Radiographic measurement of the distal tibiofibular syndesmosis has limited use.

Radiographs of 20 plastinated human cadaveric lower legs were obtained in 12 positions of rotation to determine the optimal parameter for reliable assessment of syndesmotic and ankle integrity, and to assess the effect of positioning of the ankle on this parameter. Three observers measured eight parameters twice after four repetitions of ankle positioning. Intraclass correlation coefficients and reproducibility were assessed. Some tibiofibular overlap was present in all radiographs in any position of rotation. The medial clear space was smaller than or equal to the superior clear space in all radiographs. Intraclass correlation coefficients of the other parameters were too weak for reliable quantitative measurements, as was shown with a mixed model analysis of variance. This resulted from the inability to reproduce ankle positioning, even under optimal laboratory circumstances. This study shows that no optimal radiographic parameter exists to assess syndesmotic integrity. Tibiofibular overlap and medial and superior clear space are the most useful, because one-sided traumatic absence of tibiofibular overlap may be an indication of syndesmotic injury, and a medial clear space larger than a superior clear space is indicative of deltoid injury. Additional quantitative measurement of all syndesmotic parameters with repeated radiographs of the ankle cannot be done reliably and therefore are of little value.

Applicability and reproducibility of condom catheter method for measuring isovolumetric bladder pressure.

OBJECTIVES: To report on the applicability, reproducibility, and adverse events of the noninvasive condom catheter method in the first 730 subjects of a longitudinal survey of changes in urinary bladder contractility secondary to benign prostatic hyperplasia, in which 1300 men will be evaluated three times in 5 years using this method. METHODS: Subjects were recruited by general practitioners, general publicity, and e-mail. Only those meeting the study criteria were entered in the study. If the free flow rate exceeded 5.4 mL/s, at least two consecutive condom pressure measurements were attempted using the condom catheter method. The condom pressure measured reflected the isovolumetric bladder pressure, a measure of urinary bladder contractility. The reproducibility of the method was quantified by a difference plot of the two maximal condom pressures measured in each subject. RESULTS: In 618 (94%) of 659 eligible participants, one condom pressure measurement was completed; two measurements were done in 555 (84%). The maximal condom pressure ranged from 28 to 228 cm H2O (overall mean 101, SD 34). A difference between the two pressures of less than +/-21 cm H2O was found in 80%. The mean difference was -1 cm H2O (SD 18), significantly different from 0. Some adverse events such as terminal self-limiting hematuria were encountered. CONCLUSIONS: The condom catheter method is very suitable for large-scale use. It has a success rate of 94% and a reproducibility comparable to that of invasive pressure flow studies.

Mechanical control of human osteoblast apoptosis and proliferation in relation to differentiation.

Bone cells respond to mechanical stimulation. This is thought to be the mechanism by which bone adapts to mechanical loading. Reported responses of bone cells to mechanical stimuli vary widely and therefore there is no consensus on what mechanisms of mechanotransduction are physiologically relevant. We hypothesize that the differentiation stage of osteoblastic cells used to study responses to strain in vitro determines the outcome of applied loading. A human fetal osteoblast cell line was triggered to differentiate in culture to the advanced state of mineralization by addition of the osteogenic factors dexamethasone and b-glycerophosphate. Osteoblast cultures were subjected to increasing levels of cyclic, equibiaxial stretch at different stages of differentiation. We show that differentiation of human osteoblasts affects their responses to stretch in vitro. In 7-day osteoblast cultures, stretch results in decreased cell numbers as cells are triggered into apoptosis, independent of the stretch level (between 0.4-2.5%). In more mature cultures, apoptosis is not affected by the same treatment. Stretching differentiating cultures at day 14 actually increases proliferation. This is the first study reporting on differentiation-dependent mechanical control of osteoblast proliferation and apoptosis and is fundamental in understanding mechanotransduction processes in bone. The tight regulation of these responses by differentiation implies the significance of the differentiation stage of osteoblasts for the translation of mechanical signals and corroborates with the putative role of the osteoblastic lineage as mechanotransducer in bone.

Measurement of forces during laryngoscopy.

The forces transmitted by the laryngoscope blade onto the base of the tongue are assumed to be a major cardiovascular stimulus. This study investigates the various forces applied onto a Macintosh laryngoscope during laryngoscopy. The forces acting along the axis of the handle are described, as well as the forces exerted by the anaesthetist to prevent the laryngoscope from turning. Based on a relatively simple technique, a modified laryngoscope has been designed to measure these forces. Four different laryngoscopic parameters are determined: (1) the duration of laryngoscopy, (2) the maximally applied force, (3) the mean force and (4) the integral of the force over the time (area under the curve). The force measurements of 49 anatomically normal patients undergoing uncomplicated intubation are included in the study. The duration of laryngoscopy was 16.3s (SD 11.8), the applied peak force was 35N (SD 12) and mean force necessary was 20N (SD 6) while the force-time integral was 324N (SD 194).

Computer-controlled wheelchair ergometer.

A new wheelchair ergometer has been designed in which a combination of realistic simulation of wheelchair propulsion--with adjustable parameters for rolling resistance, air drag, wind speed and slope--and force measurement has been realised. The static solution enables the measurement of physiological and kinesiological parameters. All data from force transducers in seat and backrest, torque transducers in the wheels and force transducers in the wheelframes as well as the acquired speed are sampled in a data-acquisition system. An offline curve processor allows the acquired data to be processed with standard or custom-programmed routines. Preliminary results have been added and are discussed.

Electric wheelchair simulator as a man-machine system.

The procedure for adapting an electric wheelchair for use by a particular patient has not yet been perfected. This paper describes an attempt to improve this procedure with the aid of computer-aided simulation and must be regarded as a pilot study. In this simulation a bird's-eye view of the movement of the wheelchair is represented on the screen of a display terminal. A procedure that had been worked out beforehand was tested on 16 subjects, including 4 patients who came into consideration for an electric wheelchair. Some procedural and task-oriented parameters were investigated. The discussion deals with forms of simulation and the particular influences on the learning effect, among other things. It is concluded that the simulator described may be a useful aid in the evaluation or adaptation of electric wheelchairs, though it does not give all the information needed. Further research is required.