Apparatus and method for anterior intervertebral spinal fixation and fusion

#This invention relates to a spinal fusion device. More specifically, the present invention relates to an implant and fixation device used to reconstruct spinal disk space and facilitate fusion across the spinal disk space.

#Articulations between bony vertebras of a human spine frequently deteriorate with age or trauma and become a source of pain. A spinal disk is one of these articulations and with the aging process it loses its normal consistency and volume and collapses allowing for abnormally painful motion within the anterior spinal column. The spinal disk is a complex cylindrical weight-bearing fibrous structure with a non-compressible viscous center. The spinal disk articulates with bony vertebra above and below through a large surface area circular interface known as an endplate. The endplate is a thin (1-3 mm) approximately round 2-4 cm in diameter plate of dense bone and cartilage accounting for a majority of the vertebral weight-bearing capacity (FIG. 2).

#Surgical treatment of disk disorders frequently requires elimination of movement across an abnormal spinal disk. This is accomplished by allowing bone to grow between adjacent vertebra and through a disk space of the abnormal spinal disk. It is desirable to reconstruct the disk space to its prior normal height by opening the space previously occupied by the removed spinal disk while retaining normal curvature of the spine determined by the differential height between the front and the back of the spinal disk (FIG. 3). This is commonly achieved by using inserts or implants, which open the disk space and which allow growth of bridging bone. The ultimate effectiveness of an implant is based on the following factors: (i) ability to reconstruct and maintain a normal configuration of a vertebral column; (ii) ease of insertion; (iii) facilitation of bony fusion; and (iv) restrictive movement across the disk space.

#FIG. 1 Anterior view of the lumbar spine demonstrating vertebra (1) alternating with disk (2).

#FIG. 2 Anterior view of the vertically sliced lumbar spine demonstrating internal composition of the vertebra with dense endplate (3) and softer inner part (4).

#FIG. 3 Lateral (side) view of the vertebral column demonstrating normal curvature (lordosis) of the lumbar spine.

#An implant device for reconstruction, fixation and bone fusion of bone vertebras through an anterior approach to the human spine. This implant device enables rigid fixation in all planes of motion including extension of the spine, it possesses structural characteristics necessary to reconstruct and maintain disk height, it provides space for bone grafting material and produces a plurality of perforations through endplates above and below to enhance bony fusion.

#The implant device consists of the outer structure or shell which is designed to conform to the disk space, provide openings for bony ingrowths and maintain the disk height by providing adequate structural strength and sufficient weight bearing surface. The shell or housing contains a shaft (10) which runs through its central axis from the back (9) to the front (8) and is fixed to the shell (FIG. 7).

#In the preferred embodiment the shell is impacted into the disk space (FIG. 14) using the shell introducer (FIG. 13). The shell introducer includes prongs (15) that fit inside the sides (5) of the shell but is open (16) in the center to allow for blades (FIG. 12).