Paget's disease of bone: diagnosis and management

[Pathological and metabolic bone diseases: Clinical importance for fracture treatment]

Pathological and metabolic bone diseases are common and relevant occurrences in orthopedics and trauma surgery; however, fractures are often treated as being the illness itself and not seen as the symptom of an underlying bone disease. This is why further diagnostics and systemic treatment options are often insufficiently considered in the routine treatment of fractures. This review focuses on osteoporosis, osteopetrosis, hypophosphatasia and Paget's disease of bone.In patients with osteoporotic vertebral or proximal femur fractures, pharmaceutical treatment to prevent subsequent fractures is an integral part of fracture therapy together with surgical treatment. Osteopetrosis is caused by compromised osteoclastic bone resorption; therefore, even in the face of an elevated bone mass, vitamin D3 supplementation is crucial to avoid clinically relevant hypocalcemia. Unspecific symptoms of the musculoskeletal system, especially together with stress fractures, are typically found in patients suffering from hypophosphatasia. In these patients measurement of alkaline phosphatase shows reduced enzyme activity. Elevated levels of alkaline phosphatase are found in Paget's disease of bone where bisphosphonates are still the treatment of choice.

Diagnosis and management of Paget's disease of bone

OBJECTIVE

To conduct a literature review on the diagnosis and management of Paget's disease of bone.

MATERIALS AND METHODS

This scientific statement was generated by a request from the Brazilian Medical Association (AMB) to the Brazilian Society of Endocrinology and Metabolism (SBEM) as part of its Clinical Practice Guidelines program. Articles were identified by searching in PubMed and Cochrane databases as well as abstracts presented at the Endocrine Society, Brazilian Society for Endocrinology Annual Meetings and the American Society for Bone and Mineral Research Annual Meeting during the last 5 years. Grading quality of evidence and strength of recommendation were adapted from the first report of the Oxford Centre for Evidence-based Medicine. All grades of recommendation, including "D", are based on scientific evidence. The differences between A, B, C and D, are due exclusively to the methods employed in generating evidence.

CONCLUSION

We present a scientific statement on Paget's disease of bone providing the level of evidence and the degree of recommendation regarding causes, clinical presentation as well as surgical and medical treatment.

Current perspectives on bisphosphonate treatment in Paget's disease of bone

Paget's disease of bone is a chronic metabolic bone disease with focal increase in bone turnover. The exact etiology of the disease is uncertain, although genetic and environmental factors are believed to be important. Bisphosphonate is the main class of medication being used to control disease activity via its antiresorptive effect. This review discusses the controversies concerning the use of bisphosphonates in the treatment of Paget's disease of bone, the efficacy of different bisphosphonates in controlling disease activity, and the possible rare side effects of bisphosphonates. Symptoms are the main indication for treatment in Paget's disease of bone. As treatment benefits in asymptomatic individuals remain controversial and nonevidence based, the decision to treat these patients should be individualized to their risk and benefit profiles. There are several trials conducted to evaluate and compare the efficacy of different regimes of bisphosphonates for treating Paget's disease of bone. Most trials used biochemical markers rather than clinical symptoms or outcomes as parameters for comparison. Zoledronate is an attractive option as it can achieve high rates of biochemical remission and sustain long duration of suppression by a single dose. Atypical femoral fracture and osteonecrosis of the jaw are two rare and severe side effects reported, possibly related to the use of bisphosphonates in patients with osteoporosis and malignancy-induced hypercalcemia. As the regimes of bisphosphonates used for treating Paget's disease of bone are different from those two diseases, the risks of developing these two possible side effects are expected to be very low, although this remains unknown. Vitamin D and calcium supplement should be given to patients at risk of vitamin D insufficiency when given zoledronate, as symptomatic hypocalcemia may develop. For those intolerant of bisphosphonates, subcutaneous calcitonin can be used for a limited period due to its associated risk of malignancy.

Thirteen Chinese patients with sporadic Paget's disease of bone: clinical features, SQSTM1 mutation identification, and functional analysis

