Estudio de las modificaciones anatomo-radiológicas pélvicas tras la realización del test de Downing en alargamiento

Abstract

OBJECTIVES: To assess the radiological lumbopelvic differences after the application of the lengthening phase of the Downing test, designed to evaluate the motion ability in the sacroiliac joint. HYPOTHESIS: The elongation test according to Downing produces changes in different measurements on plain Antero-posterior X-Ray, compatible with previous rotation of the iliac homolateral on the sacrum, in those subjects in which the mobilized limb stretches considerably with respect to the contralateral, changes will not be observed in those subjects in which the elongation is minimal. MATERIAL AND METHODS: Fifty subjects (both male and female), aged between 18 and 62, were included. They belonged to one out of two groups: one with a negative result to the lengthening phase of the Downing test (the lengthening of the lower limb was smaller than 0,5 cms), and other group with a positive result to the lengthening phase of the Downing test (the lengthening of the lower limb was bigger than 1,5 cms). Before and after that manoeuvre, an anteroposterior lumbopelvic radiography was taken of every subject. On these radiographies, several parameters were measured: vertical and transversal iliac diameters, vertical and transversal obturator foramen diameters, iliac crest to femoral head distance, L4 to iliac crest distance, and the sacral tilt angle. The three last parameters were only measured ipsilateral to the Downing test. The evaluator of the radiographic measurement was blinded to the result of the Downing test. RESULTS: Significant differences were obtained between groups (p<0,05) for the modifications in several of the measured parameters, with a higher decrease in the positive Downing test in the mobilized side for the anteroposterior iliac diameter and the sacral tilt angle, and a higher increase for the transversal iliac diameter, the vertical obturator foramen diameter, the iliac crest to femoral head distance and the L4 to iliac crest 7 distance. No differences were found for the ipsilateral transversal obturator foramen diameter and for none of the contralateral measurements (p>0,05). CONCLUSIONS: Radiological changes can be observed after the application of the lengthening phase of the Downing test for the sacroiliac joint whe a lengthening higher than 1,5 cms in the ipsilateral lower limb is achieved. Those changes are compatible with an anterior rotation of the ipsilateral sacroiliac joint.