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.
—————————————————————————————————————
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