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At least 1,153 records · Page 64Linked to original sources
PubMed1999

Three-dimensional magnetic resonance imaging of the interosseous membrane of forearm: a new method using fuzzy reasoning.

We now report newly developed three-dimensional magnetic resonance imaging (3D-MRI) system which is based on semiautomatic tissue extraction from the axial MR images utilizing the fuzzy reasoning calculation method and 3D-image reconstruction with surface rendering. We also studied normal in vivo dynamic changes of the interosseous membrane (IOM) of forearm during rotation using this 3D-MRI. Serial axial MRI of right forearms of five healthy volunteers was obtained in five rotational positions, and extraction and 3D-reconstruction of the radius, ulna, and IOM was made using the system. Extraction results were well with the fuzzy reasoning method. 3D-MRI of the radius and ulna, IOM were reconstructed from these images respectively, and their 3D-shapes were almost identical to the anatomic shape. 3D-MRI showed there were wavy deformities on the IOM in pronation position in the all five subjects and dorsiflexion on the most dorsal portion of the IOM at maximum supination in three forearms. In neutral position, the IOM of all five volunteers was almost flat. From anatomic orientation, these dynamic changes of the IOM mainly occurred at the membranous portion, which is soft, thin, and elastic. Otherwise, the tendinous portion which is a thick and strong complex of 5 to 10 bundles run from proximal one third of the radius to distal one fourth of the ulna, demonstrated minimal dynamic changes on the 3D-MRI. Therefore, the tendinous portion is considered to be taut during rotation to provide stability between the radius and the ulna, while the membranous portion is easy to deform and allowing smooth rotation. Furthermore, because of wide-use, our 3D-MRI system is useful for in vivo analysis of soft tissue kinesiology in normal and abnormal musculoskeletal systems.

Adult↗
PubMed2001

Preservation of venous endothelial function in the forearm venous capacitance bed of patients with chronic heart failure despite arterial endothelial dysfunction.

OBJECTIVES: The goal of this study was to assess whether endothelial dysfunction occurs in the forearm venous capacitance bed of patients with chronic heart failure (CHF) and to determine the role of nitric oxide (NO) in modulating venous tone. BACKGROUND: Control of venous tone is crucially important in CHF. More than 70% of blood volume lies in the venous capacitance beds. Therefore, small changes in venous tone may markedly affect cardiac filling pressures and cardiac output. METHODS: Venous tone was measured using radionuclide forearm venous plethysmography in 24 patients with CHF and 16 age-matched controls. The effect of basal NO activity on venous tone was assessed by infusing N-monomethyl-L-arginine 12 mg/min and stimulated NO using carbachol 15 microg/min. Brachial artery flow-mediated dilation was assessed by ultrasonic wall-tracking. RESULTS: Blockade of basal NO release caused a significant and similar venoconstriction in patients (9.6 +/- 1.8%, p < 0.01) and controls (6.6 +/- 1.7%, p < 0.01). Carbachol-induced venodilation was significant and similar in patients (36.8 +/- 3.9%, p < 0.001) and controls (40.7 +/- 3.9%, p < 0.001). Brachial artery flow-mediated dilation was impaired in patients compared with controls (2.0 +/- 0.6% vs. 7.5 +/- 2.5%, p < 0.01). CONCLUSIONS: Our data indicate that, despite marked impairment of the function of the arterial endothelium, there is preservation of both basal and stimulated NO release in the forearm venous capacitance bed. This may provide important insights into mechanisms of endothelial dysfunction in CHF and the potential for novel therapy.

Aged↗
PubMed2001

An inhibitor of inducible nitric oxide synthase decreases forearm blood flow in patients with congestive heart failure.

