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The treatment of a single hand swelling with loss of strength depends on the cause. Hence this has to be found out first. The various causes are carpel tunnel syndrome, inflammation of the tendon of the hand due to repetitive work, gout, lymphangitis, deep vein thrombosis, osteoarthritis and rheumatoid arthritis. You need to consult a doctor and rule these out by blood tests, X-rays, nerve conduction studies, rheumatoid factor, ESR, etc.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!