The effect of surgery for femoral neck fracture on lower limb venous blood flow and its relationship to deep vein thrombosis was investigated in 179 patients. Blood flow was measured using strain gauge plethysmography before surgery, in the 1st week after surgery, and at 6 week review. There was a significant reduction in both venous outflow and venous capacitance, affecting both fractured and non-fractured legs but significantly greater in the fractured leg. Venous function remained significantly impaired in both lower limbs 6 weeks after surgery. There was a significant correlation between the reduction in venous function and the development of deep vein thrombosis.

The effect of surgery for femoral neck fracture on whole blood coagulation and the relationship of altered coagulation to deep venous thrombosis were investigated in 250 patients. Whole blood coagulation was measured using thrombelastography preoperatively, in the early postoperative period and at 6-week review. Significant hypercoagulability was demonstrated after surgery and persisted to 6-week review. A significant correlation between hypercoagulability and the development of deep venous thrombosis is demonstrated. Hypercoagulability is shown to be a major factor in thrombosis formation following proximal femoral neck fracture surgery.

The mechanisms by which graduated compression stockings prevent deep venous thrombosis are not completely understood. In the current study the physiologic effect of low-pressure graduated compression stockings on the venous blood flow in the lower limb and the practical aspects of their use were assessed. Patients having elective orthopaedic surgery at a university orthopaedic department were randomized into five groups to wear two different types of graduated compression stockings in thigh and knee lengths. Patients in the fifth control group did not wear graduated compression stockings. Venous occlusion strain gauge plethysmography was used to measure venous flow. After 20-minutes bed rest there was a highly significant increase in venous capacitance and venous outflow in patients in all of the four groups wearing stockings. There was no difference in the mean of the percentage change of venous capacitance in patients in the four groups wearing stockings. The knee length Brevet stockings were less efficient in increasing the venous outflow. There was no significant change in the venous capacitance and venous outflow in patients in the control group. Visual assessment of the fit and use of stockings was done, and patients’ subjective opinion of comfort was sought. The knee length graduated compression stockings wrinkled significantly less, and significantly fewer patients reported discomfort with them. All stockings were reported to be difficult to use. Thigh and knee length stockings have a significant effect on decreasing venous stasis of the lower limb. Knee length graduated compression stockings are similarly efficient in decreasing venous stasis, but they are more comfortable to wear, and they wrinkle less.

The mechanisms by which graduated compression stockings prevent deep venous thrombosis are not completely understood. In the current study the physiologic effect of low-pressure graduated compression stockings on the venous blood flow in the lower limb and the practical aspects of their use were assessed. Patients having elective orthopaedic surgery at a university orthopaedic department were randomized into five groups to wear two different types of graduated compression stockings in thigh and knee lengths. Patients in the fifth control group did not wear graduated compression stockings. Venous occlusion strain gauge plethysmography was used to measure venous flow. After 20-minutes bed rest there was a highly significant increase in venous capacitance and venous outflow in patients in all of the four groups wearing stockings. There was no difference in the mean of the percentage change of venous capacitance in patients in the four groups wearing stockings. The knee length Brevet stockings were less efficient in increasing the venous outflow. There was no significant change in the venous capacitance and venous outflow in patients in the control group. Visual assessment of the fit and use of stockings was done, and patients’ subjective opinion of comfort was sought. The knee length graduated compression stockings wrinkled significantly less, and significantly fewer patients reported discomfort with them. All stockings were reported to be difficult to use. Thigh and knee length stockings have a significant effect on decreasing venous stasis of the lower limb. Knee length graduated compression stockings are similarly efficient in decreasing venous stasis, but they are more comfortable to wear, and they wrinkle less.

Strain gauge plethysmography (SGP) is a non-invasive method used in the detection of deep venous thrombosis (DVT). The technique is based on the measurement of calf volume changes in response to venous occlusion by a thigh cuff, the volume changes reflecting the rates of arterial inflow and venous outflow. A numerical model of the blood circulation within the limb and the response of this to a SGP test has been derived, based on treating the different parts of the circulatory system in the leg as resistance and capacitance elements. The simulation results were compared with clinical studies and support the ability of SGP to detect non-occlusive clots of more than 50–60% of the lumen, as well detecting calf vein pressure appears to be a particularly important factor within the model. In addition, increases in venous tone due to post-operative venospasm were shown to be a potential source of false positive results.

A postal survey was carried out to determine the attitudes to the use of low molecular weight heparin (LMWH) in joint replacement among two representative groups of orthopaedic surgeons practising in the UK. 72% of hip surgeons and 51% of knee surgeons replying had used LMWHs for deep vein thrombosis prophylaxis in joint replacement patients. Of these, 48% had discontinued LMWH use due to bleeding complications. Among those continuing to use LMWHs, 88% had witnessed excessive bruising around the wound and 53% had experienced increased wound bleeding or haematomas. Although LMWHs have been shown to reduce post-operative thromboembolism in these groups, clinical experience has revealed an increased incidence of bleeding complications associated with their use. This has prevented their routine use in joint replacement, as was the case with unfractionated heparin in the past.

We studied the effect of total knee replacement on venous flow in 110 patients. Resting venous blood flow was measured using straingauge plethysmography before operation, after surgery and after discharge from hospital. There was a significant reduction in mean venous capacitance (p < 0.001) and mean venous outflow (p < 0.004) affecting only the operated leg. Both improved significantly after mobilisation in the early postoperative period, returning to preoperative levels by six days after surgery and before discharge from hospital. Our findings showed that venous stasis may contribute to deep-vein thrombosis only in the first few days after total knee replacement. This would be the most important period for the use of flow-enhancing prophylactic devices. Comparison with changes in blood flow after total hip replacement identified different patterns of altered haemodynamics suggesting that there are different mechanisms of venous stasis and thrombogenesis in hip and knee arthritis and during surgery for these conditions.

