Investigation of the optimal load-bearing characteristics of patellar tendon bearing (PTB) prostheses

The long term goal of the research team is to automate the construction of the lower limb prostheses using Computer Integrated Manufacturing (CIM) techniques

Design and testing of a functional arm orthosis in patients with neuromuscular diseases

IEEE Transactions on Neural Systems and Rehabilitation Engineering, 15(2): pp. 244-251.The objective of this study was to determine the utility of a passive gravity-balanced arm orthosis, theWilmington robotic exoskeleton (WREX), for patients with neuromuscular diseases. The WREX, a four-degrees-of-freedom functional orthosis, is energized by rubber bands to eliminate gravity and is attached to the wheelchair. The development and clinical testing of WREX is described in this report. Seventeen patients (14 boys and 3 girls) with muscular disabilities participated in the study. Ages ranged from 4 to 20 years. Criteria for inclusion included a weakened arm, use of a wheelchair, the ability to grasp and release objects, and the ability to provide feedback on device use. Testing consisted of administering the Jebsen test of hand function without WREX and then testing again after approximately two weeks of wearing the WREX orthosis. The timed results of each task within the test then were compared. Specific tasks related to vertical movement required less time to perform with the WREX. A large number of subjects were able to perform the Jebsen tasks with the WREX, where they were unable to perform the task without the WREX. Patients can benefit from WREX because it increases their performance in daily living activities and makes many tasks possible. The range-of-motion in the patients’ arms increased considerably, while the time required to complete some of the Jebsen test tasks decreased. Most patients were very receptive to WREX, although a few were ambivalent

Biomechanical Optimization Of Lower Limb Orthoses Using Dynamic Surface Polyelectromyography

In the current study, preliminary testing has indicated that a suitably processed electromyography (EMG) signal is sensitive enough to display changes in muscle activity in a normal population due to changes in oithotic alignment. Anterior and posterior motion stops were used to vary alignments (range of motion) of an ankle foot orthosis with which the subjects walked. Iritegrated values of linear enveloped EMG profiles (as a measure of total muscle activity) of five gait related muscles influenced by the orthosis were statistically compared for various alignments In four of the five muscles, these profiles were found to differ in the same consistent marmer for each of the four subjects. Changes in muscle activity were justified by biomechanical changes in gait. More specifically, mechanically restricted joint motion changes demands placed on gait muscles, and may also alter their activation onset and duration As a simple example, during early stance the tibia rotates over the foot as the anide goes from ~15° plantarflexion to ~15° dorsiflexion. The soleus muscle normally checks this rotation via an eccentric contraction, so a brace which restricts dorsiflexion would reduce this soleus activity Pr eliminary results support prior clinical observations that surface EMG is sensitive enough to discriminate between relatively minor changes in muscle activity due to different orthotic alignments. Based on this conclusion, it is believed that EMG may be used to fine tune or optimize orthotic alignment. Further work relating muscle activity changes and overall energy expenditure to minor variations in or thotic alignment is currently underway

Development of a Force-Driven Distractor for Distraction Osteogenesis

Distraction osteogenesis is a routine surgical procedure to lengthen a long bone. A fixed lengthening rate is typically used. We investigate measuring forces continuously and producing a variable distraction rate. A motorized distractor was instrumented with a load cell to measure the forces developed in a limb during distraction osteogenesis. The motor moves 2.6 lm at each step, with a variable frequency depending on the distraction rate. The forces were measured every 15 s and used to change the rate on the autodistractor. The autodistractor, load cell, data logger, controller, and battery pack were all mounted on a monolateral rail fixator, which was tested on a sheep that underwent tibial lengthening. Results show the feasibility of continually recording forces in vivo. The lengthening rate changed automatically, based around a threshold force of 300 N. Findings indicate that force readings are feasible and practical with a simple device. Force determination may provide an additional means to evaluate tissue integrity in real-time and away from the clinic. An automatic variable rate device could improve limb lengthening