Search

Background Precise matching of the tibial component and resected bony surfaces and proper rotational implanting of the tibial component are crucial for successful total knee arthroplasty. We aimed to analyze the exact anthropometric proximal tibial data of Japanese patients undergoing total knee arthroplasty and correlate the measurements with the dimensions of current total knee arthroplasty systems. Methods A total of 703 knees in 566 Japanese patients who underwent total knee arthroplasty for osteoarthritis were included. The bone resection in the proximal tibia was performed perpendicular to the tibial axis in the frontal plane. Measurements of the proximal tibia were intraoperatively obtained after proximal tibial preparation. Results There were significant positive correlations between the lateral anteroposterior and medial anteroposterior and mediolateral dimensions. A progressive decrease in the mediolateral/lateral anteroposterior ratio with an increasing lateral anteroposterior dimension or the mediolateral/anteroposterior ratio with an increasing anteroposterior dimension was observed. The lateral anteroposterior dimension was smaller than the medial anteroposterior dimension by a mean of 4.8 ± 2.0 mm. The proximal tibia exhibited asymmetry between the lateral and medial plateaus. A comparison of the morphological data and dimensions of the implants, one of which was a symmetric tibial component (NexGen) and the others were asymmetric (Genesis II and Persona), indicated that an asymmetric tibial component could be beneficial to maximize tibial plateau coverage. Conclusions This study provided important reference data for designing a proper tibial component for Japanese people. The proximal tibial cut surface was asymmetric. There was wide dispersion in the lateral anteroposterior, medial anteroposterior, and mediolateral dimensions depending on the patient. Our data showed that the tibial components of the Genesis II and Persona rather than that of the NexGen may be preferable for Japanese people because of their asymmetric design.

Previous epidemiological studies revealed that anterior cruciate ligament (ACL) injuries were more frequently seen in female athletes than in male athletes. To elucidate the pathogenetic roles of estrogen in ACL ruptures, the elasticity of ACL tissue was measured using a scanning acoustic microscope (SAM) in an estrogen-controlled animal model.A total of 40 ovariectomized Japanese white rabbits were randomly divided into four groups according to the administered dose of 17beta-estradiol (groups L, M, H, and C). Injection of 17beta-estradiol was performed 1, 2, 3, and 4 weeks after surgery, and doses in groups L, M, and H were 50, 100, and 500 microg/kg, respectively. Group C received no estradiol. Only groups L, M, and C were used for current analyses because their mean serum estrogen levels were within the physiological range (groups C, L, M, and H: 37, 50, 60, and 231 pg/ml, respectively). Five weeks after ovariectomy, the lateral portion of the ligament was harvested. Specimens were fixed with 10% neutralized formalin and embedded in paraffin. Then, 10 mum thick sections were cut perpendicular to the ligament fibers for routine histological staining and measurement with SAM.The mean tissue sound speeds of groups C, L, and M were 1727 +/- 32, 1683 +/- 53, and 1665 +/- 63 m/s, respectively. Group M presented significantly lower tissue sound speed than group C (P = 0.021). Furthermore, a negative correlation was found between the mean serum estrogen level and mean tissue sound speed of the ACL among all animals in groups C, L, and M (r = 0.47, P = 0.016).The results of the present study indicated that estrogen altered the tissue elasticity of rabbit ACL. Estrogen may constitute one of the pathogenetic factors in ACL rupture in female athletes.

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been used to examine muscle activity during running. The dash is a basic activity in various kinds of sports but differs from running in terms of intensity and severity. The purpose of this study was to evaluate muscle activity during running at full speed using FDG PET.Six healthy men were investigated during a dash for 10 min after intravenous injection of FDG (37 MBq). Another six healthy men were studied as controls. PET images were obtained 45 min after the FDG injection. Regions of interest were drawn on the anterior and posterior thighs and the anterior and posterior legs. The standardized uptake value (SUV) was calculated to examine the FDG uptake of muscle tissue per unit volume according to an equation.In the control group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.49 +/- 0.04, 0.44 +/- 0.02, 0.46 +/- 0.05, and 0.44 +/- 0.07, respectively. In the dash group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.74 +/- 0.20, 0.79 +/- 0.08, 0.61 +/- 0.07, and 0.60 +/- 0.08, respectively. FDG accumulation of every one of the four compartments in the dash group was significantly higher than that in the control. FDG accumulation of the posterior thigh was significantly higher than that of the anterior and the posterior leg in the dash group (P0.02).Based on the results of our investigation, posterior thigh muscles were especially active during a dash.