Vertebral Body Tether of Lumbar Scoliosis Curves                                                        11-30-2020

 

Over the last 15 years there has been an increasing interest from patients and families in non-fusion solutions for scoliosis.  Vertebral Body Stapling (VBS) was the first non-fusion technique reported for treatment of idiopathic scoliosis, in the 1950s.  Due to the lack of advance implant technology the technique disappeared for 40+ years, but re-appeared in the early 2000s when newer high-tech implants became available. 

 

At the same time a parallel implant system, Vertebral Body Tethering, was also being developed.  Due to the ability to exert a stronger correction force to the spine VBT gained traction, since it can treat curves up to 60 degrees.  In comparison, VBS failed to maintain traction, mainly due to its lower correction force and its application only in smaller scoliosis curves (35 degrees).  Over time VBS faded, and at present there are no commercially available implants in the U.S. to perform VBS.

Many studies from around the world have reported on VBT, but most have focused on its application in the thoracic spine. 

 

 

Thoracic spine (in blue) and lumbar spine (in pink)

Though the thoracic spine has some intervertebral motion, the lumbar spine has vastly more motion at each intervertebral disc.  Conceptually it makes sense that VBT would have a greater impact on preserving spine motion, than fusion, in the lumbar spine.  So why have pediatric spine deformity surgeons focused on the application of VBT in the thoracic spine, if there may be less benefit than the lumbar spine?

Two reasons for this are:

1.      The surgical approach to the thoracic spine can be accomplished with a minimal number and length of surgical incisions, due to the use of a thoracoscope (camera inserted into the chest through small incision to view the spine through the chest).  This is obviously attractive as it leaves small aesthetically reasonable scars.  Surgeons with experience in thoracoscopic spine surgery (VBS and fusions) have considerable expertise with this approach and area of the spine.

2.      The most common curve patterns seen in idiopathic scoliosis are in the thoracic spine.  So surgeons are seeing much more scoliosis in the thoracic spine than the lumbar spine.

 

So what do we know about the use of VBT in the lumbar spine?  Overall not very much. 

There are only two studies, published in 2020, which specifically report the use of VBT in the lumbar spine. There are 6 important points of these 2 studies:

1.      1. Both of these are early-outcome studies with a minimum follow-up after surgery of 2 years and a mean follow-up in both studies of approximately 3 years.  This is very short follow-up for patients who will live another 60+ years. There is no long-term data on VBT.  What will happen long-term to the lumbar spines with a tether placed across the discs?  Will they become arthritic?  Will they cause pain? 

2.      2. Combined they report only on 9 lumbar curves, as opposed to the thoracic spine which have 100s of cases reported in the literature. 

3.      3. Tether breakage in 47-48% of all patients (thoracic and lumbar)

4.      4. Success rates of 53-74%

5.      5. Reoperation rates of 21-24% (1 patient out of 5 underwent a repeat surgery)

6.      6. VBT should only be done in patients with growth remaining.  It is not indicated in skeletally-mature patients (Sanders 7-8 or Risser 4-5)

In contrast to these VBT data, lumbar fusion surgeries for scoliosis have a long history, a high rate of success and low frequency of reoperations.

Picture credit: https://whyy.org/segments/rope-or-rod-torn-between-scoliosis-surgeries/

 

So which way should you go?  Lumbar VBT or Lumbar fusion surgery?

There are many factors which can go into the decision-making process of informed consent and should be discussed in detail with a surgeon who has experience in both approaches.  So I can’t tell you which surgery you or your child should have.

If motion preservation is an important aspect of scoliosis surgical treatment to you, then it is imperative you are fully informed as to the alternatives, benefits, complications and risks of VBT.  No surgery is without risks and potential complications.  If you fully understand the above-mentioned data, then VBT may be a reasonable procedure for lumbar scoliosis in you or your growing child. 

VBT holds significant promise.  I personally believe that VBT, or some variant of it, which can preserve spine motion and correct scoliosis will be eventually be highly successful with long-term outcomes.  However until that time, caveat emptor or “let the buyer beware". 

 

 

 

 

Spine Deformity Surgical Wound Healing                            11-24-2020

 

Back in July (7-28-2020) I published two blog post on spine wounds, specifically the concepts and methods used to close the incisions used during spine surgery, mainly posterior spinal fusion incisions in pediatric and adolescent patients.

