Paget's disease of the spine and its management

A review of the literature was conducted to study the pathomechanics by which Paget's Disease of bone (PD) alters the spinal structures that result in distinct spinal pathologic entities such as pagetic spinal arthritis, spinal stenosis, and other pathologies, and to assess the best treatment options and available drugs. The spine is the second most commonly affected site with PD. About one-third of patients with spinal involvement exhibit symptoms of clinical stenosis. In only 12-24% of patients with PD of the spine is back pain attributed solely to PD, while in the majority of patients back pain is either arthritic in nature or a combination of a pagetic process and coexisting arthritis. Neural element dysfunction may be attributed to compressive myelopathy by pagetic bone overgrowth, pagetic intraspinal soft tissue overgrowth, ossification of epidural fat, platybasia, spontaneous bleeding, sarcomatous degeneration and vertebral fracture or subluxation. Neural dysfunction can also result from spinal ischemia, when blood is diverted by the so-called "arterial steal syndrome". Because the effectiveness of pharmacologic treatment for pagetic spinal stenosis has been clearly demonstrated, surgical decompression should only be instituted after failure of antipagetic medical treatment. Surgery is indicated as a primary treatment when neural compression is secondary to pathologic fractures, dislocations, spontaneous epidural hematoma, syringomyelia, platybasia, or sarcomatous transformation. Since, in the majority of cases with pagetic spinal involvement, there are also coexisting osteoarthritic changes, antipagetic medical treatment alone may be disappointing. Therefore, one must be careful before attributing low back pain to PD alone. Five classes of drugs are available for the treatment of PD: bisphosphonates, calcitonins, mithramycin (plicamycin), gallium nitrate, and ipriflavone. Bisphosphonates are the most popular, and several forms have been investigated, but only the following forms have been approved for clinical use: disodium etidronate, clodronate, aledronate, risedronate, neridronate, pamidronate, tiludronate, ibadronate, aminohydroxylbutylidene bisphosphonate, olpadronate, and zoledronate. Several of these forms are still under investigation.