Pseudarthrosis in primary fusions for adult idiopathic scoliosis: incidence, risk factors, and outcome analysis.
METHODS
A retrospective study.


OBJECTIVE
To analyze the incidence, characteristics, risk factors, and Scoliosis Research Society Instrument-24 (SRS-24) outcome scores of pseudarthrosis in adult idiopathic scoliosis primary fusions.


BACKGROUND
The healing of spinal fusion is complex and difficult to study in a clinical setting. There are no detailed reports on pseudarthrosis in primary fusion for adult idiopathic scoliosis since the introduction of "modern" segmental fixation techniques.


METHODS
A retrospective chart and radiographic review of 96 patients (average age 42.2 years; range 18.2-62.9 years) with adult idiopathic scoliosis undergoing first time (primary) spinal instrumentation and fusion with a minimum 2-year follow-up (average 5.9 years; range 2-16.8 years) treated at a single institution between 1985 and 2001 were analyzed.


RESULTS
Sixteen patients had pseudarthroses (17%). Fifty-nine percent of the pseudarthroses occurred between T9 and L1, and 81% presented with multiple levels involved (2-6 levels). The site of crosslinks or dominoes correlated with pseudarthrosis site in 69%. Pseudarthroses were detected radiologically at 32.4 months (range 12-67 months) postoperatively. Patient age at surgery more than 55 years significantly correlated with pseudarthrosis (P = 0.007). The number of fused levels more than 12 vertebrae is also significantly correlated with pseudarthrosis (P = 0.03). Smoking history and comorbidity did not increase the pseudarthrosis rate (P = 0.71 and 0.19, respectively). A larger preoperative Cobb angle (> or =70 degrees) and a greater thoracic kyphosis (T5-T12 >40 degrees) did not correlate with a higher pseudarthrosis rate (P = 0.76 and 0.73, respectively). Thoracolumbar kyphosis (T10-L2 > or =20 degrees) correlated with a significantly higher pseudarthrosis rate (P < 0.0001). Preoperative global sagittal and coronal imbalance did not increase the pseudarthrosis rate (P = 0.45 and 0.62, respectively). Patients with pseudarthrosis had lower SRS-24 scores than those without (P = 0.01). CONCLUSION.: The incidence of pseudarthrosis following adult idiopathic scoliosis primary fusion was 17%. The pseudarthrosis was most likely to occur at the thoracolumbar junction. Older patients (>55 years), longer fusion (>12 vertebrae), and those with thoracolumbar kyphosis (> or =20 degrees) demonstrated increased risk for pseudarthrosis. Patients' outcomes as measured by the SRS-24 were "negatively" affected by the pseudarthrosis.
Kim
Yongjung J
YJ
Washington University Medical Center, St. Louis, Missouri, USA.
Bridwell
Keith H
KH
Lenke
Lawrence G
LG
Rinella
Anthony S
AS
Edwards
Charles
C
Edward
Charles
C
D000293:Adolescent; D000328:Adult; D016009:Chi-Square Distribution; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011542:Pseudarthrosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000706:statistics & numerical data*; D018709:Statistics, Nonparametric; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome