Biomedical Engineering: Applications, Basis and Communications

Accurate measurement of the three-dimensional scapular kinematics is essential for a better understanding of the mechanical interactions between the scapula and the other segments of the shoulder complex. The purposes of the study were: (i) to development a marker-based scapular locator for measuring scapular poses, and (ii) to determine the intra- and inter-rater reliability of the locator in terms of intra-class correlations (ICC). Twenty-two healthy volunteers without shoulder pathologies participated in the current study. Each subject was tested separately by two raters using the marker-based scapular locator while performing static shoulder flexion at 20, 40, 60, 80, 100 and 120 degrees in the scapular plane. Two reliability models, ICC${}_{(2,\mathrm{\text{k}})}$ and ICC${}_{(3,\mathrm{\text{k}})}$, were used to analyze the intra- and inter-rater reliability for scapular rotations and translations. Good to excellent intra-user reliability for both examiners was found for the scapular rotations (range: 0.82–0.99) and displacements (range: 0.72–0.99) for different shoulder flexion conditions. Good to excellent inter-rater reliability was found for scapular rotations (range: 0.63–0.95) and translations (range: 0.70–0.95) for all conditions. The results showed that high intra- and inter-examiner reliability could be achieved for scapular rotations and translation using the marker-based scapular locator. The proposed new scapular locator with an optical tracking system will be helpful for future applications in basic and clinical studies of the shoulder complex during arm movements.

Polymethylmethacrylate (PMMA) bone cement has been widely used in vertebroplasty to treat osteoporotic vertebral compression fracture. However, the high compression stiffness of PMMA is suspected to induce adjacent vertebral fracture following vertebroplasty. In the current study, modified low-modulus cement was prepared by combining PMMA with castor oil to solve this problem. The percentage of height recovery and compression stiffness of vertebral bodies was compared after injection of standard PMMA or low-modulus cement. This study aims to investigate whether low-modulus cement is as effective as standard PMMA for storing the initial vertebral height; while lowering the compression stiffness in treatment of osteoporotic vertebral compression fractures. A total of 20 fresh porcine lumbar vertebrae were assigned into two groups (10 per group): standard and low-modulus. All specimens received a four-week decalcification to mimic human osteoporotic vertebrae. The standard and low-modulus groups received a simulated compression fracture followed by treatment of standard and low-modulus cement augmentation, respectively. The low-modulus cement was prepared by combining standard PMMA with 15% weight fractions of castor oil. For all the 20 specimens, vertebral compression fracture was created by reducing the vertebral height of 25% using a material testing machine. The compression stiffness determined from the creation of compression fracture was defined as the intact group (20 specimens). The fractured vertebrae were then treated with standard and low-modulus cement augmentation. The vertebral height was measured pre- and post-treatment, and the percentage of vertebral height recovery was compared between two cementing groups. Following cement augmentation, axial compression test was conducted to compare compression stiffness among three groups. The results indicated that there is no significant difference in percentage of vertebral height between standard (83.42$\pm$11.60%) and low-modulus (88.50$\pm$6.15%) groups ($p>0.05$). Moreover, the compression stiffnesses were 1166.49$\pm$392.91 N/mm, 1795.85$\pm$247.45N/mm and 1362.57$\pm$236.92N/mm for intact, standard and low-modulus groups, respectively. There is significant difference among three groups ($p<0.05$). We concluded that the modified low-modulus cement is as effective as standard PMMA for storing the initial vertebral height while lowering the compression stiffness in treatment of osteoporotic vertebral compression fractures. These reduce the risks of adjacent vertebral body fracture following vertebroplasty.

A spinal fusion surgery has been the gold standard treatment for treating lumbar degenerative disc disease. Many clinical studies have demonstrated that adjacent segment degeneration was observed in patients over time. Different types of stabilization systems have been investigated using numerical approaches. However, numerical models developed in the past were simplified to reduce computational time. Additionally, it is quite difficult to compare different stabilization systems in clinical application due to variation in bone anatomy and density. The aim of this study is to evaluate and compare the biomechanical performances of different stabilization systems using a more realistic spine model. In this study, three-dimensional finite element models of the intact, injured and treated T10–S1 multilevel spines are developed. The intersegmental rotation, the maximum disc stress and the maximum implant stress are calculated. The results showed that the pedicle screw–rod system can provide better fixation stability and lower implant stress. The Coflex system (CFS) has an advantage on reducing the risk of adjacent segment degeneration. This study could provide useful information to surgeons understanding the effects of different stabilization systems on the biomechanical performances for the posterior lumbar interbody fusion surgery.

Digital periapical radiography is widely used in clinical dentistry because the technique is relatively simple and inexpensive. However, the main drawback of periapical radiography is that it represents a three-dimensional object in a two-dimensional film due to its inherent projection technique. The objective of this study was to develop a prototype intraoral computed tomosynthesis system, which can provide quasi-three-dimensional (so-called 2.5D) images. We developed a prototype intraoral computed tomosynthesis machine. Regular digital periapical radiography, computed tomosynthesis scanning, and computed tomography scanning of a human central incisor were performed. Then, reconstruction images obtained using computed tomosynthesis and computed tomography approaches were quantitatively evaluated using the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). From the experimental results, compared with periapical radiographic images, reconstruction images obtained using the computed tomosynthesis approach revealed detailed microstructures in different depth sections. In addition, the SNR and CNR of reconstruction images obtained using the computed tomography approach was better than those of the images obtained using the computed tomosynthesis approach. However, the differences could not be clearly identified by the naked eye. The preliminary experimental results indicate that an intraoral computed tomosynthesis system may be useful for clinical dental diagnosis.

