Two-part prosthetic nucleus replacement for surgical reconstruction of intervertebral discs

Abstract

A prosthetic nucleus replacement comprises a modular two-part body formed into an oval disk. The top part has a domed surface with a crest and is made of a high molecular weight polyethylene or ceramic. The bottom part is made of biocompatible metal like titanium and locks into an underlying vertebrae with a peg or brace molding that extends down into a socket. The prosthetic nucleus replacement is surgically implanted into the hollowed out intervertebral space through a flap cut in the natural annulus fibrosis. The lower vertebra is prepared to receive the peg by clearing the material covering the top of the bone matrix. Bone cement is used around the peg to ensure a tight fit and immobile attachment of the disc to the lower vertebrae.

1 . A prosthetic nucleus replacement for implanting within an annulus fibrosis in one part of a human spine, comprising: 
 a top dome comprised substantially of a first biocompatible material, and having a convex upper side for contacting and articulating with an end-plate cartilage of a supported superior vertebrae;    a base mechanically fixed to and underneath the top dome and comprised substantially of a second biocompatible material, and providing for an immobile foundation on an underlying inferior vertebrae; and    a brace molding extending from a bottom side of the base and providing for an immobilization to said underlying inferior vertebrae;    wherein, said first biocompatible material has a relatively low coefficient of friction and slides easily when in contact with natural cartilage; and    wherein, said second biocompatible material has a relatively high coefficient of friction and fixes well to the bone of said inferior vertebrae.    
     
     
         2 . The prosthetic nucleus replacement of  claim 1 , wherein: 
 the base has a porous bottom surface providing for a bone-growth fixation with said inferior vertebrae.    
     
     
         3 . The prosthetic nucleus replacement of  claim 1 , wherein: 
 the base has a textured bottom surface providing for a cement fixation with said inferior vertebrae.    
     
     
         4 . The prosthetic nucleus replacement of  claim 1 , wherein: 
 the top dome comprises ultra-high molecular-weight polyethylene.    
     
     
         5 . The prosthetic nucleus replacement of  claim 1 , further comprising: 
 a radiograph marker placed within the top dome, and that can assist a physician in determining the in stiu orientation of said prosthetic nucleus replacement by non-invasive medical imaging.    
     
     
         6 . A method for surgically correcting a degenerated nucleus pulposus by the implantation of a prosthetic in a human spine, the method comprising: 
 a flap technique incision of an annulus fibrosis corresponding to an affected area of a spine;    a diskectomy of a degenerated nucleus pulposus in said affected area;    curetting of cartilage down to the bone of an inferior vertebrae adjacent to said affected area and preparing said bone to receive a pin;    assembling a solid ellipsoidal body from interlocking ones of a modular top dome of a first biocompatible material and a modular base of a second biocompatible material, wherein the product provides for replacement of a natural nucleus pulposus;    inserting said solid ellipsoidal body into said affected area through an incision in said annulus fibrosis;    immobilizing said solid ellipsoidal body with respect to said inferior vertebrae; and    repairing incision in said annulus fibrosis;    wherein, a permanent articulation between said solid ellipsoidal body and a superior vertebrae exists after surgery.