| Objective: In this study,we performed femoral offset(FO)measurement with 3D-CT reconstruction model and X-ray respectively in both adult developmental dysplasia of hip(ADDH)patients and healthy volunteers,and the difference values of femoral offset measurement through two methods were compared and analyzed between ADDH patients and healthy volunteers,so as to provides a appropriate way for precise measurement of femoral offset and a valuable reference for preoperative planning for total hip arthroplasty(THA)in ADDH cases.Methods: In total,66 affected hips from 47 ADDH patients and 64 normal from 32 healthy volunteers from Jilin University Second Hospital Orthopedic Department were involved in this study.Affected hips were classified as group D and were then divided into three subgroups named D1,D2 and D3 according to the Hartofilakidis classification of DDH.Normal hips were classified as group N.Hip anteroposterior DR images and CT scan images were both collected in all hips involved in this study.FO values of each hip were measured through 3D-CT reconstruction model(3D method)and DR image(2D method)respectively.The observational errors were defined and calculated as the absolute values of difference between femoral offset measurements in two methods.SPSS 20.0 software was applied for statistical analysis of the data.FO values of two measurement methods were compared with paired-sample t-test.FO values measured by 3D method were compared with SNK q test among subgroup D1,D2 and D3.The observational errors of group D and group N were compared with independent-sample t-test.The observational errors and FO values measured by 3D method between group N and three subgroups were both compared with Dunnett’s t-test.Results with p<0.05 were considered as significant.Results: FO values measured in 3D method were as follows,group D: 35.70±5.63 mm(subgroup D1: 40.09±5.14 mm,subgroup: D2: 34.25±5.41 mm,subgroup D3: 34.42±4.14 mm);group N: 42.05±5.44 mm.FO values measured in 2D method were as follows,group D: 30.55±7.19 mm(subgroup D1: 34.32±7.49 mm,subgroup: D2: 29.56±5.89 mm,subgroup D3: 28.73±8.97 mm);group N: 37.60±5.64 mm.Paired-sample t-test demonstrated a high significant difference of FO between 3D method and 2D method in both group D and group N(p<0.001).There were significant differences in FO values measured in 3D method between group N and subgroups D1,D2 and D3 as the Dunnett’s t-test showed(p<0.001).The FO values measured in 3D method were significantly different among subgroup D1,D2 and D3(p=0.001),according to SNK q-test: there were significant differences between subgroup D1&D2,D1&D3,while no significant difference was found between subgroup D2&D3(p>0.05).The observational errors were 5.75±4.95 mm in group D(5.77±4.23 mm in D1 subgroup,4.70±4.09 mm in D2 subgroup,8.70±6.87 mm in D3 subgroup)and 4.46±3.03 mm in group N.Independent-sample t-test revealed a significant difference between group D and group N,which indicated that the observational error of DDH group was larger than normal group(p=0.009).In addition,there were significant differences in observational errors between group N and both subgroups D1,D2 and D3 as the Dunnett’s t-test showed(p=0.006).Conclusion: 1.FO values measured in 3D-CT reconstruction model are significantly higher than those measured in DR image.Concerning the rotation of the femur on X-ray film and reliability reconstruction of femur anatomy by CT,3D-CT reconstruction model should be a feasible way for the precise measurement of femoral offset.2.According to Hartofilakidis classification of ADDH,femoral offsets of normal hips are statistically greater than those of all types of ADDH hips;the femoral offsets of type one hips are statistically greater than those of type two and type three hips,while there is no significant difference in femoral offsets between type two and type three hips.That is,femoral offsets of ADDH patients are greater than those of normal adults;femoral offsets of DDH patients with simple acetabular dysplasia are greater than those with dislocation or partial dislocation.3.Observational errors(the absolute values of difference between femoral offset measurements in 3D-CT reconstruction model and DR image)in ADDH patients are significantly higher than those in healthy adults.What’s more,there are significant differences in observational errors between healthy adults and both three classes of affected hips according to the Hartofilakidis classification of DDH.Thus,for all types of ADDH patients,the application of 3D-CT reconstruction model is recommended in femoral offset measurement other than X-ray plain film. |
