The medical treatment of eight patients with paraparesis associated with Paget's disease of the vertebrae is described. Treatment, for 3 to 87 months, with calcitonin or with diphosphonates produced marked clinical improvement in seven of these patients. From this series and a review of 19 additional case reports it is concluded that favourable clinical response is seen in about 90 per cent of patients, and that this may occur very rapidly. Results are as good or better than those obtained by surgical decompression. It seems possible that paraparesis in some cases may be due to diversion of blood supply from the spinal cord to the highly vascular Pagetic bone giving rise to a vascular "steal" syndrome. It is suggested that medical treatment should be used more widely to avoid or delay the need for operation and reduce the risks of recurrence. These patients, however treated, require lifelong follow-up because relapses are common.

The clinical features of eight patients with myositis ossificans progressiva are described and the effects of treatment with the diphosphonate EHDP, together with surgical removal of ectopic bone, are assessed. Early correct diagnosis remains unusual, mainly because the significance of the short great toes is unrecognised, and because myositis may be mistaken for bruising, sarcoma or mumps. The diphosphonate disodium etidronate (EDHP) was given to all patients in an attempt to suppress calcification of new lesions; in five of them ectopic bone was removed during the treatment. EHDP sometimes delayed the mineralisation of newly formed bone matrix after surgical removal but this delay could not be predicted. The variable effect of EHDP may depend particularly on the amount absorbed and on the activity of new bone formation.