Objective To explore the effective method and the feasibil ity of the accurate l imb length equal ization in patients undergoing total hip arthroplasty (THA). Methods From September 2006 to September 2008, 52 patients underwentunilateral THA, including 36 males and 16 females, with an average age of 61.5 years (range, 46-76 years). Among these cases, there were 22 cases of avascular necrosis of the femoral head, 12 cases of hip osteoarthritis, 11 cases of femoral neck fracture, 4 cases of congenital dislocation of hip, and 3 cases of acetabular dysplasia. Forty cases had leg length discrepancy, and the shortened length of the legs was in the range of 10 mm to 35 mm with an average of 20 mm. The mean Harris score before operation was 45 points (range, 36-58 points). Based on the cl inical measurement and radiographic examination, the surgical protocols were designed, the type of the hip prosthesis was chosen, and the neck length of the femoral prosthesis, and the position of osteotomy were estimated. By the proper wearing of the acetabula, the best rotation point was found out. The cut plane of the femoral neck was adjusted according to the results of the radiographic and other examinations. The neck length was readjusted after the insertion of the prosthesis so as to achieve intended leg-length equal ization. The discrepancy of the leg length was measured and evaluated after operation. Results The incision healed by first intention in all patients. One patient had ischiadic nerve palsy and achieved full restoration after 5 months of symptomatic management. Forty-four patients were followed up 16 months on average (7-32 months). The mean Harris score was 87.5 points (80-91 points), showing significant difference (P lt; 0.05) whencompared with that before operation. The l imb length equal ization were got in 35 patients (equal ization rate was 79.5%). Seven patients had the prolong leg (from 10 mm to 18 mm), 2 patients had the shortened legs (15 mm and 25 mm, respectively). Conclusion By measurement of leg-length and radiographic examination before and during operation, the problem of unequal leg - length can be solved during the THA.
Transcranial magneto-acoustical stimulation (TMAS), utilizing focused ultrasound and a magnetostatic field to generate an electric current in tissue fluid to regulate the activities of neurons, has high spatial resolution and penetration depth. The neuronal spike-frequency adaptation plays an important role in the treatment of neural information. In this paper, we study the effects of ultrasonic intensity, magnetostatic field intensity and ultrasonic frequency on the neuronal spike-frequency adaptation based on the Ermentrout neuron model. The simulation results show that, the peak time interval becomes smaller, the interspike interval becomes shorter and the time of the firing of the neuron is shortened with the increasing of the magnetostatic field intensity. With the increase of the adaptive variables, the initial spike-frequency is shifted to the right with the magnetostatic field intensity, and the spike-frequency is linearly related to the increase of the magnetostatic field intensity in steady state. The simulation effect with change of the ultrasonic intensity is consistent with the change of magnetostatic field intensity. The change of the ultrasonic frequency has no effect on the neuronal spike-frequency adaptation. Under the different adaptive variables, with the increase of the adaptive variables, the initial spike-frequency amplitude decreased with the increasing of the ultrasonic frequency, and the spike-frequency is linearly related to the increase of the ultrasonic frequency in steady state. These results of the study can help us to reveal the mechanism of transcranial magneto-acoustical stimulation on the neuronal spike-frequency adaptation, and provide a theoretical basis for its application in the treatment of neurological disorders.