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Various investigations into anatomical landmarks that could be employed in spine and back surface measurement have highlighted the usefulness of the spinous processes of the vertebra and the posterior superior iliac spines of the pelvis. Earlier studies used an opto-electronic gait analysis system to examine the motion of skin markers and compared results with similar inter-vertebral movement recorded through radiographs. Consistent patterns of movement suggested a relationship between spinal and back surface motion. Further investigations into the use of opto-electronic gait analysis systems to measure dynamic back movements showed the capability of producing repeatable patterns of back movements. However, these studies, mainly measuring the range of movement (ROM) of spine, have not examined the effects of marker placements. While most ROM studies concentrate on stationary repetitive flexion/extension and bending movements, spinal ROM during walking and in scoliosis has not been widely reported. Spinal range of motion is an important indicator of spinal function and is used in the determination of disability and compensation. The present study has evaluated the placement of markers on the back and pelvis, used in three-dimensional opto-electronic systems for gait and movement studies. Various marker configurations have been compared and reported. The findings highlight the drawbacks of previously reported techniques, and particularly indicate that skin movement can adversely affect findings. However, the results confirm the feasibility of application of this technique to investigate dynamic trunk and spinal movement in both normal and deformed spines.

Background: The aim of this study was to evaluate the relationship between shoulder mobility, rotator muscles' strength and scapular symmetry, and shoulder injuries and/or pain in elite volleyball athletes., Methods: An isokinetic shoulder muscle strength test, which was performed at speeds of 60/sec and 180/sec, and shoulder mobility and scapula lateral slide tests were conducted bilaterally on 16 subjects, who represented the England elite volleyball players. The subjects also prospectively completed monthly questionnaires during the competition season to report on their shoulder condition., Results: The results showed that the active range of shoulder internal rotation and concentric external rotators' strength in the dominant arm were significantly less, than in the non-dominant arms, but the internal rotators were significantly stronger in both concentric and eccentric tests at both testing speeds. Seven of 16 subjects indicated overt shoulder injury or pain during their training season, nine subjects had shoulder mobility impairment, seven had muscle imbalance, 13 had relative muscle weakness and five had scapular asymmetry. The association between shoulder muscle strength imbalance (eccentric external < concentric internal) of rotators in the dominant arm and shoulder injuries was statistically significant (Fisher's exact test, p<0.05)., Conclusions: We conclude that rotator muscle strength imbalance may play an important role in shoulder injuries in high-level volleyball players.

The hamstrings:quadriceps muscle strength ratio has been used as an indicator of normal balance between the knee flexors and extensors. A more functional approach to this strength ratio would be to compare opposite muscle actions of antagonistic muscle groups. The dynamic strength control ratio (DSCR) should give a more appropriate measure relating to knee function. There is a lack of normative data relating to DSCR for anterior cruciate ligament (ACL) deficient subjects. Effects of ACL deficiency on isokinetic peak torque for eccentric and concentric muscle actions of the quadriceps and hamstrings, in conjunction with isometric peak torque, were examined in 10 patients awaiting reconstructive surgery (male = 8, female = 2 ; age = 32.8 +/- 8.3 years; height = 1.77 +/- 0.08 m; mass = 72.1 +/- 12.5 kg). These variables were assessed using an isokinetic dynamometer. The results were considered in terms of the conventional ratio and DSCR. Anterior tibial drawer was measured using a knee ligament arthrometer to confirm clinical diagnosis of ACL rupture. The isokinetic peak torque data analysed were for angular velocities of 1.05 rad s(-1) (60 degrees s(-1)). Significant strength deficits were apparent between normal and injured sides for: concentric isokinetic quadriceps action (p < 0.05); isometric quadriceps action at 70 degrees of knee flexion (p < 0.05); isometric quadriceps action at 40 degrees of knee flexion (p<0.01); eccentric isokinetic hamstrings action (p < 0.05). With bilateral comparison, the conventional strength ratios showed no significant difference, as did the DSCR. The bilateral comparison of isometric strength ratios revealed significant losses in quadriceps strength for the injured side (p < 0.05) but no significant losses in hamstring strength (p > 0.05). Thus, differences can be seen in conventional ratios and DSCR for ACL-deficient subjects. This is an area of clinical interest with the increasing frequency of ACL reconstruction using hamstrings tendons.

