Device and method for positioning an eccentric humeral head of a humerus prothesis for a shoulder arthroplasty

Abstract

A kit and associated method is disclosed for implanting a prosthetic device in a resected bone such as a humerus. The kit includes a trial assembly including a trial body portion having a trial bore defined therein, and a trial head portion having (i) a trail head member which includes a trial offset indicia, and (ii) an eccentrically located trial stem extending from the trial head member, the trial head stem being configured to be received within the trial bore. The kit also includes a final prosthesis assembly including a final body portion having a final bore defined therein, and a final head portion having (i) a final head member which includes a final offset indicia, and (ii) an eccentrically located final head stem extending from the final head portion, the final head stem being configured to be received within the final bore.

What is claimed is:  
     
         1 . A method of implanting a final prosthesis assembly in a resected bone, comprising the steps of: 
 positioning a trial assembly in said resected bone, said trial assembly including a trial body portion having a trial bore defined therein, and a trial head portion having (i) a trial head member which includes a trial offset indicia, and (ii) an eccentrically located trial head stem extending from said trial head member, said trial head stem being configured to be received within said trial bore;    rotating said trial head portion relative to said trial body portion while said trial assembly is positioned in said resected bone so as to position said trial head portion relative to said trial body portion at an aligned orientation whereby said trial head portion covers a resected surface of said resected bone;    removing said trial assembly from said resected bone after said rotating step;    positioning said trial assembly in a scale mechanism whereby said trial offset indicia of said trial head portion aligns with a value on said scale mechanism;    securing a final head portion to a final body portion based on said value so as to form said final prosthesis assembly; and    implanting said final prosthesis assembly in said resected bone after said securing step.    
     
     
         2 . The method of  claim 1 , further comprising the step of securing said trial head portion to said trial body portion when said trial head portion is positioned relative to said trial body portion at said aligned orientation.  
     
     
         3 . The method of  claim 2 , wherein: 
 said trial body portion includes a set of internal threads located within said trial bore,    said trial head portion further includes an externally threaded fastener positioned within a passageway which extends through said trial head portion, and    said securing step includes the step of advancing said externally threaded fastener into meshing engagement with said set of internal threads so as to secure said trial head portion in fixed relation to said trial body portion.    
     
     
         4 . The method of  claim 1 , wherein: 
 said trial body portion includes (i) a trial body stem, (ii) a neck attached to said trial body stem, and (iii) a flat attached to said neck, and    said trial bore extends through said flat and into said neck.    
     
     
         5 . The method of  claim 1 , wherein: 
 said scale mechanism includes an indicia surface, and    said value is identified on said indicia surface.    
     
     
         6 . The method of  claim 5 , wherein: 
 said indicia surface possesses markings which depict a clock which is divided into a plurality of sections, and    said value is identified on one of said plurality of sections.    
     
     
         7 . The method of  claim 5 , wherein: 
 said scale mechanism includes a channel defined therein, and    said trial assembly positioning step includes the step of locating said trial body portion within said channel.    
     
     
         8 . The method of  claim 7 , wherein: 
 said trial body portion locating step includes the step of locating said trial head portion adjacent to said indicia surface.    
     
     
         9 . The method of  claim 1 , wherein said final head portion includes (i) a final head member having a final offset indicia, and (ii) an eccentrically located final head stem extending from said final head member.  
     
     
         10 . The method of  claim 9 , wherein: 
 said final head stem possesses a male taper configuration,    said final body portion has a final bore defined therein,    said final bore possesses a female taper configuration, and    said attaching step includes the step of advancing said final head stem into said final bore in a friction fit manner.    
     
     
         11 . The method of  claim 9 , wherein: 
 said scale mechanism includes an indicia surface,    said value is indicated on said indicia surface,    said scale mechanism further includes a channel define therein, and    said attaching step includes locating said final body portion within said channel.    
     
     
         12 . The method of  claim 11 , wherein said attaching step further includes locating said final head portion adjacent to said indicia surface.  
     
     
         13 . The method of  claim 12 , wherein said attaching step further includes positioning said final head portion relative to said final body portion at said aligned orientation.  
     
     
         14 . The method of  claim 13 , wherein said step of positioning said final head portion relative to said final body portion includes the step of aligning said final offset indicia with said value identified on said indicia surface.  
     