Developmental coordination disorder (DCD) refers to the motor skill difficulty without any explainable medical conditions. The prevalence rate of DCD is estimated to be 5–12% in Taiwan. Balance deficit is one of the main characteristics of children with DCD. The aim of this study was to examine the effect of a self-developed balance training program on the balance performance in children with DCD. Twenty four children aged 5–10 years old with DCD and 12 age-matched typically developing (TD) children participated in the study. Children with DCD were randomly divided between an experimental group (DCD-exp) who received treatment with the iBalance training program and the control group (DCD-con) who did not received treatment. TD children also did not receive treatment as a comparison group. All the children were tested with the movement assessment battery for children-2nd edition (MABC-2) and iBalance assessment system before and after the intervention period. A significant improvement of the MABC-2 balance component score, time duration of one-leg standing and the number of success trials with dynamic balance tasks were noted in the children of DCD-exp but not in the children of DCD-con and TD. The results suggest that the iBalance training program is effective for a short time treatment effect for children with DCD. The long term effect and transfer effect need to be examined.

Falls are a major health concern leading cause of fatal and non-fatal injuries for neurological disorders. Balance dysfunction is one of the common factors to determine fall risk in neurological patients. Preventative measures may help to reduce the incidence and severity of falls for detecting balance function and fall risk factors. However, the objective measures for balance require expensive equipment with the assessment of clinical expertise. A main gap remains in the evaluation method to objectively characterize the balance functions in individuals with high risk of falling. With the development of wearable and mobile devices, recent advances in smart mobile devices may provide a potential opportunity to manage the gap in the detailed quantification of balance impairments. The purpose of this study is to identify whether the biomechanical data measured by the mobile device is reliable to characterize the posture stability in various balance test conditions. A total of 39 children with Down syndrome completed four balance-testing tasks under altered base of support and vision. Simultaneous biomechanical measurements were gathered from the iPod and force plate analysis system during functional balance testing. The force plate and mobile system provided similar patterns of stability across groups. Correlation ($r^2)$ between two systems for path length, 95% ellipse area, peak-to-peak, standard deviation and mean ranged from 0.60 to 0.99. We expect that the smart mobile device can provide reliable and accurate information to quantify the postural stability in individuals with elderly people or neurological disorders. The objectivity, portability and easy use of such mobile device make it ideal to apply in clinical environments for detecting balance functions and reducing the risk of falls in Down syndrome or other neurological patients.

Excessive foot pronation may alter the biomechanics of lower limbs during locomotion and is associated with a number of lower limb injuries. The motion control shoes have been found to be effective in reducing the foot pronation and peak pressure during running. However, differences in biomechanics exist between running and walking. The purpose of the present study is to investigate whether the force and pressure may be reduced while walking with motion control shoes. Thirty-five participants with unilateral pronated foot were recruited, and the motion control shoes with the possibility of adjusting its midsole hardness were prescribed. The participants walked with three shoes conditions: own shoes, motion control shoes with and without adjustments while the force and pressure were recorded via the in-shoe dynamic pressure measuring system. Better stability and decreased pain sensation were reported while walking with the motion control shoes compared with participants’ own shoes. Similarly, the decrease of both peak force and pressure was also observed while walking with motion control shoes. However, the adjustment of the midsole hardness did not provide additional effect in either force or peak pressure. Consistent to the previous findings in running, our findings suggest that the motion control shoes are effective in reducing force and pressure during walking. Future studies are needed to investigate the short- and long-term effect of the motion control shoes during walking.

The aim of this study was to investigate the immediate effect of wearing the functional insoles with different slopes of forefoot wedges on postural stability in young adults during quiet stance. In this study, the functional insole was composed of a forefoot wedge and a medial arch support. Twelve healthy young adults (six males and six females) participated. Each subject wore sneakers with and without functional insole and stood as still as possible on a force plate with feet together, arms by side and head facing ahead for 60s, while eyes open and eyes closed, respectively. The functional insole was applied in the random sequence of no insole, wearing insole with a medial arch and a four-degree forefoot wedge, as well as wearing insole with a medial arch and an eight-degree forefoot wedge. The sway areas as well as the maximal excursions of the center of pressure (COP) in anterior–posterior (AP) and medial–lateral (ML) directions were used to evaluate the static postural stability. During stance with feet together and eyes closed, the sway area and maximal excursion of the COP in the AP direction were significantly decreased when wearing an eight-degree forefoot wedge functional insole. Since the reduced displacements of the COP indicated better postural control, it was suggested that the functional insole with an eight-degree forefoot wedge and a medial arch support might be beneficial to improve the postural stability in patients with impaired balance control, especially for whom having high risk of forward falls.