FURTHER ANALYSIS OF THE RELIABILITY OF THE POSTERIOR TANGENT LATERAL LUMBAR RADIOGRAPHIC MENSURATION PROCEDURE - CONCURRENT VALIDITY OF COMPUTER-AIDED X-RAY DIGITIZATION

Objective: To investigate the reliability of a specific method of radi ographic analysis of the geometric configuration of the lumbopelvic sp ine in the sagittal plane, and to investigate the concurrent validity of a computer-aided digitization procedure designed to replace the mor e tedious and time-consuming manual measurement process. Design: A bli nd, repeated-measures design was used. The results of radiographic mea sures derived through the traditional manual marking method were compa red with measures derived by computer-aided digitization of lateral lu mbopelvic radiographs. Setting: Private chiropractic clinic. Main Outc ome Measures: Pearson's product-moment cell-elation coefficients, pair ed sample t tests and intraclass correlation coefficients (TCC) were u sed to examine intraexaminer reliability, and repeated measures of ana lysis of variance were used to examine interexaminer reliability for r elative rotation angles for T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1, overall lordosis measurement [absolute rotation angle (ARA)] from L1- L5 and Cobb angle of overall lordosis measured from the inferior surfa ce of T12 to the superior surface of SI, Ferguson's sacral base angle to horizontal, angle of pelvic tilt (arcuate angle) to horizontal and anteroposterior thoracic translation (S-z) in millimeters. Results: IC C estimates for intraexaminer reliability were in the range of 0.96-0. 98 for the L1-L5 ARA, a range of 0.87-0.99 for the arcuate angle measu rement, 0.83-0.94 for the Ferguson's angle measurement, 0.88-0.95 far the Cobb angle measurement from the inferior surface of T12 compared w ith the superior surface of S1 and 0.98-1.00 for the translation measu rement of the lower thoracic spine to S1 (S-z). The intersegmental mea surement's (T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1) correlations ra nged from a low of 0.55 to a high of 0.97. Examination of these findin gs suggests that the reliability for the three doctors is acceptable w ith only the T12-L1 intersegmental measure falling below 0.70 for the least experienced examiner. Average ICC of interexaminer reliability f or manual and computer-aided digitizing examiners were the following: 0.96 for the L1-L5 ARA; 0.84 for the arcuate angle measurement; 0.82 f or the Ferguson's angle measurement; 0.88 for the Cobb angle measureme nt; 1.00 for the S-z translation measurement; and values of 0.65, 0.73 , 0.74, 0.75, 0.89 and 0.81 for relative rotation angle measurements T 12-L1, L1-L2, L2-L3, L3-L4, L4-L5 and L5-S1, respectively. Conclusion: The data lend to support the reliability of this method of radiograph ic analysis of the geometric configuration of the lumbopelvic spine as viewed on lateral lumbopelvic radiographs. The additional data presen ted here tend to support the concurrent validity of the computer-aided digitization method of analysis inasmuch as the measures determined b y the digitizing examiners an essentially identical to those determine d by the manual method plus or minus the average standard error of mea sure of each value.