OBJECTIVES: The functional activation of inducible nitric oxide synthase (iNOS) was evaluated as a source of nitric oxide (NO) in the forearm of patients with heart failure. BACKGROUND: Although endogenous NO is normally produced by constitutive NO synthase (cNOS) in patients with congestive heart failure (CHF), expression of iNOS provides an additional source of NO. However, there are no in vivo studies showing functional activation of iNOS in humans. METHODS: A nonselective NOS inhibitor, N(G)-monomethyl-L-arginine (L-NMMA), and a selective inhibitor of iNOS, aminoguanidine, were administered intra-arterially in graded doses into the brachial arteries of 13 patients with CHF and 10 normal control subjects. Forearm blood flow (FBF) was measured simultaneously in the infused and noninfused arms by plethysmography. Arterial and venous plasma concentrations of nitrite/nitrate (NOx) were measured at baseline and at the highest dose of each drug. RESULTS: L-NMMA significantly reduced the FBF ratio between the infused and noninfused arms in both the control and patient groups (35 +/- 12% and 34 +/- 10%, respectively; both p < 0.001). Aminoguanidine at the same concentration significantly reduced the ratio in the patient group (15 +/- 9%, p < 0.01), with no change in the control group. The arterial NOx concentration was not affected by either drug; however, venous NOx concentrations were significantly decreased in both the control and patient groups by L-NMMA (18 +/- 5% and 18 +/- 17%, respectively; both p < 0.05) and in the patient group only by aminoguanidine (7 +/- 6%, p < 0.05). CONCLUSIONS: These findings suggest that NO production in the forearms of patients with CHF is induced partly by iNOS activation, whereas in normal subjects, it can be ascribed to cNOS activation.

Acetylcholine↗
PubMed1984

Forearm arterial distensibility in systolic hypertension.

It is unclear whether the stiffened arterial tree in systolic hypertension is the cause or the effect of the disease. In this study, brachial and radial arterial pulses were sensed by external Pixie transducers and measurements of pulse wave velocity converted to volume distensibility using the Bramwell-Hill equation. Blood pressure was controlled as a variable by repeating the measurements at a variety of transmural arterial pressures. This was accomplished by encasing the forearm in a rigid plastic cylinder within which pressures were varied. Twenty-nine patients with systolic hypertension were compared with 22 age-matched control subjects. At ambient pressures the volume distensibility of patients was lower than that of control subjects (0.10 versus 0.18% delta volume/mm Hg, p less than 0.001) but there was no difference in volume distensibility between the two groups at any comparable transmural pressure. Nineteen patients were treated for 1 month with a thiazide diuretic agent and the studies were then repeated. Systolic and diastolic blood pressure decreased significantly and volume distensibility increased (0.10 to 0.15% delta volume/mm Hg, p less than 0.001) at ambient pressures. But at comparable transmural pressures, volume distensibility was unchanged. It is concluded that, in the forearm, increased arterial stiffness is the result and not the cause of systolic hypertension, but these data cannot exclude increased aortic stiffness as a significant factor. Thiazide diuretic drugs increase forearm arterial compliance by lowering blood pressure without a demonstrable drug effect on this arterial wall.

Aged↗
PubMed2001

The effects of partial and total interosseous membrane transection on load sharing in the cadaver forearm.

This study was performed to examine the effects of partial and total transection of the interosseous membrane (IOM) on load transfer in the forearm. Twenty fresh frozen forearms were instrumented with custom designed load cells placed in the proximal radius and distal ulna. Simultaneous measurements of load cell forces, radial head displacement relative to the capitellum, and local tension within the central band of the IOM were made as the wrist was loaded to 134 N with the forearm at 90 degrees of elbow flexion and in neutral pronation supination. For valgus elbow alignment (radial head contacting the capitellum), mean force carried by the distal ulna was 7.1% of the applied wrist force and mean force transferred from radius to ulna through the IOM was 4.4%. For varus elbow alignment (mean 2.0 mm gap between the radial head and capitellum), mean distal ulna force was 28% and mean IOM force was 51%. Section of the proximal and distal one-thirds of the IOM had no significant effect upon mean distal ulnar force or mean IOM force. Total IOM section significantly increased mean distal ulnar force for varus elbow alignment in all wrist positions tested. The mean level of applied wrist force necessary to close the varus gap (89 N) decreased significantly after both partial IOM section (71 N) and total IOM section (25 N). The IOM became loaded only when the radius displaced proximally relative to the ulna, closing the gap between the radius and capitellum. As the radius displaced proximally, the wrist becomes increasingly ulnar positive, which in turn leads to direct loading of the distal ulna. This shift of force to the distal ulna could present clinically as ulnar sided wrist pain or as ulnar impaction after IOM injury.

Aged↗
PubMed2002

Clinical application of advances in elbow and forearm anatomy and biomechanics.

