Analysis Of Factors Related To Acetabular Retroversion In Children With Perthes Disease

Background:Acetabular retroversion has been identified in 31-60%patients with Perthes disease.Posterior wall dysplasia may be the cause of deformity reported by recent animal research.However,other studies indicated retroversion of the hemipelvis may be at the root of the retroversion.It is unclear which form of acetabular retroversion of the patients.Purposes:The purpose of this study was(1)to find relevant factors of acetabular retroversion in child with Perthes disease,and(2)looking for a good way to distinguish the type of the version.Methods:Forty children with unilateral Perthes disease who were admitted to our hospital from January 1,2012 to December 31,2018 were enrolled,and forty controls were matched based on sex and age.The acetabular anterversion angle(AV),the lateral pelvic wall anteversion angle(PV),the anterior wall height of the acetabulum(a),the acetabular posterior wall height(p),and acetabular width(w)were assessed on computed tomography(CT)at the level of the femoral head center.The acetabular wall difference index(AWDI,AWDI=(p-a)/w*100)was been calculated.The clinical feature of these children are also recorded.Results:The mean AV was significantly lower in the hips affected by Perthes disease(10.59(8.05,12.46))compared with the contralateral hips(12.04(9.02,13.33))(p=0.002),but did not differ from that of controls(9.68±3.76)(p=0.465).The mean PV was significantly lower in the Perthes hips(9.16±3.89)compared with the contralateral hips(11.31±4.04)(p=0.000)but did not differ from that of controls(9.43±3.82)(p=0.753).The mean AWDI did not differ between the Perthes hips(0.41±4.94)and the contralateral hips(-1.12(-4.50,2.17))(p=0.06)or the controls(-0.49±5.46)(p=0.437).The mean w in Perthes hips(44.61±5.06)was significantly higher than contralateral hips(43.36±4.38)(p=0.000)but did not differ from controls(45.02±5.01)(p=0.719).The mean a and p did not differ between the Perthes hips and the contralateral hips or the controls.Correlation analysis showed that the AV,PV and AWDI of the affected hips were not significantly correlated with age,gender,Waldenstr?m classification,Herring Lateral Pillar classification and Catterall classification,but analysis of all hip joints revealed a significant correlation between AV and PV(r=0.772;r=0.643;r=0.608;r=0.540).Univariate linear regression showed that the PV had a better predictive effect on the acetabular anteversion than the AWDI.Multiple linear regression showed that PV and AWDI have a good predictive value for the AV both in Perthes hips and control hips(R~2=0.842,R~2=0.869).Conclusion:In patients with unilateral Perthes disease,the affected acetabulum is more retroversion than the contralateral side,the hemipelvis retroversion may be its root.The measurement of this study can distinguish the form of acetabular retroversion.The PV and AWDI can be used as new observations in future studies of acetabular version.