Objective: To quantify the energy efficiency of locomotion and free-living physical activity energy expenditure of transfemoral amputees using a mechanical and microprocessor-controlled prosthetic knee.Design: Repeated-measures design to evaluate comparative functional outcomes.Setting: Exercise physiology laboratory and community free-living environment.Participants: Subjects (N=15; 12 men, 3 women; age, 42 +/- 9y; range, 26-57y) with transfemoral amputation.Intervention: Research participants were long-term users of a mechanical prosthesis (20 +/- 10y as an amputee; range, 3-36y). They were fitted with a microprocessor-controlled knee prosthesis and allowed to acclimate (mean time, 18 +/- 8wk) before being retested.Main Outcome Measures: Objective measurements of energy efficiency and total daily energy expenditure were obtained. The Prosthetic Evaluation Questionnaire was used to gather subjective feedback from the participants.Results: Subjects demonstrated significantly increased physical activity-related energy expenditure levels in the participant's free-living environment (P=.04) after wearing the microprocessor-controlled prosthetic knee joint. There was no significant difference in the energy efficiency of walking (P=.34). When using the microprocessor-controlled knee, the subjects expressed increased satisfaction in their daily lives (P=.02).Conclusions: People ambulating with a microprocessor-controlled knee significantly increased their physical activity during daily life, outside the laboratory setting, and expressed an increased quality of life.

Virtual reality (VR) can induce postural instability in standing and walking, as quantified with kinematic parameters. This study examines the effect of a VR environment on kinetic gait parameters. Ten healthy volunteers walked on an instrumented treadmill in a VR environment and a non-VR environment. In the VR environment, a corridor with colored vertical stripes comprising the walls was projected onto a concave screen placed in front of the treadmill. The speed of the moving image was perceptually equivalent to the speed of the treadmill, creating an illusion that subjects walked through the corridor. Vertical ground reaction forces were sampled. Kinetic parameters that reflect gait stability (weight acceptance peak force, weight acceptance rate, push-off peak force and push-off rate) were compared between the VR and non-VR environments. Subjects walked in the VR environment with increased magnitudes and rates of weight acceptance force and with increased rates of push-off force. Variability in weight acceptance rates and peak forces, and variability in push-off peak forces, were also increased in the VR environment. The gait deviations reflect a compensatory response to visual stimulation that occurs in the VR environment, suggesting that walking in a VR environment may induce gait instability in healthy subjects.

Objective. The objective of this study was to evaluate whether patients with rheumatoid arthritis (RA) are more likely to have subclinical hearing loss compared with persons without RA. Methods. This is a case-control cross-sectional study of 29 patients with RA with disease duration greater than 5 years. Five males and five females were recruited into each decade category (age 40-49, 50-59, and 60-69). These cases were matched in a 1:1 ratio by sex and age to 30 control subjects. A comprehensive set of audiometric and disease severity assessments were performed. Results. Seventeen (59%) of 29 patients with RA had abnormal hearing for at least one frequency (four in one ear, 13 in two ears) by audiometry as did 14 (47%) of 30 control subjects (five in one ear, nine in two ears). The percentage of patients with hearing loss (% RA vs. % control subjects) was: 45% versus 40% sensorineural, 10% versus 7% conductive, and 3% versus 0% mixed hearing loss. In RA versus control subjects, acoustic reflex threshold was abnormal in 17% versus 7%; speech reception threshold was abnormal in 10% versus 3%. Tympanometry and otoacoustic emission findings were similar in both groups. Word recognition did not differ between patients with RA and control subjects. In patients with RA/control subjects, hearing handicap, dizziness, and health assessment questionnaires were abnormal in 28%/7%, and 72%/7%, respectively. Conclusion: There was no difference found in objective audiometric measurements in patients with RA compared with non-RA control subjects. Subjectively patients with RA were more likely to perceive themselves as having hearing disturbances, which may be related to overall disease related functional impairment.

This controlled trial was designed to investigate the influence of osteoporosis-related kyphosis (O-K) on falls. Twelve community-dwelling women with O-K (Cobb angle, 50-65 degrees measured from spine radiographs) and 13 healthy women serving as controls were enrolled. Mean age of the O-K group was 76 years (+/-5.1), height 158 cm (+/-5), and weight 61 kg (+/-7.9), and mean age of the control group was 71 years (+/-4.6), height 161 cm (+/-3.8), and weight 66 kg (+/-11.7). Quantitative isometric strength data were collected. Gait was monitored during unobstructed level walking and during stepping over an obstacle of four different heights randomly assigned (2.5%, 5%, 10%, and 15% of the subject's height). Balance was objectively assessed with computerized dynamic posturography consisting of the sensory organization test. Back extensor strength, grip strength, and all lower extremity muscle groups were significantly weaker in the O-K group than the control group (P <0.05), except right ankle plantar flexors (P =0.09). There was a significant difference in the anteroposterior and mediolateral displacements and velocities. The O-K subjects had less anteroposterior displacement, greater mediolateral displacement, reduced anteroposterior velocity, and increased mediolateral velocity compared with controls for all conditions of unobstructed and obstructed level walking. Obstacle height had a significant effect on all center-of-mass variables. The O-K subjects had significantly greater balance abnormalities on computerized dynamic posturography than the control group (P =0.002). Data show that thoracic hyperkyphosis on a background of reduced muscle strength plays an important role in increasing body sway, gait unsteadiness, and risk of falls in osteoporosis.