A low calcium dialysate reduces hypercalcemia from calcium-containing phosphate binders and makes phosphate control possible without the use of aluminum salts. We asked whether this might, however, lead to hyperparathyroidism. We prospectively studied serum concentrations of parathyroid hormone levels (by an immunoreactive intact molecule assay) in 173 patients on continuous ambulatory peritoneal dialysis (CAPD) who were started on a low calcium dialysate (Ca2+ 1.25 or 1.00 mmol/L) because of hypercalcemia. Median follow-up was 13.2 months (range 1-28). Initial serum parathyroid hormone was [median(range)]: 70(5-1043) ng/L pre low calcium dialysate, and this rose to 130(5-914) ng/L at 0-6 months; 130(5-1030) ng/L at 6-12 months; 170(170-1400) ng/L at 12-18 months; and 130(5-1200) ng/L at 18-24 months (p = 0.0006). Twenty-two patients required a parathyroidectomy because of a sustained rise in parathyroid hormone that was not responsive to alfacalcidol and hypercalcemia. Initial serum parathyroid hormone was significantly higher in these patients at 359 (5-1073) ng/L as compared to a level of 69.5 (6-1147) ng/L in patients who did not have a parathyroidectomy (p = 0.0009). There was a significant sustained fall in mean serum corrected calcium from 2.77 (2.37-3.51) mmol/L to 2.53 (1.39-3.20) mmol/L at three months (p = 0.0006), a nonsignificant rise in mean serum alkaline phosphate from 179 (47-1858) mmol/L to 191 (55-1821) mmol/L (p = 0.15), and a fall in mean serum phosphate levels from 1.87 (0.59-3.18) mmol/L to 1.68 (0.45-3.6) mmol/L (p = 0.76). Our data suggest that the benefits of a low calcium dialysate in CAPD patients are balanced by an increased risk of hyperparathyroidism, and that this risk is higher in patients with an initially high serum parathyroid hormone level.

The challenges of integrating behavioral healthcare delivery and the demand for better management of behavioral healthcare benefits require corporate risk managers to focus on issues of quality and outcomes. A strategic partnership between the employer and a managed care organization is one tool for reducing risk and improving the quality of services for beneficiaries, using the techniques of total quality management. The following article describes a six-step process for launching such a strategic partnership, along with some potential pitfalls.

Although both physical fitness and aspects of cognitive functioning are known to be poorer among older people, there is conflicting evidence about the interaction between age and fitness. Is greater age more strongly associated with impaired cognition among less fit people than it is among more fit people? In a sample of employed men aged 17-63 years, it is shown that this interaction is significant with respect to the occurrence of exceptionally slow responses but is not significant for mean reaction time. Multiple regression analyses suggest that the former measure may be interpreted as an inability to maintain concentration over time rather than as an index of response speed.

Because aortic stenosis results in the loss of left ventricular stroke work (due to resistance to flow through the valve and turbulence in the aorta), the percentage of stroke work that is lost may reflect the severity of stenosis. This index can be calculated from pressure data alone. The relation between percent stroke work loss and anatomic aortic valve orifice area (measured by planimetry from videotape) was investigated in a pulsatile flow model. Thirteen valves were studied (nine human aortic valves obtained at necropsy and four bioprosthetic valves) at stroke volumes of 40 to 100 ml, giving 57 data points. Valve area ranged from 0.3 to 2.8 cm2 and mean systolic pressure gradient from 3 to 84 mm Hg. Percent stroke work loss, calculated as mean systolic pressure gradient divided by mean ventricular systolic pressure x 100%, ranged from 7 to 68%. It was closely related to anatomic orifice area with an inverse exponential relation and was not significantly related to flow (r = -0.15). An orifice formula was derived that predicted anatomic orifice area with a 95% confidence interval of +/- 0.5 cm2 (orifice area [cm2] = 4.82 [2.39 x log percent stroke work loss], r = -0.94, SEE = 0.029). These results support the clinical use of percent stroke work loss as an easily obtained index of the severity of aortic stenosis.

This paper describes a microcomputer controlled pump which generates pulsatile flows similar to those found in the human peripheral circulation. Continuous wave Doppler ultrasound was used to investigate the flows generated by the pump and the behaviour of diagnostic indices derived from the spectra was examined. Sonograms were recorded from elastic and rigid tubes with various degrees of axisymmetric constriction. Heart rate, stroke volume, severity of vessel constriction, vessel wall elasticity, distal resistance, and systemic peripheral impedance were varied in turn and the resulting Doppler spectra compared. Indices considered were the pulsatility index, spectral broadening index and peck Doppler frequency. In general, the indices lacked the sensitivity to detect low to moderate levels of disease.

A characteristic 'crow's foot' pattern is seen around the eye in many flash burns. The protective blink reflex underlies this, and the injury is due to convected rather than radiant energy.

A case of recurrent basal cell carcinoma resistant to repeated excision is reported. The forehead defect was covered with a deltopectoral free flap transfer in which 1 artery and 2 veins were anastomosed.

