IMAGE-BASED MEASUREMENT AND BIOMECHANICAL ANALYSIS OF THE KNEE JOINT DURING FUNCTIONAL ACTIVITIES

A new approach based on the integration of medical image-based measurement techniques, infrared stereophotogrammetry and finite element modelling (FEM) was developed for comprehensive subject-specific biomechanical analyses of the knee joint during weight-bearing functional activities including cycling. The medical image-based methods include digitally reconstructed radiograph (DRR) based 3D fluoroscopy methods, and a new slice-to-volume registration method using FLASH MRI for the real-time measurement of the 3D kinematics of the knee in vivo. With the new approach, the soft tissue artefacts associated with skin marker-based stereophotogrammetry and their effects on the calculated biomechanical variables were also investigated

EFFECTS OF SEAT POSITION ON JOINT LOADS OF THE UPPER EXTREMITIES DURING HANDCYCLING IN WHEELCHAIR-DEPENDENT INDIVIDUALS

The current study aimed to quantify the joint moments of the upper extremities with different seat positions during handcycling in wheelchair-dependent individuals. Sixteen subjects performed handcycling while the handgrip reaction forces were measured by a handgrip instrumented with a six-component load cell and body segment kinematic data by a motion capture system. Both data sets were used to calculate joint moments of the upper limbs during a crank cycle. The loads at the shoulder were affected mostly by the vertical seat positions. The higher the seat, the greater loads transmitted by the muscles with relatively greater strength. The current data will be helpful for future handcycle design and fitting for wheelchair-dependent individuals

EFFECTS OF SEAT POSITION ON THE JOINT MOMENTS OF THE LOWER EXTREMITIES DURING CYCLING IN THE ELDERLY

The purpose of this study was to quantify the joint moments of the lower extremities with different seat positions during cycling in elderly. Fifteen older adults performed cycling on a self-developed bicycle ergometer at three horizontal and three vertical seat positions. The pedals were instrumented with six-component load cells to measure pedal reaction forces; and a motion capture system was used to measure body segment kinematic data. Both data sets were used to calculate joint moments during a crank cycle. The results showed that seat positions affected joint moments significantly, especially the horizontal positions. A more posterior seat position led to a more balanced loading at the hip and knee, with less peak muscle loadings. The results will be helpful for cycle design and fitting for the elderly

Biomechanical Strategies for Obstacle Crossing in Patients with Anterior Cruciate Ligament Deficiency

The current study aimed to investigate the biomechanical control strategies in patients with anterior cruciate ligament deficiency (ACLD) when crossing obstacles of different heights. Eighteen patients with unilateral ACLD and sixteen age-matched healthy controls were recruited. They crossed obstacles of heights of 10%, 20% and 30% of their leg lengths at a self-selected pace while the kinematic and kinetic data were measured and analyzed using inverse dynamics analysis. Patients with ACLD were found to avoid using the quadriceps on both affected and unaffected sides during stance phase. Training programs on both quadriceps are needed for more efficient rehabilitation of the patients with unilateral ACLD

Effect of Influenza Vaccination on Mortality and Risk of Hospitalization in Elderly Individuals with and without Disabilities: A Nationwide, Population-Based Cohort Study

Purpose: The effects of influenza vaccines are unclear for elderly individuals with disabilities. We use a population-based cohort study to estimate the effects of influenza vaccines in elderly individuals with and without disabilities. Methods: Data were taken from the National Health Insurance Research Database and Disabled Population Profile of Taiwan. A total of 2,741,403 adults aged 65 or older were identified and 394,490 were people with a disability. These two groups were further divided into those who had or had not received an influenza vaccine. Generalized estimating equations (GEE) were used to compare the relative risks (RRs) of death and hospitalization across the four groups. Results: 30.78% elderly individuals without a disability and 34.59% elderly individuals with a disability had vaccinated for influenza. Compared to the unvaccinated elderly without a disability, the vaccinated elderly without a disability had significantly lower risks in all-cause mortality (RR = 0.64) and hospitalization for any of the influenza-related diseases (RR = 0.91). Both the unvaccinated and vaccinated elderly with a disability had significantly higher risks in all-cause mortality (RR = 1.81 and 1.18, respectively) and hospitalization for any of the influenza-related diseases (RR = 1.73 and 1.59, respectively). Conclusions: The elderly with a disability had higher risks in mortality and hospitalization than those without a disability; however, receiving influenza vaccinations could still generate more protection to the disabled elderl

