A VISUAL FEEDBACK TRAINING SYSTEM FOR A BELOW ELBOW MYOELECTRIC PROSTHESIS
Rod Cooper
Supervisors: T. M. Bach, PhD1 and B. Contoyannis2
1 La Trobe University, Melbourne, Australia
2 Rehabilitation Technology Research Unit, Monash University, Melbourne
One of the major disadvantages of myoelectric prostheses is that the user is deprived of the sensory feedack provided by the harness of a body powered design. The amputee using a myoelectric prosthesis relies heavily upon visual feedback to perform th e task. In order to enance the information available to the amputee, a visual feedback system was designed at Monash Rehabilitation Technology Research Unit. The feedback mechanism uses L.E.D.s which display information regarding electrode activation, gri p and the level of battery power. The purpose of this study was to determine the effects of the enhanced visual feedback provided by this device on learning in novice myoelectric users.
Fourteen able-bodied subjects were fitted with an adjustable myoelectric training arm. Subjects were randomly assigned to two groups: an experimental group which received training with feedback and a control group which trained with the feedback unit t urned off. Subjects received five one-hour training sessions and were evaluated on a form board test at the end of each session.
A two-way ANOVA for repeated measures indicated that the effect of training was significant in that both groups improved across training sessions (F=8.38, df=48,4, p<0.001). However, enhanced feedback did not significantly affect learning (F=0.71, df=4 ,4, p=0.591). Subjects in the experimental group commented that the feedback was useful in the early learning stages but that they relied les and less on the feedback unit as training progressed. Based on the results and the comments of participants, desi gn modifications to the feedback unit were recommended.
THE EFFECTS OF ORTHOTICS ON EMG PATTERNS DURING WALKING IN PATIENTS WITH POST-POLIO SYNDROME
Catherine E. Evans
Supervisors: T. M. Bach1 and R. Adler2
1 La Trobe University, Melbourne
2 Bethesda Hospital, Melbourne
Late effects of polio include joint and muscle pain and decreased endurance which may indicate progressive decrease in muscle strength. Although the effects of muscle paralysis on walking patterns have been studied, the effects of muscle weakness have not. In order to provide the best possible outcomes through orthotic management in such patients, it is important to understand the compensatory motor patterns associated with muscle weakness and fatigue and the ways in which orthoses can modify and impro ve motor patterns. The purpose of this study was to examine EMG profiles in post-polio patients who exhibited instability, muscle pain or joint pain and who experienced relief through orthotic management.
Ten post-polio subjects were examined using a Motion Lab Systems MA100 EMG system. Eight lower extremity muscles (erector spinae, gluteus maximus, gluteus medius, vastus lateralis, biceps femoris, gastrocnemius, soleus, peroneus longus) were examined d uring walking with and without orthotics. Comparisons between normal and post-polio EMG patterns were made to determine compensatory patterns in post-polio patients and to determine the effects of orthotic treatment.
Comparison of individual EMG patterns in the post-polio group with normative data provided insights into the sources of muscle fatigue and pain during unaided walking and into the improvements in gait and the relief in symptoms experienced by patients using orthoses.
EFFECTS OF INERTIAL LOADING ON ENERGY EXPENDITURE AND GAIT CHARACTERISTICS IN TRANSTIBIAL AMPUTEES
Mark Anthony Jans
Supervisor: T. M. Bach, PhD
A number of investigations have demonstrated that, in transfemoral (TF) amputees, energy expenditure can be reduced and gait characteristics can be improved by addition of mass to the prosthesis. Although there have been suggestions that the same appli es in transtibial (TT) amputees, there have been no well controlled studies which have examined this issue. The purpose of this study was to examine the effects of inertial loading on TT amputee gait.
Six TT amputees were examined during treadmill walking at a comfortable velocity. Oxygen consumption was measured using a metabolic cart. Gait characteristics were determined from motion analysis data obtained using a VICON system. Each subject was exa mined during overground and treadmill walking wearing a lightweight (1.38 ± .25 kg) prosthesis. Four experimental conditions were examined: no added mass and added masses of 375, 750 and 1125 grams. Added masses were located at a position on the prosthesi s which was calculated to substantially reduce the period of oscillation of the stump-prosthesis system.
Subjective preferences were significantly higher for the 375 and 750 gram added mass conditions. All added mass conditions significantly increased walking velocity. The 750 gram added mass condition significantly improved gait symmetry. No significant differences in oxygen consumption were observed although problems with the metabolic cart resulted in loss of data for 3 subjects. The results of this study suggest that inertial characteristics of TT prostheses should be considered as an important aspect of the overall prescription.
IMPACT CHARACTERISTICS OF AUSTRALIAN RULES FOOTBALL HELMETS
Patrick Kenny
Supervisors: T. M. Bach, PhD1 , and W. E. Morrison, PhD2
1 La Trobe University
2 Victoria University of Technology, Melbourne
The impact attenuating capabilities of four commercially available brands of Australian Rules Football helmets were determined using the National Operating Committee on Standards for Athletic Equipment (NOCSAE) protocol and apparatus. The helmets teste d were the Albion Head-pro, Madison, OPAL Soft-top and Albion Club. Each was subjected to a drop on the anterior, lateral, posterior and crown aspects of the helmet from drop heights of 59, 79, 99 and 119 cm. Combinations of helmet, head region and drop h eight were performed in a predetermined random order. Each combination was repeated three times.
Analogue signals from the triaxial accelerometer located in the headform utilized by the NOCSAE apparatus were processed to compute a resultant acceleration-time curve from which peak accelerations were determined. The peak accelerations were used to c ompare the four helmets using a repeated measures ANOVA. Statistically significant differences were observed between helmets and head regions
Results suggested that the OPAL Soft-top would provide the best overall impact protection. In order of performance, the remaining helmets were the Albion Head-pro, the Albion Club and the Madison. In terms of the NOCSAE standard that helmets should tra nsmit a maximum of 225 G from a height of 122 cm, all helmets failed. The Albion Head-pro and the OPAL Soft-top exceeded the 225 G limit at the 99 cm drop height; the Madison and Albion Club failed at the 79 cm drop height.
THE EFFECT OF TWO DIFFERENT TRANSFEMORAL BENCH ALIGNMENT METHODS ON THE DYNAMIC ALIGNMENT OF TRANSFEMORAL PROSTHESES
Bill Marmaras
Supervisor: T. M. Bach, PhD
La Trobe University, Melbourne, Australia
Considerable attention has been given to the role of prosthetic alignment in achieving the best function and comfort for the patient. Two main alignment formats for the bench alignment of a transfemoral prostheses have been documented: the American or TKA format and the German alignment format. This study examined the effects of the two bench alignment formats on the final dynamic alignment of the trnasfemoral prosthesis.
Two identical prostheses were fabricated for each of four transfemoral amputees. One was set up according to TKA bench alignment, the other according to the German alignment. A VICON motion analysis system and a force platfrom were used to gather stati c posture data for both of the alignment formats before and after dynamic alignment. An Oxylog was used to measure metabolic energy expenditure during comfortable velocity walking. Walking velocity was also measured. The dynamic alignment of each prosthes is was measured upon completion of all other testing.
The results showed that similar dynamic alignments are achieved despite substantial differences in the bench alignment. Changes during dynamic alignment form the starting bench alignment were towards a common final alignment.