Blog Topic: “How much correction of the scoliosis did you get during surgery?”
This is a common question asked after spinal deformity surgery.
Parents and caregivers are interested in how close their child’s spine was able to be returned to a “normal” alignment on x-ray. It is a very reasonable question. I would probably ask a similar question if my child was having scoliosis surgery. As a parent, I would want my child’s spine to be as close to “normal” as possible. At first glance it would appear to make sense that the closer the spine correction was to 100%, the better the person will look, the less pain they will have in their back and the better they will function now, and for the long-term. This however is not often true. To explain why this is the case, a few important facts/points must be first presented:
#1 Scoliosis is a 3-dimensional spine deformity. The spine twists as it turns, much like a water slide that banks when the slide turns side-to-side. For a more detailed explanation of this please go to the blog post on 6-6-2020.
#2 The x-rays we take of the spine can only easily document 2 of the 3 planes of the scoliosis (coronal and sagittal plane, see below). The third plane is the axial or transverse plan, which is the “twisting” of the spine. Sometimes there is a lot of twist in a scoliosis, and sometimes there is not much twist. Each child and scoliosis is different. It is hard to measure the twisting of the plane on the x-rays.
We can more easily measure the amount of twist or rotation of the spine in the office using the scoliometer (see below).
#3 When we talk about how much the scoliosis changes the body, from the patient’s perspective, we really are trying to assess how much different the right side is from the left side of the body. How asymmetric is the body side-to-side.
#4 The outward changes to each person’s body, by the scoliosis, is unique. For example, two people could have a 60-degree scoliosis, with one person having a lot of changes to their body, while other person has very little obvious asymmetry.
As a surgeon, we often try to achieve maximal 3-dimensional correction (see the below radiographs). It is important to note the x-ray which shows the scoliosis is the view from the front/back of the patient, and is only in a single plane (coronal plane). However, scoliosis is a 3-dimensional problem, as I explained in a previous blog post when I talked about the abnormal rotation of the spine and how we can correct this in surgery. Sometimes the transverse plane or axial plane, which is what cause the rib prominence and asymmetry, may be the most aesthetically important part of the deformity.
So when the surgeon answers the parent/caregiver’s question and says “80%” they are only referring to correction in only one plane of a 3 plane problem (coronal plane). However, as a surgeon I know that maximally correcting a scoliosis is not always desirable, or safe. If you make the spine completely straight over the areas you operate, the spine above and below the surgical area may suffer secondarily and then cause pain, spinal instability and need further surgery.
The next blog post the reason why we don’t always want 100%, or even 90% of the spine deformity, will be presented.