To assess the effect of fluid flow on orifice area and to test the Gorlin formula, six Carpentier-Edwards mitral valve prostheses were studied in a positive displacement pulse duplicator at 20 different rate-stroke volume combinations. Peak transvalvular velocity (V max) was measured by continuous wave Doppler ultrasound, and orifice area was determined from hard copy of video images. Orifice area was directly related to mean flow (Q), although cusp opening behavior was asymmetric and complex and varied among the individual valves. There was a strong correlation between measured orifice area (OA) and the modified Gorlin relation, Q/V max (r = 0.88; p less than 0.00001) given by the regression formula OA = 0.18 x Q/V max - 0.15. There was also a good correlation between measured orifice area and the conventional Gorlin relation, Q/root mean pressure drop. The derived empiric Gorlin constant did not vary significantly with flow.

A computer model of the cardiac conduction process and an integral equation mathematical model have been employed to study the functions of the atrioventricular (AV) node. Special attention has been paid to the dependence of conduction delay on cycle length. The models have been used to evaluate the question as to whether simple cycle length dependences of AV nodal conduction could cause the oscillations of cycle length which are sometimes observed in AV reentry tachycardia. The models consider the AV node as a linear structure in which the depolarisation wavefront radiates in one dimension only. A model representing the node by two parallel linear structures has also been examined. Some results obtained do not conform with those of natural circumstance and clinical experiments, suggesting that the above hypotheses of AV nodal function are too simple and restricted to explain the natural processes.

The efficacy of balloon valvoplasty of calcific aortic stenosis remains controversial. We studied, therefore, 5 human aortic valves obtained at necropsy in a positive-displacement pulse duplicator which delivered stroke volumes of 40-100 ml with a quasiphysiological waveform of flow. All valves had three leaflets without commissural fusion and were preserved in antibiotic solution before study. Orificial area was planimetered from videotape of opening of the valve and varied with flow in all cases. Valvoplasty with a 20 mm diameter balloon had no effect on the orifice of the normal valve but increased the orifice of 2 mildly calcified valves from 0.70-1.77 cm2 (range) at baseline to 1.06-1.95 cm2. In 2 valves with severe calcification of the leaflets, the orifice was increased from 0.31-0.82 cm2 to 0.73-1.07 cm2. Dual balloon valvoplasty achieved a variable but small further increase in orificial area. No valve showed tears of the leaflets or fracture of calcific deposits after valvoplasty. We conclude that balloon valvoplasty can acutely increase orificial area, independently of any change in stroke volume. In valves without commissural fusion, its mechanism appears to be an increase in the pliability of the leaflets which does not require macroscopic fracture of calcific deposits.

A discrete computer model simulating the operation of the cardiac impulse transmission apparatus and the electropotential changes of the heart musculature has been developed on a NORD-100 minicomputer. The model is written in NORD-FORTRAN and allows description of practically all basic pathologies of the transmission apparatus. A simulated ECG curve is produced in each case. The current version of the model is especially suited for studies of heart rhythms. Pacemaker descriptions (of most important pacemaker types) have been introduced into the model and the computer computations make it possible to assess the effects of different pacemaker modes under different pathological situations. The principles on which the model is based is described and the paper shows concisely several examples in the form of simulated ECG records.

A computer model simulating the electrical activity of the heart is described. The model is designed for use in clinical cardiological research. Its implementation is based on the methods of discrete process simulation. The simulation program is written in FORTRAN, has approximately 12,000 lines and requires 160 kilobytes of memory to run. The whole heart is modelled, including a realistic description of the conduction system and a 'hollow shell' structure with a central plane representing the atrial, ventricular and septal components of the cardiac musculature. The myocardium itself is represented by simple hexagonal elements, which are pieced together to form the 'hollow shell'. The ideas used to develop the model are briefly described, but emphasis is given to clinical applications. The model is first validated by examining its output under well-known pathological conditions. Clinical applications, including predictive value, testing of hypotheses, and evaluation of pacemaker function, are then described, results being presented in the form of orthogonal lead projections.

This paper describes a universal simulation system which enables simulation models of cardiac rhythm disturbances and of artificial pacemaker actions to be constructed. Three types of heart element are introduced according to the way in which excitation impulses are propagated or produced. Cycle rate dependence of repolarization periods and of impulse transmission speeds is incorporated. Random and predetermined deviations from natural behavior are also allowed for in the model. Using the universal system, a model of simple configuration has been developed. There are five physiological and five pathological heart components joined together by uni- and bidirectional connectors. Additional bidirectional channels allow a variety of pacemakers to be "implanted" in the simulated heart.