The use of radioisotopes in normal and diseased joints

Uptake and biodistribution of 99mtechnetium methylene-[32P] diphosphonate during endosteal healing around titanium, stainless steel and hydroxyapatite implants in rat tibial bone

Early evaluation of intraosseous implant success and failure is critical, but, until now, there have been no reliable systems of measurement. The present study assessed whether the use of 99mtechnetium methylene-[32P]diphosphonate (99mTcMD32P), a marker for both bone formation and mineralization, can indicate if an implant is bone-bonding or non-bonding. Moreover, this study examined how bone-bonding (titanium and hydroxyapatite) and non-bonding (stainless steel) implants affected the normal healing of bone after marrow ablation, as measured by uptake of 99mTc and 32P. Titanium, hydroxyapatite and stainless steel implants were placed in the right tibiae of Sabra strain rats following ablation of the marrow, and 99mTcMD32P was injected 18 h before harvest. AT 3, 6, 14, 21 and 42 d (and in some experiments, on days 28 and 35) post-injury, the treated and contralateral tibiae were removed and cleaned of soft tissue. The uptake of 99mTc and 32P was measured in the whole bone, as well as in its organic and inorganic phases. Effects of the implants were assessed by comparing the treated to the untreated tibia in each rat. The distribution of 99mTc and 32P varied with each implant. After the insertion of titanium, increased 99mTc uptake was seen in whole bone and in the inorganic and organic phases at days 6-14. 32P uptake in whole bone and in the inorganic phase increased only at day 6, and 32P uptake was decreased in the organic phase at that time. In tibiae implanted with hydroxyapatite, 99mTc and 32P uptake was seen in the whole bone at days 6 and 14. While 99mTc uptake was increased in both the organic and inorganic phases, 32P uptake into the organic phase was decreased at both day 6 and day 14. In tibiae implanted with stainless steel, effects were observed only on day 6. The increased 99mTc uptake in whole bone reflected increases in both the organic and mineral phases. Increased 32P uptake was observed in whole bone as well, due to an increase in the 32P uptake in the mineral phase only; incorporation of 32P in the organic phase was comparable to that found in the contralateral limb. The results of this study indicate that implants alter bone healing, as indicated by the uptake of 99mTc and 32P in the different bone compartments. Moreover, decreased 32P uptake by the organic phase in the presence of bone-bonding implants suggests that cleavage of 99mTcMD32P into its technetium and methylene diphosphonate moieties was inhibited, perhaps as a function of the onset of calcification in the newly synthesized osteoid. The effect of the implants on bone healing was observed on days 6-14, when active bone formation and mineralization were occurring, supporting the hypothesis that these materials events associated with initial calcification. Uptake of 99mTc varies as a function of time, and uptake of 32P varies with time and distribution in the mineral or organic phase of bone, suggesting that these parameters may be useful as indicators of bone-bonding.

A combined method for quantitative pertechnetate scintigraphy in the diagnosis of sacroiliitis. A controlled study

A simplified scintigraphic technique for the assessment of sacroiliitis is described. It is based on the fact that an inflamed joint shows increased perfusion activity after administration of sodium pertechnetate. The sacroiliac joints are located by injection of a small amount of bone-seeking activity. Thereafter the pertechnetate activity is injected and the bone-seeking activity subtracted. The perfusion (pertechnetate) activity of the sacro-iliac joints is related to the activity of the large vessels of the thigh. Normal values have been established based on a study of 39 healthy controls. The method has been applied to 2 groups of patients with clinical sacroiliitis, one with and one without radiographical signs of sacroiliitis. The patients with radiographically verified sacroiliitis showed significantly higher values than the controls. The technique offers a high specificity and a high positive predictive value.

Plasma and synovial fluid kinetics of flurbiprofen in rheumatoid arthritis

Clinical assessment, plasma and synovial fluid kinetics were studied in 29 rheumatoid patients receiving 100 mg flurbiprofen twice daily. Clinical assessment and pharmacokinetic measurements varied widely within the group of patients. The average values for plasma clearance, volume of distribution and elimination halflife of flurbiprofen were 0.65 +/- 0.24 ml min-1 kg-1, 0.160 +/- 0.093 l kg-1 and 3.1 +/- 1.7 h, respectively. Synovial fluid drug concentrations peaked later and were lower than corresponding plasma concentrations: 5.2 h and 4.4 mg l-1 as against 1.49 h and 12.5 mg l-1, respectively. At 48 h after an oral dose of flurbiprofen, all the drug had been cleared from the synovial fluid. Synovial fluid drug concentrations were not related to synovial fluid albumin concentration or pH. There was a weak relationship between synovial fluid drug concentration and the thermographic measurements of disease activity. The fractions of flurbiprofen not bound to protein in synovial fluid and plasma were not significantly different. A simple model is proposed to account for the plasma and synovial fluid pharmacokinetics.

A method for combined quantitative pertechnetate and bone scintigraphy of the sacro-iliac joints

A technique for combined quantitative bone and pertechnetate (perfusion) scintigraphy of the sacro-iliac joints is described. The method is based on localization of the joints in the image obtained after the injection of a small dose of bone-seeking technetiated methyldiphosphonate. This image is later subtracted from the image obtained after the injection of pertechnetate. This combination of methods is believed to constitute a more accurate way of localizing the sacro-iliac joints than the previously used method, based on fluoroscopy. A minor comparison between these two ways of localising the joints is reported too. It is possible that the combination of quantitative bone and pertechnetate scintigraphy will improve the overall sensitivity of the scintigraphic method.

