Scaphotrapeziotrapezoid joint loading during key pinch grip before and after trapeziometacarpal arthroplasty: a cadaver study.

In a previous cadaver study, we directly measured the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces. We noted that the joint load ranges from 2 kg to 4 kg during progressively greater key pinch from 0.5 kg to 1.5 kg. Using the same experimental approach, the aim of the current study was to measure and compare the load acting on the scaphotrapeziotrapezoid joint for the same levels of isometric key pinch force, and how it changes after trapeziometacarpal arthroplasty. We performed a cadaver study using 7 fresh-frozen, unembalmed adult forearms and hands (2 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). Before the trapeziometacarpal joint surgery, median load values recorded in the scaphotrapeziotrapezoid joint were 1.2 kg (IQR, 1.0-1.4), 1.6 kg (IQR, 1.6-2.5) and 2.4 kg (IQR, 2.3-3.4) during 0.5 kg, 1 kg and 1.5 kg key pinch, respectively. After the trapeziometacarpal arthroplasty, median joint contact forces did not change significantly relative to the original configuration. Our findings indicate that the loads measured in the scaphotrapeziotrapezoid joint during a simple key pinch are in fact lower than those measured inside the trapeziometacarpal joint. After trapeziometacarpal arthroplasty, the values are similar with no increase in load, suggesting that clinically asymptomatic scaphotrapeziotrapezoid radiographic involvement may not be a contraindication to arthroplasty.

Trapeziometacarpal joint loading during key pinch grip: A cadaver study.

To our knowledge, no study has directly measured the loads in the trapeziometacarpal joint during an isometric key pinch. The aim of this study was to measure the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces (0.5 kg-1.5 kg). We performed a cadaver study using 10 fresh-frozen, unembalmed adult forearms and hands (5 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). All specimens were tested twice in a row in the same condition. The median load values recorded in the trapeziometacarpal joint were 1.9 kg (IQR 2.2-1.5), 3 kg (IQR 3.4-2.7) and 4.1 kg (IQR 4.4-3.9) during 0.5 kg, 1 kg, and 1.5 kg key pinch, respectively. For each specimen, similar load values were observed during both loading trials. Our findings indicate that the loads measured directly in the trapeziometacarpal joint during a simple key pinch are materially lower than those estimated in biomechanical models of the thumb (generally greater than 10 kg for 1 kg of applied force) probably due to intersubject variability. This pilot study will serve as a basis for further studies, for example, comparing biomechanical thumb models and experimental measurements under the same set-up conditions.

Assessment of trapezial prosthetic cup migration: A biomechanical study.

We performed a biomechanical study using 60 Sawbones® rigid foam blocks of two simulated densities (osteoporotic, n = 30 and non-osteoporotic, n = 30) and 10 cadaveric trapezium bones from fresh-frozen, unembalmed adult cadaver hands to assess the trapezial prosthetic cup migration with progressively greater compression loads (10-40 kg). Two cups from the Touch® prosthesis were compared: 9-mm conical cup and 9-mm spherical cup. Uniaxial compression tests were carried out using an MTS Criterion® Series 40 Electromechanical Testing System. Cup migration was measured in millimeters (mm) at 10, 20, and 40 kg of compression load. Median cup migration values were similar in the cadaveric trapezium bones and Sawbones® non-osteoporotic blocks, and higher in the Sawbones® osteoporotic blocks. In the cadaveric trapezium bones and the Sawbones® non-osteoporotic blocks, migration values were less than or equal to 0.1 mm for 10 and 20 kg loads; it was 0.2 mm for 40 kg load. In the Sawbones® osteoporotic blocks, migration values were less than or equal to 0.3 mm for 10 and 20 kg loads; it was 0.4-0.5 mm for 40 kg load. There was no significant difference between the two cup shapes in both cadaveric trapezium bones and Sawbones® non-osteoporotic blocks. In Sawbones® osteoporotic blocks, the largest difference between the two cup shapes was 0.1 mm for loads up to 40 kg, which corresponded to our measurement accuracy. Our findings indicate that the trapezial component of total trapeziometacarpal joint arthroplasty undergoes very weak migration for axial compression loads up to 40 kg, presumably below the threshold of clinical relevance. The cup shape did not have an obvious influence; however, low bone mineral density may result in greater cup migration.

Comparison of two radiographic landmarks for centering the trapezial component in total trapeziometacarpal arthroplasty.

We performed a retrospective review of standard anteroposterior and lateral radiographs of the thumb in 80 patients, to compare two radiographic landmarks, in terms of mediolateral bone support, for centering the trapezial component in total joint arthroplasty. On anteroposterior view, we identified the distal articular surface of the trapezium and trapezium width, and defined the two midpoints as radiographic landmarks for positioning a 9-mm trapezial cup. Mean trapezium width was significantly greater than the distal articular surface of the trapezium, and the midpoints did not match. Thus, after positioning simulated 9-mm prosthetic cups centered on each landmark, the residual radial bone distance was significantly greater using the landmark based on trapezium width. The mean value was 33% greater with this landmark, and the minimum value was 2.1 mm, compared to 0.2 mm using the landmark based on the distal articular surface. Our study thus suggested that the midpoint of the trapezium width is the more relevant radiographic landmark for centering the trapezial prosthetic cup in total joint arthroplasty, by preserving better bone stock on the radial side without depleting the ulnar side. On an intraoperative anteroposterior fluoroscopic view, this landmark could be used to check cup positioning.

Experimental system design for the integration of trapped-ion and superconducting qubit systems.