The static and dynamic stabilizers of the elbow and forearm axis are closely interrelated in elbow and forearm unit motion and load handling. An [figure: see text] understanding of elbow and forearm anatomy is crucial to the surgeon evaluating and treating complex pathologies resulting from acute or remote trauma.

Biomechanical Phenomena↗
PubMed2002

Pediatric elbow and forearm fractures requiring surgical treatment.

In the modern pediatric orthopedic practice, operative management plays a vital and not infrequent role in the management of significant and difficult forearm and elbow fractures in the skeletally immature. Although the majority of forearm and many elbow fractures can be treated successfully by nonoperative measures, operative intervention is warranted in selected cases to optimize outcomes. Anatomic reconstruction of articular surfaces, along with obtaining and maintaining a stable, anatomic fracture reduction, are the goals of any operative treatment. Appropriate use of surgical techniques for pediatric forearm and elbow fractures, when indicated, is essential to optimize results and achieve the ultimate goal of a pain-free functional extremity for the child.

Child↗
PubMedDate not supplied

Development and evaluation of a precision forearm and hand volumeter and measuring cylinder.

Water displacement methods are commonly used to measure upper limb swelling. The purpose of this study was to improve upon currently used volumetric equipment and methods by developing a volumetric method that would be reliable, accurate, and sensitive to changes in forearm and hand volume of less than 1%. The first two phases involved measuring a sample of inert objects (bottles), and the next two phases involved measuring a sample of forearms and hands across a range of water temperatures. Data confirmed that the volumetric method could be used reliably and accurately to measure bottle volumes and was able to detect a change of 10 mls (< 1%). The method also reliably measured forearm and hand volumes using the same anatomic landmark to reference depth of immersion in all subjects. Water temperatures across the range of 20 to 32 degrees Celsius were not found to affect the volume of segments measured.

Adult↗
PubMedDate not supplied

The effects of arm elevation and overnight head-up tilt on forearm and hand volume.

Methods to reduce increased fluid volume, or swelling, were evaluated as short- and long-term interventions. Forearm and hand volumes were measured in 45 fit and healthy subjects using a water displacement device with previously established reliability. Volumes were measured before and after 2 hours of recumbency and before and after overnight sleep under different conditions of arm elevation or head-up tilt. No arms-at-side lying-down position, whether after 2 hours awake or after overnight sleep or with bed-head elevated or not, resulted in significant changes in forearm and hand volume. Only 2 hours in a supine lying-down position with 30 degrees of arm elevation caused a significant effect, with an average decrease of 51 ml in forearm and hand volume.

Adolescent↗
PubMedDate not supplied

The radioulnar joints and forearm axis: surgeons' perspective.

Forearm injuries are common and can vary in complexity. The fractures are easily diagnosed, but the associated soft tissue injuries may not be as obvious. Treatment results are dependent not only on the fracture healing but on the return of normal relationships about the distal radioulnar joint, the interosseous membrane, and the proximal radioulnar joint. Alteration in any of these elements can result in permanent loss of forearm rotation and stability. Recent anatomic and biomechanical studies have increased our knowledge of these structures and their role in forearm function. The findings from these studies may lead to earlier repair of soft tissue injuries about the radioulnar joints and the interosseous membrane. Further follow-up of these procedures will be needed to validate their indications.

Biomechanical Phenomena↗
PubMedDate not supplied

Sphygmomanometer-induced increases in forearm and hand volume.

Swelling, or increased volume, secondary to venous congestion is thought to be a factor in some upper limb conditions. This study aimed to establish a safe, easily applied method of inducing a transitory increase in forearm and hand volume that could be used as a symptom provocation test for upper limb conditions. Using the principles of venous occlusion plethysmography, movement of blood volume into the forearm and hand of asymptomatic subjects was measured after occlusion with three different sphygmomanometer cuff pressures over four minutes. Increases of between 37 and 62 ml (2.5% and 4.1%) were achieved at pressures between diastolic pressure minus 30 mm Hg and diastolic pressure plus 5 mm Hg, with minimal reported side effects. These data demonstrate that a sphygmomanometer can be used to induce transitory fluid congestion of the forearm and hand.

Adolescent↗
PubMedDate not supplied

Fuzzy C-means clustering and principal component analysis of time series from near-infrared imaging of forearm ischemia.