To increase awareness of the rarity of Paget's disease of bone (PDB) in the Chinese population, we characterized the clinical manifestations and features of 13 Chinese sporadic PDB patients. The clinical features of our Chinese PDB patients show similarities with cases reported in Western countries. The most common lesion sites were the pelvis, femur, and tibia; the next most common lesion sites were the spine and skull. Most patients had a higher serum alkaline phosphatase (ALP) level. Treatment with bisphosphonates was effective. In addition, we screened for PDB-causing mutations and performed a functional analysis in an attempt to elucidate the molecular pathogenesis of PDB. A total of 216 persons, including 13 sporadic PDB patients, three unaffected relatives of 1 patient, and 200 healthy donors, were recruited. All eight exons and exon-intron boundaries of the SQSTM1 gene were amplified by polymerase chain reaction (PCR) and directly sequenced. We identified a 53-year-old man who harbored a heterozygous T-to-C transversion at position 1250 in exon 8 (1250T > C), which resulted in a methionine-to-threonine (ATG > ACG) substitution at codon 404 (M404T). The M404T mutant SQSTM1 protein exhibited increased NF-κB activation and drove a significantly increased number of osteoclast-like cells (OLCs) that formed in response to RANKL and an increased number of OLC nuclei. This is the first report of an SQSTM1 genetic mutation that contributes to the pathogenesis of PDB in Chinese patients. These results may partially explain the mechanism by which this SQSTM1 mutation contributes to the pathogenesis of sporadic PDB in Chinese patients.

Management of patients with Paget's disease: a consensus document of the Belgian Bone Club

Paget's disease of bone (PDB) is a potentially crippling condition. Pain, fracture, spinal stenosis, nerve entrapment, vascular steal syndrome, secondary osteoarthritis, bone deformity, dental problems, deafness, excessive bleeding during orthopaedic surgery, rare sarcomatous degeneration, and hypercalcaemia constitute complications that may impair the quality of life. The therapeutic approach varies from symptomatic (analgesics, anti-inflammatory drugs) to more specific drugs such as increasingly potent bisphosphonates. Studies such as the PRISM study should in the future help to determine the superiority or not of aggressive treatment over symptomatic treatment in the prevention of complications. Various oral and/or intravenous (i.v.) bisphosphonates have been tested and are currently on the market. The most recently available nitrogen-containing bisphosphonate, i.v. zoledronic acid, is the most potent therapy available for the treatment of PDB. Its therapeutic efficacy, its long-term effect on biologic activity and its good tolerance currently supports its use as a first-line therapeutic option in patients suffering from PDB.

[Treatment of Paget's disease of bone: importance of the zoledronic acid]

Paget's disease is a localised monostotic or polyostotic bone disease of unknown origin. It may be caused by a slow viral infection and/or genetic factors. It is characterised by increased bone remodelling and an initially excessive osteoclastic bone resorption, followed by a secondary increase in osteoblastic activity, leading to replacement of the normal bone by a disorganized, enlarged, and weakened osseous structure prone to deformities and fractures. The disease may be diagnosed by radiography, scintigraphy and biochemical tests. The primary aim of treatment is to reduce pain and risk of developing long-term complications. Potent antiresorptive drugs are now available, which control the increased bone remodelling and have led to a dramatic improvement in treatment. Zoledronic acid, a new generation of bisphosphonates, has the advantage of great potency and long duration of remission and a short infusion time.

Paget's disease of bone

Paget's disease of bone is a focal disorder of bone remodeling accompanied initially by an increase in bone resorption, followed by a disorganized and excessive formation of bone, leading to pain, fractures and deformities. It exhibits a marked geographical variation in its prevalence. In Brazil it predominantly affects persons of European descent. The majority of the reported cases of the disease in Brazil are from Recife, owing to its peculiar mixed European colonization over approximately four centuries. The etiology is complex and involves both genetic and environmental factors. The disease is often asymptomatic and diagnosis is usually based on biochemical markers of bone turnover, radionuclide bone scan and radiological examination. Bisphosphonates, in particular zoledronic acid, are regarded as the treatment of choice for Paget's disease of bone.

Zoledronic acid in the treatment of Paget's disease and other benign bone disorders

Zoledronic acid is a potent bisphosphonate widely used to counteract cancer-related bone loss. Once-yearly or even less frequent doses may be an effective therapy for benign bone disorders and may also result in improved compliance and tolerability. Data from two Phase III clinical trials have demonstrated the efficacy and safety of zoledronic acid in the treatment of Paget's disease of bone. Other studies have provided preliminary evidence for the utility of zoledronic acid in osteoporosis and other benign bone disorders. The major adverse effects associated with zoledronic acid infusions are transient flu-like symptoms. Ongoing clinical trials will provide key data on the ability of this agent to treat osteoporosis and prevent fractures in high-risk patients and on its long-term safety profile.

Paget's disease of bone in a Chinese patient: A case report and review of the literature

Although it is fairly common in the Western countries, Paget's disease of bone is very rare in Chinese individuals. Through an extensive literature search, only 8 Chinese Paget's disease cases were found in the English language literature and all were reported in local medical journals of Asia that may not be accessible to international readers. To enhance the awareness of the rarity of Paget's disease in Chinese individuals to pathologists worldwide, we present a case of Paget's disease in a 54-year-old Chinese male. We also compare the clinical features of Paget's disease reported in Chinese patients to Paget's disease reported in the Western countries. No familial cases and no malignant transformation are found in the reported cases of Paget's disease in Chinese patients. In addition, more often skull involvement, higher frequency of monostotic cases, and symptomatic cases are observed in this limited number of Paget's disease cases reported in Chinese individuals.