Patients with traumatic brain injury (TBI) complain of “imbalance” or “unsteadiness” while walking, despite a normal gait on clinical examination. Thus, the purpose of this study was to determine if it was possible to quantitatively assess dynamic stability that did not have an obvious neuromuscular origin in individuals following TBI. Ten patients with documented TBI and 10 age, gender, and stature-matched healthy individuals participated in the study. All subjects were instructed to perform unobstructed level walking and to step over obstacles corresponding to 2.5%, 5%, 10%, and 15% of their height. A 13-link biomechanical model of the human body was used to compute the kinematics of the whole body center of mass (COM). Subjects with TBI walked with a significantly slower gait speed and shorter stride length than their matched controls. Furthermore, subjects with TBI displayed a significantly greater and faster medio-lateral (M-L) COM motion and maintained a significantly greater M-L separation distance between their COM and center of pressure (COP) than their matched control subjects. These measurements indicate that subjects with TBI have difficulty maintaining dynamic stability in the frontal plane and have a reduced ability to successfully arrest their sagittal momentum. These findings provide an objective measurement that reflects the complaints of instability not observable on clinical examination for individuals who have suffered a TBI. This ability to identify any functional impairment after a traumatic brain injury that may affect patient safety is critical for prevention of re-injury during the recovery period.

Inhaled tobramycin is being used increasingly in patients with cystic fibrosis and other forms of bronchiectasis for treatment of bronchial colonization with Pseudomonas aeruginosa. The goal of inhaled antibiotics is to provide maximal concentrations at the site of infection without risking systemic toxicity. We report an unusual case of reversible vestibular toxicity due to inhaled tobramycin in a patient with renal failure who was undergoing hemodialysis. Although systemic absorption after inhaled tobramycin is reportedly negligible, no recommendations have been published regarding monitoring of serum concentrations in patients receiving this form of therapy. We suggest that clinicians consider monitoring serum concentrations of tobramycin in patients at risk of renal toxicity and/or ototoxicity, such as those with predisposing renal or otologic compromise. Further studies in at-risk patients are needed to determine the optimal frequency and timing of such monitoring.

Falling to the side has been found to be an important risk factor for hip fracture (Greenspan et al., 1998). Additionally, imbalance and tripping over obstacles have been confirmed as two of the most common causes of falls in the elderly (Tinetti et al., 1989). An increased understanding of the factors influencing falls in the elderly should help reduce the risk of falls, thereby limiting the number of debilitating injuries suffered later in life.

Integration of the visual, vestibular, and proprioceptive systems contributes to the maintenance of postural stability. In recent years, postural stability has been examined in virtual reality (VR) environments in which visual and/or vestibular conflicts can be induced. Akiduki et al. (2003) report that visual-vestibular conflicts induced by VR produce increased postural sway and symptoms of motion sickness in healthy subjects. Jasko et al. (2003) report that influences on peripheral and central visual fields result in increased postural sway when proprioceptive inputs are unreliable. These studies, however, were performed while subjects were standing. It is not clear whether instability is also reflected while walking in a VR setting. Therefore, the purpose of this study was to examine gait deviations and subjective responses of dizziness associated with walking in a VR environment.

As the elderly population continues to grow, the need for indicators of dynamic instability during locomotion also increases. Such indicators may enhance early identification of at-risk individuals, thereby reducing the risk of traumatic falls. Greenspan et al. (1998) found that falls to the side are a major risk factor for hip fracture. Addit ionally, Tinetti et al. (1989) showed imbalance and tripping over obstacles to be two of the most common causes of falls in the elderly. Therefore, mediallateral (M-L) body sway during obstacle crossing may be used to distinguish individuals at risk for sideways falling from healthy individuals.

Auditory brainstem electrical responses (BSER) of right and left ears of active stutterers, recovered stutterers, and nonstutterers, both male and female adults, were obtained at click rates of 11.1 and 71.1/sec. Latency intervals of waves I, III, and V were measured. The auditory systems of subjects were stressed using a rapid rate of 71.1 clicks/sec. The latency of wave V was used as the measure of the stress condition.