Wrist implants

Abstract

An implant system and apparatus configured to permit motion of the wrist in at least one physiological direction, as well as in a dart thrower's motion, and constrain motion of the wrist in at least one non-physiological direction are provided. The implant according to one embodiment includes a distal component and proximal component. Each of the distal and proximal components includes a primary articulating portion and a secondary articulating portion. Primary and secondary articulating portions include at least one component having either a substantially convex or a substantially concave shape. The secondary articulating portion is configured to be radially and volarly disposed in relation to the primary articulating portion.

1 . A wrist implant comprising: 
 a distal component; and    a proximal component;    wherein each of the distal and proximal components is configured to have a primary articulating portion and a secondary articulating portion; and    each of the primary and secondary articulating portions including a section that has a substantially convex shape or a substantially concave shape.    
   
   
       2 . The wrist implant system of  claim 1 , wherein the secondary articulating portion is configured to be radially and volarly disposed in relation to the primary articulating portion.  
   
   
       3 . The wrist implant system of  claim 1 , wherein the primary and secondary articulating portions are spherical in shape.  
   
   
       4 . The wrist implant system of  claim 3 , wherein the primary and secondary articulating portions are configured to have different sizes.  
   
   
       5 . The wrist implant system of  claim 1 , wherein at least one articulating portion is configured to have a spherical shape.  
   
   
       6 . The wrist implant system of  claim 1 , wherein at least one articulating portion has a non-spherical shape.  
   
   
       7 . The wrist implant system of  claim 1 , wherein the primary articulating portion includes a primary articulating surface and the secondary articulating portion includes a secondary articulating surface, the primary articulating surface being configured to be continuous with the secondary articulating surface.  
   
   
       8 . The wrist implant system of  claim 1 , wherein the primary articulating portion includes a primary articulating surface and the secondary articulating portion includes a secondary articulating surface, the primary articulating surface being configured to be partially continuous with the secondary articulating surface.  
   
   
       9 . The wrist implant system of  claim 1 , wherein each primary articulating portion of each of the distal and proximal components is configured to have a geometrical center that is configured to correspond to the geometric and/or kinematic center of the wrist within the proximal pole of the capitate bone.  
   
   
       10 . The wrist implant system of  claim 1 , wherein the secondary articulating portion of each of the distal and proximal components is configured to move about a predetermined location of each of the primary articulating portions based on a range of wrist movements.  
   
   
       11 . The wrist implant system of  claim 10 , wherein the predetermined location is a center of the primary articulating portion.  
   
   
       12 . The wrist implant system of  claim 10 , wherein the range of movements includes at least one movement selected from the group consisting of flexion/extension, radial and ulnar deviation.  
   
   
       13 . The wrist implant system of  claim 10 , wherein the range of wrist movements includes a dart thrower's movement.  
   
   
       14 . The wrist implant system of  claim 13 , wherein the dart thrower's movement includes any combination and/or any degree of coupling of flexion-extension and radioulnar deviation.  
   
   
       15 . The wrist implant system of  claim 1 , wherein the secondary articulating portions are configured to limit non-physiological motions.  
   
   
       16 . The wrist implant system of  claim 15 , wherein the non-physiological motions includes extreme radioulnar deviation and extreme flexion-extension.  
   
   
       17 . The wrist implant system of  claim 1 , wherein the secondary articulating portions are configured to limit extremes of supination and/or pronation of the wrist.  
   
   
       18 . A wrist implant comprising: 
 a first component having a first protrusion and a first recessed portion; and    a second component having a second protrusion and a second recessed portion;    wherein the first recessed portion has a concave shape configured to accommodate placement of the second protrusion having a convex shape;    wherein the second recessed portion has a concave shape configured to accommodate placement of the first protrusion having a convex shape; and    wherein the first and second components mate with one another in such a way to permit motion of the wrist in at least one physiological direction and constrain motion of the wrist in at least one non-physiological direction.    
   
