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.