Factors Affecting Tibial Tuberosity-Trochlear Groove Distance in Recurrent Patellar Dislocation

BACKGROUND: The tibial tuberosity-trochlear groove (TT-TG) distance is used to determine the necessity of tibial tubercle osteotomy. We conducted this study to determine the extent to which each of the tibial tuberosity lateralization, trochlear groove medialization, and knee rotation angle affects the TT-TG distance in both normal and patella dislocated patients and thereby scrutinize the rationale for tuberosity transfer based on the TT-TG distance. METHODS: Retrospective analysis of rotational profile computed tomography was done for patella dislocated and control group patients. Femoral anteversion, tibial torsion, knee rotation angle, tuberosity lateralization, and trochlear groove medialization were assessed in all patients. Relationship of these parameters with the TT-TG distance was investigated to evaluate their effects on the TT-TG distance. RESULTS: We observed that the patellar dislocation group, compared to the control group, had increased TT-TG distance (mean, 19.05 mm vs. 9.02 mm) and greater tuberosity lateralization (mean, 64.1% vs. 60.7%) and tibial external rotation in relation to the femur (mean, 7.9° vs. −0.81°). CONCLUSIONS: Tuberosity lateralization and knee rotation were factors affecting patellar dislocation. These factors should be considered in addition to the TT-TG distance to determine the need for tibial tubercle osteotomy in patients with patellar dislocation.

Comparison of Radiological Parameters between Normal and Patellar Dislocation Groups in Korean Population: A Rotational Profile CT-Based Study

PURPOSE: Patellofemoral instability is a common cause of anterior knee pain in adolescents and young adults. Most normal and pathological values for diagnosing patellofemoral instability are based on Western literature. We conducted this radiological study to determine normal values for different patellofemoral parameters in a Korean population and to evaluate their usefulness in diagnosis. MATERIALS AND METHODS: We retrospectively reviewed the rotational profile computerized tomography (CT) scans of the patellar dislocation and control groups. Trochlear, patellar, rotational profile, and trochleo-patellar alignment parameters were compared between the groups. Receiver operating characteristic curves were drawn for significant parameters, and sensitivity and specificity were calculated for the cut-off values. RESULTS: There were 48 patients in the patellar dislocation group and 87 patients in the control group. In the control group and patellar dislocation group, the mean sulcus angle was 132.5° and 143.3°, respectively, trochlear depth was 6.04 mm and 3.6 mm, bisect offset was 56.4% and 99.9%, lateral patellar tilting was 9.8° and 19.2°, patellar facet asymmetry was 63.5% and 45.16%, and the tibial tuberosity-trochlear groove (TT-TG) distance was 10.91 mm and 27.16 mm, respectively. CONCLUSIONS: The trochlear depth, bisect offset, patella tilting, and TT-TG distance were parameters that significantly contributed to patellar instability. Rotational profile CT can be considered a good diagnostic tool to assess all these parameters that help to identify anatomical aberration resulting in patellofemoral instability, thereby helping in formulating the most effective treatment plan.

Effect of Tranexamic Acid on Blood Loss and Blood Transfusion Reduction after Total Knee Arthroplasty

PURPOSE: Total knee arthroplasty (TKA) accompanies the risk of bleeding and need for transfusion. There are several methods to reduce postoperative blood loss and blood transfusion. One such method is using tranexamic acid during TKA. The purpose of this study was to confirm whether tranexamic acid reduces postoperative blood loss and blood transfusion after TKA. MATERIALS AND METHODS: A total of 100 TKA patients were included in the study. The tranexamic acid group consisted of 50 patients who received an intravenous injection of tranexamic acid. The control included 50 patients who received a placebo injection. The amounts of drainage, postoperative hemoglobin, and transfusion were compared between the groups. RESULTS: The mean amount of drainage was lower in the tranexamic acid group (580.6±355.0 mL) than the control group (886.0±375.5 mL). There was a reduction in the transfusion rate in the tranexamic acid group (48%) compared with the control group (64%). The hemoglobin level was higher in the tranexamic acid group than in the control group at 24 hours postoperatively. The mean units of transfusion were smaller in the tranexamic acid group (0.76 units) than in the control group (1.28 units). CONCLUSIONS: Our data suggest that intravenous injection of tranexamic acid decreases the total blood loss and transfusion after TKA.