   
       19 . The wrist implant of  claim 18 , wherein each of the first protrusion and second recessed portion is configured to have a geometrical center that is configured to correspond to the kinematic and/or geometrical center of the wrist within the proximal pole of the capitate.  
   
   
       20 . The wrist implant of  claim 18 , wherein the first component has a continuous convex and concave articulating surface defined by the first protrusion and the first recessed portion and the second component has a continuous convex and concave articulating surface defined by the second protrusion and the second recessed portion.  
   
   
       21 . The wrist implant of  claim 18 , wherein the first and second components are configured to permit movement about a predetermined location of each of the first and second protrusions based on a range of wrist movements.  
   
   
       22 . The wrist implant of  claim 21 , wherein the predetermined location is a center of each of the first and second protrusions.  
   
   
       23 . The wrist implant of  claim 21 , wherein the range of movements includes a dart thrower's motion movement.  
   
   
       24 . The wrist implant of  claim 21 , wherein each of the first and second recessed portions is configured to limit radial deviation.  
   
   
       25 . The wrist implant of  claim 21 , wherein the first and second recessed portions are configured to constrain supination and pronation of the wrist.  
   
   
       26 . The wrist implant of  claim 21 , wherein surfaces of respective recessed portions are configured to be continuous with surfaces of respective protrusions.  
   
   
       27 . A wrist implant configured to replicate a midcarpal joint of a human comprising: 
 a first component that is configured to be attached to metacarpal bones, the first component including a first part that has a convex shape and replicates the midcarpal surface of the capitate and hamate and a carpal plate to which the first part is detachably coupled to define a modular system, the carpal plate being fixed to the metacarpal bones; and    a second component that is configured to be attached to the radius bone, the second component including an articulating surface that is constructed to simulate the proximal shape of the midcarpal joint and mate with the first part;    wherein the modularity of the implant permits different degrees of constraint or motions between the first and second components to be selected according to a particular disease condition.    
   
   
       28 . The wrist implant of  claim 27 , wherein a substantially concave primary articulation is provided between the first and second components that simulates the normal midcarpal joint in shape and orientation, and is continuous with a substantially convex secondary articulation that is radial and volar to the first  
   
   
       29 . The wrist implant of  claim 27 , wherein the first part is a carpal ball and wherein the carpal plate includes a tapered shank portion and the carpal ball is press fitted onto the shank portion for coupling the carpal ball to the carpal plate.  
   
   
       30 . The wrist implant of  claim 27 , wherein a major motion of the wrist implant is orientated in a dart thrower's functional arc of motion (radial extension to ulnar flexion) in contrast to traditional orthogonal axes of flexion-extension and radial-ulnar deviation.  
   
   
       31 . The wrist implant of  claim 29 , wherein an axis of the carpal articulating surface is oriented so as to enable a dart thrower's motion.  
   
   
       32 . The wrist implant of  claim 27 , wherein the each of the first and second components is in the form of a liner that is configured to be attached to a respective plate, wherein a shape of the articulating surface of at least one of the liners is based on the particular disease condition, thereby permitting the modular system to include a plurality of different shaped liners from which the surgeon selects.  
   
   
       33 . A hemi-arthroplasty implant that preserves the portions of the distal carpal row comprising: 
 a component that includes a stem portion for implantation in the radius bone and a modular bearing surface that is constructed to provide an articulating surface that replicates the normal function and kinematics of the wrist.    
   
   
       34 . The hemi-arthroplasty implant of  claim 33 , wherein the native capitate and hamate bones are preserved and articulate with the articulating surface, thereby resembling the native midcarpal joint.  
   
   
       35 . The hemi-arthroplasty implant of  claim 33 , wherein the curvature of the articulating surface preserves the curvature of the midcarpal joint and maintains the curvature of the midcarpal space.  
   