Maladie de Paget, exploration et surveillance

Paget's disease is a progressive bone disease, characterized by bone hypertrophy and increased bone resorption. The pain and deformity that characterize its clinical course are not simple to assess, but it has a characteristic radiographic appearance. In most cases, treatment can be monitored through biological markers of bone turnover. Total alkaline phosphatase is the best marker and measurement of collagen breakdown products is useful in difficult cases. The goal of treatment is the normalization of these biological markers, to prevent complications of the disease.

Paget's disease of bone in patients younger than 40 years

Paget's disease of bone, although common in the United States, is relatively rare in patients younger than 40 years. In a large archival series, 10% of patients with Paget's disease of bone were younger than 40 years. Pain followed by pathologic fracture was the most common presenting complaint in this group of patients. There was no gender difference comparing the younger group with the older group of patients. Of the 521 patients in this series, only 10 were African-American; the others were Caucasians. Seven African-American patients were in the group of patients who were younger than 40 years. Appendicular and monostotic bone involvement was more frequent in the younger age group although these differences were not statistically significant. The incidence of malignant transformation in pagetic bone was high (30.3%), and is a reflection of the high volume of uncommon tumor referrals to our consultation service. However, there were no cases of associated malignancies in the group of patients younger than 40 years.

Two cases of monostotic Paget's disease: effects of bisphosphonate

We report two cases of monostotic Paget's disease which were effectively treated with bisphosphonate. Case 1 was a 60-year-old female. Medical examination revealed high alkaline phosphatase (ALP) levels making her visit our clinic. Hematological examination showed high levels of ALP isozyme 3 and bone metabolism markers, and bone scintigraphy demonstrated strong accumulation of 99mTc on the skull. With the diagnosis of monostotic Paget's disease of the skull, treatment with bisphosphonate (etidronate) was started. The response to etidronate was good and after 12 weeks of treatment, the ALP levels decreased to about 26% of the levels before treatment, without the appearance of any symptoms or lesion development. One year and three months later, ALP increased again, and etidronate administration was resumed. However, four years after the diagnosis of the disease, etidronate became ineffective and oral administration of alendronate, a stronger bisphosphonate, was started at 5 mg/day. The patient responded favorably to the bisphosphonate and is still under observation. Case 2 was a 71-year-old female. High ALP levels were found during the follow-up of type 2 diabetes, and the case was diagnosed as monostotic Paget's disease of the pelvis based on bone metabolism markers and bone scintigraphy. Etidronate treatment at 200 mg/day resulted in the improvement of bone metabolism markers and bone scintigraphy findings. When she died of colon cancer twelve months later, with no marked progress of the Paget's disease of bone observed clinically.

Symptomatic and Scintigraphic Improvement after Intravenous Pamidronate Treatment of Paget’s Disease of Bone in Patients with Normal Serum Alkaline Phosphatase Levels

OBJECTIVE

To describe three patients with symptomatic Paget's disease of bone who presented with normal levels of serum alkaline phosphatase.

METHODS

We present three cases of Paget's disease of bone and chronicle the laboratory, scintigraphic, and clinical findings relative to treatment with intravenously administered pamidronate.

RESULTS

Although measurement of serum total alkaline phosphatase usually provides a general indication of bone turnover in Paget's disease, about 15% of patients present with normal serum alkaline phosphatase levels. Nonetheless, these patients may have active Paget's disease when assessed with bone scintigraphy or urinary markers of bone resorption. All three study patients had xray findings characteristic of Paget's disease of bone, increased uptake of radiotracer material on bone scans, and elevated levels of urinary markers of bone resorption but normal alkaline phosphatase levels. They were treated with intravenously administered pamidronate, 60 mg once weekly for 2 to 3 consecutive weeks. After treatment, the serum alkaline phosphatase level decreased by 19 to 36%, markers of bone resorption normalized, bone scans showed improvement, and bone pain resolved.

CONCLUSION

Pagetic activity in bone and related clinical manifestations may be present in the setting of a normal serum alkaline phosphatase level. Appropriate therapy should not be withheld because of the normal alkaline phosphatase.

