Synovial Volume Research Articles

Relation between trans-synovial flow and plasma osmotic pressure, with an estimation of the albumin reflection coefficient in the rabbit knee.

The volume of synovial fluid in a joint correlates inversely with plasma colloid osmotic pressure (COP). The inferred influence of plasma osmotic forces on trans-synovial flow was investigated directly here, in isolated perfused hindquarters of sixteen rabbits. Flow of intra-articularly infused Krebs solution across the synovial lining of the cannulated knee was recorded at controlled intra-articular pressure (18 cmH2O). Colloid osmotic pressure in the synovial microcirculation was varied by perfusion with oxygenated red cells resuspended in albumin solution or plasma from an extra-corporeal system at constant perfusion pressure. Studies in vitro showed that the COP versus concentration curve for commercial bovine albumin samples was variable and not reliably described by a widely used polynomial. The rate of trans-synovial absorption Qs was a positive linear function of intravascular COP pi p (r = 0.936, P less than 0.001, n = 83). The average slope dQs/d pi p was 0.20 microliter min-1 cmH2O-1 (S.E. +/- 0.01 microliter min-1 cmH2O-1), the slope depending on hydraulic conductance and osmotic reflection coefficient. Trans-synovial flow was a negative linear function of synovial capillary pressure (Pc). Absolute slope dQs/d pi p was on average only 78% of dQs/dPc in the same joint. The osmotic reflection coefficient of the blood-joint barrier to serum albumin was estimated from these slopes as 0.78-0.81 (S.E.M. +/- 0.06). Vascular perfusion with a hyperosmolar solution of glucose, sucrose or NaCl generated a transient, rapidly decaying osmotic absorption from the joint cavity, with a half-life of 17-60 s. A reversed osmotic transient occurred on reperfusion with isotonic fluid. It was concluded that the blood-joint barrier, which comprises fenestrated endothelium and synovial intima, approximates to an imperfect semipermeable membrane for albumin solutions, justifying the application of Starling's hypothesis to trans-synovial flow. For small solutes the tissues form a highly permeable but nevertheless slightly osmotically reflective membrane.

Osmotic flows across the blood-joint barrier.

The effective osmotic pressure across the blood-joint barrier is a key factor controlling synovial fluid volume and joint effusions. The effect of plasma colloid osmotic pressure (COP) on trans-synovial flow was studied directly in rabbit knees expanded by intra-articular fluid infusion. The synovial microcirculation was perfused with blood of varying COP. Absorption of fluid from the joint cavity was a linear function of COP; but albumin COP was only 78% effective across the blood-joint interface. Hyperosmolar solutions of small solutes (e.g., glucose) generated transient osmotic flows across the blood-joint barrier, but far less effectively than albumin. The hydraulic permeability of synovium increased at pathological intra-articular pressures--a phenomenon of potential importance to effusion kinetics.

Monosodium urate crystals in the knee joints of patients with asymptomatic nontophaceous gout.

We aspirated synovial fluid from the knees of 50 patients with asymptomatic, nontophaceous gout, in whom synovial fluid monosodium urate (MSU) crystals had previously been documented in the knees or other joints. Fifty-eight percent of these asymptomatic patients had MSU crystals in their knee joints. Serum uric acid levels, serum creatinine levels, volume of synovial fluid aspirated, and cell counts of the aspirated fluid did not differentiate the MSU crystal-positive group from the group without MSU crystals. Clinical factors such as alcohol abuse, coronary heart disease, hypertension, duration of gout, duration of the intercritical period, and drug therapy did not differentiate the 2 groups. Nineteen patients consented to aspiration of their other knee. Seven of these patients (37%) had MSU crystals bilaterally, and 6 patients (32%) had them unilaterally. The implications of the persistence of MSU crystals (including those in intracellular locations) in many patients, despite normalization of serum uric acid levels, should be determined. Knee joint aspiration is a sensitive method for the demonstration of MSU crystals in asymptomatic patients. The procedure might also be useful in documenting these crystals in patients who have had attacks of arthritis with features consistent with a diagnosis of gout, but in whom MSU crystals have not been documented.

Intraarticular volume and clearance in human synovial effusions.

Intraarticular volumes were measured by radiolabeled albumin (RISA) distribution in chronic knee effusions from 11 rheumatoid arthritis patients and 9 osteoarthritis patients. Volumes of synovial fluid obtained at joint aspiration were substantially less than those found by RISA dilution. Up to 24 hours was needed for full distribution of RISA throughout the intraarticular compartment. Measured 123I and RISA radioactivity over the knee described monoexponential rate constants, lambda (minute-1). The clearance of 123I and RISA from synovial effusions was derived by the formulation volume (ml) X lambda (minute-1) = clearance (ml/minute). RISA clearance in rheumatoid effusions was significantly greater than that found in osteoarthritis effusions. Intraarticular volume and isotope clearance were easily quantified and provide measures for further evaluating the microvascular physiology of synovial effusions.

