Biomedical subjects

Michael Orendurff

Publications and source records attributed to Michael Orendurff.

3 recordsLinked to original sources

PubMed2006

Does having a computerized prosthetic knee influence cognitive performance during amputee walking?

OBJECTIVE: To compare objective cognitive performance and perception of cognitive burden during walking tasks using 2 different prosthetic knees: a computerized hydraulic knee (Otto Bock C-leg) and a noncomputerized hydraulic knee (Ossur Mauch SNS). DESIGN: Two-group crossover trial, with participants randomly assigned to order of prosthesis. Participants completed assessments under 2 conditions, a self-selected speed walk and a controlled speed walk, on 2 separate occasions (precrossover, postcrossover). SETTING: Veterans Health Administration hospital. PARTICIPANTS: Eight transfemoral amputees. INTERVENTION: Computerized versus noncomputerized prosthetic knee. MAIN OUTCOME MEASURES: Objective cognitive performance measures included verbal fluency (Controlled Oral Word Association Test, Category Test), attention and working memory (serial subtraction), and walking speed during cognitive tasks. Measures of perceived cognitive burden included subjective attentional requirements of walking and cognitive tasks and subjective general cognitive burden of prosthesis. RESULTS: There were no significant differences in objective cognitive performance on any task between prostheses, nor did walking speed vary by prosthesis during the free-speed walk. Participants reported that walking required less attention while wearing the C-leg and that the C-leg was less of a cognitive burden than the noncomputerized prosthesis. CONCLUSIONS: In nondemanding walking conditions with experienced amputees, participants reported that the more costly C-leg required less cognitive attention than the noncomputerized knee. However, this subjective experience did not translate to improved performance on neuropsychologic screening instruments or on walking speed. Noncomputerized prostheses may be adequate for a majority of amputees, and further research is needed to identify particular groups of amputees (ie, new amputees, amputees with complex physical or cognitive demands) who may benefit from computerized prostheses.

Adult↗

PubMed2004

The efficacy of two methods of ankle immobilization in reducing gastrocnemius, soleus, and peroneal muscle activity during stance phase of gait.

BACKGROUND: Immobilization to limit muscle activity is a common therapeutic and posttreatment event. There are potential time and resource savings if a prefabricated boot can replace a custom applied cast. The purpose of this study was to determine if muscle activity reduction is similar using a fiberglass cast versus a prefabricated (Aircast FoamWalker) boot. METHODS: Surface EMG data were recorded from the gastrocnemius, soleus, and peroneals of 12 normal adults while walking barefoot, in a fiberglass cast with a cast shoe (cast), and while wearing an Aircast FoamWalker (boot). Subjects walked at their self-selected speed for 10 trials in each condition, and the order of barefoot, cast, and boot was randomly assigned. The data were rectified, integrated across stance phase and normalized to a percent of each subject's barefoot mean integrated EMG (iEMG) value. For each muscle, a linear mixed-effects statistical model (subject by trial by condition) was utilized to determine if iEMG activity levels were reduced by immobilization compared to barefoot walking. RESULTS: Activity for all muscles was significantly lower in the boot compared with barefoot (p <.05). The cast iEMG levels were significantly different from barefoot for the soleus and peroneals (p <.05). Gastrocnemius activity was significantly decreased in the boot when compared with the cast (p <.0001). The greater reduction in iEMG levels for the boot indicates that it is superior to a fiberglass cast in reducing gastrocnemius muscle activity during the stance phase of gait. CONCLUSIONS: The data show that a prefabricated boot is as effective as a custom applied cast in reducing soleus and peroneal muscle iEMG during stance phase. The boot was more effective in reducing gastrocnemius activity when compared to the cast. CLINICAL RELEVANCE: This study suggests that a prefabricated boot may be used in place of a custom cast when the goal of treatment is to limit muscle activity of the leg.

Adult↗

PubMed2004

The effect of walking speed on peak plantar pressure.

BACKGROUND: Plantar pressure measurements often are used as a tool to evaluate pathologic gait. Previous studies, often done at self-selected walking speeds, have used peak plantar pressure to try to predict ulcer formation, compare surgical outcomes, and evaluate orthotic device efficacy. However, the relationship between walking speed and plantar pressures at specific plantar regions has not been clearly defined. METHODS: Twenty normal subjects walked on a treadmill at six speeds (0.75 to 2.00 m/s). In-shoe peak plantar pressure was measured at five plantar regions and compared across the range of speeds. RESULTS: Walking speed affected peak plantar pressure differently at the five examined plantar regions. The hallux and heel regions had the highest pressures, which increased linearly with faster speeds. The central and medial forefoot pressures initially increased but plateaued at the faster speeds, while the lateral forefoot had the lowest overall peak pressures, which decreased at the faster walking speeds. Therefore, significant quadratic effects were found at the forefoot. Best-fit regression equations defined distinct pressure-speed relationships at each plantar region (p < 0.0001). CONCLUSION: The effect of walking speed on peak plantar pressure varied with plantar region. To achieve more robust peak plantar pressure measurements, walking speed should be controlled. Determining the normal plantar function across a range of speeds can aid in the development of shoes and foot orthoses. The pressure-speed relationships presented in this study can be used as a comparative tool for evaluating the efficacy of clinical interventions for pressure reduction, especially when walking speed changes may confound the outcomes.

Adult↗