The effect of contrast media on the synovial membrane.

To examine the effect of intra-articular injection of contrast media, sorbitol and normal saline on the synovial membrane. Sixty three rabbits (126 knees) were used in this study. We injected the knees with amidotrizoate, ioxaglate, iopamidol, iotrol and diluted gadolinium-DTPA (2 mmol/l). Normal saline and sorbitol 27.25% were used for comparison. A histological and histochemical examination of the knees was carried out 1, 2, 10, 20, 30, 40 and 60 days after the injection. On histological examination, the knees injected with normal saline, ioxaglate and gadolinium-DTPA had a normal appearance. Intra-articular injection of amidotrizoate, iopamidol, iotrol and sorbitol caused early, mild and transient histological changes of the synovium (synovial hyperplasia, infiltration by leucocytes). Furthermore, the knees injected with amidotrizoate presented with late, extensive histological changes (severe synovial hyperplasia, moderate vascular dilatation, severe infiltration by leukocytes). The results suggest that the chemical structure and not the osmolality of the contrast media is the main cause for the histological changes of the synovium.