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Identifying Thoracic Compensation and Predicting Reciprocal Thoracic Kyphosis and Proximal Junctional Kyphosis in Adult Spinal Deformity Surgery.
Abstract
STUDY DESIGN:Retrospective analysis. OBJECTIVE:To define thoracic compensation and
investigate its association with postoperative reciprocal thoracic kyphosis and proximal
junctional kyphosis (PJK) SUMMARY OF BACKGROUND DATA.: Adult spinal deformity (ASD)
patients recruit compensatory mechanisms like pelvic retroversion and knee flexion.
However, thoracic hypokyphosis is a less recognized compensatory mechanism. METHODS:Patients
enrolled in a multicenter ASD registry undergoing fusions to the pelvis with upper
instrumented vertebra (UIV) between T9 and L1 were included. Patients were divided
into those with postoperative reciprocal thoracic kyphosis (reciprocal kyphosis [RK]:
change in unfused thoracic kyphosis [TK] ≥15°) with and without PJK and those who
maintained thoracic alignment (MT). Thoracic compensation was defined as expected
thoracic kyphosis (eTK) minus preoperative TK. RESULTS:For RK (n = 117), the mean
change in unfused TK was 21.7° versus 6.1° for MT (n = 102) and the mean PJK angle
change was 17.6° versus 5.7° for MT (all P < 0.001). RK and MT were similar in age,
body mass index (BMI), sex, and comorbidities. RK had larger preoperative PI-LL mismatch
(30.7 vs. 23.6, P = 0.008) and less preoperative TK (22.3 vs. 30.6, P < 0.001), otherwise
sagittal vertical axis (SVA), pelvic tilt (PT), and T1 pelvic angle (TPA) were similar.
RK patients had more preoperative thoracic compensation (29.9 vs. 20.0, P < 0.001),
more PI-LL correction (29.8 vs. 17.3, P < 0.001), and higher rates of PJK (66% vs.
19%, P < 0.001). There were no differences in preoperative health-related quality
of life (HRQOL) except reciprocal kyphosis (RK) had worse Scoliosis Research Society
questionnaire (SRS) appearance (2.2 vs. 2.5, P = 0.005). Using a logistic regression
model, the only predictor for postoperative reciprocal thoracic kyphosis was more
preoperative thoracic compensation. Postoperatively the RK and MT groups were well
aligned. Both younger and older (>65 yr) RK patients had greater thoracic compensation
than MT counterparts. The eTK was not significantly different from the postoperative
TK for the RK group without PJK (P = 0.566). CONCLUSION:The presence of thoracic compensation
in adult spinal deformity is the primary determinant of postoperative reciprocal thoracic
kyphosis and these patients have higher rates of proximal junctional kyphosis. LEVEL
OF EVIDENCE:3.
Type
Journal articlePermalink
https://hdl.handle.net/10161/17640Published Version (Please cite this version)
10.1097/brs.0000000000002843Publication Info
Protopsaltis, Themistocles S; Diebo, Bassel G; Lafage, Renaud; Henry, Jensen K; Smith,
Justin S; Scheer, Justin K; ... International Spine Study Group (2018). Identifying Thoracic Compensation and Predicting Reciprocal Thoracic Kyphosis and
Proximal Junctional Kyphosis in Adult Spinal Deformity Surgery. Spine, 43(21). pp. 1479-1486. 10.1097/brs.0000000000002843. Retrieved from https://hdl.handle.net/10161/17640.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Christopher Ignatius Shaffrey
Professor of Orthopaedic Surgery
I have more than 25 years of experience treating patients of all ages with spinal
disorders. I have had an interest in the management of spinal disorders since starting
my medical education. I performed residencies in both orthopaedic surgery and neurosurgery
to gain a comprehensive understanding of the entire range of spinal disorders. My
goal has been to find innovative ways to manage the range of spinal conditions, straightforward
to complex. I have a focus on managing patients with complex s

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