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.
Fardin Mirzatolouei, MD; Majid Mohseni Kabir, MD
Abstract
Background: Perfect rotational positioning of femoral component in total knee arthroplasty is mandatory for good outcome, particularly in knees with severe varus. Posterior condylar line (PCL) and transepicondylar axis TEA are the two current methods used to determine the appropriate rotational positioning ...
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Background: Perfect rotational positioning of femoral component in total knee arthroplasty is mandatory for good outcome, particularly in knees with severe varus. Posterior condylar line (PCL) and transepicondylar axis TEA are the two current methods used to determine the appropriate rotational positioning of femoral component. The aim of this study was to compare the accuracy of femoral component rotation after TKA, using either PCL or TEA reference points. Methods: In a retrospective study, 42 consecutive TKA candidates with severe varus knees were divided into two groups: In group I posterior condylar line, and in group II transepicondylar axis was considered as the primary landmark for rotational positioning. Erosion of medical femoral condylar was recorded in millimeters. One year after operation all the patients underwent CT scan and the angles between TEA and PCL of the prosthesis was meausured. The degree of knee flexion and also WOMAC scores were recorded. Results : The female gender was prominent in both groups (81% in group 1, 85.7% in group II). There was no significant femoral condylar erosion in either group. The mean Womac score in group 1 was 71.4±17.51 and 72.07±15.48 in group II (p < /i>=.9). The degree of external rotation according to condylar twisting angle was 3.35±1.74 in group 1 and 1.9±1.7 in group 2 (p < /i>=.009). Conclusions: In severe Knee-varus deformity, TEA landmark gives more external rotation position for femoral component, despite of lack of significant erosion in femoral condyle.
Arash Maleki; Firoozeh Madadi; Ramin Arjang; Firooz Madadi
Abstract
Background: Tibial torsion is a term used to describe the physiologic twist of the distal relative to the proximal articular axis of the tibial bone in the transverse plane around its longitudinal axis. This study focuses on a method of tibial torsion measurement with computerized tomography cuts. Methods: ...
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Background: Tibial torsion is a term used to describe the physiologic twist of the distal relative to the proximal articular axis of the tibial bone in the transverse plane around its longitudinal axis. This study focuses on a method of tibial torsion measurement with computerized tomography cuts. Methods: Sixty four volunteers aged over 16 years old had CT imaging of proximal and distal tibia in a teaching hospital in Tehran-Iran. The images were evaluated for leg rotation by four physicians using two different techniques in two different occasions, one month apart. In the first technique the middle of tibia and middle of fibula were used as reference points and in the second method the perpendicular axis to the line connecting the distal fibular notches on CT scans was used. The values were analyzed, and the intra and inter observer agreements for tibia torsions were assessed. Results: The inter-observer agreement in tibial torsion was .861 and .863 in the first and second methods respectively. The intra-observer reliability in both measurements techniques were .868. The two techniques also had excellent agreement in tibial torsion measurements. Conclusion: The second technique has high reliability and reproductivity in assessing tibial rotation in fibula deformity.
