Armin Nikzad, BSc; Farid Abbaszade, MSc; Zahra Saghaei, MSc; Soheil Mehdipoor, MD; Firooz Madadi, MD; Morad Karimpoor, PhD
Abstract
Background: Total knee arthroplasty is an accepted method for treatment of osteoarthritis of the knee. Measuring the distal femoral rotation is one of the most important problems in such operations. In the conventional 2D method, measuring the angle is based on CT scan images but these methods usually ...
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Background: Total knee arthroplasty is an accepted method for treatment of osteoarthritis of the knee. Measuring the distal femoral rotation is one of the most important problems in such operations. In the conventional 2D method, measuring the angle is based on CT scan images but these methods usually contain errors. In this study, the three-dimensional measurement of the aforementioned angle was investigated.
Methods: In this research, using CT scans and 3D modeling, 3D lower extremity models of 40 patients were extracted. The rotation of distal femur was measured for plane perpendicular to the anatomical and the plane of mechanical axis of femur. Four axes were drawn on these planes using anatomical landmarks: posterior condylar line (PCL), anatomical and surgical transepicondylar line (ATEA+STEA), and the Whiteside line (WL).
Results: The mean difference of these measurements on the plane perpendicular to the mechanical axis of the femur, between PCL and WL, STEA, ATEA was 3.41, -1.31, 5.53; and angles on the plane perpendicular to the anatomical axis of femur were -0.74, -1.26, and 5.67, respectively. In addition, Bland-Altman diagram was plotted between every two measurements and no relationship found, except for STEA and ATEA.
Conclusions: The measurements between PCL, ATE, and STEA are not affected by the plane on which these measurements are carried out on, except for the 4 degrees difference present in WL axis. With a greater sample size and proper grouping, some relationship might be found between the aforementioned axes.
Pooneh Dehghan, MD; Zahra Saghaei ,MSc; Farid Abbaszadeh, MSc; Morad Karimpour, PhD; Soheil Mehdipoor, MD
Abstract
Background: Femoral neck anteversion is usually measured on the 2-dimensional (2D) images on CT slices. The 3D method uses 3-dimensional model of the femur reconstructed from CT scan images. The aim of this study was to compare these two methods of measurement of femoral ante-version. Methods: In ...
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Background: Femoral neck anteversion is usually measured on the 2-dimensional (2D) images on CT slices. The 3D method uses 3-dimensional model of the femur reconstructed from CT scan images. The aim of this study was to compare these two methods of measurement of femoral ante-version. Methods: In a retrospective study, CT scans of 40 patients (6 men, 34 women) of a teaching hospital in Tehran-Iran were included. Both methods use the same anatomical landmarks, i.e. center of femoral head, femoral neck axis and posterior apex of the femoral condyles. In the 3D method, anteversion angle was measured on a plane perpendicular to the anatomical axis of femur. Whereas in the 2D method the measurement is performed on CT scan slices.Results: Mean anteversion was found to be 9.8 for the 2D and 16.11 for the 3D method. Bland-Altman plot shows that the difference between the two methods is significant.Conclusions: This difference between 2D ad 3D measurement of femoral anteversion may be depend on the level of the selected CT slices, patients positioning during CT examination, and the impact of the deformity. The 3D method eliminates obvious sources of error, namely identifying landmarks and individual orientation of femur. Due to the lack of any gold standard there is a need to further review and study the measurement of this angle.
Soheil Mehdipour, MD; Farid Abbaszadeh, MSc; Morad Karimpour, PhD; Farzam Farahmand, PhD; Zahra Saghaie, MSc
Abstract
Background: Conventional X-rays, due to 2D viewing, may not have accuracy in assessing lower limb deformities. The aim of this study was to analyze the deformities in 3D and simulated the corrective surgery in virtual space and to built patient-specific guide to achieve the precise correction.Methods: ...
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Background: Conventional X-rays, due to 2D viewing, may not have accuracy in assessing lower limb deformities. The aim of this study was to analyze the deformities in 3D and simulated the corrective surgery in virtual space and to built patient-specific guide to achieve the precise correction.Methods: In this descriptive study, 10 lower limbs with various deformities around the knee were studied. Weight bearing alignment x-rays and CT scans were processed digitally to produce 3D weight bearing models.The landmarks were determined and lower limb indices were calculated to determine the deformities in 3 dimensions Under surgeon's supervision, virtual correction of the deformity was performed, based on which, a patient-specific guide was designed and printed in 3D. The guide was then used in the surgery.Results: The deformity and deviation from standard angles was obsereved in frontal plane in 6 cases, frontal and sagittal planes in one, frontal and axial planes in two, and a three planar deformity in one cases. The results showed that this method is effective in achieving the precise correction of the deformity. In all the patients who underwent surgery, the correction was the same or very close to what had been planned in frontal and sagittal planes (±1). Clinical assessment was used for rotational correction in the absence of postoperative CT-scan.Conclusions: The computer-assisted pre-op planning and patient-specific guide usage can highly optimize the results of corrective osteotomies, especially in difficult deformities around the knee.