We present a design for the experimental integration of ion trapping and superconducting qubit systems as a step towards the realization of a quantum hybrid system. The scheme addresses two key difficulties in realizing such a system: a combined microfabricated ion trap and superconducting qubit architecture, and the experimental infrastructure to facilitate both technologies. Developing upon work by Kielpinski et al. (Phys Rev Lett 108(13):130504, 2012. doi:10.1103/PhysRevLett.108.130504), we describe the design, simulation and fabrication process for a microfabricated ion trap capable of coupling an ion to a superconducting microwave LC circuit with a coupling strength in the tens of kHz. We also describe existing difficulties in combining the experimental infrastructure of an ion trapping set-up into a dilution refrigerator with superconducting qubits and present solutions that can be immediately implemented using current technology.

Educational intervention in farmers with occupational asthma: long-term effect on exhaled nitric oxide.

BACKGROUND: The fraction of exhaled nitric oxide (FE(NO)) has been found reduced 4 to 6 weeks after an educational intervention in farmers with occupational asthma. OBJECTIVE: To reveal whether long-term changes in FE(NO) would still be detectable a year after the intervention. METHODS: We evaluated airway inflammation and obstruction at baseline and after 1 year in animal farmers with occupational asthma (n = 43, 16 women, mean [SD] age, 46.5 [8.9] years) who participated in a 1-day educational program, and in a control group of farmers without intervention (n = 15, 3 women, mean age, 44.1 [10.7] years). FE(NO), spirometry results, and questionnaire data were compared between measurements and between the intervention and control group. RESULTS: In the intervention group, geometric mean (SEM) FE(NO) decreased from 31.5 (1.1) to 25.0 (1.1) parts per billion (ppb) (P = .001), whereas in the control group there was a slight but not statistically significant increase from 27.2 (1.2) to 30.7 (1.2) ppb. Spirometric values remained unchanged in both groups. CONCLUSIONS: We found that FE(NO) was still decreased 1 year after an educational intervention in farmers with occupational asthma. It would thus seem that FE(NO), a noninvasive marker of airway inflammation that can be easily assessed in occupational field work, may be suitable for the evaluation of both short-term and long-term effects of preventive measures in occupational asthma.

Educational intervention decreases exhaled nitric oxide in farmers with occupational asthma.

Allergic occupational asthma is frequent in farming populations. As educational interventions can improve disease management, the short-term effect of an educational intervention in asthmatic farmers was evaluated on the basis of spirometric indices and exhaled nitric oxide fraction (F(eNO)). Farmers with occupational asthma (n = 81), mostly sensitised against cow dander and storage mites, participated in a 1-day educational programme. Outcome measures were assessed at baseline and after 4-6 weeks, using F(eNO), lung function and a questionnaire. Results were compared with those of a control group without intervention (n = 24). In the educational group, the proportion of subjects reporting work-related symptoms was reduced after the intervention. The F(eNO) decreased from a geometric mean of 28.2 to 25.7 ppb, and, in subjects with an elevated (>35 ppb) baseline F(eNO) (n = 32), from 59.7 to 49.2 ppb. The corresponding changes in the control group were 25.6 versus 27.7 ppb and 49.5 versus 48.1 ppb. Spirometric results were unaltered in the two groups. Thus exhaled nitric oxide fraction, a marker of allergic airway inflammation, indicated a beneficial effect of a short-term educational intervention in farmers with occupational asthma. This suggests a potential for exhaled nitric oxide fraction in assessing the efficacy of preventive measures within a short time with higher sensitivity than spirometry.

The regulation of release parameters in underarm precision throwing.

The aim of this study was to determine if adults spontaneously exploit the laws of physics to achieve better accuracy when throwing at various distances. Eight adults performed 25 underarm throws at five horizontal circular targets located 4, 5, 6, 7 and 8 m away with a constant 5% relative accuracy requirement. Angle and speed of the ball at release were found to increase with throwing distance, while the coordinates of the release point did not change significantly. These results support the idea that people minimize the variability in impact distance by adapting both the angle and the speed at ball release following a mechanical optimum predicted by the laws of physics. Moreover, variability in distance was found to be less than expected because of independent variations in the angle and speed at ball release. Hence, the control of precision throwing seems to imply compensatory variability, as frequently reported in the control of skilled actions.

Crush injury to peripheral nerve. An electron microscope study employing horseradish peroxidase.

Electron microscope observations were made of rat peroneal nerve after crushing using intravenously injected horseradish peroxidase (HRP) as a tracer protein to indicate changes in vascular permeability. At 1/2 h and 2 d after the crush there was gross leakage of HRP from damaged capillaries at the site of injury but none from vessels above or below this. Ultrastructurally vessels at the site of crush showed broken and separated endothelial cells. Proximally and distally there was little abnormal in the vessel walls; vesicles containing HRP were absent and tight-junctions between cells remained intact. Twenty-one days after the crush, leakage of HRP was found both at the site of crush and along the distal segment. The only change in vessel walls was an obvious increase in vesicles filled with HRP. Tracer was also found both in perivascular locations and throughout the endoneurial space.

A study of the perineurium in peripheral nerve pathology.

The response of the perineurium to the following experimental systems was investigated by light and electron microscopy: nerve crush, cold lesion and microinjection of (a) histamine liberator, (b) potassium cyanide, (c) lysophosphatidyl choline (LPC). Where myelin breakdown occurred, lipid globules were seen within Schwann cells, macrophages and also perineurial cells. Where increased vascular permeability occurred, proteinaceous material leaked from endoneurial vessels into the endoneurial space and later appeared between perineurial laminae. It is suggested that the normal homeostatic function of the perineurium is extended in pathology to the removal of protein and lipid debris. In this way the perineurium contributes to the restoration of the normal microenvironment of peripheral nerve fibres.