Idiopathic Scoliosis: Options of Fixation and Fusion of Thoracic Curves

Spine Surgery Option for Scoliosis

The surgical treatment of thoracic curves in patients with idiopathic scoliosis has evolved over the years. The development of new techniques along with new technology has allowed for enormous changes in this treatment and has given surgeons and patients a wide variety of options.

History of the Posterior Approach in Surgery to Treat Scoliosis

In the 1960s, the gold standard for fixation for a thoracic curve in idiopathic scoliosis was a posterior approach (ie, from behind) using a single Harrington rod. The Harrington rod is anchored to each end of the spine (see Figures 1-3). This yielded a “good result” in most cases.

However, post-operative recovery involved bed rest, casts, and braces, and unsatisfactory results, such as flatback when lumbar curves were included, became apparent over time.

single harrington rod
Figure 1A: Single Harrington rod applied through a posterior approach
single harrington rod
Figure 1B: Single Harrington rod applied through a posterior approach
posterior spine
Figure 2: Posterior Approach
posterior spine
Figure 3: Posterior Approach

In the 1970s, the next step in the evolution of this treatment was beginning. A new technique was developed that involved the use of two rods that, along with wires, were attached segmentally (at each level of the spine). This was the first truly segmental spinal instrumentation system (see Figures 6A-6D). It allowed patients to be out of bed soon after surgery, usually without needing a cast or brace.

idiopathic scoliosis preoperative x-ray
Figure 6A: Pre-operative x-ray
idiopathic scoliosis preoperative x-ray
Figure 6B: Side view x-ray before surgery
harrington rods
Figure 6C: 1 Harrington rod / 1 Luque rod
sublaminar wires
Figure 6D: With sublaminar wire

The 1980s brought about the next evolutionary stage of fixation which proved to revolutionize spinal deformity surgery, initiated by CD (Cotrel-Dubousset) Instrumentation.

This technique used multiple hooks with rods in an effort to get even stronger fixation, and better correction in all 3 dimensions of the spine. The main advantage to this technique was the ability of the surgeon to use multiple hooks on the same rod in the same or different directions (see Figures 7A-7D). In most cases, this technique eliminated the need for post-operative bracing.

idiopathic scoliosis preoperative x-ray
Figure 7A: Pre-operative x-ray
idiopathic scoliosis preoperative x-ray
Figure 7B: Side view x-ray before surgery
CD instrumentation
Figure 7C: CD instrumentation
CD instrumentation with multiple hooks
Figure 7D: Multiple hooks

Today, this technique has further evolved, especially with the use of pedicle screws throughout the lumbar spine and into the thoracic spine (see Figures 8A-8D).

This is done in order to achieve more fixation, to reduce the number of levels being fused, and to reduce the number of junctional problems. Junctional problems refer to breakdown or kyphosis that develops in segments above or below the instrumented vertebrae.

idiopathic scoliosis preoperative x-ray
Figure 8A: Pre-operative x-ray
idiopathic scoliosis preoperative x-ray
Figure 8B: Side view x-ray before surgery
pedicle screws
Figure 8C: Pedicle screws
pedicle screws
Figure 8D: Pedicle screws side view


Cons Pros
disrupts posterior muscles pseudarthrosis rate known
implant prominence in thin patient easier to revise
small incidence of junctional deformities very stable
1-2 more fusion levels than with anterior segmental spinal instrumentation  

History of the Anterior Approach to Treat Scoliosis

Recently, anterior instrumentation for a thoracic curve has become popular (this approach has been used for many years for thoracolumbar and lumbar curves).

The anterior technique has evolved from use of a threaded rod which allowed for compression between the screws attached to the vertebral body, to the use of a solid rod and screw system (see Figure 9) that can be used over many levels if necessary, to potentially the use of two solid rods in certain patients (see Figures 10A-10D).

anterior instrumentation
Figure 9: Anterior instrumentation

preoperative x-ray
Figure 10A: Pre-operative AP x-ray
preoperative idopathic scoliosis x-ray
Figure 10B: Side view (pre-operative)
x-ray of vertebral body screws
Figure 10C: Vertebral body screws
vertebral body screws
Figure 10D: Side view

The anterior approach does involve incising and then repairing scapular (shoulder blade) muscles. Also, many surgeons and patients decide to have a thoracoplasty done at the time of the correction to reduce the size of the rib hump. Anterior surgeries done with open thoracotomy or thoracoplasty techniques do diminish pulmonary functions which then take about two years to recover.

Most recently, the anterior approach has expanded into using an endoscopic/video-assisted thoracoscopic technique. Rather than a single incision, five smaller incisions are made to perform otherwise the same surgery with a screw at each level and a single rod.

Cons Pros
disrupts shoulder muscles different incision
pseudarthrosis rate not clear saves 1-2 fusion levels
effect on pulmonary function slightly better correction
harder to revise  


Cons Pros
longer operation less post-op soreness
smaller implants less effect on pulmonary function!??
post-op brace needed different scars
pseudarthrosis rate not known  

Today and Tomorrow: Future of Scoliosis Surgery

In the modern day, virtually no spine surgeons in North America use Harrington implants. Surgeons use either posterior approaches (most common) with bilateral rods, hooks, wires and/or pedicle screws or open or endoscopic anterior approaches (less common).

At present, there is no strong data to suggest that one technique is better than others. Each technique has the potential to work quite well for the patient (as it does in most cases). Patients usually stand and walk the day after surgery and do not wear casts or braces (except after the anterior endoscopic techniques).

However, each of the techniques has limitations. For example, each technique has the risk of pseudarthrosis (the fusion not healing). With any posterior technique, there is a potential for implant prominence. With any anterior technique, there is a potential for reduced pulmonary function.

In 5 to 10 years, it may become clear that one technique is superior to the others. It is also quite possible in five to ten years that we will decide that the various posterior and anterior techniques are all equivalent. However, based on the changes we have seen in the last few decades, the future promises to generate more viable surgical options for correcting thoracic idiopathic scoliosis.

Updated on: 02/23/17
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Causes of Scoliosis
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Causes of Scoliosis

There are many types of scoliosis such as adolescent idiopathic scoliosis and adult degenerative scoliosis. Causes of scoliosis can be congenital, syndromic, neurological, muscular and sometimes not known, which is called idiopathic.
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