Thursday, September 20, 2007

Anterior/Posterior (A/P) spine reconstruction for 50 yo woman with flatback syndrome, and L5S1 severe disc collapse below previous long fusion, with removal of unusual hardware. Hey Clinic Surgery Sep 20 2007. Spine Surgeon Surgical Tips: Instruction Manual for Removing Grubb Spinal Hardware.

Today at Duke Raleigh Hospital we helped a 50 yo woman who has had 6 major spinal surgeries done elsewhere for scoliosis and extension fusions.  Her last surgery was several years ago, and extended her fusion down to L5, leaving one remaining disc.  Over the past few years, she had noted severe increasing back and leg pain, trouble walking, and increasing problems with a forward lean, also known as “kyphosis” and “Flatback Syndrome”. What has happened over the past few years is her last remaining L5S1 disc has gradually deteriorated and lost disc height, allowing the whole spine, with her whole body to gradually lean forward.  Discs below a long fusion, especially if there are only one or 2 remaining can be subject to this type of “adjacent level degeneration” or “Adjacent level failure”, which can cause severe pain both in the back and down the legs, as well as weakness, numbness and fatigue when standing and walking.  This woman has had been to multiple pain clinics, has had multiple injections and has been on increasing narcotics, including a very strong 100 ug Fentanyl Duralgesic patch, while her quality of life continued to deteriorate.  Her X-Rays confirmed the complete collapse of the L5S1 disc, with her center of gravity pitched forward like the “Leaning Tower of Pisa” --- causing her to have to bend her knees in order to keep her spine somewhat erect, which is very tiring.  Her CT scan of LS spine confirmed the severe L5S1 degeneration with the bone literally rubbing on the bone, with some anterolisthesis or slippage of L5 forward on S1.  There is some stenosis at L5S1 as well, especially around the exiting L5 nerve roots. There appears to be a possible pars fracture of L5 as well.

We ended up fixing this woman’s degenerative disc and “flat back” problem by doing an anterior/posterior or “A/P” or “front and back” spinal procedure.  First, working with Dr. Chris Watters from General Surgery here in Raleigh we went in through her abdomen through a small transverse “bikini” incision, and exposed the L5S1 disc from the front.  I scraped out the disc, which was really completely gone, with bone rubbing on the bone.  I distracted open the space, roughed up the bony surfaces, and removed the small amount of residual disc toward the back.  I then inserted a titanium anterior lumbar interbody fusion (ALIF) cage, which is the blue cage pictured above, packed with bone.  These cages come in a variety of sizes.  By putting a special “jack” to lift open her L5S1 space, I was able to open the anterior L5S1 disc space from zero mm up to 15 mm anteriorly, and then slip in the 15 mm ALIF cage with bone graft.  The ALIF cage is shaped like a wedge, to help recreate the proper lordosis, or backward curvature that the lumbar spine is supposed to have.  Very small improvements in this angle at L5S1 can have HUGE effects on the center of gravity of the patient, just as jacking up one side of the leaning Tower of Pisa has a huge effect on the displacement of the floors a hundred feet or more above. I then put a screw with a washer into the S1 vertebra to prevent the cage from migrating after surgery. The anterior wound is then closed up with a plastic surgery-type subcuticular closure, and then the patient is turned to the prone position to fix the posterior part of the spine.

The next big challenge is to remove the old hardware.  Today we have a special challenge.

How to Take Out Grubb Spinal Hardware.
Her hardware is not a commonly used pedicle screw system invented by a Dr. Grubb who used to work at Durham Regional years ago.  This system is very difficult to remove, so if this X-Ray looks familiar, and you are a spine surgeon planning a revision, you may want to see one of my old Blogs in my archive from last year for some tips on hardware removal, or check out my “Tips” below.  As my senior residents said at the Brigham and Mass General Hospitals:  “You Never Look Good Taking Out Hardware”!  This is definitely true when you are trying to remove Dr. Grubb’s custom hardware.  The defining characteristics of the Grubb hardware is the unusual “rough rod”, combined with an unusual pedicle screw to rod connector that appears as a big rectangle on X-Ray.  Do not bother trying to contact the vendor or Durham Regional Hospital to get the tools for extraction — there are none.  

Here is a list of the tools you will need to get this system out:
  1. Large Bolt Cutter.  You need to cut the rod between every pedicle screw, very often.
  2. 1/2 inch curved osteotome to get the bone away from around the pedicle screws and other hardware, and also to pry off the initial top small wire on the top of each pedicle screw connector.
  3. Large fragment Synthes screw driver to take out the pedicle screw,
  4. Small head universal driver to remove the approximately 5mm nut on the top of the pedicle screw connector.
  5. A lot of patience.
  6. High speed burr can be helpful as well.

