Master device for teleoperated needle insertion-type interventional robotic system.

This paper proposes a new master device for teleoperated needle insertion-type interventional robotic system. The 5-DOF master device is optimally designed based on the newly defined interventional procedures and the physicians' requirements. It comprises a 2-DOF rotational mechanism for adjustment of needle orientation, a 2-DOF translational mechanism for fine-tuning of needle entry point, and a handle assembly. The handle assembly includes a 1-DOF translational mechanism for needle insertion and buttons for operation mode selection. The passive actuation modules of the rotational mechanism and the active actuation modules of the translational mechanism are controlled appropriately for the selected mode according to the procedure phase. The needle insertion mechanism also warns the user by vibrating the shaft when the needle reaches the dangerous region.

Bone formation on biomimetic calcium phosphate-coated and zoledronate-immobilized titanium implants in osteoporotic rat tibiae.

PURPOSE: Coating prostheses with calcium phosphate (CaP) can boost ossification and provide an appropriate vehicle for drug delivery. In this study, CaP coating was performed using a biomimetic method, and zoledronate (ZOL) was incorporated to promote peri-implant bone formation in an osteoporotic environment. MATERIALS AND METHODS: Twenty female 8-week-old rats were ovariectomized to induce osteoporosis. Twelve weeks later, the animals were randomly separated into four groups representing different ZOL concentrations in the immersion solution: 0 (control), 8, 80, and 800 µg/mL. Surface-treated implants were inserted in both tibiae, and the rats were sacrificed 8 weeks after implantation. Specimens were retrieved for histomorphometric and microcomputed tomographic analyses. RESULTS: A thin CaP coating was formed on the surface of the titanium implants, and ZOL was successfully incorporated into the structure of the biomimetic CaP coating. There were significant differences between the groups with regard to bone volume, whereas bone-implant contact comparisons did not yield any significant differences. The microstructural results clearly illustrated the positive effect of ZOL loading on the implants, as compared to the controls. CONCLUSIONS: The data suggest that biomimetic CaP coating followed by bisphosphonate immobilization is effective in improving bone quality and preserving bone volume around dental implants; therefore, this technique may be beneficial for osteoporosis patients.

Age-gender differences in the reaction times of ankle muscles.

AIM: Reaction times of the hip abductor were reported to be longer in elderly women than in elderly men, and this was suggested to be related to mediolateral balance performance. The aim of the present study was to investigate the effects of age and gender on the reaction performance of ankle muscles, which have predominant roles in anterioposterior balance control. METHODS: A total of 40 elderly subjects and 40 young subjects (even number of men and women) carried out a series of isometric plantarflexions and dorsiflexions, as forcefully and quickly as possible, in response to auditory stimulus. Surface electromyogram at the dorsiflexor and plantarflexor were recorded, together with foot plantar force. Premotor time, motor time and total reaction time derived from the experimental data were compared between age groups and genders by two-way anova. RESULTS: Both dorsiflexor and plantarflexor showed similar reaction performance. Premotor time increased with age with no gender difference. Motor time increased with age in women and not in men, resulting in longer motor time in elderly women than in elderly men. Total reaction time was dominated by premotor time, so that it was longer in the elderly with no gender difference. CONCLUSION: Although age-related elongation of motor time was greater in women, total reaction time was not different between the genders. This may be related to no gender difference in anterioposterior balance performance.

Quantification of bradykinesia during clinical finger taps using a gyrosensor in patients with Parkinson's disease.

This study aims to develop a quantitative measure of bradykinesia which can be conveniently used during clinical finger taps test in patients with Parkinson's disease. A miniature, light-weight gyrosensor free from gravitational artifact was used for measurement of finger taps in order to impose minimal constraint on patients. Forty Parkinson's disease patients and 14 age-matched control subjects participated in the experiments. Subjects' finger taps in both right and left hands were scored by two independent neurologists according to the unified Parkinson's disease rating scale and were also measured by a gyrosensor. Four performance indices were derived from the gyrosensor signal of the index finger. All indices showed significant differences between control and patients (P < 0.001) and also significant correlations with the clinical finger taps score (r = -0.73 to -0.80, P < 0.001). ANOVA showed significant differences in all indices among different finger taps scores (P < 0.001), and post hoc tests showed significant differences in indices between most pairs of non-neighboring and part of neighboring pairs of finger taps scores (P < 0.01). The results suggest that indices from a gyrosensor can be used as quantitative measures of bradykinesia during the finger taps test.

Sex differences in the postural sway characteristics of young and elderly subjects during quiet natural standing.

AIM: It has been reported that the fall incidence in women is much higher than men and that fallers have worse postural balance performance than non-fallers. However, it is controversial whether any sex difference in postural balance performance exists. The purpose of this study was to investigate the effects of sex and age and their interactions in balance performance during quiet standing with natural stance width. METHODS: Sixty-three elderly subjects (aged 65-86 years) and 66 young subjects (aged 18-26 years) performed quiet standing with self-selected natural feet distance on a force plate. Four analysis variables - mean distance, mean velocity, 95% power frequency and total power - were derived from the center of pressure (COP) and they were evaluated both in anteroposterior and mediolateral directions. RESULTS: In anteroposterior direction, no sex effect and interaction existed, however, all variables except mean distance showed significant age effects (P < 0.01). In contrast, mediolateral direction variables showed significant sex effect where women had greater but less frequent COP movement than men (P < 0.01). Interactions of age and sex were also significant in mediolateral direction, where age-related changes were significant only in women so that sex differences (faster COP movement with more total power in women than men) existed only in the elderly (P < 0.01) but not in the young. CONCLUSION: The sex difference in balance performance (some of which are significant only in the elderly) and the sex difference in age-related change of balance performance were demonstrated in mediolateral direction. These sex differences may contribute to the sex difference in balance-related problems, such as falls.