A hypothesis on the pathogenesis of rheumatoid and other non-specific synovitides. IV A. The possible intermediate role of local hypoxia and metabolic alterations

According to the original hypothesis, synovial tissue (ST) oedema and synovial fluid (SF) volume increase contribute to local hypoxia and metabolic alterations and to inflammation (A 1). Studies on biochemical mechanisms (A 2) in synovitides show that the SF volume correlates to SF hypoxia that correlates to lactate increase, acidosis and to some decrease in glucose. Normal ST produces lactate by glycolytic and pentose phosphate pathway activity, both, as well as the normally low oxygen utilization, being increased in synovitides. In ST very little carbohydrate seems to pass directly into the citric acid cycle and oxidation of fat may be involved, but it is not known if the fat is carried to ST by the blood or if it is synthetized locally (B). ST oedema and effusions may be most important as causes of local hypoxia (C). Acidosis alters physico-chemical properties of proteins, possibly changing their chemotactic and antigenic qualities, etc. Hypoxia and fuel supply might be related to fibroblast, macrophage and neutrophil reactions, and, in view of the high metabolic demands of villi, they may contribute to, e.g., ST necroses, and to erosions (D). I shall summarize some essentials of my present views on the pathogenesis (E 1 a) and causes in single cases (E 3 b) of synovitis, and comment on two other new hypotheses on rheumatoid arthritis (E 2) and on therapeutic (E 4) and other implications of this concept (E).

Factors determining the level and changes in intra-articular pressure in the knee joint of the dog.

Intra-articular pressure levels were determined for joint positions throughout the normal physiological range of movement of dogs' knee joints. Change in joint position resulted in change in intra-articular pressure. It was demonstrated that intra-articular pressure is highest with the joint in the fully flexed position. Minimum pressure was recorded at a position between 80 degrees and 120 degrees. Minimum pressures were usually subatmospheric. The rate of change of joint position affected intra-articular pressure. The relationship of intra-articular pressure and joint position before and after full flexion demonstrated a hysteresis effect; the pressures were lower than for the same joint position before flexion. Maintenance of the joint in the fully flexed position for increasing periods of time between repeated movement cycles resulted in a similar reduction, of constant magnitude, in pressure between joint positions before and after each period of flexion. However, there was also a progressive decrease in pressure for all joint angles over the total number of movement cycles. There is a contribution to intra-articular pressure of joint capsular compliance and fluid movement into and out of the joint (both of which are time-dependent). The recording of intra-articular pressure in conscious, upright dogs revealed similar pressure levels to those measured in anaesthetized supine dogs. The major determinants of intra-articular pressure in normal dog knee joints include joint size, synovial fluid volume, position of joint, peri-articular tissue and joint anatomy, membrane permeability, capsular compliance, and movement of fluid into and out of the joint.

Mononuclear phagocytes, prostanoids and rheumatoid arthritis

We describe a new, simple procedure for obtaining and studying mononuclear phagocytes from inflammatory synovial fluid. The viability and functional characteristics of these macrophages have been carefully checked. This technique has been used to evaluate the macrophagic synthesis of prostaglandins in 16 patients with evolutive rheumatoid arthritis. Significant amounts of prostaglandins, mainly PGE 2 and TxB 2, are released and increased after zymosan administration. The three tested prostaglandins (PGE 2, PGF 2α and TxB 2) responded in a similar manner. The in vitro PG biosynthesis and the number of harvested adherent cells are negatively correlated with the synovial fluid volume but positively correlated with the disease activity. In fact, we found an heterogeneity among the analyzed macrophages; these can be divided into two populations with marked differences in their PG biosynthesis. The one with the highest synthesis corresponded to the more severe disease.

Reciprocal relationship of synovial fluid volume and oxygen tension.