   
       36 . The hemi-arthroplasty implant of  claim 33 , wherein the articulating surface is formed of multiple concave and convex surfaces that are arranged to cradle the native capitate bone and articulate with the trapezium and trapezoid so as to provide a replacement midcarpal joint.  
   
   
       37 . The hemi-arthroplasty implant of  claim 36 , wherein the multiple concave surfaces include concavity in the dorsal to palmar direction and concavity in a radial to ulnar direction.  
   
   
       38 . A method of converting a hemi-arthroplasty wrist implant to a total arthroplasty wrist implant comprising the steps of: 
 implanting a modular hemi-arthroplasty implant that preserves the distal carpal row and includes a proximal radial component that includes a stem portion for implantation in the radius bone and a first articulating liner including a modular bearing surface that is constructed to provide an articulating surface that replicates the function of healthy proximal carpal row bones and is configured to articulate with the native capitate bone;    subsequently removing the first articulating liner from the stem portion which is kept in place when it is desired to convert the hemi-arthroplasty implant to the total arthroplasty implant;    coupling a second articulating liner to the stem portion of the proximal radial component, the second articulating liner being one that is constructed to simulate the proximal shape of the midcarpal joint; and    implanting a distal carpal component that includes an articulating surface that mates with an articulating surface of the second articulating liner that is constructed to simulate the proximal shape of the midcarpal joint to provide a total arthroplasty implant.    
   
   
       39 . The method of  claim 38 , wherein the distal carpal component is configured to be attached to metacarpal bones and includes a first part that has a convex shape and replicates the distal midcarapal surface of the capitate and hamate and a carpal plate to which the first part is detachably coupled to define a modular system, the carpal plate being fixed to the metacarpal bones.  
   
   
       40 . The method of  claim 38 , wherein the articulating surface of the second articulating liner is different than the articulating surface of the first articulating liner.  
   
   
       41 . A modular kit for replacing a wrist joint comprising: 
 a hemi-arthroplasty implant that preserves the distal carpal row including a component that has a stem portion for implantation in the radius bone and a removable and interchangeable first liner that has a bearing surface that is constructed to provide an articulating surface that replicates the function of healthy proximal carpal row bones;    a second liner that includes a bearing surface and is configured to be coupled to the stem portion when converting the hemi-arthroplasty implant to a total arthroplasty implant; and    a distal carpal component that is configured, in combination with the second liner, to convert the hemi-arthroplasty implant to the total arthroplasty implant, the distal carpal component including an articulating surface that mates with the bearing surface of the second liner to provide the total arthroplasty implant, the distal carpal component being configured to be attached to metacarapal bones when it is desired to convert the hemi-arthroplasty implant to the total arthroplasty implant.    
   
   
       42 . The kit of  claim 41 , wherein the native capitate and hamate bones are preserved with the hemi-arthroplasty implant and articulate with the articulating surface, thereby resembling the native midcarpal joint.  
   
   
       43 . The kit of  claim 41 , wherein the curvature of the articulating surface preserves the curvature of the midcarpal joint and maintains the curvature of the midcarpal space.  
   
   
       44 . The kit of  claim 41 , wherein the articulating surface of the hemi-arthroplasty implant is formed of multiple concave surfaces that are oriented to cradle the native capitate bone so as to provide a replacement midcarpal joint.  
   
   
       45 . The kit of  claim 41 , wherein the distal carpal component includes a first part that has a convex shape and replicates the distal midcarpal surface of the capitate and hamate and a carpal plate to which the first part is detachably coupled to define a modular system, the carpal plate being fixed to the metacarpal bones.  
   
   
       46 . The kit of  claim 41 , wherein both the hemi-arthroplasty implant and total arthroplasty implant are configured to permit a range of wrist movements includes a dart thrower's movement which is a combination or coupling of flexion-extension and radioulnar deviation.  
   
   
       47 . The kit of  claim 41 , wherein the articulating surface of the first liner of the hemi-arthroplasty implant is formed of pyrolytic carbon and the articulating surface of the second liner is formed of polyethylene.