Blog Topic: Posterior Spinal Fusion for Thoracic Scheuermann’s Kyphosis

10-28-2022

 

Two blog posts ago the topic of thoracic Scheuermann’s Kyphosis (SK) was presented, stopping short of discussing the surgical treatment.  In this post we will show a patient who underwent correction of his SK using posterior column osteotomies (see blog post from 9-6-2020) and posterior spinal fusion (see blog post from 1-16-2022).

 

The two main reasons patients choose to undergo surgical correction are:

 - Back pain. Surgery can be an option when the back pain has not responded to nonsurgical treatments and is severe enough that the patient is unsatisfied with their quality of life.

- Aesthetics/Appearance of the body. SK causes changes in the body, which are viewed as unappealing, such as slouching, having a “poochy” belly and small chest/breasts, and tendency to look down at the ground with difficulty in looking straight ahead.  Patients can have a very negative opinion of their body, and this can negatively impact their self-image and social interactions. We cannot underestimate, or minimize, the impact of SK on the patients, specifically on their mental health.  Body dysmorphia is real issue in SK.

 

What is our goal of surgery (posterior spinal fusion)?

We aim to correct the kyphosis to be in, or very close, to the normal range of thoracic kyphosis.  Not all kyphosis deformities should be corrected into the normal range (<50 degrees) since this can increase the risk of having a complication during or after surgery. 

 

What are the overall risks of surgery? In spine deformity surgery, there are two layers of risk:

- Risks possible with any surgery on the human body

- Risks unique to spine deformity surgery

 

What are the “risks possible with any surgery on the human body”?

- General anesthesia.  This means patients are completely asleep under anesthesia and are intubated having a ventilator breathe for them.

- Surgical Site Infections (SSIs). Surgery is done through incisions on the skin. Even in minimally-invasive surgery, skin incisions have to be made to access areas of the body.  This introduces the risk of SSIs, most commonly a bacterial infection, such as Staphylococcus aureus. This risk is minimized by the surgical team and O.R. in many ways, such as using intraoperative antibiotics and diligent sterile technique. 

- Worsening of pre-existing medical conditions. Heart disease, lung disease, neurologic diseases can all increase the risk of a complication related to surgery.

 

What are the “risks unique to spine deformity surgery”?

- Spinal Cord Function. In spine deformity, surgery the focus of attention is mainly on the spinal column, or the bone of the spine.  Inside the spinal column are the spinal cord and nerve roots, and around the spinal column are blood vessels and other organ systems.  Most spinal deformity surgeries never encounter the major blood vessels or other organ systems, so we are more concerned with the spinal cord and nerve roots.  For surgery of the thoracic and lumbar spine, the spinal cord and nerve give muscle function and sensation in the legs and control the bowel and bladder.  It is desirable the spinal cord and nerve roots work the same after surgery as they do before surgery. However, during surgery the patients are under general anesthesia so they cannot tell us if there is a problem with spinal cord function, and cannot actively move the legs.  During surgery, the spinal cord function is assessed by an intraoperative neuromonitoring specialist, which evaluate the electrical signals of the spinal cord.  This method of spinal cord testing is 99.8% accurate in determining final neurologic outcome from surgery. 

- Early Movement/Migration/Pull-out of Spinal Fixation.

- Failure of Spinal (Bone) Fusion.

- Need for Reoperation.

- Adjacent Segment Angulation/Breakdown.

- Back and Leg Pain.

*** Please note the risks of surgery just listed are some of the most common, which may occur.  This list is not exhaustive nor inclusive of all potential complications.  A discussion about complications is important to have before surgery.

 

So let us go to the surgical case…….

 

The case is an 18-year-old male with SK. His pain is mainly over the area of his back where the red arrow is pointing.

 

The left side radiograph is the patient standing upright. On the right is him lying on his back with a bump under the area of kyphosis, which makes him extend his back.  This gives us information about his spinal flexibility and how difficult it will be to correct his deformity. In general, a more flexible spine makes the surgery easier, faster and safer.

 

Here is the patient now 1 year after surgery.  His thoracic kyphosis is 56 degrees, which is just above the normal range.  However, his overall appearance and spinal balance is excellent and he has no back pain.

 

Here he is now 2 years after surgery

 

In 2022 the three most common metals used for spinal rods in spine deformity surgery are cobalt chrome, titanium (pure and alloy) and stainless steel. For SK surgeries, we need to use very stiff spinal rods, such as a 6.0 mm Cobalt Chrome or 6.35 mm Stainless Steel.  Smaller, more flexible rods will not allow us to achieve a new spine position and will not maintain the new spine position as the spine fusion develops.

