw fastened to the said elongated arm and a bushing through which said screw passes and which serves as a second roller means to reduce friction when engaged by the spring rod during extension and flexion.  
       
     
     
       3. An orthotic device for providing extension stability and limiting hyperextension while providing flexion mobility, said device including: 
       
         a. an array of elongated, first and second arms;  
       
       
         b. means for attaching said arms to the body of a user on opposite sides of a joint that is to be protected by the device;  
       
       
         c. connector means at the apposite ends of said arms which connect said arms together for relative angular movement limited to a plane common to said arms; and  
       
         d. motion decelerating means for reducing the relative rate of movement between said arms, said decelerating means including; an elongated, energy - absorbing member capable of generating a reactive force that is proportional to the displacement of one end of the member relative to the other, means at a point intermediate the ends of the elongated member for fixing said member against movement relative to said connector means, and first and second stop means so located on said first and second arms as to be engageable only at particular times by opposite ends of said elongated member, said stop means being so relatively located and said elongated member being so contoured that both of said stop means are engageable by said elongated member only with the relative angle between said arms approaching a maximum, whereby:  ( a )  said deceleration means remains inoperative and said arms can angularly move freely relative to each other as long as the relative angular displacement of said arms remains small enough that said elongated member does not simultaneously engage both of said stop means, but  ( b )  both of said stop means will be engaged and the relative rate of angular movement between said arms increasingly reduced as the angular displacement between said arms is thereafter increased.    
     
     
       4. An orthotic device as defined in claim  3  wherein: 
       
         a. said connector means includes meshing gear means on the apposite ends of said arms, connector members so disposed on opposite sides of the array of arms as to prevent relative sideways movement of said arms, and members which extend through and span said connector members near the apposite ends of said arms to couple together said members and said arms and to provide shafts about which said arms can rotate; and  
       
       
         b. said decelerating means also includes means fixing said elongated member at approximately its midpoint and as aforesaid to one of said connector members.  
       
     
     
       5. An orthotic device as defined in claim  4  wherein: 
       
         a. the connector means comprises a headed member with a head that is engageable with said shaft providing members to prevent rotation of said shaft providing members;  
       
       
         b. said elongated member is trapped against one of said connector members by said headed member; and  
       
       
         c. the means for fixing said elongated member to said one of said connector members comprises a second headed member also confining said elongated member against said one of said connector members, said second headed member being so located on the opposite side of the elongated member from the first headed member as to trap the elongated member against the first headed member.  
       
     
     
       6. An orthotic device as defined in claim  4  which includes bushings supported from said one of said connector members and engageable by said elongated member to increase the resistance to relative angular movement of the arms afforded by said elongated member.  
     
     
       7. An orthotic device as defined in claim  6  in which the shaft- providing members extend through said bushings and fix said bushings to said one of said connector members.    
     
     
       8. An orthotic device as defined in claim  5  in which said shaft- providing members are threaded into a second of said connector members whereby, with said members locked against rotation, said one of and said second connector members can move apart to an extent which is sufficient to prevent said one of and said second members from frictionally restricting the relative rotation of said arms.    
     
     
       9. An orthotic device as defined in claim  5  in which: 
         a. said first threaded member is located along a line extending between the axes of elongation of the shaft - providing members and approximately midway between said axes; and    
         b. the second threaded member is located along a second line extending normally to the first - mentioned line and passing through the axis of elongation of the first headed member.    
     
     
       10. An orthotic device as defined in claim  4  in which: 
       
         a. the apposite end portions of said arms have parallel sides and are of equal thickness; and  
       
       
         b. said connector members are flat plates.  
       
     
     
       11. An orthotic device as defined in claim  3  in which said elongated member is fabricated of a resiliently deformable material and has a serpentine configuration.  
     
     
       12. An orthotic device as defined in claim  3  in which: 
       
         a. the end portions of the elongated member are trained around the stop means when they are engaged with said stop means as aforesaid; and  
       
       
         b. said stop means comprise rollers so engageable by said elongated element end portions as to minimize friction between said elongated member and said stop means and thereby provide for flexion mobility in said device.