Quantitation of arthritis by 99mTc-uptake measurements in the mouse knee-joint: correlation with histological joint inflammation scores

A method is described to detect and to quantitate inflammation in knee-joints of mice. Approximately 10 muCi 99mTechnetium pertechnetate (99mTc) is injected subcutaneously in the neck region and the accumulation of the short-lived isotope in the knee-joint is detected by external gamma counting. 99mTc-uptake values correlate well with histological grading of joint inflammation at various intervals after induction of the inflammation. The method can be used to detect changes in activity of unilateral as well as bilateral joint inflammation using either the ratio of 99mTc uptake in the right knee versus that in the left knee or absolute 99mTc-uptake values.

A comparison of 99mTc-MDP and 99mTc-pertechnetate by computerized quantitative joint scintigraphy

Computerized, quantitative joint scintigraphies were performed using both 99mTc-MDP and 99mTc-pertechnetate. 17 joint pairs with asymmetric active arthritis were selected for the study. The joint activity ratio was calculated by dividing the curve peak value of the inflamed joint by the curve maximum of the contralateral symptomless joint. A very high joint activity ratio with 99mTc-MDP was observed in the case of septic arthritis with osteolytic lesions. In all the rheumatoid joints the activity ratios were higher with 99mTc-MDP than with 99mTc-pertechnetate. In reactive arthritis the mean joint activity ratio was equal with both tracers. It appears that 99mTc-MDP is more sensitive in detecting active rheumatoid arthritis than 99mTc-pertechnetate and that high 99mTc-MDP values might be prognostic of destructive changes.

Clinical therapeutic trial of aspirin and azapropazone in rheumatoid arthritis when prescribed singly and in combination

A double-blind, crossover trial was carried out to assess the clinical efficacy of 3.6 g aspirin, 1200 mg azapropazone and the two drugs together in 24 adult patients with classical or definite rheumatoid disease. Pain score, morning stiffness and patients' assessment of pain were significantly improved for each drug regimen when compared to placebo. There was no significant difference among the individual drug regimens. Azapropazone was the best drug regimen in terms of improving pain score, morning stiffness and patient assessment of pain, but this was not statistically significant. It is concluded that there is no justification for prescribing aspirin with azapropazone in patients with rheumatoid disease.

Effects of corticosteroids and local anaesthetics applied directly to the synovial vascular bed

The effects of intra-articular injection of triamcinolone hexacetonide on the rate of clearance of radioactive xenon (133Xe) was studied in 11 patients with rheumatoid arthritis. No effect of the corticosteroid injection was observed, which suggests that the drug has no immediate effect on synovial blood vessels.

A double-blind, crossover trial of mefenamic acid, sulindac and flurbiprofen in rheumatoid arthritis

A double-blind crossover trial was carried out in 24 patients to compare the effects of mefenamic acid, flurbiprofen, sulindac and placebo. Each drug was given for 2 weeks, the treatment sequence being randomized. Daily doses were 1500 mg mefenamic acid, 150 mg flurbiprofen or 150 mg sulindac. All of the active drugs were significantly superior to placebo in terms of pain score, patients' assessment, articular index of joint tenderness, and duration and severity of morning stiffness. There was improvement in grip strength compared with placebo, but the differences were not statistically significant with sulindac. There was slight reduction in joint circumference but this was only statistically significant in the right hand with flurbiprofen and sulindac. No significant differences were found in technetium uptake in knee joints. The three drugs appeared to be equally effective and tolerated, and no significant differences were noted.

Digital skin capillary flow of xenon-133 in rheumatoid arthritis

An atraumatic method for measuring digital capillary blood flow with(133)xenon is described here. It has the advantage of not requiring the handling of xenon in the gaseous phase, and is a comfortable procedure for the patient. A study of rheumatoid patients without overt vaculitis, and controls showed similar values, suggesting that despite digital deformities, the digital blood flow of the usual rheumatoid is adequate.

The effects of prostaglandins PGE1, PGE2, PGF1a, and PGF2alpha on canine synovial perfusion

In these experiments we have examined the effects of PGE1, PGE2, PGF1alpha and PGF2alpha on synovial perfusion in the normal canine synovial microcirculation. The effects of the drugs on synovial perfusion were determined indirectly from the changes produced in the rate of clearance of 133Xenon from the joint by their intra-articular injection. Prostaglandins PGE1 and PGE2 were found to be strongly vasodilator with PGE1 being the more active. PGF1alpha appeared to have little or no vasoactive properties in doses up to 1 ugm. (2.8 times 10(-5M)) in our preparation while PGF2alpha was vasodilator at this high dosage only. Neither SC19920 nor diphloretin phosphate antagonished the effects of PGE1 in these experiments.

Histamine receptors in the synovial microcirculation

This study was designed to investigate the respective roles of H(1) and H(2) receptors in the control of the microcirculation by examining the effectiveness of the H(2) receptor antagonist metiamide (Met.) and H(1) receptor antagonist mepyramine is blocking the action of histamine on synovial perfusion. Synovial perfusion was monitored indirectly by calculating the half-life (T1/2 min.) of the clearance rate of 133-Xe from canine diarthrodial joints. The 133-Xe clearance rate, unaffected by metiamide alone, was consistently increased by histamine alone. Metiamide produced a dose related effect on the histamine response with consistent abolition of response at high dose ratios of metiamide to histamine variable response at intermediate and a pronounced histamine response at low dose ratios. Mepyramine produced no such antagonism of the histamine response and in certain doses, by itself caused an increase in 133-Xe clearance rate. This effect of mepyramine was thought to be related to its histamine releasing properties a view supported by the reduction in this vasodilator response following certain doses of metiamide. The response of the 133-Xe clearance rate to histamine returned approximately one hour after treatment with metiamide (500 mug) and metiamide did not antagonise the effects of alpha and beta adrenergic agents on the 133-Xe clearance rate. Thus, this study has provided evidence for the presence of H(2) but not H(1) receptors in the synovial microcirculation.