Preclinical Strength Checking for Artificial Pelvic Prosthesis under Multi-activities-A Case Study

Customized prostheses are normally employed to reconstruct the biomechanics of the pelvis after resection due to tumors or accidents.The objective of this study is to evaluate the biomechanics of the pelvis under different daily activities and to establish a functional evaluation methodology for the customized prostheses.For this purposes,finite element model of a healthy pelvis as well as a reconstructed pelvic model after type II+III resection were built for biomechanical study.The biomechanical perfonnance of the healthy and reconstructed pelvic model was studied under routine activities including standing,knee bending,sitting down,standing up,walking,stair descent and stair ascent.Subsequently,the strength and stability of the prosthesis were evaluated under these activities.Results showed that,for the heathy pelvic model,the stresses were mainly concentrated around the upper part of the sacrum and the sacroiliac joint undergoing different activities,and the maximum stress occurred during stair ascent.As for the reconstructed pelvis,the stress distribution and the tendency of the maximum stress variation predicted for the bone part during all the activities were similar to those of the natural pelvic model,which indicated that the load transferring function of the reconstructed pelvis could be restored by the prosthesis.Moreover,the predicted maximum von Mises stress of the screws and prosthesis was below the fatigue strength of the 3D printed Ti-6A1-4V,which indicated the prosthesis can provide a reliable mechanical performance after implantation.

Conceptual Method of Temperature Sensation in Bionic Hand by Extraordinary Perceptual Phenomenon

Lack of temperature sensation of myoelectric prosthetic hand limits the daily activities of amputees.To this end,a noninvasive temperature sensation method is proposed to train amputees to sense temperature with psychophysical sensory substitution.In this study,22 healthy participants took part besides 5 amputee participants.The duration time of the study was 31 days with five test steps according to the Leitner technique.An adjustable temperature mug and a Peltier were used to change the temperature of the water/phantom digits to induce temperature to participants.Also,to isolate the surroundings and show colors,a Virtual Reality(VR)glass was employed.The statistical results conducted are based on the response of participants with questionnaire method.Using Chi-square tests,it is concluded that participants answer the experiment significantly correctly using the Leitner technique(P value<0.05).Also,by applying the“Repeated Measures ANOVA”,it is noticed that the time of numbness felt by participants had significant(P value<0.001)difference.Participants could remember lowest and highest temperatures significantly better than other temperatures(P value<0.001);furthermore,the well-trained amputee participant practically using the prosthesis with 72.58%could identify object’s temperature with only once time experimenting the color temperature.