Résumé
ObjectiveTo investigate the injury risk of simplified 24-action Taiji Quan wild horse mane splitting practice at different postures with mechanical analysis. MethodsThe mechanical model of the action of Taiji Quan wild horse mane splitting was establishied, and then the coordinates, velocity, acceleration and horizontal angle of thigh and lower leg were determined by image analysis. The force arm of quadriceps femoris was detected by X-ray, and the quadriceps femoris tension, femoral tibial joint force and patellofemoral joint pressure of wild horse mane splitting practice with different postures were compared. ResultsCompared with the high posture, the coordination and velocity decreased, the average angle of knee joint decreased from 128° to 115° at the low posture; and the knee moment, the quadriceps femoris tension, femoral tibial joint force and patellofemoral joint pressure significantly increased (F > 37.187, P < 0.001). ConclusionWhen practicing Taiji Quan wild horse mane splitting, the risk of knee injury at the low posture is higher than that at high posture.
Résumé
[Objective]To measure the in vivo knee joint reaction force in a rabbit model of tibial diaphyseal lengthening.[Method]Sixteen immature (8 weeks old) New Zealand White rabbits were underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4 mm incremental lengthenings per day.The knee joint reaction force was measured at the end of lengthening (8 rabbits,13 weeks old) and 5 weeks later (8 rabbits,18 weeks old).An instrumented bilateral distractor and an extensometer were fixed cross the knee joint.The joint distraction force and distraction displacement were measured immediately after each incremental distraction of the joint.[Result]The joint reaction force on the lengthened side was significantly higher than that of the control side at both time points (44.4?7.8 N v.27.2?4.0 N at 13 weeks of age,44.3?6.5 N v.31.3?3.0 N at 18 weeks of age).[Conclusion]The knee joint reactive force could be increased in 30% tibial disphyseal lengthening which potentially could lead to the risk of damage to artic ular cartilage.
Résumé
We studied 16 cases intracapsular pressure in displaced fracture of femoral neck(Garden stage III, IV), the pressures were measured range between 12-62 mmHg(mean, 23.4 mmHg). Aspirated blood amount from hip joint did not exceed 3cc, this amount not correlate with intracaspsular pressure. Of 10 cases examined scintimetry, 2 had incressed uptake after aspiraton, it is suggested that early decompression of hemarthrosis in femur neck fracture regaredless of displacement may be considered.