Proper femoral and tibial component rotational positioning in TKA is critical for outcomes. Several rotational landmarks are frequently used with different advantages and limitations. We wondered whether coronal axes in the tibia and femur based on the transepicondylar axis in the femur would correlate with anteroposterior deformity. We obtained computed tomography scans of 100 patients with arthritis before they underwent TKA. We measured the posterior condylar angle on the femoral side and the angle between Akagi's line and perpendicular to the projection of the femoral transepicondylar axis on the tibial side. On the femoral side, we found a linear relationship between the posterior condylar angle and coronal deformity with valgus knees having a larger angle than varus knees, ie, gradual external rotation increased with increased coronal deformity from varus to valgus. On the tibial side, the angle between Akagi's line and the perpendicular line to the femoral transepicondylar axis was on average approximately 0°, but we observed substantial interindividual variability without any relationship to gender or deformity. A preoperative computed tomography scan was a useful, simple, and relatively inexpensive tool to identify relevant anatomy and to adjust rotational positioning. We do not, however, recommend routine use because on the femoral side, we found a relationship between rotational landmarks and coronal deformity.
In a prospective randomized double-blind study we compared the postoperative recovery and early results of two groups of 30 patients having total knee arthroplasty with minimally invasive techniques using either a mini-subvastus or a modified "quadriceps-sparing" approach. All knees were implanted with the same posterior-stabilized prosthesis (LPS-Flex, Zimmer, Warsaw, IN) by the same surgeon with the same dedicated set of downsized instruments. Epidural anesthesia with the same postoperative analgesia and rehabilitation protocol was used in all patients. Evaluation was performed preoperatively, postoperatively in the first week, and at 1 and 3 months. In five cases in the "quadriceps- sparing" group, the incision was extended a few cm to facilitate exposure. Tourniquet time, estimated blood loss, and postoperative pain were similar in the two groups. Active straight leg raising was achieved half a day earlier, on average, in the mini-subvastus group (1.9 vs 1.4 days). Average maximum active flexion was similar in the two groups at each interval, and reached 117 degrees and 119 degrees at 3 months for the mini-subvastus and "quadriceps-sparing" group, respectively. We believe there was no difference between the mini-subvastus and "quadriceps-sparing" approach in relation to short term recovery or early results.
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