9-12-2021

Blog Post on the latest, hot-off-the-presses publication on Vertebral Body Tethering:

 

Some important points of this paper:

1.     1.  Surgeries done 2011-2015, prior to FDA approval

2.     2.  FDA primarily interested in device safety, secondarily on efficacy

3.    3.   Inclusion criteria:

a.      Only include Type 1A and 1B curve patterns, which means only main thoracic curves.

b.      There were NO curve patterns with structural proximal thoracic or lumbar curves, and no lumbar curves which deviated from midline (1C curve patterns)

c.      Risser grade 0-4 (median grade 0, 96% were </= 2) and a Sanders </= 5 (median 3).  There was no Sanders grade reported for 20 patients (35% of cohort)

4.    4.   Shoulder balance (no definition in Methods): 54% unlevel  preop and 25% at latest follow up

5.     5.  Follow-up: a minimum of 2 years, mean 55.2 +/-12.5 months.  Though the mean Risser sign at last follow-up was 4.2 +/- 0.9.  Sander Score at last follow-up was 7.5 +/- 0.9

6.      6. Results

a.      Mean age at surgery 12.4 years +/- 1.3 years

b.      49 female; 8 male

c.      Preop MT curve: mean 40.4 degrees +/- 6.8 degrees

d.      Last MT curve: mean 18.7 degrees +/- 13.4 degrees

7.    7.  No neurological complications

8.      8. Thoracic rotation

a.      Preop: 13.6 degrees +/- 3.9 degrees

b.      Postop: 8.6 degrees +/- 4.9 degrees

9.     9. Reoperation rate: 12.3%

a.      5 had tether release for overcorrection

b.      2 had tether extension

c.      1 conversion to PSF

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The data is not presented in a granular fashion, but if you assume a normal statistical distribution of their 57 patients:

 

Standard Deviation	% distribution of patients	Preoperative Main Thoracic Curve Magnitude (in degrees)	# of patients	Last Follow-up Main Thoracic Curve Magnitude (in degrees)
-3	2.1%	18-25	1	-18 to -7
-2	13.6%	26-32	8	-6 to +5
-1	34.1%	33-39	19	6-18
+1	34.1%	40-47	19	19-32
+2	13.6%	48-54	8	33-46
+3	2.1%	55-63	1	47+

 After backwards-engineering the data (which may not be accurate), 68% of patients had curves 33-47 degrees.  Only 15% of patients had a curve 48+ degrees.

 

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So, based on this paper who MAY be a candidate for a VBT procedure?

Idiopathic Scoliosis

Type 1A and 1B curve patterns (thoracic curves only)

Sanders 2-3-4

Curves 35-55

Rib prominence is less than 20 degrees rotational deformity;

Shoulders level or right shoulder high

Patient and family:

1.      Can accept a 3x reoperation risk vs. posterior spinal fusion (short-term)

2.      Understands risk for a future surgery is unknown and likely to be the same as for a posterior spinal fusion (long-term)

3.      Do not view rib prominence s as a significant part of deformity (VBT only improved 37%)

4.      May not permit detectable difference (to patient and family) in physical activity or function vs. posterior spinal fusion

 

 

Blog Post: High-Grade Spondylolisthesis (Part 5)              8-29-2021

This is Part 5 on Spondylolistheses and we have gone from the mild deformities and progressing to the severe grades.

In this post we will present a Type 5 High Grade deformity.  This means the patient is compensating for the spondylolisthesis slippage, by rolling the pelvis backwards.  In the Type 5 deformities it means the patients successfully compensate and stay globally balanced, so they are not leaning forward or backwards.

The case we will present is one of a 16-year old female, who was having low back pain for 2-3 years which was shooting down both of her legs, right more than left leg.  In addition she was tripping frequently, as she was having difficulty lifting her foot up.  This happens in High-Grade slips, as the nerve root which permits us to lift our foot up gets pinched and may not work normally.

The below figure focuses on the radiographic deformity.  The numbers on the slide are very technical, but are important when we diagnosis, classify and plan surgery for this problem.  For this blog post we will not discuss these numbers.

Rather look at the middle 2 x-rays, especially the one third from the left with the red arrow.  The L5 vertebra should be sitting on top of the S1 vertebra, but it has slid forward and down.

Below is the MRI of the deformity.

The yellow arrow is pointing at the nerve roots which can be pinched as the L5 vertebra slips forward and down on S1.

 

Since this is an unbalanced patient, we needed to partially reduce L5 on S1.  We don’t want to fully reduce the slip, as the nerve roots (yellow arrow above) can be stretched too much and not work normally.  If this happens the patient may not be able to lift her foot up, making walking difficult and need to wear a brace on her foot/ankle long-term.  By partially reducing the deformity, we can balance the spine and not cause a nerve root problem (or muscle weakness).

