ObjectiveTo investigate the effect of power-assisted intravascular shunt in replantation of amputated limbs of rabbits. MethodsEighty rabbits weighing 1.8-2.5 kg (male or female) were selected to establ ish the model of circular amputation at the hind groin, only femoral arteries and veins were completely preserved. After the femoral artery was clamped in 60 rabbits, the rabbits underwent power-assisted intravascular shunt with high-flow rate (group A, n=20), powerassisted intravascular shunt with low-flow rate (group B, n=20), and no power-assisted intravascular shunt (group C, n=20) to reconstruct blood supply; the femoral artery was not clamped in another 20 rabbits of sham group (group D). Before and after intravascular shunt (1, 3, 6, and 12 hours), the malondialdehyde (MDA), lactate dehydrogenase (LDH), and creatine kinase (CK) of the serum were determined. The myeloperoxidase (MPO), MDA, and wet to dry weight ratio (W/D ratio) of the gastrocnemius muscle were measured, and the thrombogenesis and survival rate of limb were observed. ResultsBefore intravascular shunt, MDA, LDH, and CK of the serum and MPO, MDA, and W/D ratio of the muscle showed no significant difference among 4 groups (P>0.05). At each time point after intravascular shunt, no significant difference was found in all indexes between groups A and D (P>0.05); the indexes of groups B and C were significantly higher than those of groups A and D (P<0.05); the values were the highest in group C (P<0.05), and reached the peak at 12 hours. All limbs of group A survived with low thrombosis rate, and less limbs could survive with high thrombosis rate in group C. ConclusionThe power-assisted intravascular shunt with high-flow rate can effective ensure the blood supply of the amputated limbs of rabbits with lower limb injury and higher survival rate of amputated limbs after replantation.
A micro silicone oil liquid spring was designed and manufactured in this article. The performance of the liquid spring was studied by simulation analysis and mechanical test. A self-force source power-assisted knee orthosis was designed based on the liquid spring. This power-assisted knee orthosis can convert the kinetic energy of knee flexion into the elastic potential energy of liquid spring for storage, and release elastic potential energy to generate assisted torque which drives the knee joint for extension. The results showed that the average maximum reset force of the liquid spring was 1 240 N, and the average maximum assisted torque for the knee joint was 29.8 N·m. A musculoskeletal multibody dynamic model was used to analyze the biomechanical effect of the knee orthosis on the joint during knee bending (90°knee flexion). The results showed that the power-assisted knee orthosis could effectively reduce the biomechanical load of the knee joint for the user with a body weight of 80 kg. The maximum forces of the femoral-tibial joint force, patellar-femoral joint force, and quadriceps-ligament force were reduced by 24.5%, 23.8%, and 21.2%, respectively. The power-assisted knee orthosis designed in this article provides sufficient assisted torque for the knee joint. It lays a foundation for the subsequent commercial application due to its small size and lightweight.