Flavonoids and antioxidant capacity of Georgia-grown Vidalia onions

Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia, Georgia, were analyzed for flavonoid content. A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for quantification. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on comparison of its retention time and UV spectra with those of pure commercial standards. Three major flavonoids, kaempferol, myricetin, and quercetin, were identified and quantified. Quercetin was the major flavonoid (7.70-46.32 mg/100 g fresh weight, FW) present in all varieties, followed by myricetin (2.77-4.13 mg/100 g FW). Minor quantities of kaempferol (1.10-1.98 mg/100 g FW) were also detected. The total polyphenols and Trolox equivalent antioxidant capacity (TEAC) ranged from 73.33 to 180.84 mg/100 g FW and 0.92-1.56 microM TEAC/g FW, respectively. A positive but weaker correlation was obtained for total polyphenols versus antioxidant capacity. Nevertheless, a stronger correlation (r(2) = 0.34) was obtained between flavonoid content versus antioxidant capacity. The data indicate that Vidalia onions are a rich source of quercetin, and they also contain myricetin and kaempferol.

Paget's disease of the elderly

Paget's disease of bone affects 10% of those surviving to the eighth decade of life. Relatively easy to diagnose, treatment decisions are more complex. Surgery and immobilization present unique challenges often requiring prophylaxis to prevent activation/exacerbation of the disease.

The treatment with alendronate in hemifacial spasm associated with Paget's disease of bone

The association of Paget's disease of bone and hemifacial spasm has rarely been reported. Hemifacial spasm is often associated with compression of the facial nerve by a vascular loop at the point where the nerve leaves the brainstem before traversing the cerebellopontine angle. It is believed that narrowing of the cerebellopontine angle cistern caused by Paget's disease increases the chance of vascular compression of the facial nerve. Whilst specific antipagetic therapy such as calcitonin has been used with good response in hemifacial spasm associated with Paget's disease, the usefulness of the newer bisphosphonates is not clear. A 65-year-old woman with hemifacial spasm associated with Paget's disease was treated with alendronate, and the hemifacial spasm became very infrequent 4 months after commencement of the therapy.

Treatment of patients with Paget's disease of bone

Paget's disease is a progressive bone disease, monostotic or polyostotic, characterised by hypertrophy of affected bones and accelerated disorganised bone remodelling. It results in bone deformities and pain, with a risk for articular and neurological complications, and fractures. The risk of complications, and thus the therapeutic decision, is a function of the age of the patient, and the severity and the activity of the disease. Bisphosphonates are first-line therapy for Paget's disease, and the advent of the new bisphosphonates permits a dramatic improvement in treatment. The optimal treatment regimen should obtain normalisation or quasi-normalisation of markers of bone remodelling. This result has the potential for a long-term control of the disease.

Treatment of Paget's disease of bone with alendronate

In summary, the clinical efficacy studies provide clear evidence that treatment with oral alendronate markedly suppresses bone turnover and produces clinical improvement in pagetic patients. Serum alkaline phosphatase was greatly decreased by treatment, and the response to alendronate was superior to that observed for currently available therapies such as etidronate and calcitonin, which usually reduce alkaline phosphatase, on average, by 40%-50%. Alendronate also markedly reduced urinary resorption markers and induced radiologic improvement of pagetic osteolysis. A majority of alendronate-treated patients normalized their serum alkaline phosphatase by month 6. This observation is likely to be relevant to the duration of response to treatment, as previous studies have shown that the degree of suppression of alkaline phosphatase after antiresorptive treatment correlates with the duration of remission. Therefore, patients who responded to treatment with alendronate, especially those who normalized their alkaline phosphatase levels, are likely to maintain the biochemical remission for several years. Indeed, preliminary unpublished data seem to indicate that alendronate is capable of producing long-term biochemical remission in the majority of patients. In addition to its efficacy, the safety and tolerability profile of alendronate 40 mg/day was very favorable and, overall, comparable to that of placebo.

Bisphosphonates in bone diseases

Bisphosphonates are a class of drugs which are strongly attracted to the bone where they influence the calcium metabolism, mainly by inhibition of the osteoclast-mediated bone resorption. This property makes these compounds suited for the treatment of several diseases of the bone. In Paget's disease, several bisphosphonates can reduce bone pain and decrease the bone turnover 60-70%. Cyclical oral etidronate and daily oral alendronate both proved to reduce the vertebral fracture rate for postmenopausal osteoporotic woman, while most investigated bisphosphonates can increase spinal bone mass in osteoporosis. Bisphosphonates can help lowering serum calcium and reverse skeletal complications in malignancy mediated bone diseases. Oral and intravenous administration of therapeutic doses is relatively safe. In general, gastrointestinal disturbances are described most often and the oldest, least potent, bisphosphonate etidronate can induce osteomalacia. The various characteristics of bisphosphonates: physicochemical, biological, therapeutic and toxicological, vary greatly depending on the structure of the individual bisphosphonate. Even small changes in the structure can lead to enormous differences in potency. Overall, this class of drugs offers several prospects for the future.