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Spontaneous Proximal Thoracic
Curve Correction Following Selective Fusion of the Main Thoracic Curve
in Adolescent Idiopathic Scoliosis
T.R. Kuklo*,
L.G. Lenke*,
D.S. Won*,
E.J. Graham*,
F.A. Sweet*,
R.R. Betz#,
K.M. Blanke*.
* St. Louis, MO,
#Philadelphia, PA, USA
INTRODUCTION:
There are no studies reporting the response of a structural proximal thoracic
(PT) curve following instrumented fusion of the main thoracic (MT) curve
in AIS.
PURPOSE:
The purpose of this study was to evaluate the spontaneous correction of
the non–instrumented PT curve after correction of the MT curve by either
a posterior (PSF) or anterior (ASF) instrumentation and fusion.
METHODS:
85 pts (single surgeon) with a PT curve ³ 20° (ave 29°. range 20–49°;
ave residual side bending 18°, range 3–40°) were evaluated for PT curve
flexibility – correction following PSF – PT curve not instrumented (n=44)
and ASF – PT curve not instrumented (n=4 1). PT, MT, thoracolumbar–lumbar
(TL–L) coronal and sagittal Cobb measurements, side bending Cobb, T1 tilt,
clavicle angle, shoulder balance, and PT, MT and TL–L apical vertical
translation (AVT) were also evaluated preop, one week postop, and at a
minimum 2–yr postop (ave. 3.2 yrs). A patient outcome questionnaire was
also completed to correlate patient satisfaction with respect to their
shoulder balance and overall appearance. RESULTS: Radiographic: The two
groups were found to be statistically equivalent (p=0.66) in terms of
preop PT curve and PT side bending curve measurements. The improvement
in the PT curve on both immediate postop and 2–yr minimum postop follow–up
was significant (p<0.0001) for both groups. Additionally, the correction
was maintained over time. However, the ASF correction of the PT curve
was significantly greater than the PSF correction on both the immediate
postop (p=0. 017) and minimum 2–yr postop (p=0.0024) evaluation, yet the
MT curve correction was the same in both groups (p=0.45).
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Preop PT
Curve
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Preop side
bending
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Immediate
postop
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Immed
Postop
Change
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Postop
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Postop
Change
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PSF
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29(20–49)*
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20(8–40)
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20
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–9
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21(5–39)
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–8
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ASF
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28 (20–46)
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17(3–35)
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16
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–12
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16(2–31)
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–12
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*( ) denotes range
There was no difference in radiographically measured shoulder balance
(p=0.27) or postop sagittal change in the PT curve (p=0. 12).
PATIENT OUTCOME:
Both groups reported improvement in shoulder balance and clinical appearance,
but there was no statistical difference between the two groups (p=.24).
Additionally, there was no reported deterioration in either parameter.
CONCLUSIONS:
Spontaneous proximal thoracic curve correction consistently occurs after
instrumented correction of the main thoracic curve. Further, this spontaneous
correction is significantly greater following an ASF vs. PSF of the MT
curve.
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