Validation and Reliability Analysis of the Spinal Deformity Study Group Classification for L5-S1 Lumbar Spondylolisthesis.
METHODS
An intra- and interobserver reliability study.


OBJECTIVE
To assess the intra- and interobserver reliability of the Spinal Deformity Study Group (SDSG) system for classifying adolescent and adult L5-S1 spondylolisthesis.


BACKGROUND
Reliability of the SDSG classification has only been previously validated in adolescent patients as performed by the SDSG study group investigators.


METHODS
A total of 80 patients with L5-S1 spondylolisthesis were included in this study. Only dysplastic and isthmic spondylolisthesis were included in this study. Long-cassette standing lateral radiographs of the spine and pelvis were obtained. All 80 cases were classified according to the SDSG classification by four observers. After a 2-week interval, the same classification was independently repeated by each observer with the cases in a different randomly assigned order. The Fleiss' κ coefficient was calculated to test the intra- and interobserver reliabilities of the SDSG classification.


RESULTS
The present study included all six types of SDSG classification. Overall intra- and interobserver agreements were 86.6% (κ: 0.830) and 73.3% (κ: 0.648), respectively. The intra- and interobserver agreements and repeatability associated with slip grade were 89.7% (κ: 0.824) and 87.7% (κ: 0.721), respectively. Regarding sacropelvic and spinal balance, intra- and interobserver agreements and repeatability were 83.7% (κ: 0.735) and 77.5% (κ: 0.602) for low-grade slips, and 90.75% (κ: 0.883) and 90.4% (κ: 0.851) for high-grade slips, respectively.


CONCLUSIONS
Substantial intra- and interobserver reliability was found for the SDSG classification in L5-S1 lumbar spondylolisthesis. SDSG classification system is a simple and clear classification scheme incorporating spinopelvic parameters, which provides significant clinical utility.


METHODS
3.
*Spine Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China †Geisel School of Medicine, Dartmouth College, Hanover, NH.
Hongda
H
Bao
Peng
P
Yan
Weiguo
W
Zhu
Mike
M
Bao
Yang
Y
Li
Zhen
Z
Zhang
Yong
Y
Qiu
Feng
F
Zhu
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D008161:Lumbosacral Region / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D013168:Spondylolisthesis / Q000145:classification* / Q000000981:diagnostic imaging*; D055815:Young Adult