Comparison of Valgus Correction Angle between Patients with Developmental Dysplasia Hip and Normal Volunteers Measured by Three-Dimensional Reconstruction and X-Ray.

Aobo Zhang,Jincheng Wang,Qing Han,Xue Zhao,Chenyu Wang,Bingpeng Chen

doi:10.1155/2020/2049306

Abstract

Methods Bilateral VCA of 50 DDH patients and 56 normal volunteers were measured by Mimics software in the 3D method and X-ray in 2D. Two VCA (the upper VCA and the lower VCA) were measured in both two methods. Every VCA was measured by observer A and observer B for twice separately. The statistical analyses of the differences were calculated among the measurements of the VCA. Results The mean value of the upper VCA measured in 3D was 4.95° ± 0.76° in DDH group and 5.56° ± 0.62° in the normal group with significant difference (t = −6.457, p < 0.01). The VCA of DDH group and normal group measured by 3D was larger than 2D, both the upper VCA and the lower VCA. The differences indicated statistically significant. The mean value of lower VCA was 0.60° smaller than the mean value of upper VCA in normal volunteers. The mean value of the lower VCA was 0.58° larger than the mean value of the upper VCA in DDH patients. Conclusions Compared to X-ray, 3D reconstruction technology is more accurate without conventional limitations. The lower VCA of DDH patients should be regarded as the femoral intramedullary guide angle in TKA, especially for patients with femoral deformities.

Highlights

Accurate restoration of limb alignment is one of the crucial preconditions to the success of total knee arthroplasty (TKA) [1,2,3,4]; otherwise, it can cause loosening, instability, and polyethylene wear during the long period of usage [5]
The values of valgus correction angle (VCA) measured by the different methods in the DDH group and the normal group were analyzed by paired samples t-test
The values of VCA measured by the same method between the DDH group and the normal group were analyzed by independent samples t-test

Summary

Introduction

Accurate restoration of limb alignment is one of the crucial preconditions to the success of total knee arthroplasty (TKA) [1,2,3,4]; otherwise, it can cause loosening, instability, and polyethylene wear during the long period of usage [5]. A fixed VCA can cause unacceptable planning errors in many cases [1, 9,10,11] For this reason, it is important to measure the VCA of every patient before the operation to comprehensively evaluate physical condition and prepare for surgical planning. When the femoral bowing is in an excessive degree, which is very common in DDH patients, the rotational conditions will influence the measurement [2, 4] Another main shortcoming of conventional radiography is that the marker lines used for VCA calculation are 2D projections of anatomical 3D bone structures; it is considered with biases since the VCA is the space angle [4]. The differences between the 2 VCA can be the evaluation of the accuracy and sensitivity of these two methods

Materials and Methods

Measurement of VCA in 3D

Results

Comparison of VCA between DDH Group and Normal Group

Discussion

Conclusion