An anthropomorphic transhumeral prosthesis socket developed based on an oscillometric pump and controlled by force-sensitive resistor pressure signals.

While considering the importance of the interface between amputees and prosthesis sockets, we study an anthropomorphic prosthesis socket whose size can be dynamically changed according to the requirements of the residual limb. First, we introduce the structure and function of the anthropomorphic prosthesis socket. Second, we study the dynamic model of the prosthesis system and analyze the dynamic characteristics of the prosthesis socket system, the inputs of an oscillometric pump, and the control mechanism of force-sensitive resistor (FSR) pressure signals. Experiments on 10 healthy subjects using the designed system yield an average detection result between 102 and 112 kPa for the FSR pressure sensor and 39 and 41 kPa for the oscillometric pump. Results show the function of the FSR pressure signal in maintaining the contact pressure between the sockets and the residual limb. The potential development of an auto-adjusted socket that uses an oscillometric pump system will provide prosthetic sockets with controllable contact pressure at the residual limb. Moreover, this development is an attractive research area for researchers involved in rehabilitation engineering, prosthetics, and orthotics.

Transtibial prosthetic socket pistoning: static evaluation of Seal-In(®) X5 and Dermo(®) Liner using motion analysis system.

BACKGROUND: The method of attachment of prosthesis to the residual limb (suspension) and socket fitting is a critical issue in the process of providing an amputee with prosthesis. Different suspension methods try to minimize the pistoning movement inside the socket. The Seal-In(®) X5 and Dermo(®) Liner by Ossur are new suspension liners that intend to reduce pistoning between the socket and liner. Since the effects of these new liners on suspension are unclear, the objective of this study was to compare the pistoning effect of Seal-In(®) X5 and Dermo(®) Liner by using Vicon Motion System. METHODS: Six transtibial amputees, using both the Iceross Seal-In(®) X5 and the Iceross Dermo(®) Liner, participated in the study. The vertical displacement (pistoning) was measured between the liner and socket in single limb support on the prosthetic limb (full-weight bearing), double limb support (semi-weight bearing), and non-weight bearing on the prosthetic limb, and also under three static vertical loading conditions (30 N, 60 N, and 90 N). FINDINGS: The results demonstrated that the pistoning within the socket when Seal-In(®) X5 was used, decreased by 71% in comparison to the Iceross Dermo(®) Liner. In addition, a significant difference between the two liners under different static conditions was found (p<0.05). INTERPRETATION: Participants needed to put in extra effort for donning and doffing the prosthesis with Seal-In(®) X5; however, this type of liner provided less pistoning. The new approach that uses the motion analysis system in this study might be an alternative for measuring the pistoning effect in the prosthetic socket.

The metabolic dynamics of cartilage explants over a long-term culture period.

INTRODUCTION: Although previous studies have been performed on cartilage explant cultures, the generalized dynamics of cartilage metabolism after extraction from the host are still poorly understood due to differences in the experimental setups across studies, which in turn prevent building a complete picture. METHODS: In this study, we investigated the response of cartilage to the trauma sustained during extraction and determined the time needed for the cartilage to stabilize. Explants were extracted aseptically from bovine metacarpal-phalangeal joints and cultured for up to 17 days. RESULTS: The cell viability, cell number, proteoglycan content, and collagen content of the harvested explants were analyzed at 0, 2, 10, and 17 days after explantation. A high percentage of the cartilage explants were found to be viable. The cell density initially increased significantly but stabilized after two days. The proteoglycan content decreased gradually over time, but it did not decrease to a significant level due to leakage through the distorted peripheral collagen network and into the bathing medium. The collagen content remained stable for most of the culture period until it dropped abruptly on day 17. CONCLUSION: Overall, the tested cartilage explants were sustainable over long-term culture. They were most stable from day 2 to day 10. The degradation of the collagen on day 17 did not reach diseased levels, but it indicated the potential of the cultures to develop into degenerated cartilage. These findings have implications for the application of cartilage explants in pathophysiological fields.

Investigation to predict patellar tendon reflex using motion analysis technique.

The investigation of patellar tendon reflex involves development of a reflex hammer holder, kinematic data collection and analysis of patellar reflex responses using motion analysis techniques. The main aim of this research is to explore alternative means of assessing reflexes as a part of routine clinical diagnosis. The motion analysis system was applied to provide quantitative data which is a more objective measure of the patellar tendon reflex. Kinematic data was collected from 28 males and 22 females whilst subjected to a knee jerk test. Further analysis of kinematic data was performed to predict relationships which might affect the patellar tendon reflex. All subjects were seated on a high stool with their legs hanging freely within the capture volume of the motion analysis system. Knee jerk tests were applied to all subjects, on both sides of the leg, by eliciting hypo, hyper, and normal reflexes. An additional reinforcement technique called the Jendrassik manoeuvre was also performed under the same conditions to elicit a normal patellar tendon reflex. The comparison of reflex response between genders showed that female subjects generally had a greater response compared to males. However, the difference in reflex response between the left leg and the right leg was not significant. Tapping strength to elicit a hyper-reflex produced greater knee-jerk compared to the normal clinical tapping strength. All results were in agreement with clinical findings and results found by some early researchers.

The metabolic dynamics of cartilage explants over a long-term culture period

INTRODUCTION: Although previous studies have been performed on cartilage explant cultures, the generalized dynamics of cartilage metabolism after extraction from the host are still poorly understood due to differences in the experimental setups across studies, which in turn prevent building a complete picture. METHODS: In this study, we investigated the response of cartilage to the trauma sustained during extraction and determined the time needed for the cartilage to stabilize. Explants were extracted aseptically from bovine metacarpal-phalangeal joints and cultured for up to 17 days. RESULTS: The cell viability, cell number, proteoglycan content, and collagen content of the harvested explants were analyzed at 0, 2, 10, and 17 days after explantation. A high percentage of the cartilage explants were found to be viable. The cell density initially increased significantly but stabilized after two days. The proteoglycan content decreased gradually over time, but it did not decrease to a significant level due to leakage through the distorted peripheral collagen network and into the bathing medium. The collagen content remained stable for most of the culture period until it dropped abruptly on day 17. CONCLUSION: Overall, the tested cartilage explants were sustainable over long-term culture. They were most stable from day 2 to day 10. The degradation of the collagen on day 17 did not reach diseased levels, but it indicated the potential of the cultures to develop into degenerated cartilage. These findings have implications for the application of cartilage explants in pathophysiological fields.

Interface pressure profile analysis for patellar tendon-bearing socket and hydrostatic socket.

Conventionally, patellar tendon-bearing (PTB) sockets, which need high dexterity of prosthetist, are widely used. Lack of chartered and experienced prosthetist has often led to painful experience of wearing prosthesis and this will in turn deter the patients to wear the prosthesis, which will further aggravate stump shrinkage. Thus, the hydrostatic socket which demands relatively lower level of fabricating skill is proposed to replace the PTB socket in order to produce the equivalent, if not better, quality of support to the amputee patients. Both sockets' pressure profiles are studied and compared using finite element analysis (FEA) software. Three-dimensional models of both sockets were developed using MIMICS software. The analysis results showed that hydrostatic socket did exhibit more uniform pressure profiles than that of PTB socket. PTB socket showed pressure concentration near the proximal brim of the socket and also at the distal fibula. It was also found that the pressure magnitude in hydrostatic socket is relatively lower than that of PTB socket.