Surgeons often encourage patients to move their feet in an attempt to prevent venous stasis, but there is little evidence that this measure is beneficial. We investigated the effect of active movement of one foot on the venous blood flow four days after total hip replacement. The actual venous outflow at rest was measured with use of venous occlusion strain-gauge plethysmography in thirty-eight patients. The patients were randomly allocated to the control group (eighteen patients) or the exercise group (twenty patients). A baseline measurement was followed by a one-minute period of rest (control group) or of maximum plantar flexion and dorsiflexion of the foot, ankle, and toes at a rate of thirty cycles per minute (exercise group). The venous outflow was measured again at two, seven, twelve, and thirty minutes in both groups. Movement of the foot for one minute produced a significant and sustained increase (p < 0.002) in the venous outflow (mean maximum increase, 22 per cent). The value remained greater than the baseline level for thirty minutes (mean increase, 6.5 per cent) (p < 0.2). The increase was gradual, reaching a maximum twelve minutes after the completion of exercise. Our results confirm the beneficial hemodynamic effects of active movement of the foot in the postoperative period and suggest that patients should move the feet and ankles postoperatively as part of a prophylactic regimen directed at decreasing the risk of venous thrombosis.

Objectives:To compare the effect of four types of thigh-length graduated compression stockings (GCS) on lower limb venous blood flow using strain-gauge Plethysmography (SGP).Design:A randomized controlled study.Setting:Inpatient Orthopaedic Centre.Patients:200 preoperative patients admitted for elective lower limb orthopaedic surgery.Interventions:Patients were randomized to five groups to wear one of four types of GCS or no stocking (control). Resting venous flow parameters were measured prior to application of GCS and after 20 min bed rest with the stockings in situ.Main outcome measures:Effects on resting venous capacitance (Vc) and venous outflow (Vo).Results:In the control group 20 min bed rest had no effect on the parameters studied. Both Vc and Vo were significantly increased ( p<0.001) in all the groups wearing stockings. There was a significant variation in the changes in outflow produced by the different stocking types ( p<0.05).Conclusions:GCS have a beneficial effect on lower limb venous outflow, preventing venous stasis, an important factor in the development of deep venous thrombosis. This effect varies depending on which type of stocking is used.

potentially infecting organism from thyroid gland and injection into an experimental animal to test for possible induction of autoimmune thyroid diseases.

I was interestedin the brief report of a case of spinal stenosis due to pseudogout in your July 1994 issue (l994;76-B:672-3), having reported a very similar case of nerve-root compression in a 64-year-old patient with unilateral intermiuent claudication (Dehais et al 1977).I agree that pyrophosphate deposition should be considered as a possible cause of nerve-root compression in patients with intermittent claudication suggestive of lumbar stenosis.

A model for describing the ligand-field spectra of cubic chromophores in a molecular orbital basis is derived and tested by carrying out least-squares-fits of the spectra of the tetrahedral ions CoX 2- 4 (X = Cl Br). Independent assignments of the ligand-field spectra of the latter ions are obtained by analysing the site-group splittings and vibrational fine-structure in the polarized spectra of Cs 3 CoCl 5 and Cs 3 CoBr 5 at 4.2 K. General expressions are calculated for the electron repulsion matrix elements of pairs of electrons occupying orbitals transforming as e, t 1 and t 2 in Oh and Td point groups, without further assumption about the functional form of the orbitals. Tanabe & Sugano’s (1954) matrices for d 1 ~d 5 configurations are rewritten in the more general form. The two-electron reduced matrix elements appearing in these expressions are further approximated in terms of orbital overlap populations (Mulliken 1955), one- and two-centre coulomb integrals and one-centre exchange integrals. An analogous reduction of the matrix elements of the molecular spin-orbit operator within a molecular orbital basis is also described. The energies of the spin-orbit baricentres of the ligand-field transitions are then calculated as functions of three orbital population parameters and the energy separation between the e and t 2 molecular orbitals. From the least-squares analysis of the independently assigned experimental spectra, empirical values of the four parameters are extracted, and their relation to the parameters of conventional ligand-field theory is discussed. The experimentally based molecular orbital parameters are further used to calculate spinorbit splittings of the cubic Russell-Saunders ligand-field states, and the relative dipole strengths of transitions to those which are formally spin-forbidden from the ground state.

Methods of producing profile tools and gauges remained for many years particularly conservative and often expensive in the use of highly skilled toolroom labour. Up to comparatively recent times it was not uncommon to find high-class machine tools, such as jig boring machines, applied to the task of marking out centres of radii and so on, because they embody accurate means of measurement. The early introductions of special-purpose machines for this work were mainly continental, and the advantages normally to be expected from the use of such machines were not altogether realized as the result of designs based inherently upon the use of master copy. Later, machines were developed intended to be independent of copy to a very large extent, and this was facilitated by a trend of component design based upon the use of geometric and definable shapes wherever possible. The application of optics to this class of machine, mainly in the form of microscopes or projection systems, is now fairly common, and in its application to engineering the optical projector perhaps reaches its highest standard of definition and accuracy of reproduction. The incorporation of optical and electrical measuring devices has also helped greatly in providing an accurate and versatile machine tool. The object of the paper is to reveal aspects of design more peculiar to this type of machine, particularly the association of optics and mechanical linkages, and is therefore mainly confined to the copying and generating mechanisms. It also indicates the development trend of this class of design. Methods of forming and truing the grinding wheel are not considered.