Fuzzy C-means clustering and principal components analysis were used to analyze a temporal series of near-IR images taken of a human forearm during periods of venous outflow restriction and complete forearm ischemia. The principal component eigen-time course analysis provided no useful information and the principal component eigen-image analysis gave results that correlated poorly with anatomical features. The fuzzy C-means clustering analysis, on the other hand, showed distinct regional differences in the hemodynamic response and scattering properties of the tissue, which correlated well with the anatomical features of the forearm.

Cluster Analysis↗
PubMed2000

Transvascular albumin leakage and forearm vasodilatation to acetylcholine in essential hypertension.

The impact of hypertension on microvascular permeability and nitric oxide-mediated endothelial vasomotion in humans has been studied by measuring either the transcapillary albumin escape rate (TERalb, a measure of permeability through systemic capillary endothelium where most of the albumin permeation takes place) and forearm vasodilatation to locally infused acetylcholine (used as a probe for the nitric oxide-releasing potential of arteriolar endothelial cells). It is unknown, however, how the two parameters relate to each other in the same hypertensive subject. This piece of evidence may enhance our understanding about the relative effect of hypertension on two biological functions (ie, permeability and nitric oxide-mediated vasomotion), both dependent on vascular endothelium, and also may allow to appreciate in greater detail the profile of parameters frequently used as markers of microvascular dysfunction in human hypertension. For these reasons, TERa1b (the 1-h decline rate of intravenous 125I-albumin) and forearm vasodilatation (strain gauge venous plethysmography) to graded intraarterial acetylcholine infusion were measured in 44 never-treated men with uncomplicated essential hypertension, and 15 male normotensive controls with comparable age, lipids, and proportion of current smokers. TERalb was increased in patients, whereas acetylcholine-mediated vasodilatation did not differ significantly between the two groups, indicating a heterogeneous impact of elevated blood pressure on capillary permeability and endothelial vasomotion in still uncomplicated mild to moderate essential hypertensive patients. The dissociation between TERalb and forearm responsiveness to acetylcholine also demonstrates that different endothelial-dependent biologic parameters do not behave uniformly in human hypertension.

Acetylcholine↗
PubMed2002

Magnesium infusion improves endothelium-dependent vasodilation in the human forearm.

The effect of intra-arterial magnesium infusion on endothelium-dependent vasodilation (EDV) in the forearm was studied in nine young healthy students (four men and five women). The EDV was assessed as forearm blood flow (FBF), measured by venous occlusion plethysmography, during infusion of methacholine (MCh). Endothelium-independent vasodilation (EIDV) was defined as FBF during infusion of sodium nitroprusside (SNP). During magnesium infusion in the brachial artery, 0.066 mmol/min, the concentration of ionized magnesium in venous plasma in the infused arm increased by 114%, from 0.59 (SD 0.04) to 1.26 (0.34) mmol/L (P = .0002). The FBF at baseline (ie, before administration of MCh or SNP) increased from 3.5 (1.1) to 7.3 (3.4) mL/min/100 mL tissue during magnesium infusion (P = .002). During low-dose MCh administration (2 microg/min), FBF increased by 24%, from 15.4 (5.5) to 19.1 (6.8) mL/min/100 mL tissue (P = .04), and during high-dose MCh administration (4 microg/min) FBF increased by 18%, from 20.3 (6.4) to 24.0 (7.2) mL/min/100 mL tissue (P = .04). The EIDV did not change significantly. Systemic blood pressure was not significantly altered by magnesium infusion. No change in FBF either at rest or during infusion of MCh or SNP was observed during the time-control protocol. In conclusion, this in vivo study showed that intraarterial magnesium infusion increased EDV in the infused human forearm, which is in accordance with findings in previous in vitro and animal experiments.

Adult↗
PubMed1992

Anatomical study of the valves of the superficial veins of the forearm.

The valves of the cephalic, basilic and median cubital veins were investigated in the superficial veins of the left forearm in 9 cadavers, aged 25-95. The radial forearm flaps involving these veins are of special clinicoanatomical importance. The following results were obtained: (1) Valves were most frequently evident at Site G of the cephalic vein. No valves were present in Section A-B, (2) type B valves were located at confluences, junctions and branches and were more frequent (54.7%) than Type A (45.3%) located in the straight trunks of superficial forearm veins, (3) Type 2 valves accounted for most (82.3%), and these were followed by Type 1 and Type 4b (5.9%), Type 4a (4.4%) and Type 3 (1.5%).

