'Joint bends' (a deep aching or intense throbbing periarticular pain) most often affect the upper limbs, particularly the shoulder, asymmetrically in recreational divers. In caisson workers bends in the lower limbs, particularly the knee, predominate. The pain is probably produced by bubbles formed in well-innervated and non-compliant tissues like tendons and tendinous capsules. Tendons may have low and even intermittent blood flow, limiting the rate of gas clearance during ascent and thus favoring bubble formation.
'Skin bends', manifested as pruritus and urticaria affecting the hands, wrists, and trunk, are caused by subcutaneous microbubbles probably combined with a localized inflammatory reaction. Sometimes skin bends are accompanied by marbling or mottling of the affected skin area (cutis marmorata). Localized soft tissue swelling is believed to be due to obstruction of lymphatic vessels by microbubbles.
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