Pelvic Rotation Calculator App

We have developed the Pelvic Rotation Calculator App which is a program to calculate true measurements and rotation amounts using measurements taken from the radiograph and the x-ray positioning environment. It was developed as a non profit contribution by the Gonstead Clinical Studies Society Research Department. It is based on the article published in the Journal of Chiropractic Medicine which proposed a mathematical method to quantify Y-Axis pelvic rotation on the anteroposterior radiograph.

Click on the README document link and follow the directions to access the free Pelvic Rotation Calculator App

Plaugher G, Cremata EE, Phillips RB. A retrospective consecutive case analysis of pretreatment and comparative static radiological parameters following chiropractic adjustments. J Manipulative Physiol Ther. 1990 Nov-Dec;13(9):498-506.
An investigation was undertaken to determine the effect of chiropractic adjustments on static radiological parameters. Standard plain film radiography was used. A retrospective consecutive case analysis approach was used for obtaining the data from the pretreatment and comparative posttreatment radiographs. Measurements for cervical lordosis, sacral base angle, lumbar lordosis, scapular angle, Cobb's angle and retrolisthesis of adjusted lumbar segments were determined by marking films in a blinded fashion. Intra- and interexaminer reliability for the measurement of cervical lordosis and retrolisthesis were determined to be excellent with a low standard error (Pearson's r range 0.89-0.97, p < .001 for cervical lordosis and Pearson's r 0.74-0.90, p < .001 for retrolisthesis). The data from pre- and comparative post-measurements of retrolisthesis showed a significant reduction of approximately 34%. No reduction was seen in a control group with retrolisthesis. No pre/post comparative changes were observed with cervical lordosis angle, sacral base angle, lumbar lordosis angle, scapular angle or Cobb's angle.
A. Letter to the editor; In reply. J. Manipulative Physiol Ther 1991; 14:335-336.
B. Letter to the editor; In reply. J Manipulative Physiol Ther 1991; 14:539.
C. Letter to the editor; In reply. J Manipulative Physiol Ther 1992; 15:331-332.

Coleman RR1, Lopes MA, Suttles RA. Computer modeling of selected projectional factors of the 84-in focal film distance anteroposterior full spine radiograph compared with 40-in focal film distance sectional views. J Chiropr Med. 2011 Mar;10(1):18-24.
OBJECTIVE: The purpose of this study was to compare the 84-in focal film distance anteroposterior (A-P) full spine view to selected sectional views taken at a 40-in focal film distance for angles of divergence and changes produced by lateral translation and variation in source object distance.
METHODS: Computer models were used to determine angles of divergence and study the effects of lateral translation and changes in source object distance.
RESULTS: Lateral translation produced less projected axial (y-axis) vertebral rotation on the 84-in A-P full spine view than the film at 40 in. Angles of divergence are equal on the 14 × 17-in film at 40 in compared with the 84-in A-P full spine, and 70% of the 84-in full spine view is within the angles of divergence of the 40-in 10 × 12. The 84-in A-P full spine produced lowering and lengthening of the projected ilium when source object distance was reduced.
CONCLUSION: In this study, the 84-in A-P full spine produced less projected vertebral rotation on lateral translation. Its angles of divergence were greater than the 40-in 10 × 12 and equal to the 40-in 14 × 17-in film. Except for a 5.4-in section at both the upper and lower margins, the 84-in full spine view was within the angles of divergence of a 40-in 10 × 12. The full spine film produced projected ilium lengthening and lowering.

Plaugher G, Hendricks AH. The inter- and intraexaminer reliability of the Gonstead pelvic marking system. J Manipulative Physiol Ther. 1991 Nov-Dec;14(9):503-8.
An investigation was undertaken to determine the inter- and intraexaminer reliability of the Gonstead pelvic radiographic marking system. This methodology analyzes the relative dimensions and spatial positions of the two innominate bones and sacrum and measures leg length inequality through an evaluation of femur head height. Two examiners marked 71 full spine radiographs twice to provide data from 284 analyses. Reliability was ascertained with the Pearson r, Spearman, intraclass correlation coefficient (ANOVA) and Kappa statistics. All results were statistically significant (less than 0.001) and indicated high levels of concordance. In every case, intraexaminer agreement was superior to interexaminer concordance.

Plaugher G, Hendricks AH, Doble RW Jr, Bachman TR, Araghi HJ, Hoffart VM. The reliability of patient positioning for evaluating static radiologic parameters of the human pelvis. J Manipulative Physiol Ther. 1993 Oct;16(8):517-22.
OBJECTIVE: To determine the reproducibility of patient positioning on radiographically evaluated static configurations of the human pelvis.
DESIGN: Repeat anteroposterior radiography of the human pelvis was performed in vivo. Comparative examinations were performed after 1 hr in one subject pool. A second sample underwent repeat examination after a mean of 18 days.
SETTING: Outpatient private practice chiropractic clinic.
SUBJECTS: Thirty-seven relatively asymptomatic subjects participated in the experiment.
MAIN OUTCOME MEASURES: Millimetric evaluations were made for leg length inequality, right/left sacral discrepancies and right/left innominate differences. The null hypothesis was that the difference of the measurements from the two radiographs would be equal to zero. A paired t-test was used to analyze if there were any significant differences. The mean measured difference in millimeters and correlation coefficients were also determined for each variable.
RESULTS: Individual variations for several roentgenometric parameters, including leg length inequality and pelvic torsion, did not reach statistical significance (p > .05) although minor millimetric discrepancies were recorded. Correlation coefficients, in most cases, were relatively high.
CONCLUSION: A subject can be reliably positioned for repeat anteroposterior pelvic radiography for both 1 hr and 18-day intervals. The methodology described has applicability to full spine radiography when roentgenometric parameters of the pelvis are scrutinized.

Plaugher G. Letter to the editor; re: Gonstead Technique. Chiropractic 1991; 7:62.

Plaugher G. The role of plain film radiography in chiropractic clinical practice. Chiropractic Journal of Australia 1992; 22(4):153-161.