Again we place a cage between L5 and S1 to give support after we removed the disc, and to permit a fusion to happen between L5 and S1 in the front of the spine.

Since there are huge forces to reduce and hold the spine in its new position, the use of iliac screws (green arrow) is necessary.

After surgery this patient did not have any nerve root problems (no muscle weakness) and her back and leg pain has resolved.  The below figure is now 1 year after surgery and the red arrow shows a robust, thick fusion mass between L5 and S1 (which incorporates the cage).

This is the last post on spondylolisthesis, for now.

If you have questions let me know!  This is a complicated problem which is infrequently cared for by most pediatric spine surgeons.

Blog Post: High-Grade Spondylolisthesis (Part 4)              8-22-2021

The several posts were on Low-Grade Slip/Spondylolisthesis Fusion Surgery, which are done for Grade 1 and 2 severity slips.

We will now move onto High-Grade Slip/Spondylolisthesis Fusion Surgery…..which if you recall are for Grade 3-5 severity slips

 

One of the best publications on the treatment of High-Grade Spondylolistheses is shown in the below two figures:

 

 

 

The first type of High-Grade Spondylisthesis is the Type 4 (see above diagram)

The below case demonstrates a Type 4 surgical case, which means the patient overall has good overall spine/body balance, called Sacropelvic Balance.  Since this patient has good balance we do not have to alter the preoperative position of the slipped vertebra, and can fix as it sits….called in-situ.

 

The loose posterior part of the spine is removed, called a Gill laminectomy and the nerve roots of L5 and S1 are inspected and decompressed, as needed.

 

Fixation is then placed at L4, L5 and S1.  Since we don’t need to move L5 we can place our S1 screws into the L5 body, to give additional fixation strength to the construct.

 

The below figure shows the patient before and after surgery.  As you see we haven’t altered the slipped vertebra position nor the overall spinal balance.

 

Below the patient is now 3 years after surgery, having no pain and the fusion has solidly healed.

 

In the next blog post we will demonstrate a Type 5 deformity.

 

Blog Post: Low-Grade Spondylolisthesis (Part 3)                                                                                          8-17-2021

The case in the last post is a Low-Grade Slip/Spondylolisthesis Fusion Surgery. The cage which is placed in the front add to the strength of the repair, by minimizing deflection due to cantilever forces.

The below link explain this:

https://en.wikipedia.org/wiki/Deflection_(engineering)

 

However, sometimes a cage isn’t needed or simply cannot be placed into the front of the spine.

The below case demonstrates a Low-Grade Slip/Spondylolisthesis L5-S1 Fusion Surgery without a cage.

The young lady is now 5 years out from surgery, has no pain and is participating in the activities she wants without limitation.

Regardless if a cage is placed, or not, the goal is a solid, stable, durable fusion which should enable the individual to participate in activities of daily living and athletics with minimal back/leg pain.

 

FAQs:

If I have surgery will my back pain and leg pain go away 100%? In general, fusion surgery allows significant low back pain relief, and if they have buttock/leg pain that is also improved. Since pain is a subjective sensation, the amount of pain relief can vary.

How long will I be out of sports? The fusion process, L5 to S1, takes several years to get strong, but we can often let our athletes return to their sports at 6 months postoperatively, depending on the sport, its intensity and level of participation.  Advanced imaging at 6 months, such as a CT scan, can be helpful.

Are there any activities or sports which are not recommended to do after surgery? Long-term, after this surgery, I do not recommend sports such as American football, rugby, wrestling, tumbling and gymnastics. These sports place an extreme amount of force on the low back, and the surgical repair site.  In addition, weightlifting exercises of dead lift and squats are discouraged, for the same reason. All other sports and recreational activities can otherwise be restarted, as long as healing is on track.

Can the slip get worse after surgery? If the surgery is a success, meaning the fusion occurs, then the slip cannot get worse.

Will I need more than one surgery? The goal is to perform one surgery.  The spine implants stay in forever.

 In the next posts we will show High-Grade Spondylolistheses/Slips

 

 

Blog Post: Low-Grade Spondylolisthesis (Part 2)                                                               8-9-2021

To restate, a Low-Grade Spondylolisthesis is one which is a Meyerding Grade 1 or 2.

This means the vertebra has slipped forward up to 50% of the vertebral body. To use a football analogy it hasn’t crossed the 50-yard line. Below is a Grade 2.

We typically call spondylolistheses “slips”.