Adult↗
PubMed2002

A motion of forearm supination with maintenance of elbow flexion produced by electrical stimulation to two elbow flexors in humans.

Motions of the forearm induced by electrical stimulation to two elbow flexors (brachioradialis: BR, biceps brachii: BB) were examined in five healthy human subjects. Stainless steel wire electrodes were implanted percutaneously into each motor point of the muscles. The muscles were stimulated separately with a computer-controlled multi-channel stimulator. The motions were taken with a digital video system. Angular changes of the motions in elbow flexion/extension and forearm pronation/supination were measured. Electromyograms (EMG) of BR, BB, and the triceps brachii (TB) were recorded. Electrical stimulation to BR induced a motion of flexion and that to BB motions of flexion and supination. The stimulation to BR with an adequate intensity provided holding of flexion with the prone forearm in all the subjects. In this situation, additional stimulation to BB resulted in motions of flexion and supination. However, the additional stimulation accompanied with a decrease of the stimulation intensity for BR provided a motion of supination with maintenance of the flexion in all the subjects. Since during the stimulation BR, BB, and TB showed no voluntary contraction in EMG, it is suggested that modulation of contraction between BR and BB by the stimulation can produce force in supination with keeping constant force in flexion to support the weight below the elbow.

Adult↗
PubMed1998

Regulation of regional norepinephrine spillover in heart failure: the effect of angiotensin II and beta-adrenergic agonists in the forearm circulation.

BACKGROUND: Prejunctional receptors for angiotensin II (A-II) and norepinephrine (NE) have been reported to facilitate NE release. If operative in patients with congestive heart failure (CHF), such receptors could participate in positive feedback cycles amplifying sympathoactivation. METHODS AND RESULTS: A-II and isoproterenol (ISO) would increase regional NE spillover via facilitation of presynaptic release of NE in the forearm circulation of patients with chronic stable CHF. A-II, ISO, and nitroprusside (NP) were sequentially infused into the brachial arteries of 10 patients with chronic stable CHF, which was attributed to dilated cardiomyopathy. Forearm blood flow (FBF) was measured via plethysmography and regional spillover of NE was measured by using the isotope dilution method of Esler. A-II (5 ng/min) produced a nonsignificant decline in FBF (1.87+/-0.14 to 1.46+/-0.1 mL/100 g/min, P = .07) and did not change regional NE spillover (418+/-128 to 409+/-121 ng/min). ISO increased FBF from 1.6+/-0.12 to 4.3+/-0.7 mg/100 g/min (P < .001). Regional NE spillover increased from 337+/-86 to 856+/-300 ng/min (P < .001). Venous NE and regional extraction of NE did not change. NP increased FBF from 2.0+/-0.3 to 6.3+/-1.2 mL/100 g/min (P < .001; P = NS v change with ISO) and also increased regional NE spillover (301+/-99 to 712+/-288 ng/min, P < .001; P = NS v change with ISO). As with ISO, venous NE and extraction of NE were not altered. CONCLUSIONS: Mild vasoconstrictor infusions of A-II do not increase regional NE spillover in the forearm circulation of patients with CHF. The beta-adrenergic agonist ISO does increase regional spillover, but the effect seems to be primarily related to flow rather than presynaptic stimulation of NE release. These data argue against an important positive feedback loop involving A-II and NE on sympathoactivation, at least with the dosages of the agonists studied and in the limb circulation in chronic stable CHF.

Adult↗
PubMedDate not supplied

Ultrasound guidance for ulnar nerve block in the forearm.

OBJECTIVE: The objective of this study was to establish the feasibility of ulnar nerve block under direct imaging. CASE REPORTS: Two patients undergoing surgery on the fifth digit or medial hand received ulnar nerve blocks in the mid-forearm (approximately 15 cm proximal to the styloid process of the ulna). Ultrasound imaging was used to identify the ulnar nerve in the forearm and guide local anesthetic infiltration. Both patients had successful blocks, including sensory anesthesia of the dorsomedial hand. CONCLUSIONS: Ultrasound guidance for ulnar nerve block in the forearm is a promising technique that includes block of the dorsal cutaneous branch. Anatomic and sonographic considerations are discussed.

Adult↗