To investigate the impact of synovial fluid volume on oxygen tension (PO2) and other metabolic correlates, 24 specimens of synovial fluid from the knees of 22 patients were analyzed for volume, number of leukocytes (WBC), pH, PO2, PCO2, glucose, protein, and complement (CH50) levels. Concurrent arterial blood samples were obtained in 21 instances. Synovial fluid PO2 values varied inversely with volumes of synovial fluid (r = -0.54, P less than 0.01), but when patients with rheumatoid arthritis were excluded, the correlation was more significant (r = -0.76, P less than 0.001). When synovial fluid PO2 dropped below 45 mm Hg, intraarticular acidosis resulted. The decrease in pH (r = 0.93, P less than 0.001), the lowering of glucose values (r = 0.89, P less than 0.001), and the rise in PCO2 (r = -0.79, P less than 0.01) can be explained by a shift toward anaerobic metabolism coupled with the impaired elimination of its products. Systemic acidosis and hypoxia were not found. Intraarticular hypoxia most likely represents circulatory imbalance at the level of the synovial membrane, although an inverse relationship of synovial fluid PO2 and WBC was also noted. Complement and protein levels had no correlation with volume, pH, or respiratory gas tensions of synovial fluids. Our data support the importance of the effective blood flow to the joint in maintaining homeostasis. The volume of synovial effusion and the compliance of the joint capsule appear to be important determinants of the articular blood supply.

An objective assessment of synovitis of the knee: measurement of the size of the suprapatellar pouch on xeroradiography.

Measurement of the size of the suprapatellar pouch of the knee appears to be a simple, useful, objective, and reproducible assessment of synovitis of the knee. Changes in the apparent size of the suprapatellar pouch have been shown to correlate closely with the volume of synovial fluid aspirated from the knee and with changes in circumferential measurements. Aspiration of 20 ml of fluid will produce a change in size significant at the 1% level. Lateral xeroradiographs were used in this study, as soft-tissue planes are more closely defined on xeroradiographs than on standard radiographs.

Absorption of Artificial Effusions from Synovial Joints: An Experimental Study in Rabbits

1. The absorption of fluid from the joint cavity was studied by measurement of the flow of Ringer solution or paraffin oil, from an infusion reservoir, into rabbit knee joints at constant pressures between 0 and 25 cm water. 2. Although no oil was absorbed across the synovium, oil flowed continuously into the joint cavity at constant intra-articular pressure. It was concluded that the joint capsule expanded with time (delayed compliance, viscous creep). Viscous creep of the capsule could explain, in part, the poor correlation observed clinically between effusion volume and pressure. 3. The rate of absorption of Ringer solution by the synovium was calculated by subtraction of the volumetric rate of creep from the volume inflow of Ringer solution. The absorption rate increased as a linear function of intra-articular pressure up to 9 cm water but as a much steeper (six-times) function of pressure above 9 cm water (the ‘breaking point’ phenomenon). Since pressure increases upon joint flexion, flexion may minimize synovial fluid volume by promoting fluid absorption. 4. The absorption rate was unaffected by ligation of the lymphatic drainage of the joint, but was reduced to between 79 and 85% by intermittent interruption of blood flow to the joint. Fluid accumulated in connective tissue outside the synovium. 5. It is concluded that these artificial effusions are absorbed partly into the synovial micro-circulation, in accordance with Starling's hypothesis of fluid exchange, and partly into compliant connective tissue outside the joint capsule. The increased sensitivity of flow to pressure above 9 cm water is explained by a progressive reduction in synovial resistance to flow, and implies facilitation of absorption of joint effusions of pressures over 9 cm water.

Immunochemical quantitation of complement components of Clq and C3 in sera and synovial fluids of patients with bone and joint diseases.

The amount of the initiating complement component (Clq) in the classical pathway and the first essential component (C3) in the alternative complement pathway were measured with a single radial immunodiffusion (SRID). A high ionic strength was used corresponding to that of 0 . 25 M NaCl and 0 . 01 M EDTA to avoid nonspecific binding of Clq with immune aggregates. Measurements were made on sera and/or synovial fluids from 165 patients with various bone and joint diseases. Values of Clq and C3 in synovial fluids were also expressed as ratios to that of albumin in the same specimens to avoid the influence of differences in volume of synovial fluid in various diseases, and this appeared to provide a reliable index reflecting pathological conditions. Both serum Clq and C3 levels were raised highly in rheumatoid arthritis, gout, and osteomyelitis, but the extent of the elevation of C3 was less conspicuous. Values of Clq and C3 in synovial fluids also markedly increased in rheumatoid arthritis.