 

 

 

 

 

 

 

 

Blog Topic: Published study in Journal of Bone and Joint Surgery: Trunk Motion of Vertebral Body Tethering vs. Posterior Spinal Fusion

10-17-2022

 

 

This was a study of trunk (back) motion from the Philadelphia Shriners hospital by a previous spine fellow from Washington University, Dr. Joshua Pahys.  This elegant study used a motion analysis lab to quantify back motion between two groups of patients: 1) 65 patients having undergone Vertebral Body Tethering (VBT), and 2) 47 patients who had a Posterior Spinal Fusion for idiopathic scoliosis.

They evaluated thoracic and lumbar flexion, extension, sidebending and rotation.

 

 

PSF had significant loss of motion in all 4 directions at 2 years postoperative. 

Flexion loss at L1 11 degrees

Flexion loss at L4 30 degrees

For each level of the fusion down from L1 there was a 7 degree decrease in flexion motion

 

VBT had significant loss of flexion and sidebending at 2 years postoperative.

               Flexion loss at L1 11 degrees

               Flexion loss at L4 17 degrees

 

Take away message from this study about trunk motion after PSF and VBT:

1.      No clinical difference in trunk motion when PSF vs. VBT are instrumented to </= L1.  This means there is not a compelling argument about using VBT to preserve back motion if the surgeries end at T11, T12 or L1.  In fact, a PSF is probably a better choice since the spine can be actively derotated to decrease the rib prominence, much better than a VBT procedure. When surgery goes down to L2, L3 or L4 VBT does preserve more motion

2.      VBT did decrease in flexion and sidebending vs. preop.  This means only back extension and rotation were preserved and there was no significant impact by performing VBT surgery

3.      SRS scores are similar at 2 years postop.  Patients did well in both groups and there was no perceptible difference in pain, appearance, or function.

 

Blog Topic: Thoracic Scheuermann’s Kyphosis

10-16-2022

 

What is thoracic kyphosis? From the side the human spine is wavy, unlike the view from the front in which it should be straight. The only part of the spine with kyphosis is the thoracic spine, the cervical and lumbar spine are in lordosis.

 

 

How much thoracic kyphosis is normal? In general normal kyphosis is in the 20-50 degree range. A higher degree of kyphosis is called hyper-kyphosis

 

 

What are the different types of hyper-kyphosis? There are broad, and sometimes overlapping, sub-groups in hyper-kyphosis:

1.      1. Congenital: parts of the spine never developed or separated or both

2.     2.  Postural: this type of increased kyphosis is flexible, some is of thought of “slouching”.  When they lay down the kyphosis improves

3.     3. Syndromic/Neuromuscular

4.     4.   Post-traumatic: after a spine fracture

5    5. Scheuermann’s

 

What is Thoracic Scheuermann’s Kyphosis?

Angular wedging >5 degrees per level over 3 consecutive levels, called Sorensen’s criteria.  Instead of the vertebra being the normal rectangular shape, they become trapezoidal, shorter in the front than in the back. 

 

 

Over the area of Scheuermann’s it looks like the St. Louis Arch on its side.

 

 

How does is develop? No one is exactly certain, but we do know it is due to asymmetric growth of the vertebra which occurs during the pubertal growth spurt, the second fastest time of spine growth.  So the individuals are normal alignment when they are 9-10 years of age and then develop more and more kyphosis as they go through puberty.

 

Is it due to sports or wearing a heavy backpack? No

 

Can it be prevented? If it is identified very early bracing may be an option to prevent worsening.

 

What are the main symptoms of Scheuermann’s?

1.      The obvious physical changes of the body, the pronounced angular deformity of the back.

2.      Back pain.  Pain develops over the angular area of the back and also the low back, which needs to hyperextend to compensate for the increased thoracic kyphosis.

 

Can physical therapy help? Physical therapy can help the back pain related to Scheuermann’s.  Working on aerobic conditioning and strengthening the back and core musculature can decrease pain.  However, it will not change the Scheuermann’s deformity.

 

When is surgery an option? In general surgery is an options for deformities greater than 75 degrees and the patient is having significant back pain which is not responsive to nonsurgical management (physical therapy, over-the-counter medications, weight loss, aerobic conditioning).

Does surgery have to be done for deformities >75 degrees? No.  If the person doesn’t have significant pain then surgery is not needed.

 

What is the long-term implications of Thoracic Scheuermann’s Kyphosis? Mainly pain.  All the other quality of life measures, such as function, job, etc… is the same with and without Scheuermann’s kyphosis.

 

The next blog post will be on the surgery for Thoracic Scheuermann’s Kyphosis……