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DOS Kongressen 2016 ·
91
Radiographic Predictors for Mechanical Failure
following Adult Spinal Deformity Surgery
Dennis Winge Hallager, Sven Karstensen, Naeem Bukhari, Martin Gehrchen,
Benny Dahl
Spine Unit, Dept. of Orthopedic Surgery, Rigshospitalet, University of
Copenhagen
Background:
Mechanical failure rates following adult spinal deformity surgery
is reported up to 37%. The importance of spinal alignment and balance is well
documented for surgical outcome, however the role of these parameters as
predictors for mechanical failure remains uncertain.
Purpose / Aim of Study:
We aimed at evaluating radiographic predictors for
mechanical failure following adult spinal deformity correction.
Materials and Methods:
All adult spinal deformity patients having at least five
thoracolumbar levels of instrumentation between 2008 and 2012 were in-
cluded. Inability to measure pre- and postoperative SVA and radiography wear-
ing a brace were exclusion criteria. Pre-, postoperative and change in coronal
Cobb, central sacral vertical line, thoracic kyphosis (TK), lumbar lordosis (LL),
sacral slope (SS) and sagittal vertical axis (SVA) were evaluated as predictors
for mechanical failure using cause-specific Cox regression. Mechanical failure
was defined as a revision procedure because of rod breakage, screw loosening
or breakage, pseudarthrosis, fractures or symptomatic degeneration immediate
above or below the instrumentation.
Findings / Results:
138 of 165 patients were included. Mean follow-up was
3.9 years (range 2.1-6.8). Median age at surgery was 61 years. Median 10 lev-
els were instrumented with 71% ending at S1 and 44% had 3-column osteoto-
my performed. 47% had mechanical failure requiring revision during follow- up.
Multivariate regression adjusting for age showed significant increased hazard
from change in LL>30° (HR: 1.9 (95%CI: 1.0-3.4), P=0.038), postoperative
TK>50° (HR: 1.9 (95%CI: 1.1-3.4), P=0.001) and postoperative SS≤30° (HR:
2.1 (95%CI: 1.3-3.5), P<0.001).
Conclusions:
Change in LL>30°, postoperative TK>50° and postoperative
SS≤30° independently increased the hazard of mechanical failure following
adult spinal deformity correction.
Conflict of Interest
Dennis Winge Hallager: Travel support from Globus Medical Inc.
42.