     
         15 . The method of  claim 9 , wherein: 
 said trial offset indicia includes a notch defined in a surface of said trial head member, and    said final offset indicia includes a removable sticker positioned on said final head member.    
     
     
         16 . The method of  claim 1 , wherein said resected bone is a resected humerus.  
     
     
         17 . A method of implanting a final prosthesis assembly in a resected bone, comprising the steps of: 
 providing a trail assembly which includes a trial body portion having a trial bore defined therein, and a trial head portion having (i) a trial head member which includes a trial offset indicia, and (ii) an eccentrically located trial head stem extending from said trial head member;    positioning said trial body portion in said resected bone;    positioning said trial stem in said trial bore after said trial body positioning step;    moving said trial head portion in relation to said trial body portion after said trial stem positioning step so as to locate said trial head portion relative to said trial body portion at a user-selected orientation;    securing said trial head portion to said trial body portion at said user-selected orientation;    removing said trial assembly from said resected bone after said securing step;    positioning said trial assembly in a scale mechanism after said removing step whereby said trial offset indicia of said trial head portion aligns with a value on said scale mechanism;    attaching a final head portion in fixed relation to a final body portion based on said value so as to form said final prosthesis assembly; and    implanting said final prosthesis assembly in said resected bone after said attaching step.    
     
     
         18 . The method of  claim 17 , wherein: 
 said trial body portion includes a set of internal threads located within said trial bore,    said trial head portion further includes an externally threaded fastener positioned within a passageway which extends through said trial head portion, and    said securing step includes the step of advancing said externally threaded fastener into meshing engagement with said set of internal threads so as to secure said trial head portion in fixed relation to said trial body portion.    
     
     
         19 . The method of  claim 17 , wherein: 
 said trial body portion includes a (i) a trial body stem, (ii) a neck attached to said trial body stem, and (iii) a flat attached to said neck, and    said trial bore extends through said flat and into said neck.    
     
     
         20 . The method of  claim 17 , wherein: 
 said scale mechanism includes an indicia surface, and    said value is identified on said indicia surface.    
     
     
         21 . The method of  claim 20 , wherein: 
 said indicia surface possesses markings which depict a clock which is divided into a plurality of sections, and    said value is identified on one of said plurality of sections.    
     
     
         22 . The method of  claim 20 , wherein: 
 said scale mechanism includes a channel defined therein, and    said trial assembly positioning step includes the step of locating said trial body portion within said channel.    
     
     
         23 . The method of  claim 22 , wherein said trial body portion locating step includes the step of locating said trial head portion adjacent to said indicia surface.  
     
     
         24 . The method of  claim 17 , wherein: 
 said final head portion includes (i) a final head member having a final offset indicia, and (ii) an eccentrically located final head stem extending from said final head member,    said final head stem possesses a male taper configuration,    said final body portion has a final bore defined therein,    said final bore possesses a female taper configuration, and    said attaching step includes the step of advancing said final head stem into said final bore in a friction fit manner.    
     
     
         25 . The method of  claim 24 , wherein: 
 said scale mechanism includes an indicia surface,    said value is indicated on said indicia surface,    said scale mechanism further includes a channel define therein, and    said attaching step includes the steps of (i) locating said final body portion within said channel, (ii) positioning said final head portion relative to said final body portion so that said final offset indicia is aligned with said value identified on said indicia surface.    
     
     
         26 . The method of  claim 24 , wherein: 
 said trial offset indicia includes a notch defined in a surface of said trial head member, and    said final offset indicia includes a removable sticker positioned on said final head member.    
     
     
         27 . The method of  claim 17 , wherein said resected bone is a resected humerus.  
     
     
         28 . A kit, comprising: 
 a trial assembly including a trial body portion having a trial bore defined therein, and a trial head portion having (i) a trail head member which includes a trial offset indicia, and (ii) an eccentrically located trial stem extending from said trial head member, said trial head stem being configured to be received within said trial bore; and    a final prosthesis assembly including a final body portion having a final bore defined therein, and a final head portion having (i) a final head member which includes a final offset indicia, and (ii) an eccentrically located final head stem extending from said final head portion, said final head stem being configured to be received within said final bore.    
     