A STORAGE‐LIKE DISEASE WITH SKELETAL INVOLVEMENT IN A DOG

A storage‐like disease in a 14‐month‐old Rhodesian Ridgeback dog is described. Clinically the dog was lame on all legs, and appendicular joint capsules were distended. Radiographically and at necropsy, there was evidence of osteoarthritis, increased volume of synovial fluid, and marked hypertrophy of the synovial membranes. Large mononclear cells with vacuolated cytoplasm were evident in synovial membranes. Large mononuclear cells with vacuolated cytoplasm were evident in synovial membranes. Large mononuclear cells with vacuolated cytoplasm were evident in synovial membranes, bone marrow, liver, lymph nodes, and endocrine glands. Vacuolated cells in lymph nodes stained positively for fat. Transmission electron microscopy revealed empty membrane‐bound cytoplasmic vacuoles. The similarity of this disease to storage diseases in man where arthropathy is a feature is discussed.

An investigation into the validity of subatmospheric pressure recordings from synovial fluid and their dependence on joint angle.

1. Synovial fluid hydrostatic pressures were measured in normal knee (stifle) joints of anaesthetized rabbits using perforated cannulae. Pressures were subatmospheric in seventy out of seventy-two joints, with a mean value of -4.6 cm H2O (range 0 to -12 cm H2O) at joint angles of 120--150 degrees. 2. Similar values were obtained by a wick-in-needle technique (mean -4.0 cm H2O), which along with several other tests indicated that the subatmospheric values were not artifactual. 3. A slow rise in pressure of 1--2 cm H2O per hour in the motionless joint was attributed to a net filtration of fluid into the joint space. 4. Pressure increased as a curvilinear function of joint angle when the joint was flexed passively, the slope of the relationship depending on synovial fluid volume. Pressure also increased on active flexion of the joint, or on passively increasing the tension of soft peri-articular tissues. 5. Positive (above atmospheric) pressures in acutely flexed joints declined with time. Pressures declined less rapidly when synovial fluid was replaced by nonabsorbable paraffin oil. It was concluded that joint fluid can be absorbed by the synovium during acute flexion. 6. Processes which might generate subatmospheric pressures are discussed. The hypothesis is advanced that the flexion-dependent 'trans-synovial pump', possibly in series with a lymphatic pump, may account for the maintenance of a small synovial fluid volume and subatmospheric pressure in the face of a net filtration of fluid from synovial capillaries into the joint space.

Studies of Hydroarthrosis of the knee in old age

The pathogenesis of Hydroarthrosis in old age is still obscure. It is well known that synovial fluid play an important role for nutrition of articular cartilage. In order to clarify the pathogenesis of osteoarthritis and hydroarthrosis in old age, an attempt has been made by author to determine the total protein levels in synovial fluid of patients with osteoarthritis and hydroarthrosis.1) The total protein levels in synovial fluid of osteoarthritis or hydroarthrosis was approximately 2.8g/dl.2) No relation was found between the total protein levels and the volume of synovial fluid.3) The total protein in the synovial fluid in inflammatory osteoarthritis is higher than that in the non-inflammatory osteoarthritis.

Effects of cold and heat on urate crystal-induced synovitis in the dog.

AbstractLocal cooling decreased, while heating increased, the acute inflammation produced by a single injection of urate crystals into dog knees. Synovial fluid leukocyte counts and volume, polymorphonuclear infiltration of synovial membrane, and 133Xe clearance were decreased by cold, and increased by heat. There was good correlation between altered inflammation and vascular changes, but not with enzyme levels, cell death, or leukocyte structural changes. Chronic synovitis from repeated crystal injections was not altered by cold or heat.

Measurement of Synovial Fluid Volume by a Radioisotope Method

Measurement of Synovial Fluid Volume by a Radioisotope Method

Measurement of Synovial Fluid Volume by a Radioisotope Method

The present paper introduces a method for measuring joint fluid volumes using 113mIn-radionuclide and a conventional iodine-measuring system. The method gave an average volume of rheumatoid knee joint effusions of 47 ml. After removal of effusion the residual vol- i uine was 24 ml (48%), on average, thus showing the inefficiency of ordinary joint aspiration. Even after a forced aspiration, 41% of the fluid was left in the joint cavity. The method is recommended to be used in connection with intra-articular therapy for obtaining optimal drug concentrations. An example is presented of the use of the method in dose calculation of 90Y.

The Permeability of Traumatically Inflamed Synovial Membrane to Commonly Used Antibiotics

The diffusion of nine commonly used antibiotics into traumatically inflamed human knees was studied in fifty young men. The antibiotic level in the synovial fluid was found to approximate that in the blood. There was a suggestion that a correlation existed between diffusibility and the molecular weight of the antibiotic tested, as previously reported10,15. The free diffusibility of antibiotics into traumatically inflamed human joints was demonstrated. Therapeutic effectiveness should correlate better with the antibacterial activity obtained in the joint fluid than with the concentration of the antibiotic in micrograms per unit volume of synovial fluid.