Measurement of spinal kyphosis: implications for the management of Scheuermann's kyphosis.
METHODS
Repeat clinical radiograph measurement of kyphosis was performed.


OBJECTIVE
To evaluate precision in kyphosis measurement, the presence of intra- and interobserver error, and the effect of endplate selection and curve magnitude on error.


BACKGROUND
One study thus far has shown no interobserver difference in readings and an error interval of +/-11 degrees.


METHODS
Four experienced examiners measured 30 radiographs of varying angles of kyphosis without preselected end vertebrae twice using the Cobb method.


RESULTS
The mean intraobserver variance was 4.3 degrees (95% confidence interval, +/-9.6 degrees). One examiner had significantly better precision (P= 0.02) than the other examiners, who had no significant difference among them (P = 0.41). This examiner's mean intraobserver difference was 2.3 degrees (95% confidence limit, +/-6.2 degrees ). The 95% confidence limit for the interobserver difference was +/-8.7 degrees. The vertebral error index did not have a rank correlation with precision between readings. Magnitude of curve did not correlate with variance in measurement.


CONCLUSIONS
The broad range in intra- and interobserver differences in the measurement of kyphosis should be taken into account in making management decisions or evaluating the success or failure of a treatment program. Careful technique in measurement may allow for improvement in individual precision.
Stotts
Alan K
AK
University of Utah School of Medicine, Salt Lake City, Utah, USA. alan.stotts@hsc.utah.edu
Smith
John T
JT
Santora
Steven D
SD
Roach
James W
JW
D'Astous
Jacques L
JL
D015897:Comorbidity; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D015588:Observer Variation; D011859:Radiography / Q000379:methods*; D015203:Reproducibility of Results; D012544:Scheuermann Disease / Q000453:epidemiology* / Q000628:therapy