Procedures

Posterior Lumbar Fusion Using
Intervertebral Cage and Grafton® DBM Putty

Randall F. Dryer, M.D., F.A.C.S.
Central Texas Spine Institute, Austin TX
This patient is a 42-year-old male who has a recurrent disc herniation at L5 and S1, causing severe back and leg pain. Previous surgery at this level has failed to improve the condition. This surgery will involve the implantation of a titanium interbody fusion cage between the L5 and S1 vertebrae. The interbody cage will be packed with autograft bone supplemented with Grafton® DBM Putty to help achieve optimal fusion.
     
     
Gadolinium-enhanced MRI reveals recurrent disc herniation between
L5 and S1
Lateral view of spine one month after implantation of intervertebral fusion cages.
The intervertebral disc between L5 and 51 is removed using a rongeur.
A titanium interbody fusion cage is implanted and recessed approximately 1 mm into the posterior aspect of the vertebral body.
Grafton® DBM Putty is packed tightly into the cage, filling the interstices and gaps between the patient's own bone.
Once the fusion cage is fully packed with a combination of autograft bone and Grafton®, a polyethylene cap is positioned and ready to be snapped into place.


"I've found the fusion rate is much higher when using Grafton® mixed with autograft bone in these interbody cages. I'm seeing a much earlier sentinel path of bone growth that's coming around the anterior and posterior aspects of the cage, and well around the sides of the cage."

Dr. Randall F. Dryer
 
General Remarks
By supplementing the patient's own bone (harvested from around the facet joint and lamina) with Grafton® DBM, the need to make a separate incision to harvest bone from the patient's iliac crest is eliminated. This simplifies the procedure and results in a more comfortable operation for the patient.

Detailed Description
  • The supraspinal and interspinal ligament complex between L5 and S1, is removed using a rongeur.

  • A high-speed bur is also used, gently touching the bone, to carefully remove all of the soft tissue over the lamina and spinous process. This makes it much easier to clean the soft tissues and harvest the bone graft.

  • The lamina is then removed, in small, piecemeal fashion. A ball-ended dissecting instrument is used to free the dura from the bone and ligamentum flavum.

  • The soft tissues around the facet joint and lamina are cleaned further using a curette.

  • The nerve roots and the calsac are retracted gently to the midline, and hemostasis of the ventral surface of the canal is maintained with bipolar electrocoagulation. Coftonoid pledgets are placed superiorly and inferiody around the nerve roots to protect them during this portion of the operaton.

  • A pituitary rongeur is used to remove the annulus of the disc and then passed into the disc space to remove the substance of the nucleus pulposus, followed by removal of the cartilaginous endplate from the vertebral body using a downpushing Scoville curette.

    •
  • A tang retractor is positioned into the center of the disc space, enlarging the opening of the disc space in preparation for fusion cage insertion. To hold the implant in place, threads are made using a calibrated tap.

  • The implant is placed into the intervertebral space using a T-handled instrument to guide it through the drilling tube. The fusion cage is recessed approximately 1mm into the posterior aspect of the vertebral body.

  • Autograft bone, harvested from the spinous process and lamina, is pushed and packed tightly into the fusion cage. The Grafton® DBM Putty is then packed into the cage, filling the interstices and gaps between the patient's own bone.

  • Once completely packed, a polyethylene cap is snapped gently into place onto the top of the fusion cage.

  • Gelfoam is placed around the area of the implant for hemostasis, while an identical drill, tap, and fusion cage implantation procedure is accomplished on the opposite side.

BACK TO TOP

© Copyright Osteotech, Inc. 2007. All rights reserved.