VALIDITY OF A MAKER-BASED LOCATOR FOR MEASURING IN VIVO THREEDIMENSIONAL SCAPULAR STATIC POSES USING STEREOPHOTOGRAMMETRY

The study aimed to (1) develop a marker-based scapular locator for measuring scapular poses and (2) to design an in vivo experimental procedure for this static marker-based measurement method to decrease measurement errors, and (3) to validate this scapular locator and the experimental procedure. Six young male adults were implanted into the spine of the scapula with two bone-pins that were attached with a cluster of four retroreflective markers (bone markers). The scapular poses were measured simultaneously using the developed scapular locator and the bone markers. The results showed that very high validity for scapular rotations and for the acromial angle (AA), the root of spine (RS) and the inferior angle (IA) of the scapular translation were achieved. Two main reasons contributed to the results: (1) the adjustable scapular locator and (2) careful palpation of the bony landmarks over the scapula

Influence of Step Length and Cadence on the Sharing of the Total Support Moments Between the Lower Limbs During Level Walking

The current study aimed to investigate the effects of walking speed on the inter-limb sharing of whole body support in terms of total support moments (Ms) during walking. A multiple linear regression model was conducted to explore the relationship between gait speed in terms of step length and cadence, and the difference of the first and second peaks of the Ms (DMs) during walking. The DMs were found to increase with either increased step length or cadence. Walking with greater speed relied more on the leading limb to provide support for the forward progression of the body. In addition, variations of gait speed parameters affected the load-sharing pattern between the lower limbs during weight transfer of walking. Gait speed parameters have to be taken as covariates when analysing the coordination of the kinetics between lower limbs

MUSCLE RECRUITMENT SEQUENCE AND TOTAL REACTION TIME DURING A KARATE ROUNDHOUSE KICK

The purpose of the current study is to quantify the muscle recruitment sequence and total reaction time of fourteen national karate athletes and fourteen college karate athletes while performing upper level roundhouse kick. A 16-channel electromyography was used to measured the muscle activities and an instrumented target was for the evaluation of the response time. The experimental results show that both groups recruited the biceps femoris on the kicking (right) side, followed by the right gastrocnemius, but the subsequent muscle firing sequence was slightly different. This resulted in smaller total reaction time of the national group (736.32 ms) than the time of the control group (770.28 ms) because of different across skill level

EFFECTS OF FUNCTIONAL KNEE BRACES ON NEUROMUSCULAR ADAPTATION IN ANTERIOR CRUCIATE LIGAMENT INJURED PATIENTS

INTRODUCTION: Neuromuscular adaptation in the lower extremity has been found in anterior cruciate ligament (ACL) injured patients, with mechanical and electromyographic alterations such as reduced knee extensor moment and power, increased hamsrings muscle activity, and decreased muscle strength (Berchuck, Andriacchi, Bach, & Reider, 1990; DeVita, Lassiter, Hortobagyi, & Torry, 1998). Functional knee bracing has been a common method to enhance functional knee stability in these patients for the past three decades. However, the long-term effects of knee bracing on ACL-reconstructed (ACL-R) patients have not been reported in the literature. There is thus an urgent need to identify the effects of bracing on the gait displayed by these patients

Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone

<p>Abstract</p> <p>Background</p> <p>This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws).</p> <p>Methods</p> <p>This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct.</p> <p>Results</p> <p>The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and <it>R</it>²= 0.93. On the other hand, the average error and <it>R</it>²value of the literature formula were as high as -32.3% and -0.26, respectively.</p> <p>Conclusion</p> <p>The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests.</p