The optimal means for measuring the abduction angle before Spica cast in developmental dysplasia of the hip / 中华骨科杂志

ABSTRACT

Objective:Comparison of four methods in intraoperative abduction angles (AA) measurements of human cast immobilization in developmental dysplasia of the hip (DDH) by visual inspection and electronic software according to different body surface markers.Methods:Data were retrospectively collected from January 2019 to November 2021 in a total of 27 patients (54 hips) who underwent closed or simple open reduction. There were 6 males and 21 females with an average age of 13.2 months. Five doctors used visual inspection and mobile phone software to measure the AA of the hip joint immediately during the operation, and compared with the postoperative MRI measurement results (AA-MRI). The four methods of intraoperative measurement were Junior visualization (AA-JV), the intersection angle between the line connecting the center of the popliteal fossa and the contact center of the plaster frame and the line connecting the two ischial tuberosities; the same methods as method one by Senior visualization (AA-SV); the intersection angle between the line connecting the center of the popliteal fossa and the center of the anus and the line connecting the ischial tubercle (anus-popliteal, AA-AP); the intersection of the vertical line between the center of the popliteal fossa and the groin and the horizontal line of the center of the anus and the vertical line connecting the two ischial tuberosities intersect (anus-groin crease-popliteal, AA-AGCP). The t-test, correlation coefficient, linear regression and Bland-Altman test were used to evaluate the measurements. Results:Comparing the four intraoperative and postoperative AA-MRI measurement methods, AA-JV (42.69°±4.13°) < AA-SV (44.80°±4.08°) < AA-AGCP (46.25°±5.15°) < AA-MRI (47.68°±4.21°) < AA-AP (51.77°±5.30°), and the difference between AA-JV and AA-SV, AA-AP and AA-AGCP was statistically significant ( t=2.53, P=0.013; t=5.47, P=0.001), there was no significant difference between AA-AGCP and AA-MRI ( t=1.57, P=0.118). The inter-group agreement of the five methods ICC test ranged from 0.807 to 0.892, and the intra-group average agreement of AA-MRI was 0.948. All ICC results were greater than 0.75 with good agreement. Linear regression results showed that the four intraoperative measurement methods had a good or moderate linear relationship with AA-MRI, AA-AGCP ( R 2=0.499)>AA-AP ( R 2=0.318)>AA-SV ( R 2=0.253)>AA-JV ( R 2=0.217), AA-AGCP was the best measurement method. The results of Bland-Altman scatterplot of AA-AGCP and AA-MRI were in good agreement, the mean and standard deviation of bias were -0.796±3.247, and the limit of agreement was 95% LoA (-7.16, -5.57). Conclusion:The AA method of visualization before Spica casting was smaller than truth. The method AA-AGCP objectively by landmarks was the advocated means measuring abduction angle during operation with highly consistency, agreement and easily performed.