As I explained previously the goal in the end is a nice narrow (or thin) scar which blends into the individual’s normal skin tone.  What we want to avoid is a wide scar which has a different color and/or skin tone compared to the individual’s normal skin.  Simply put, we want the scar to be as unnoticeable as possible.  Spinal deformity surgery currently requires longer incisions, so we do whatever we can do to make the surgical scars more aesthetically pleasing and as “invisible” as possible

 

Preoperative

Typical appearance of the back of an adolescent with idiopathic scoliosis

 

 

Discharge from the hospital 3 days after surgery

Notice the thin strip of glue on the skin, this surgical glue seals the incision.  The glue typically falls off around 3-4 weeks after surgery. The small wound dressing, below picture on the right, is where the surgical drains were placed, and were now removed.  This dressing is removed after a couple of days and the small holes where the drains came out will be healed.

The back tissues are also swollen, which is normal after surgery.  This patient is only 3 days after surgery.  The purple markings are from the skin marker we use during surgery, which has not yet worn off.

 

 

 

2 years postoperatively (same patient which was 3 days postoperatively)

The surgical scar has completely remodeled.  It is narrow and similar to the patient’s normal skin tone.

The normal contours of the back are now present as the postoperative swelling which was present in the previous picture has long been resolved.  The incision is in the hollow of the back.

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Here is another adolescent patient

She is only 3 days after surgery.

 

Here she is now only 6 weeks after surgery

Notice the glue is all off the incision….

The back is a little swollen and the skin at the scar is slightly pink and raised.  Over the next 6-12 months the scar will fade to the patient’s normal skin tone, the pinkness will resolve and the swelling will return to baseline.

 

“Internal Dis-traction”

The last 4 posts have been on spine traction, and this is the last one, which details the third type traction we use in pediatric and adolescent spine deformity surgery: Temporary Intra-operative Distraction Rods (TIDR).  This type of traction, like Halo-Gravity and Intraoperative Halo-Femoral Traction, are used for the correction of severe scoliosis.  Each of these have positives and negatives.  In general, in most instances in which halo traction is considered for a thoracic or lumbar spinal deformity, TIDR may be also be considered.  The only absolute requirement is the presence of sufficient temporary bony fixation points in which to anchor the rods near the top and bottom of the deformity.  Anchor points may include the spine, pelvis or ribs.  This technique can be utilized in situation with cervical problems (i.e. deformity or instability) or distal deformity (i.e. hip flexion deformity). 

 

This picture shows how the upgoing rib hooks are positioned and push upwards (red arrow).  By pushing up on the ribs, which are attached to the spine, the scoliosis is stretched straighter. 

 

 

 

 

 

The below case is a 14 year old with severe idiopathic scoliosis of 110 degrees, for which the Temporary Intra-operative Distraction Rods (TIDR) was used during surgery. 

 

The first stage of the surgery was to expose the spine, perform osteotomies (to loosen up the spine and get better scoliosis correction) and place the TIDR.  In this case we placed 4 rib hooks (green arrows in intraoperative photos and green circle on accompanying x-ray).  When we distract the rod (direction of blue arrows) you can see how much correction was obtained (110 degrees down to 61 degrees), when compared to the above x-ray before surgery.

The patient was brought back one week later to complete the surgery, which was to remove the TIDR and place two new spinal rods (and get more correction).  The final scoliosis measurement is 40 degrees!  A huge correction!

 

We don’t need to use this technique often, but when we do it can often be extremely helpful!

 

  

Intraoperative Halo-femoral Traction Part 2

 In nonambulatory neuromuscular scoliosis (i.e. cerebral palsy, spinal muscle atrophy, myelomeningocoele, muscular dystrophy) progressive scoliosis with long, sweeping curves can cause significant tipping of the hips which can create sitting imbalance, pressure sores and pain. 

 

12 year old female with spastic quadriplegic CP

 

The goal of surgical treatment for this population is different than for the idiopathic scoliosis patient, specifically to correct the tilt of the hips and to obtain, and maintain, a painless, well-balanced spine above the pelvis.  Hence the aim is to establish a good sitting balance, as you see below.

 

 

 

 

 

 

Here she is now 5 years after surgery

 

The major challenge in the surgical correction of neuromuscular scoliosis is how to obtain spinal correction and, secondarily, how to maintain this alignment during the postoperative period. 

 Soft bones is a common problem which poses challenges in how to obtain spinal correction. 

 The use of intraoperative halo-femoral traction (IHFT) allows direct skeletal traction and correction of the spinal deformity and pelvic obliquity. 

 

Pulling up on the halo helps center the head over the hips, and pulling down on the hip that is higher helps level the hips.

 

During the surgical procedure most, if not all, the correction is obtained by the IHFT obviating the need for significant spinal implant manipulation for correction. 

 

In this 13 year old female with spastic quadriplegic cerebral palsy, who in the second x-ray is in surgery, it is easy to see how the scoliosis is improved and the hips more level, simply due to traction.

 

By off-loading the implants the chance of loosening losing fixation at the bone-implant interface is lessened.

 

Here the patient is 5 years after surgery with excellent three-dimensional spine position and a solid spine fusion.