Outcome Analysis Of Dega Osteotomy For DDH In Pre-school Children

Developmental Dislocation of Hip(DDH)is one of the common deformities in pediatric orthopaedic.Pemberton and Dega osteotomies are both the most common acetabular arthroplasties for DDH in pre-school children(1.5-6 years)with more related reports.But each report is an effect analysis for just one operation not for the relation among different acetabular shapes,choices of operations and operational details.It means that it is not for the indication of osteotomy according to acetabular shape.Concentric reduction is the premise of acetabular arthroplasty,but what acetabulum is to be made by arthroplasty after reduction?There is no answer.Objective:To analyse the outcome of Dega osteotomy for DDH in pre-school children(1.5-6 years),and to summarize the personalized application experience of acetabular arthroplasty.Methods:34 involved hips of 28 pre-school children with DDH of age 28 ±10 months(18～72 months)at operation were analyzed retrospectively.All of the 34 hips were dislocated and were classified into 4 groups according to the shapes of the false acetabula in X-ray pre-operation.3 hips of 3 children with no false acetabula with conservative treatment previously were distributed into group A.7 hips of 7 children with no false acetabula and with no conservative treatment previously were distributed into group B.9 hips of 6 children with obvious false acetabula pressing and eroding the true acetabula were distributed into group C.15 hips of 12 children with extensive fusion of true and false acetabula(fused acetabula)were distributed into group D.Changes of the morphologies and improvements of the functions of hips involved and the incidence of avascular necrosis were evaluated pre-and post-operation.Results:28 children with 34 involved hips were followed up successfully with an average period of 67±14 months(48～96 months)at the average ages of 95±15 months(73～126 months).Acetabular index improved from 450 ±6°(32～57°)to 10°±70(-6～27°),Reimer’ s index improved from 0.95±0.12(0.53～1)to 0.15±0.11(-0.2～0.42),and center edge angle was 23° ±70(11～43°)post-operation..All the differences of changes were statistically significant(p<0.01).All the Shenton lines of 34 hips were disrupted pre-operation and 31 of them turned to be continuous at last with disruption of 2 hips and reversed disruption of 1 hip.Modified Severin classification was applied to evaluate the radiographic improvement with 20 hips of type I as excellent,12 hips of type II as good,and 2 hips of type III as moderate,and the excellent-good rate was 94%.Kalamchi&MacEwen avascular necrosis(AVN)classification was applied to evaluate the AVN of femoral heads with 9 hips of type II and 25 hips of no AVN,and the incidence was 26%,Modified McKay classification was applied to evaluate the clinical function with 29 hips as excellent,4 hips as good,and 1 hip as moderate,and the excellent-good rate was 97%.No AVN was found in 5 hips of high-level Dega osteotomy in group A and C,but 5 hips of 7 hips(71%)of low-level Dega osteotomy were found with AVN(p=0.028).AVN was found in all 3 hips of high-level Dega osteotomy in group B and D,but only 1 hip of 19 hips(5%)of low-level Dega osteotomy was found with AVN(p=0.003).Both the differences were statistically significant(p<0.05).Conclusions:The effect of Dega osteotomy for DDH in pre-school children is really significant,and this operation is deserved to spread in clinical.High-level Dega osteotomy with higher hinge and less range of suppressing of acetabular roof is applicable to correct the residual developmental dysplasia after conservative treatment and the hip with obvious false acetabula.Low-level Dega osteotomy with lower hinge and greater range of suppressing of acetabular roof is applicable for true acetabula and the fused acetabula.To acquire satisfying coverage and to forge matching containing of femoral head with acetabulum are both the basic requirements of acetabular arthroplasty.Corresponding operation according to different morphologies of acetabula must be choose to achieve the personalized treatment for DDH.Each osteotomy has its own range of application and should not be applied across.Meaning:The effect evaluation of this study is not for degree of dislocation but different acetabular shapes,and is to analyze the outcome of operation according to acetabular shape.So the significance of this study is to explore the distinctions and relations among indications of different operations.