     
         29 . The kit of  claim 28 , further comprising a scale mechanism having an indicia surface, wherein: 
 said scale mechanism has a channel defined therein which is configured to receive said trial body portion, and    said channel is configured so that said trail head portion is positioned adjacent to said indicia surface when (i) said trial body portion is located within said channel, and (ii) said trial head portion is supported by said trial body portion.    
     
     
         30 . The kit of  claim 29 , wherein: 
 said indicia surface possesses markings which depict a clock which is divided into a plurality of sections, and    each of said plurality of sections possesses a distinct value indicated thereon.    
     
     
         31 . The kit of  claim 28 , wherein: 
 said trial body portion includes a set of internal threads located within said trial bore,    said trial head portion further includes an externally threaded fastener positioned within a passageway which extends through said trial head portion, and    said externally threaded fastener is configured to meshingly engage said set of internal threads so as to secure said trial head portion in fixed relation to said trial body portion.    
     
     
         32 . The kit of  claim 28 , wherein: 
 said final head stem possesses a male taper configuration,    said final body portion has a final bore defined therein,    said final bore possesses a female taper configuration, and    advancement of said final head stem into said final bore of said final body portion in a friction fit manner causes said final head portion to be secured to said final body portion.    
     
     
         33 . The kit of  claim 28 , wherein: 
 said trial body portion includes (i) a trial body stem, (ii) a neck attached to said trial body stem, and (iii) a flat attached to said neck, and    said trial bore extends through said flat and into said neck.    
     
     
         34 . The kit of  claim 28 , wherein: 
 said trial offset indicia includes a notch defined in said trial head member, and    said final offset indicia includes a removable sticker positioned on a surface of said final head member.    
     
     
         35 . The kit of  claim 28 , wherein: 
 said trial body portion is configured to be advanced into a humerus, and    said final body portion is also configured to be advanced into said humerus.    
     
     
         36 . A kit, comprising: 
 a trial assembly including (i) a trial body portion, (ii) a trial head portion which includes a trial offset indicia, and (iii) a fastener for securing said trial head portion to said trial body portion; and    a final prosthesis assembly including a final body portion having a final bore defined therein, and a final head portion having (i) a final head member which includes a final offset indicia, and (ii) an eccentrically located final head stem extending from said final head portion, said final head stem being configured to be received within said final bore.    
     
     
         37 . The kit of  claim 36 , wherein: 
 said trial body portion has a trial bore defined therein, and    said trial head portion has (i) a trial head member which includes said trial offset indicia, and (ii) an eccentrically located trial stem extending from said trial head member, said trial head stem being configured to be received within said trial bore.    
     
     
         38 . The kit of  claim 36 , further comprising a scale mechanism having an indicia surface, wherein: 
 said scale mechanism has a channel defined therein which is configured to receive said trial body portion, and    said channel is configured so that said trail head portion is positioned adjacent to said indicia surface when (i) said trial body portion is located within said channel, and (ii) said trial head portion is supported by said trial body portion.    
     
     
         39 . The kit of  claim 38 , wherein: 
 said indicia surface possesses markings which depict a clock which is divided into a plurality of sections, and    each of said plurality of sections possesses a distinct value indicated thereon.    
     
     
         40 . The kit of  claim 37 , wherein: 
 said trial body portion includes a set of internal threads located within said trial bore,    said fastener includes an externally threaded portion,    said fastener is configured to be received within a passageway which extends through said trial head portion, and    said externally threaded portion is configured to meshingly engage said set of internal threads so as to secure said trial head portion in fixed relation to said trial body portion.    
     
     
         41 . The kit of  claim 36 , wherein: 
 said final head stem possesses a male taper configuration,    said final body portion has a final bore defined therein,    said final bore possesses a female taper configuration, and    advancement of said final head stem into said final bore of said final body portion in a friction fit manner causes said final head portion to be secured to said final body portion.    
     
     
         42 . The kit of  claim 37 , wherein: 
 said trial body portion includes a (i) a trial body stem, (ii) a neck attached to said trial body stem, and (iii) a flat attached to said neck, and    said trial bore extends through said flat and into said neck.    
     
     
         43 . The kit of  claim 37 , wherein: 
 said trial offset indicia includes a notch defined in said trial head member, and    said final offset indicia includes a removable sticker positioned on a surface of said final head member.    
     
     
         44 . The kit of  claim 36 , wherein: 
 said trial body portion is configured to be advanced into a humerus, and    said final body portion is also configured to be advanced into said humerus.