Risk Factors Associated With Avascular Necrosis Of The Femoral Head Following Surgical Treatment For Developmental Dislocation Of The Hip In Children

Objective: To explore the related factors of avascular necrosis of the femoral head(AVN)after treatment of developmental dislocation of the hip(DDH)in children,and to provide clinical reference for clinical effective prevention and reduction of AVN after DDH treatment.Methods: The clinical data,imaging data and follow-up results of children admitted to the Affiliated Hospital of Zunyi Medical University from January 2009 to December 2019 who underwent closed reduction or incisional reduction for DDH were retrospectively analyzed.The clinical data such as gender,age,occurrence side,and treatment method of the children were counted,and the preoperative dislocation degree,acetabular index,and femoral head necrosis were judged by imaging data such as frontal X-ray of the hip.Postoperative necrosis of the femoral head is judged according to the Kalamchi-Mac Ewen(K&M)imaging classification criteria,and the degree of preoperative dislocation will be graded according to the International Hip Dysplasia Institute(IHDI)grading criteria,in which grade I means normal hip joint.Univariate analysis was performed on factors that may affect femoral head necrosis,such as gender,age,side,degree of preoperative dislocation,and treatment methods.The treatment methods include closed reduction(CR)and open reduction(OR).The CR group was divided into RAD group and non-RAD group according to the presence or absence of residual acetabular dysplasia(RAD).The OR group was divided into a simple pelvic osteotomy group and a combined pelvic femoral osteotomy group according to the surgical method,and the related factors of postoperative AVN in children with DDH were statistically analyzed.Results: 1.General data A total of 444 children with DDH who met the inclusion criteria were collected,with a total of 572 hips,including 48 males with 59 hips,and 396 females with 513 hips;316 unilateral hips and 256 bilateral hips;<1-year-old group 72 Hip,200 hips in the 1-1.5-year-old group,135 hips in the 1.5-3-year-old group,97 hips in the 3-6-year-old group,and 68 hips in the ≥6-year-old group.Hip,73 hips of grade IV;a total of 207 cases(272 hips)were treated with closed reduction.RAD96 hips occurred postoperatively,and the average acetabular index was about(29.7±3.1)°,and the average acetabular index of non-RAD176 hips was about(19.1±2.8)°;A total of 237 cases of 300 hips underwent open reduction,including 111 hips in the pelvic osteotomy group and 189 hips in the pelvic combined femoral osteotomy group.2.The occurrence of AVN According to the K&M classification standard,163 hips in 572 hips had postoperative AVN,and the total incidence was about 28.5%.Type I 52(31.9%)hips,Type II 82(50.3%)hips,Type III 26(16.0%)hips,Type IV 3(1.8%)hips;incidence was 25.4%(15/59)in men and 25.4%(15/59)in women The incidence rate was 28.8%(148/513);the unilateral incidence rate was 26.3%(83/316),the bilateral incidence rate was 31.3%(80/256);The incidence of 1.5-year-old group was 32.0%(64/200),the incidence of 1.5-3-year-old group was 22.2%(30/135),the incidence of 3-6-year-old group was 27.8%(27/97),and the incidence of ≥6-year-old group 54.4%(37/68);in the IHDI classification,the incidence of grade II was 19.5%(51/261),the incidence of grade III was 33.2%(79/238),and the incidence of grade IV was 45.2%(33/73).The incidence of reduction was 25.4%(69/272),and open reduction was 31.3%(94/300).In the closed reduction cases,the incidence rate of the RAD group was 44.8%(43/96)and the non-RAD group was 14.8%(26/176),and the difference between the two groups was statistically significant(p<0.001).The incidence of AVN in the bone group was 12.7%(38/300),and the incidence of combined pelvic and femoral osteotomy was 18.7%(56/300).There was no significant difference between the two groups(p=0.440).3.AVNrelated risk factors The occurrence of AVN is related to age,preoperative dislocation degree and postoperative residual acetabular dysplasia.The incidence of AVN in the <1-year-old group in closed reduction cases is lower than that in the 1-1.5-year-old group;open reduction cases Among them,the 1.5-3 year old group had the lowest incidence,followed by the 3-6 year old group,and the ≥6 year old group had the highest risk of postoperative AVN(P<0.001).In the IHDI classification of preoperative dislocation degree,the incidence of AVN gradually increased with the higher the classification degree(P<0.001);children with residual acetabular dysplasia after operation were more likely to develop AVN(p<0.001).There was no significant relationship between gender,side,and treatment method with postoperative AVN.Conclusions: Older age,high degree of preoperative dislocation and RAD are all risk factors for AVN after DDH in children.There was no significant relationship between gender,side and operation method and the occurrence of AVN after treatment.