 

What is the most common symptom for Low-Grade slips? Just like spondylolysis/pars fractures, the main symptom for Low-Grade slips is low back pain which worsens with activities.  There is a wide range of symptoms, from no pain to severe disabling pain. 

Are there other symptoms? At times there will be nerve root pain, or sciatica down one or both legs.  This type of pain is usually not constant, but more episodic, and worsens with more stressful activities, such as sports.  If present, this type of pain can be described as “shocky” but also people report decreased sensation or numbness in part of the leg.

So how do we treat Low-Grade slips?  There are several factors which must be considered: previous treatment, length of symptoms, type and severity of symptoms, and how symptoms interfere with activities (sports and activities of daily living).

1.      The first intervention is pain management (over-the-counter medications), activity modification, and physical therapy for paraspinal and core muscle strengthening.  These interventions can be continued long-term, and we discussed these interventions in the previous posts on spondylolysis.

2.      If all nonsurgical management fails to adequately relieve the back +/- leg pain, then surgery may be an option.

What is “surgery” for a Low-Grade Spondylolisthesis? The main goal is to halt the slip progression and to fuse the slipped vertebra to the vertebra on which it is slipping.

The below case is how I generally treat Low-Grade slips surgically:

 

There is a midline incision on the low back

The spine is exposed

Since most of the surgical cases are the isthmic type (have pars fractures), the loose posterior elements are removed, which is called a Gill laminectomy.

The nerve roots are identified and decompressed if necessary.

Pedicle screws are placed into the two vertebra to be fused.

 

The disc space is opened up, from the back and the disc is removed.

To improve the stability of the one-level fusion, a cage is placed between the vertebral bodies (where the disc was before removal) and bone is also placed in the disc space.  This also allows the vertebra to be fused in the front.

The slip MAY be reduced.

Rods are placed (one on each side) to stabilize the vertebra.

Bone graft is placed to get a fusion in the back of the spine.

The surgical wound is closed over a drain (which evacuates blood which collects in the surgical site).

 

Blog Post: Spondylolisthesis (Part 1)                                                                                  8-6-2021

 

The last 6 posts have been discussing spondylolysis or pars fractures, which is crack in the posterior part of the spine which causes low back pain.

If the vertebra slides forward (see below diagram), it is no longer spondylolysis, it is now called “spondylolisthesis” which means “vertebral slippage”.

 

There are 6 types of spondylolistheses, using the Wiltse classification (below).

 

 

In pediatric/adolescent patients there are two main kinds of spondylolisthesis:

1.      Isthmic. There is a crack in the pars region, which allows the vertebra to slip forward.

                                                                                           ISTHMIC

2.      Dysplastic.  In this type the posterior elements do not have a crack in them.  Rather the bone never developed normally and allows the vertebra to slip forward.

DYSPLASTIC

                                                                          

Most of the spondylolisthesis I have taken care of have been the isthmic type.

 

Treatment of Spondylolisthesis

The first step in determining treatment is to establish the grade of the spondylolisthesis.  We use the Meyerding classification, which goes from 1-5.

The more the vertebra slips the higher the grade (see above diagram):

If the vertebra slips 1-25%, it is a Grade 1 slip

If the vertebra slips 26-50%, it is a Grade 2 slip.

If the vertebra slips 51-75%, it is a Grade 3 slip

If the vertebra slips 76-100%, it is a Grade 4 slip

If the vertebra slip >100%, it is a Grade 5 slip

 

The Meyerding classification is used to determine the first step:

               If the spondylolisthesis is a Grade 1 or 2, we call it “Low Grade” and the primary treatment is nonsurgical.

               If the spondylolisthesis is a Grade 3, 4 or 5, we call it “High Grade” and the primary treatment is surgical.

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The next blog post we will discuss Low Grade Spondylolisthesis and treatment.

 

 

 Blog Post: Spondylolysis/Pars Fracture                                                8-3-2021

Part 6: Surgical Treatment (continued)

 

The last blog post demonstrated my preferred method to fix spondylolysis/pars fractures, when nonsurgical methods fail to adequately relieve low back pain.

 There have been other method to stabilize the surgery as demonstrated below:

 

The below case demonstrates why I prefer pedicle screw fixation-rod-laminar hook fixation:

At this point he was 1 year out from surgery by another surgeon, with an unhealed spondylolysis/pars fracture repair.

Because L5 has now slipped forward we could not do another pars repair surgery, as it would definitely fail. Demonstrated below, instead we had to fuse L5 to S1 by using a posterior screw-rod-screw construct and by removing the disc from the back then placing bone graft/cage between the vertebral bodies in the front.

At 6 months after his 2^nd surgery he has no back pain for the first time in 4 years and can participate in school activities fully!