Radiographic Study About Hip-spine Sagittal Relation Of Position Changes In Ddh

Objective: Developmental dysplasia of the hip(DDH)is a pelvic deformity which can influence the sagittal balance of the pelvic-spine balance.Studies have shown that the change of positions will affect the pelvic-spine balance.There is no research focusing on pelvic-spine sagittal balance in DDH patients in different positions including standing and sitting.Lateral radiographs were performed in both standing and sitting positions to evaluate the pelvic orientation and identify the parameters expressing the pelvic orientation in DDH patients.Methods: We collected patients from August 2019 to January 2020.Patients were stratified into 3 groups: A: low dislocation group(Crowe ?and ?),B: high dislocation group(Crowe ? and ?)according to Crowe classification and C:normal control group.We measured anterior pelvic plane(APP),lumber lordosis(LL),and pelvic incidence(PI),pelvic tilt(PT),and sacral slope(SS)in standing and sitting positions.Student's t-test and Pearson correlation coefficient were used to test the differences and the correlations between different parameters.Results: 32 subjects were collected according to the inclusionexclusion criteria,including 14 in the low dislocation group,3 in the high dislocation group,and 15 in the normal control group.In the standing position,all the parameters(APP,LL,PI,PT,SS)in low dislocation group and normal control group were statistically different with high dislocation group.In the sitting position,there was significant difference between low dislocation group and high dislocation group.There was also significant difference between high dislocation group and normal control group.When the position changed from standing to sitting,the three parameters ?APP,?PI,?SS were significantly different between all groups.No relationship was found between APP and PI in both positions in all three groups.APP correlated with PT and SS in both standing and sitting positions in low dislocation group and normal control group.SS correlated with PI and PT in standing and sitting positions in low dislocation group and normal control group.No relationship was found among parameters in high dislocation group.Conclusions: The pelvic anteversion and lunbar lordosis were reduced from standing to sitting position.However,DDH patients have less change in this progress.SS can be used for detecting sagittal pelvic rotation in normal people and DDH patients with type ? and ?.