| Objective: To investigate the validity of the methods and mechanical principles employed in the Gonstead method to analyse the positional integrity of the sacroiliac joints on erect pelvic radiographs. The results were used to assess the need and basis for formulating an alternative method of analysis that maximises the projection and mechanical factors identified. Method: Radiographs were taken of a surrogate right innominate bone fixed in 3 specified positions representing the AS, PI and normal alignment of the ilium as suggested by Gonstead. Radiographic graphical and geometrical assessment was made to determine the validity of radiographic pelvic analytical methods employed by practitioners using the Gonstead method. Results: Measurements or calculations were made with the ilium in the normal, rotated +5o and –5o around the x-axis direction and with the tube in the standard erect AP lumbo-pelvic position as well as a sacral base view. This resulted in 6 sets of numbers. The measured difference in height on the Gonstead views was 2 mm, while for the sacral base views the difference ranged from 19-29 mm. Conclusion: The calculations and measurements derived from 3 investigation methods support the contention that the analytical methods currently taught and used in clinical chiropractic practice as part of the Gonstead method of pelvic x-ray analysis do not involve optimisation of projection and mechanical principles when measuring the theorised misalignment of one or both ilia relative to the adjacent sacrum. The Gonstead method of pelvic radiographic analysis can be shown to be inappropriate for the type and amount of misalignment anticipated. The alternate method presented would meet the requirements outlined without compromising the theoretical basis of the Gonstead analysis method. This abstract is reproduced with the permission of the publisher; full text (print only) by subscription.
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