Radiography and Clinical Decision-Making in Chiropractic.

The concern over x-ray exposure risks can overshadow the potential benefit of radiography, especially in cases where manual therapy is employed. Spinal malalignment cannot be accurately visualized without imaging. Manual therapy and the load tolerances of injured spinal tissues raise different criteria for the use of x-rays for spinal disorders than in medical practice. Current regulatory bodies rely on radiography risk assessments based on Linear-No-Threshold (LNT) risk models. There is a need to consider radiography guidelines for chiropractic which are different from those for medical practice. Radiography practice guidelines are summaries dominated by frequentist interpretations in the analysis of data from studies. In contrast, clinicians often employ a pseudo-Bayesian form of reasoning during the clinical decision-making process. The overrepresentation of frequentist perspectives in evidence-based practice guidelines alter decision-making away from practical assessment of a patient's needs, toward an overly cautious standard applied to patients without regard to their risk/benefit likelihoods relating to radiography. Guidelines for radiography in chiropractic to fully assess the condition of the spine and spinal alignment prior to manual therapy, especially with high velocity, low amplitude spinal manipulation (HVLA-SM), should necessarily differ from those used in medical practice.

A Proposed Mathematical Method to Quantify y-Axis Pelvic Rotation on the Anteroposterior Radiograph.

OBJECTIVE: Researchers have identified potential errors in the Gonstead method's analysis of pelvic alignment resulting from y-axis rotation of the pelvis on the anteroposterior (A-P) radiograph. The purpose of this article is to propose a method that can be used to determine the magnitude of y-axis rotation of the pelvis present on the A-P radiograph. METHODS: In this proposed method, measurements are obtained from the patient and from the lateral and A-P radiographs. With a mathematical method, these measurements are used with the focal film distance to calculate the degree of pelvic rotation present on an individual A-P radiograph. RESULTS: This method may help with the accuracy of measurement of pelvic y-axis rotation on the A-P radiograph. CONCLUSION: The method proposed can be used to calculate the magnitude of pelvic y-axis rotation on an A-P radiograph.

Exploratory evaluation of the effect of axial rotation, focal film distance and measurement methods on the magnitude of projected lumbar retrolisthesis on plain film radiographs.

OBJECTIVE: The purpose of this exploratory study was to evaluate the amount of error in retrolisthesis measurement due to measurement methods or projection factors inherent in spinal radiography. In addition, this study compared how accurately these methods determine positions of the lumbar vertebrae being studied and the expected projected size of the retrolisthesis. METHODS: Vertebral models were situated in a retrolisthesis position. Radiographs of the models were obtained in positive and negative y-axis rotations at 40- and 84-in focal film distances. The projected retrolisthesis was measured using the Gohl, Iguchi, and Lopes methods. RESULTS: At the 40-in focal film distance, the Iguchi method and Lopes methods were significantly more accurate than the Gohl method. At the 84-in focal film distance, the Lopes method was significantly more accurate than the Gohl method. Almost all measurements overestimated both the actual amount of retrolisthesis as well as the amount of trigonometrically calculated retrolisthesis that should have been present on the radiographs. Findings suggest that measurements were less accurate with vertebrae rotated more than 10°. CONCLUSIONS: This study demonstrated that lumbar vertebral rotation, focal film distance, and measurement methods are potential sources of error in retrolisthesis measurement.

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.

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.