Various types of tibial alignment guides exist, the results in performing the tibial resection in total knee arthroplasty (TKA) are more or less than we desired. In addition, it is difficult to estimate the accuracy of tibial component alignment with radiograph because it is difficult to get true frontal and lateral view. In this study, we use new tibial alignment guide and estimate tibial component alignment by using postoperative CT scan. 30 knees underwent TKA using an accelerometer-based, portable navigation device (KneeAlign 2) and postoperative CT scans were obtained. Postoperative CT scans of the lower limbs analysed by 3D digital template system (Athena), demonstrated that 96.6% of the tibial components were placed within 90°± 2°to the mechanical axis in the coronal plane, and 96.6% of the components were placed within 3°± 2°to the mechanical axis in the sagittal plane. As a result of this study, an accelerometer-based, portable navigation device can expect to decrease outliers in tibial component alignment.
It is very important for implanting tibial component to prevent bearing dislocation in Oxford UKA. One of the keys is accurate rotational position of tibia. But the problem remains what is accurate rotation of tibia in UKA. Oxford Signature decided the rotation of tibia component from MRI images. We measured the component rotation of tibia using CT after operation. 14 patients were operated by Oxford Signature and 11 patients were operated by Microplasty method. Patients were examined by CT 2 or 3 weeks later after operation. We compared component axis of tibia and A-P axis by best fit circle, Akagi's line. In Oxford Signature group, component angle were 7.1 degree external rotation compared with A-P axis by best fit circle and were 3.6 degree external rotation compared with Akagi's line. In Microplasty group, component angle were 8.1 degree external rotation compared with A-P axis by best fit circle and were 3.8 degree external rotation compared with Akagi's line.Patients and Methods
Results
