In order to restore the neutral limb alignment in total knee arthroplasty (TKA), surgical procedure usually starts with removing osteophytes in varus osteoarthritic knees. However, there are no reports in the literature regarding the exact influence of osteophyte removal on alignment correction. The purpose of this study was to define the influence of osteophyte removal alone on limb alignment correction in the coronal plane in TKA for varus knee. Twenty-eight medial osteoarthritic knees with varus malalignment scheduled for TKA were included in this study. After registration of a navigation system, each knee was tested at maximum extension, and at 30, 40 and 60 degrees of flexion before and after osteophyte removal. External loads of 10 N-m valgus torque at each angle and in both states were applied. Subsequently, the widths of the resected osteophytes were measured.Background
Methods
A femoral rotational alignment is one of the essential factors, affecting the postoperative knee balance and patellofemoral tracking in total knee arthroplasty (TKA). To obtain an adequate alignment, the femoral component must be implanted parallel to the surgical epicondylar axis (SEA). We have developed “a superimposable Computed Tomography (CT) scan-based template”, in which the SEA is drawn on a distal femoral cross section of the CT image at the assumed bone resection level, to determine the precise SEA. Therefore, the objective of this study was to evaluate the accuracy of the rotational alignment of the femoral component positioned with the superimposed template in TKA. Twenty-six consecutive TKA patients, including 4 females with bilateral TKAs were enrolled. To prepare a template, all knees received CT scans with a 2.5 mm slice thickness preoperatively. Serial three slices of the CT images, in which the medial epicondyle and/or lateral epicondyle were visible, were selected. Then, these images were merged into a single image onto which the SEA was drawn. Thereafter, another serial two CT images, which were taken at approximately 9 mm proximal from the femoral condyles, were also selected, and the earlier drawn SEA was traced onto each of these pictures. These pictures with the SEA were then printed out onto transparent sheets to be used as potential “templates” (Fig. 1-a). In the TKA, the distal femur was resected with the modified measured resection technique. Then, one template, whichever of the two potential templates, was closer to the actual shape, was selected and its SEA was duplicated onto the distal femoral surface (Fig. 1-b). Following that, the distal femur was resected parallel to this SEA. The rotational alignment of the femoral component was evaluated with CT scan postoperatively. For convention, an external rotation of the femoral component from the SEA was given a positive numerical value, and an internal rotation was given a negative numerical value.Introduction
Patients and methods
For restoration of neutral limb alignment in Total Knee Arthroplasty (TKA), we usually start by removing osteophytes in varus osteoarthritic knees. However, we have found no reports in the literature regarding research on the exact influence of osteophyte removal on angle correction. The purpose of this study was to define the influence of osteophyte removal on limb alignment correction in the coronal plane in TKA. Nine patients with varus malalignment that were scheduled for TKA were included in this study. Only patients with degenerative osteoarthritis were considered. After registration of a navigation system, each knee was tested at maximum extension, and 30 and 60 degrees of flexion before and after osteophyte removal. The same examiner applied all external loads of 10 N-m valgus torque at each angle and in both states. Subsequently, the widths of the osteophytes were measured. All data were analyzed statistically using paired t-test and correlation coefficient. A significant difference was determined to be present for P < .05.Introduction
Materials and Methods
Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in TKA. This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with an intact knee (S0), and thereafter femoral arthroplasty only (S1), tibial arthroplasty (S2), release of the dMCL (S3), and finally, release of the POL (S4). The same examiner applied all external load of 10 N-m valgus and a 5 N-m internal and external rotation torque at each flexion angle for the each cutting state. All data were analyzed statistically using one-way ANOVA and we investigated the correlation between the medial gap and the rotation angle. A significant difference was determined to be present for P < .05.Introduction
Materials and Methods
Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on kinematics in TKA. This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with femoral arthroplasty only (S1), and thereafter sequentially; medial half tibial resection with spacer (S2), ACL cut (S3), tibial arthroplasty (S4), release of the dMCL (S5), and finally, release of the POL (S6). The same examiner applied all external loads of 10 N-m valgus and 5 N-m internal and external rotation torques at each flexion angle and for each cut state. The AP locations of medial and lateral condyles were determined as the lowest point on each femoral condyle. All data were analyzed statistically using paired t-test. A significant difference was determined to be present for P < .05.Introduction
Materials and Methods
