Dynamic Ossicular Prosthesis

Abstract

An ossicular replacement prosthesis includes first and second engagement structures for engaging middle ear structures, a spring that biases the first and second engagement structures longitudinally apart when under compression, and a rod that axially stabilizes longitudinal movement of the first and second engagement structures and conducts sound waves between the first and second engagement structures. Relative axial pressure on the first and second engagement structures causes compression or expansion of the spring which results in movement of the rod to adjust the length of the prosthesis to accommodate changes in anatomical distance as occurs under changes in pressure or abnormal middle ear conditions.

1 . An ossicular prosthesis, comprising:
 a) a first prosthesis portion having a first end for engaging a first middle ear structure;   b) a second prosthesis portion having a second end for engaging a second middle ear structure and defining an axial bore having an opening facing said first prosthesis portion;   c) a coil spring that biases said first and second prosthesis portions longitudinally apart and which is expandable or compressible to self adjust a length of said prosthesis when said first and second prosthesis portions are subject to axial forces, said spring having first and second ends and defining an internal space, said first end of said spring retained relative to said first prosthesis portion such that said first end of said spring extends external to a portion of said first prosthesis portion defining said axial bore, and said second end of said spring retained relative to said second prosthesis portion; and   d) a rod extending from said first prosthesis portion and into said internal space of said spring and said axial bore, said rod longitudinally displaceable through said internal space of said spring and within said axial bore upon longitudinal movement of said first and second prosthesis portions relative to each other,   wherein displacement of said rod within said axial bore stabilizes movement of said first and second prosthesis portions relative to each other.   
     
     
         2 . An ossicular prosthesis according to  claim 1 , further comprising:
 a first spring mount fixed relative to said first prosthesis portion that retains said first end of said spring relative to said first prosthesis portion; and   a second spring mount fixed relative to said rod under physiological loads that retains said second end of said spring relative to said second prosthesis portion, said second end of said second prosthesis portion provided distal said first end of said first prosthesis portion,   wherein said spring is retained between said first and second spring mounts.   
     
     
         3 . An ossicular prosthesis according to  claim 2 , wherein:
 said first and second spring mounts are longitudinally displaced platforms between which said spring is retained and upon which said spring acts to bias said first and second ends of said first and second prosthesis portions apart when said spring is under compression.   
     
     
         4 . An ossicular prosthesis according to  claim 2 , wherein:
 said second end of said second prosthesis portion and said first spring mount are longitudinally adjustable relative to each other.   
     
     
         5 . An ossicular prosthesis according to  claim 1 , wherein:
 said first end of said spring is fixed relative to said first prosthesis portion and said second end of said spring is fixed relative to said second prosthesis portion.   
     
     
         6 . An ossicular prosthesis according to  claim 1 , wherein:
 said rod at least partially conducts sound waves between said first and second prosthesis portions.   
     
     
         7 . An ossicular prosthesis according to  claim 1 , wherein:
 said prosthesis has a maximum length between 1.75 and 8 mm.   
     
     
         8 . An ossicular prosthesis according to  claim 1 , wherein:
 said spring is compressible by up to 6 mm.   
     
     
         9 . An ossicular prosthesis according to  claim 1 , wherein:
 said first end of said first prosthesis portion includes an element that is adapted to couple said prosthesis relative to a long process of a malleus.   
     
     
         10 . An ossicular prosthesis according to  claim 1 , wherein:
 said first end of said first prosthesis portion includes a head for placement at or adjacent to a tympanic membrane.   
     
     
         11 . An ossicular prosthesis according to  claim 10 , wherein:
 said first end of said first prosthesis portion includes an element that is adapted to couple said prosthesis relative to a long process of a malleus.   
     
     
         12 . An ossicular prosthesis, comprising:
 a) a first prosthesis portion having a first end for engaging a first middle ear structure;   b) a second prosthesis portion having a second end for engaging a second middle ear structure, said second prosthesis portion defining an axial bore;   c) a spring that biases the first and second prosthesis portions longitudinally apart and which is expandable or compressible to self adjust a length of said prosthesis when said first and second prosthesis portions are subject to axial forces, said spring having first and second ends, said first end of said spring retained relative to said first prosthesis portion and said second end of said spring retained relative to said second prosthesis portion; and   d) a rod fixed to said first prosthesis portion and extending into said axial bore, said rod longitudinally displaceable within said axial bore upon longitudinal movement of said first and second prosthesis portions relative to each other, said extension of said rod into said axial bore providing stabilization to said prosthesis during longitudinal movement of said first and second prosthesis portions relative to each other about said spring.   
     
     
         13 . An ossicular prosthesis according to  claim 12 , further comprising:
 a first spring mount fixed relative to said first prosthesis portion that retains said first end of said spring relative to said first prosthesis portion; and   a second spring mount fixed relative to said rod under physiological loads that retains said second end of said spring relative to said second prosthesis portion, said second end of said second prosthesis portion provided distal said first end of said first prosthesis portion,   wherein said spring is retained between said first and second spring mounts.   
     
     
         14 . An ossicular prosthesis according to  claim 13 , wherein:
 said first and second spring mounts are longitudinally displaced platforms between which said spring is retained and upon which said spring acts to bias said first and second ends of said first and second prosthesis portions apart when said spring is under compression.   
     
     
         15 . An ossicular prosthesis according to  claim 13 , wherein:
 said second end of said second prosthesis portion and said first spring mount are longitudinally adjustable relative to each other.   
     
     
         16 . An ossicular prosthesis according to  claim 12 , wherein:
 said first end of said spring is fixed relative to said first prosthesis portion and said second end of said spring is fixed relative to said second prosthesis portion.   
     
     
         17 . An ossicular prosthesis according to  claim 12 , wherein:
 said rod at least partially conducts sound waves between said first and second prosthesis portions.   
     
     
         18 . An ossicular prosthesis according to  claim 12 , wherein:
 said second end of said second prosthesis portion includes an element that is adapted to couple said prosthesis relative to a long process of a malleus.   
     
     
         19 . An ossicular prosthesis according to  claim 12 , wherein:
 said second end of said second prosthesis portion includes a head for placement at or adjacent to a tympanic membrane.   
     
     
         20 . An ossicular prosthesis according to  claim 12 , wherein:
 said spring defines an internal space, and said rod extends within said internal space during longitudinal displacement of said rod within said axial bore.   
     
     
         21 . An ossicular prosthesis according to  claim 13 , wherein:
 said second end of said second prosthesis portion includes a cup adapted to receive a superstructure of the stapes.