Here are some tips on how to get it out.
Expose the hardware and overlying bone.
Chisel out the bone from around the rod and pedicle screw connectors.  The pedicle screws may be quite a ways away from the connecting rod.
Chisel off the top small piece of wire which holds on a rectangular piece of metal that prevents the top nut from loosening.
Chisel off the top rectangular piece of metal with the chisel.
Loosen nut on top of pedicle screw connector.  The connector should gradually lift off.  Sometimes you can cut the connector below the rectangular metal piece.
Cut the rods between each pedicle screw so you can slip out the pieces of rod. This could be many cuts.
Now you are going to look in there and just see some little threaded pieces of metal sticking out of the fusion mass and wonder where the pedicle screws are.
The answer is this:  The pedicle screws are connected to that little piece of threaded rod, but not directly below it.  Instead, the pedicle screws have a large, flat head, about 1/2 inch in diameter with the Synthes female hex hole in the middle of the screw.  On the edge of that 1/2 inch circle is attached the vertical threaded post that you see sitting out of the bone.  So now what you have to do is to chisel down and around that vertical post at every level, and find that 1/2 inch flat circular top of the pedicle screw.  You may literally have to explore 360 degrees around each post to find the top of the pedicle screw, which can take a while.  Now it gets even worse.  At this point when you have that 1/2 inch shiny metal top of pedicle screw, and you get your Synthes screw driver in the middle of it, but when you go to turn it, it won’t turn.  At this point, you may say something bad.  Hold your tongue.  Here’s the problem.  While the huge pedicle screw top looks round, it actually is not completely round, since the vertical post actually sticks out slightly from the circumference of the big pedicle screw head.  Therefore, when you go to turn it in bone, this acts like a lock, and prevents screw turning.  To solve this, you need to chisel some more (or use burr) , down and around the head of the screw, giving yourself a 2-4 mm extra diameter opening another 3-4 mm deep.  Now when you go to turn the Synthes screwdriver, the pedicle screw unscrews.  At this point the Halleluiah Chorus begins to sing all around you, as you lift the last piece of evil hardware from the patient, feeling a bit like Indiana Jones outsmarting the Temple of Doom.  All kidding aside, my Surgical assisting PA Brittany helped me keep my sanity on our last Grubb hardware removal case by giving an enthusiastic “Woo Hoo!!!” after every screw I successfully removed.  There were about 12 screws to come out, so there was a lot of “Woo Hooing” going on!

After we removed her old hardware, we put in new hardware from L2-Iliac wing bilaterally.  This was a bit challenging since both of her iliac crests have been used for her previous 6 spinal fusions, with most of the posterior iliac crest on the R side removed.  On the L side I was able to get a great passage down the remaining iliac crest, but on the L side had to use some of the sacrum combined with SI joint for the most distal set of screws.  Long iliac wing fixation when combined with Sacral screws provides a very strong foundation for these high stress long constructs.

I then did a posterior osteotomy of L5, removing the entire lamina and pars so that I could “close the book”, and create additional lumbar lordosis by closing down the posterior part of the spine.  Putting the OR table into a “V” position, as well as taking time to contour your rods to maximize the lumbar lordosis is very helpful.  I was able to create an additional 15-20 degrees of lordosis this way.  We did not have to hook our instrumentation to the old instrumentation above since there was a very solid fusion in between these two areas of hardware.  The old fusion mass as well as the sacrral ala are roughed up to help bone healing and bone graft is packed out over this decorticated bone to promote the necessary new fusion.  A special three cross-connector system is used to help decrease bending loads around the sacral screws.

Total surgical time was six hours 45 minutes. EBL 2200 cc.  2 units of PRBC transfused in addition to cell saver.  Patient is doing well tonight recovering in ICU extubated.  Husband very happy.

So what can we learn from today?
  1. One way to fix flat back syndrome is by “jacking up” the disc or discs that have collapsed with ALIF cages, combined with posterior osteotomies and hardware.
  2. You never look good taking out hardware.
  3. Always be prepared to have right equipment to take out hardware, which always includes a large bolt cutter, chisel and burr.
  4. If you are a young spine surgeon trying to figure out what instrumentation to use, please consider the “ease of removal” issue, as well as the “ease of adding on” or extending a fusion with connectors, etc.  It might make your life, or the life of your patient and another surgeon much more pleasant and less risky in the future.
  5. You can get in pelvic hardware like iliac wing screws in patients who have had iliac crest bone graft removed, but study your CT scan of pelvis preop, and be willing to adapt a little if there is not enough bone on both sides.

Tomorrow we will get this young lady standing up for first time, with her center of gravity back where it belongs, and without the raw bone rubbing on raw bone at L5S1.  I have had many patients with this problem tell me that they feel like the “top half of their body is not well connected to the bottom” when walking, or changing position.  Some can even feel a “clunk”, often painful when changing position as the L5 slips on S1.  Well, now her top half is well connected to the bottom, and the nerves in between are no longer being crushed. There is hope for renewed quality of life despite her long history of many spine surgeries.

Lloyd A. Hey, MD MS  em: hey at
Hey Clinic for Scoliosis and Spine Surgery
Raleigh, NC  USA

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