Methods of using, providing and manufacturing a shoulder prosthesis with a one-piece humeral head

Abstract

A humeral head augment device in use in a modular shoulder prosthesis. The humeral head augment device has an external bearing surface with at least one surface portion that includes a radius of curvature. The radius of curvature is configured to constrain transitional movement of the implanted shoulder prosthesis when the humeral head augment device is positioned within the shoulder prosthesis. The humeral head augment device also includes a coupling mechanism designed to lock the humeral head augment device to either the stem or the humeral head, thereby ensuring proper operational positioning of the device within the shoulder prosthesis and allowing the implanted shoulder prosthesis to function in a patient suffering from rotator cuff arthropathy. A shoulder prosthesis using a humeral head augment device, a method tor assembling a shoulder prosthesis and method for using a humeral head augment device in a shoulder prosthesis are also disclosed.

What is claimed is: 
     
         1 . A method of using a shoulder prosthesis, the method comprising: obtaining at least one one-piece humeral bead, the at least one one-piece humeral head having an external articulation surface portion with a radius of curvature, an external bearing surface portion with at least two radii of curvature, and an interior surface with a first connector extending therefrom;
 obtaining at least, one stem, the at least one stem comprising a shaft, a proximal end, and a distal end defining a longitudinal axis therebetween, the proximal end having a second connector; and   engaging the first connector of the at least one one-piece humeral head to the second connector of the at least one stem to assemble the shoulder prosthesis such that the radius of curvature of the external articulation surface portion extends at least across the longitudinal axis of the stem,   wherein the external bearing surface portion of the at least one one-piece humeral head comprises at least a first bearing surface portion of a first radius of curvature and a second bearing surface portion of a second radius of curvature that is different from the first radius of curvature, the first bearing surface portion being positioned adjacent the external articulation surface portion and the second bearing surface portion being positioned adjacent the first bearing surface portion, and   wherein the first radius of curvature of the first bearing surface portion is greater than the radius of curvature of the external articulation surface portion at least immediately adjacent the first bearing surface portion to constrain translation of the assembled shoulder prosthesis when implanted,   
     
     
         2 . The method of  claim 1 , further comprising implanting the assembled shoulder prosthesis into a humerus of a recipient such that when in an operable position, at least the first bearing surface portion constrains translational movement of the implanted assembled shoulder prosthesis. 
     
     
         3 . The method of  claim 2 , wherein at least the first bearing surface portion constrains superior translation of the implanted assembled shoulder prosthesis during abduction of the recipient's arm. 
     
     
         4 . The method of  claim 1 , wherein the first radius of curvature of the first beating surface portion of the at least one one-piece humeral head is greater than the second radius of curvature of the second hearing surface portion of the at least one one-piece humeral head. 
     
     
         5 . The method of  claim 1 , wherein the second radius of curvature of the second bearing surface portion of the at least one one-piece humeral head is greater than the first radius of curvature of the first bearing surface portion of the at least one one-piece humeral head to further constrain translation of the implanted assembled shoulder prosthesis. 
     
     
         6 . The method of  claim 1 , wherein the external bearing surface portion of the at least one one-piece humeral head defines a medial side, a lateral side and a posterior side, and wherein a relief is disposed on the posterior side and extends at least one of from the medial side to the lateral side, from the medial side to a location intermediate the lateral side and medial side, and from the lateral side to a location intermediate the lateral side and medial side, thereby providing a space for passage of a posterior positioned soft tissue structure when the assembled shoulder prosthesis is implanted. 
     
     
         7 . The method of  claim 1 , wherein the external bearing surface portion of the at least one one-piece humeral head comprises at least one hole disposed therein, thereby allowing securement of a soft tissue structure to the at least one one-piece humeral head when the assembled shoulder prosthesis is implanted. 
     
     
         8 . The method of  claim 1 , wherein the radius of curvature of the external articulation surface portion extends to an angle of at least 180 degrees. 
     
     
         9 . The method of  claim 1 , wherein the radius of curvature of the external articulation surface portion extends from a side of the humeral head. 
     
     
         10 . The method of  claim 1 , wherein the external articulation surface portion encompasses the entire exterior articulation surface of the at least one one-piece humeral head, and wherein the combination of the first bearing surface portion and the second bearing surface portion encompasses the entire external bearing surface of the at least one one-piece humeral head. 
     
     
         11 . The method of  claim 1 , wherein when the assembled shoulder prosthesis is implanted in a recipient, the external articulation surface portion of the at least one one-piece
 humeral head articulates with a first shoulder structure of the recipient's shoulder, and the first bearing surface portion of the at least one one-piece bears against a second shoulder structure of the recipient's shoulder that is different from the first shoulder structure during abduction of the recipient's arm to constrain superior translational movement of the assembled shoulder prosthesis and thereby the recipient's arm,   
     
     
         12 . A method of providing a shoulder prosthesis, the method comprising:
 providing at least one one-piece humeral head, the at least one one-piece humeral head having an external articulation surface portion with a radius of curvature, an external bearing surface portion with at least two radii of curvature, and an interior surface with a first connector; and   providing at least one stem, the at least one stem comprising a shaft, a proximal end, and a distal end defining a longitudinal axis therebetween, the proximal end having a second connector configured to engage the first connector of the at least one one-piece humeral head to assemble the shoulder prosthesis,   wherein the shoulder prosthesis is configured such that the radius of curvature of the external articulation surface portion extends at least across the longitudinal axis of the stem when the shoulder prosthesis is assembled,   wherein the external bearing surface portion of the at least one one-piece humeral head comprises at least a first bearing surface portion of a first radius of curvature and a second bearing surface portion of a second radius of curvature that is different from the first radius of curvature, the first bearing surface portion being positioned adjacent the external articulation surface portion and the second bearing surface portion being positioned adjacent the first bearing surface portion, and   wherein the first radius of curvature of the first bearing surface portion is greater than the radius of curvature of the external articulation surface portion at least immediately adjacent the first beating surface portion to constrain translation of the shoulder prosthesis when assembled and implanted.   
     
     
         13 . The method of  claim 12 , further comprising engaging the first connector of the at least one one-piece humeral head to the second connector of the at least one stem to assemble the shoulder prosthesis. 
     
     
         14 . The method of  claim 13 , further comprising implanting the assembled shoulder prosthesis into a humerus of a recipient such that when in an operable position, at least the first bearing surface portion constrains superior translational movement of the implanted shoulder prosthesis during abduction of the recipient's arm. 
     
     
         15 . The method of  claim 12 , wherein the first radius of curvature of the first bearing surface portion of the at least one one-piece humeral head is greater than the second radius of curvature of the second bearing surface portion of the at least one one-piece humeral head. 
     
     
         16 . The method of  claim 12 , wherein the second radius of curvature of the second bearing surface portion of the at least one one-piece humeral head is greater than the first radius of curvature of the first bearing surface portion of the at least one one-piece humeral head to further constrain translation of the implanted shoulder prosthesis. 
     
     
         17 . The method of  claim 12 , wherein the radius of curvature of the external articulation surface portion extends to an angle of at least  180  degrees and from aside of the humeral head. 
     
     
         18 . The method of  claim 12 , wherein the external articulation surface portion encompasses the entire exterior articulation surface of the at least one one-piece humeral head, and wherein the combination of the first bearing surface portion and the second bearing surface portion encompasses the entire external bearing surface of the at least one one-piece humeral head.