Radiological analysis on femoral tunnel positioning between isometric and anatomical reconstructions of the anterior cruciate ligament

Abstract

Objectivethe aim of this study was to radiologically evaluate the femoral tunnel position in anterior cruciate ligament (ACL) reconstructions using the isometric and anatomical techniques.Methodsa prospective analytical study was conducted on patients undergoing ACL reconstruction by means of the isometric and anatomical techniques, using grafts from the knee flexor tendons or patellar tendon. Twenty-eight patients were recruited during the immediate postoperative period, at the knee surgery outpatient clinic of FCMMG-HUSJ. Radiographs of the operated knee were produced in anteroposterior (AP) view with the patient standing on both feet and in lateral view with 30° of flexion. The lines were traced out and the distances and angles were measured on the lateral radiograph to evaluate the sagittal plane. The distance from the center of the screw to the posterior cortical bone of the lateral condyle was measured and divided by the Blumensaat line. In relation to the height of the screw, the distance from the center of the screw to the joint surface of the lateral condyle of the knee was measured. On the AP radiograph, evaluating the coronal plane, the angle between the anatomical axis of the femur and a line traced at the center of the screw was measured.Resultswith regard to the p measurement (posteriorization of the interference screw), the tests showed that the p-value (0.4213) was greater than the significance level used (0.05); the null hypothesis was not rejected and it could be stated that there was no statistically significant difference between the anatomical and isometric techniques. With regard to the H measurement (height of the screw in relation to the lower cortical bone of the knee), the p-value observed (0.0006) was less than the significance level used (0.05); the null hypothesis was rejected and it could be stated that there was a statistically significant difference between the anatomical and isometric techniques. It can be concluded that the latter difference occurred because the isometric technique generated greater values for the H measurement than the anatomical technique. With regard to the MED variable (position of the screw on the AP radiograph), the observed p-value (0.000) was less than the significance level (5%); the null hypothesis was rejected and it could be stated with 95% confidence that there was a significant difference between the anatomical and isometric techniques.Conclusionsthere were statistically significant differences in the radiological evaluations of the femoral tunnel, both in the sagittal and in the coronal plane, between the ACL reconstruction techniques.

Radiological evaluation of the femoral tunnel positioning in anterior cruciate ligament reconstruction

“…In this study, the mean difference between the angles was 16.8°. However, unlike the present study, Vieira et al 14 measured the inclination of the tunnels in relation to the anatomical axis of the femur.…”

“… 12 A study by Aglietti et al 13 demonstrated that the two-incision technique presented a significantly lower mean femoral angle in the AP X-ray (37°) when compared with the one-incision technique (68°). Vieira et al 14 observed that the angles in anatomical reconstructions are smaller than in transtibial procedures, as the former have a more horizontal orientation. The mean difference between the tunnel angles, measured on X-rays, was 16.74°.…”

Transtibial technique versus two incisions in anterior cruciate ligament reconstruction: tunnel positioning, isometricity and functional evaluation

“…This finding is in agreement with recent studies, in which the gliding on maximum extension was similar in both techniques. 28 , 29 , 30 …”

Effects of extremity positioning on radiographic evaluation of femoral tunnel location with digitally reconstructed femoral lateral radiographs after anterior cruciate ligament reconstruction

“…Three-dimensional (3D) imaging techniques, like computerized tomography (CT) and magnetic resonance imaging (MRI) are now commonly used to evaluate ACL injury and progress following ACL reconstruction [ 11 ]. Nevertheless two-dimensional (2D) imaging measurements, such as BL on plain x-rays, remain the most common technique for estimating the position of the distal femoral tunnel [ 10 , 13 – 18 ], due to its simplicity, easy access, availability, low radiation exposure and low costs. Spatial orientation of the knee joint in the X-ray setup may affect the comparative position of landmarks in a 2D image [ 11 ].…”