Can clodronate be effective in the treatment of disabling hydroxyapatite crystal-deposition disease? A report of two cases.

Hydroxyapatite crystals are often deposited in the vicinity of joints, where they can cause a clinical periarthritis. Clodronate is a first-generation bisphosphonate that has the ability to reduce ectopic calcifications. Two women were affected by disabling calcific periarthritis of the shoulders lasting for years and resistant to any traditional drug (including glucocorticoids), infiltration and surgical treatment. We treated both patients with low-dose methylprednisolone added to intramuscular clodronate at the daily dose of 100 mg administered for 20 days every 3 months for 5 cycles (18 months). In both cases, the results were clinically evident within 1 month, showing a significant reduction in pain and disability. After 18 months, the result was furthermore radiologically evident in both cases with a great reduction in the size of calcifications. These improvements were still present at follow-up after 7 and 5 years with complete functional recovery.