Interbody fusion grafts and instrumentation

Abstract

This invention relates to implants formed from donor bone for use in lumbar interbody fusion procedures and instruments for performing such procedures. The implants are formed to include a concave surface formed from a portion of the medullary canal of a long bone. The concaved surface defines a recess in the implant that serves as a depot for osteogenic material. Specific instruments for inserting the implants prepared according to this invention and for preparing the intervertebral space to receive the implants are also provided.

Description

FIELD OF THE INVENTION [0001] The present invention relates to implants for use in lumbar interbody fusion procedures and instruments for performing such procedure. More specifically, this invention relates to implants formed from donor bone that are useful to restore disc height and promote bone fusion after discectomy and to instruments and methods for preparing the intervertebral space and inserting the implant into an intervertebral space. BACKGROUND OF THE INVENTION [0002] One of the leading causes of lower back pain and disability results from the rupture or degeneration of one or more lumbar discs in the spine. Pain and instability are caused by compression of the spinal nerve roots because the damaged discs protrude into the vertebral canal and do not provide sufficient biomechanical support for the full range of vertebral motion. Normally intervertebral discs, which are located between endplates of adjacent vertebrae, stabilize the spine and distribute forces between the ve...

AI Technical Summary

Benefits of technology

The present invention provides an improved implant of bone to maintain an intervertebral space after discectomy. The implant has a shaped body with sufficient biomechanical support to maintain the desired space and is secured in place by an implant holder. The implant holder includes a gripping head for releasably securing the implant. The implant can be impacted into position within the intervertebral space using an implant holder and an impacting surface. The invention also provides instruments for preparing and inserting spinal fusion implants, including a bone chisel, scrapers, and drills. The invention also provides a protective guide sleeve for minimizing tissue impacted by surgery and a retractor for manipulation of neural structures.

Problems solved by technology

Pain and instability are caused by compression of the spinal nerve roots because the damaged discs protrude into the vertebral canal and do not provide sufficient biomechanical support for the full range of vertebral motion.

The spinal discs may be displaced or damaged due to trauma, disease or aging.

A herniated or ruptured annulus fibrosis may result in nerve damage, pain, numbness, muscle weakness, and even paralysis.

Furthermore, as a result of the normal aging processes, discs dehydrate and harden, thereby reducing the disc space height and producing instability of the spine and decreased mobility.

However, patients who have failed to respond to conservative treatment and who have demonstrable disc pathology often require surgical correction.

Current treatment methods have been unable to accurately control the endplate removal using conventionally designed chisels, scrappers and cutters.

Use of conventional surgical instruments does not adequately control the depth of cut into the disc space nor provide a means to accurately the countersink the implant into the prepared cavity-particularly for non threaded impacted.

Furthermore, current methodologies do not provide sufficient protection of the neural structures during surgery to prevent neural injury.

While it is desirable to use natural bone grafts as implants, use of bone is often limited because of a small supply of suitable sources.

Xenografts from non-humans, animals, suffer from rejection problems once implanted.

Removal of an autograft requires further surgery and is limited in amount and structural integrity by the patient's anatomy.

Much of the donor bone is wasted, particularly the remnants of the slices from the diaphysis used to provide the dowels as well as the end portions of the long bone which cannot be utilized.

Thus, these portions of the femur are not considered suitable for forming cortical dowels having the required dimensions for inserting into vertebral spaces.

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