PubMed · 5174973
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J Donovan. No hands.. https://pubmed.ncbi.nlm.nih.gov/5174973/
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OBJECTIVE: The ability to measure skin surface slippage relative to the internal wall of a lower extremity prosthesis under various loading conditions is important for evaluation of socket fit and function, and creation of finite element models. Skin surface three-dimensional (3D) shape measurements with tracking of fiducial displacements in situ under axial loading of the prosthesis have not previously been reported. Analysis of slippage within the prosthesis has been performed using a new experimental measurement method based on spiral x-ray computed tomography (SXCT) imaging. DESIGN: Small lead markers were placed on the residuum of an adult with a below-knee amputation, and SXCT scans were obtained with the prosthesis in situ under two static axial loading conditions (44.5N and 178N). The 3D scan data were used to assess slippage with three methods: gross displacement of the tibia and distal end of the residuum; relative displacement of markers; and distance measurements between markers. RESULTS: The markers affixed to the below-knee skin surface within the prosthesis were measured. The skin slipped from 2 to 6 mm relative to the internal prosthesis wall when an additional load of 133.5N was applied in the axial direction to the distal end of the prosthesis. The tibial remnant moved 10.0 mm distally relative to the prosthesis internal wall. CONCLUSION: This method provides a feasible means for measuring residuum skin slippage relative to the prosthesis and skin deformation relative to tibia within an in situ prosthesis under load.
A prosthetic hand is essential to provide rehabilitation for individuals who lose a hand. A prosthetic hand serves two purposes: cosmetic and functional. In this paper, a prototype of the artificial hand with an emphasis on the functionality purpose is presented. A new mechanism, the NTU-Hand (NTU-Hand, patent number 107115, Taiwan, R.O.C.), which has 5 fingers with 17 degrees of freedom, has been designed and fabricated in our laboratory. Due to the special design of the mechanism, the hand has an uncoupled configuration in which each finger and joint are all individually driven. The size of the hand is almost the same as a human hand. All actuators, mechanical parts, and sensors are on the hand. The compact design makes it feasible to adapt the hand to the injured wrist. A computer simulation with three-dimensional graphics was also built to evaluate the manipulative range of the artificial hand. From the results of this simulation, the relationship between the hand and the grasped object in a specific viewpoint can be obtained.
The aim of this study was to assess, by means of gait analysis, the effect on the gait of a trans-tibial amputee of altering the mass and the moment of inertia of a dynamic elastic response prosthesis. One male amputee was analysed for four to five walking trials at normal and fast cadences, using the VICON system of motion analysis and an AMTI force plate. The kinematic variables of cadence, swing time, single support time and joint angles for the knee and hip on the affected and intact sides were analysed. The ground reaction force was also analysed. The sample size was limited to one as an example to indicate the changes which are possible through simply changing the inertial characteristics. Descriptive statistics are used to demonstrate these changes. Three mass conditions for the prosthesis were analysed m1: 1080g; m2: 1080 + 530g; m3: 1080 + 1460g. The m1 condition is the mass of the prosthesis with no added weight while m2 and m3 were attachments of the same geometrical shape but were made from different materials. It was felt that the large mass range would highlight biomechanical adjustments as a result of its alteration. The effect on selected temporal characteristics were that as the speed increased the cadence changed and the affected side single support times as a percentage of the gait cycle were altered. The effect on the joint angles was also apparent at the hip and knee of both sides. The ground reaction force patterns were similar for all three mass conditions, though the impact peak which was evident in the intact limb was missing, indicating a shock absorbing property in the prosthesis. Clearly, changing the mass and moment of inertia has an effect on the kinematic variables of gait and should be considered when designing a prosthesis.