Synovial irritants: crystals, microbes and others - their implications for diagnosis, pathogenesis and therapy

An overview is presented of the types of foreign matter that can cause inflammation within joints together with their diagnosis, how they cause disease, and treatments. Crystals may be deposited within the joint, the most common of which is urate crystals, the cause of gout. Treatment is available to dissolve urate crystals and the crystal deposits that sometimes occur with kidney dialysis but not other types of crystals. Joint inflammation resulting from infection may be difficult to diagnose with without biopsy of the joint membrane and specialized laboratory techniques. The most common entry is via the circulation. Pathogens may cause inflammation by infecting cells, producing toxins, or triggering an immune response. Antibiotics and drainage usually effect cure, although some pathogens are recalcitrant. Artificial joints can introduce foreign bodies through wear. Materials should be used that do not create this problem.