Radiographic Study Of Pelvic Sagittal Tilt In Young Adult DDH

Objectives: To explore the characteristic of pelvic sagittal tilt in young developmental dysplasia of the hip(DDH),changes of pelvic tilt and acetabular morphologic characteristics between supine and standing anterior and posterior pelvic radiographs and the effect of Bernese periacetabular osteotomy(PAO)on the pelvic tilt.The important parameters provided coule help the preoperative design of PAO,and improve the operative outcome.Content and Methods: The study was divided into three parts: 1.We enrolled 36 volunteers,10 males and 26 females,as control group.257 young adult DDH patients who underwent PAO were enrolled,as DDH group.Strict inclusion and exclusion criteria were set.All of them underwent the same screening radiographic series,such as standing pelvic anteroposterior radiographs,pelvic lateral radiographs,lumbar anteroposterior and lateral radiographs,pelvis CT.The relevant parameters were measured.The pelvis sagittal parameters: pelvic incidence(PI),sacral slope(SS),pelvic tilt(PT),lumbar lordosis(LL),anterior pelvic inclination(APP angle).S1 front edge and the pubic symphysis connection angle with the horizontal angle(PS-SP angle),pelvic transverse diameter(T)and longitudinal diameter(L).We compared the parameters of the control group and the DDH group,summarized the characteristics of pelvic tilt of DDH2.A total of 121 patients with DDH who underwent PAO were collected and 11 cases were screened to exclude by the history of hip surgery.A total of 110 cases met the inclusion criteria and exclusion criteria of the study,including 32 males and 78 females,aged 14-49 years(mean,27.59 years).36 volunteers(10 males and 26 females)were enrolled as control group.We measured LCEA based on the anteroposterior pelvic radiographs and less than 20 ° for DDH.The PSSC was used to assess the pelvic sagittal plane tilt.SA,TA and LCEA were used to evaluate the degree of hip dysplasia.Teardrop distance was used to evaluate the hip medial space.The change of teardrop distance indicated the horizontal displacement of femoral head.To determine the characteristics of the pelvic tilt in different imaging positions for DDH and to explore whether imaging positions is capable of altering measures of acetabular anatomy.3.In first part,we collected 253 cases of DDH patients who underwent PAO for follow-up.A total of 60 cases were collected.Contrasted the paramerers in preoperative and postoperative imagings.Pelvic sagittal parameters: pelvic incidence(PI),sacral slope(SS),pelvic tilt(PT),lumbar lordosis(LL),anterior pelvic inclination(APP angle).S1 front edge and the pubic symphysis connection angle with the horizontal angle(PS-SP angle).Data collection and statistical analysis: Paired-samples t test was used to measure distance data using SPSS18.0.Angle data,belonging to circular data,And there are negative numbers,the use of rank sum test.(wilcoxon signed ranks test),P <0.05 was statistically significant.We analyzed and determined the characteristics of the pelvic tilt between young adult DDH patients and normal subjects,and established the pelvic tilt angle estimation formula of young adult DDH.To explore that imaging position would significantly alter pelvic tilt and some measures of acetabular anatomy.If younger DDH patients have a certain degree of pelvic forward contrasted with normal subjects.Explore changes in pelvic tilt before and after surgery in patients with DDH.Results: 1.Female subjects comparisons DDH group and the control group: LL,APP angle,PS-SP angle,SS,PT,PI,and d,p<0.05,were statistically significant.The pelvic incidence(PI)of DDH female patients is about 5.49° higher than that of normal females.Pelvic anterior tilt increased: APP angle increased by approximately 4.50°,PS-SP angle increased by approximately 5.95°,and PT decreased by 2.96°.SS increased by about 7.00° and LL increased by about 7.95°.d is reduced by about 8.35 mm.Male subjects in the two groups had no statistically significant difference in LL,APP angle,PS-SP angle,SS,PT,PI,and d,p>0.05.It shows that the parameters of pelvic index,pelvic tilt and lumbar lordosis are basically the same in male DDH patients and normal people.The linear regression equation was: female,PS-SP=34.7+6.77×(L/T);male,PS-SP=56.30+15.20×(L/T).2.PSSA showed a decreasing trend from supine position to standing position in the control group and DDH group.PSSC in the control group decreased by about 17 mm and decreased by about 8mm in the DDH group.In the DDH group,the decrease of PSSC was 8.53 mm in bilateral patients and 7.53 mm in unilateral patients,there was no significant difference.The LCEA median of female patients in the DDH group was 6.10 ° and 4.30 ° in the supine and standing positions,respectively,p <0.05;the TA median were 22.04 ° and 22.71 ° respectively.In the male patients,the supine and standing LCEA median were 8.45 ° and 7.30 ° respectively,p <0.05;the TA median was 21.11 ° and 21.56 °,respectively,p <0.05;with significant statistical difference.In the control group,the TD was about 6.65-7.03 mm,and the TD in DDH group was 10.51-11.76mm;p <0.05,with significant statistical difference.From the supine position to standing position DDH patients standing TD increased 0.43-0.45 mm.The TD was correlated with TA and LCEA,and the correlation range(r from 0.494 to 0.664,p <0.05).3.The PI of female patients after PAO increased by 1.89° and SS increased by 1.64°,p<0.05.The others pelvic tilt parameters had no significant difference before and after surgery,p>0.05.There was no significant difference in parameters of male patients before and after surgery,p>0.05.Conclusion: Compared with the control group,the female DDH group had anatomical deformity in the sagittal plane(increase in PI),and the spinal and pelvic structures compensated for anatomical deformity through changes in posture,resulting in increased SS and decreased PT.The final result of compensation is pelvic positional forward,increased lumbar lordosis.The DDH causes the standing sagittal pelvis to tilt forward.The pelvic tilt can be easy estimated by the maximal pelvis length and longitudinal diameter.Pelvis tilt backward is the main trend,from the supine position to the standing position.DDH patients are less inclined than normal persons between the two positions.Unilateral and bilateral illnesses had no significant effect on pelvic tilt.From the supine position to the standing position,LCEA has a decreasing trend,while TA has an increasing trend.TD in the DDH group was statistically significant compared to the control group.The increase of TD is one of the imaging features of DDH.TD in standing position was greater than that in the supine position with DDH,the TD indicating that the femoral head appeared to shift outward relative to the acetabulum base under weight load.TD can be used as a parameter to reflect the extent of acetabular dysplasia.The increase in PI after PAO was 1.89°,which was related to the anterior motion of the femoral head during surgery.Although SS increased 1.64°,suggesting a tendency to antegrade pelvis,follow-up results of other parameters did not show significant differences and may be related to fewer follow-up samples.Considering the advancement of the femoral head during PAO surgery increases the anatomic abnormality of PI.It is recommended that the relevant parameters of the acetabular osteotomy should be taken into consideration in the surgical design,and that the sagittal tilting of the DDH should be corrected after the femoral head is removed.