Prosthetic hip implants

Abstract

Prosthetic hip stems and acetabular cups for use in prosthetic hip joints. The hip stem may include a core having a stem portion and a neck portion, a polymer matrix layer substantially covering the stem portion of the core, and a porous metal layer substantially covering the polymer matrix layer. The polymer matrix layer connects the core and the porous metal layer and provides a stiffness for the hip stem which more closely mimics the stiffness of bone than do known hip stems. The hip stems and acetabular cups additionally include a number of improvements adapted for more optimized results with certain types of patient anatomy, such as the anatomy of female patients, for example.

1 . A prosthetic hip stem, comprising:
 a stem portion having a proximal end and a distal end, said stem portion defining a medial/lateral plane; and   a neck portion projecting from said proximal end, said neck portion having a longitudinal axis therealong which is oriented at a first angle between 13 degrees and 25 degrees anteriorly with respect to said medial/lateral plane.   
   
   
       2 . The hip stem of  claim 1 , wherein said stem portion further comprises:
 a core;   a polymer matrix layer covering at least a portion of said core; and   a porous metal layer substantially covering said polymer matrix layer.   
   
   
       3 . The hip stem of  claim 1 , wherein said neck portion is integrally formed with said stem portion. 
   
   
       4 . The hip stem of  claim 1 , further comprising a head portion of substantially spherical shape, said head portion integrally formed with said neck portion. 
   
   
       5 . The hip stem of  claim 1 , wherein said neck portion comprises a modular component separate from said stem portion, said neck portion selected from a plurality of neck portions having varying first angles. 
   
   
       6 . The hip stem of  claim 1 , further comprising a head portion of substantially spherical shape and having a center disposed on said longitudinal axis, said head portion connected to said neck portion along a second axis which is disposed at a second angle of between 1 and 25 degrees anteriorly with respect to said longitudinal axis. 
   
   
       7 . The hip stem of  claim 6 , wherein said head portion comprises a modular component separate from said neck portion, said head portion selected from a plurality of head portions having varying second angles. 
   
   
       8 . A prosthetic hip stem, comprising:
 a stem portion having a proximal end and a distal end, said stem portion defining a medial/lateral plane therethrough;   a neck portion projecting from said proximal end of said stem portion and having a first, longitudinal axis; and   a head portion of substantially spherical shape and connected to said neck portion along said first axis, said head portion having a center disposed on second axis which is disposed at a second angle of between 1 and 25 degrees anteriorly with respect to said first axis.   
   
   
       9 . The hip stem of  claim 8 , wherein said first, longitudinal axis is disposed at a first angle of between 13 degrees and 25 degrees anteriorly with respect to said medial/lateral plane. 
   
   
       10 . The hip stem of  claim 8 , wherein said stem portion, said neck portion, and said head portion are integrally formed with one another. 
   
   
       11 . The hip stem of  claim 8 , wherein said neck portion comprises a modular component separate from said stem portion, said neck portion selected from a plurality of neck portions of varying first angles, and said head portion comprises a modular component separate from said neck portion, said head portion selected from a plurality of head portions having varying second angles. 
   
   
       12 . The hip stem of  claim 8 , wherein said stem portion further comprises:
 a core;   a polymer matrix layer covering at least a portion of said core; and   a porous metal layer substantially covering said polymer matrix layer.   
   
   
       13 . A prosthetic hip stem, comprising:
 a stem portion having a proximal end and a distal end, and a first, proximal/distal longitudinal axis; and   a neck portion projecting from said proximal end, said neck portion having a second longitudinal axis therealong which is oriented at a first angle of between 90 and 145 degrees with respect to said first axis.   
   
   
       14 . The hip stem of  claim 13 , wherein said neck portion is integrally formed with said stem portion. 
   
   
       15 . The hip stem of  claim 13 , wherein said neck portion is a modular component separate from said stem portion, said neck portion selected from a plurality of neck portions having varying first angles. 
   
   
       16 . A prosthetic hip stem, comprising:
 a stem portion having a proximal end and a distal end; and   a distal end fixation mechanism operable between a first condition wherein said distal end of said stem portion has a first width with respect to at least one of a medial/lateral plane and an anterior/posterior plane of said stem portion and a second condition wherein said distal end of said stem portion has a second width with respect to at least one of said medial/lateral plane and said anterior/posterior plane, said second width greater than said first width.   
   
   
       17 . The hip stem of  claim 16 , wherein said distal end fixation mechanism comprises at least one expansion point in said stem portion defining radially expandable portions of said stem portion, wherein when said stem portion is in said first condition, said radially expandable portions are substantially non-expanded and when said stem portion is in said second condition, said radially expandable portions are at least partially expanded. 
   
   
       18 . The hip stem of  claim 16 , wherein said distal end fixation mechanism comprises an expandable structure and at least one passage in said stem portion, wherein upon insertion of a filler substance through said at least one passage, said filler substance expands said expandable structure, wherein when said stem portion is in said first condition, said expandable structure is substantially empty, and when said stem portion is in said second condition, said expandable structure is at least partially expanded by presence of said filler substance therewithin. 
   
   
       19 . An acetabular cup, comprising:
 a substantially hemispherical cup portion made of a relatively thin, flexible porous metal; and   a liner fitted within said cup portion, said liner including a substantially hemispherical bearing surface.   
   
   
       20 . An acetabular cup, comprising:
 a liner including a substantially hemispherical bearing surface;   a porous metal cup portion; and   an intermediate layer disposed between said liner and said porous metal cup portion, said intermediate layer formed of a polymer matrix.   
   
   
       21 . An acetabular cup, comprising:
 a liner including a substantially hemispherical bearing surface; and   a cup portion including an outer hemispherical portion including a substantially annular loading rib.   
   
   
       22 . A prosthetic hip stem, comprising:
 a proximal end including a core, a polymer matrix layer covering at least a portion of said core, and a porous metal layer substantially covering said polymer matrix layer; and   a distal end including a core and a porous metal layer substantially covering said core.   
   
   
       23 . A prosthetic hip stem, comprising:
 a proximal portion and a distal portion;   an inner core;   a porous metal outer layer; and   an elongated cavity formed in said distal portion, wherein said distal portion is flexible.   
   
   
       24 . The hip stem of  claim 23 , wherein said proximal portion is between 30 mm and 45 mm in length, and said distal portion is between 100 mm and 135 mm in length. 
   
   
       25 . The hip stem of  claim 23 , wherein said proximal portion includes lateral and medial sides which are substantially complementary radiused. 
   
   
       26 . The hip stem of  claim 23 , wherein said proximal portion includes anterior and posterior sides which each flare outwardly as same approach a proximal end of said hip stem. 
   
   
       27 . The hip stem of  claim 23 , wherein said distal portion includes a distal end having a width of between 10 mm and 18 mm in the posterior/anterior dimension and a width of between 11 mm and 19 mm in the medial/lateral dimension.