No osteonecrosis in jaws of young patients with osteogenesis imperfecta treated with bisphosphonates

Bisphosphonate-associated osteomyelitis of the jaw: guidelines for practicing clinicians

OBJECTIVE

To evaluate the literature and discuss the risk factors, mechanisms, pathophysiologic aspects, and recommended management of bisphosphonate-associated osteomyelitis of the jaw (BAOMJ).

METHODS

More than 350 published articles, case reports mentioning BAOMJ, and independent histology slides from BAOMJ lesions were reviewed critically. The most pertinent publications are cited and discussed.

RESULTS

The incidence of BAOMJ increases after extraction of teeth, dentoalveolar surgical procedures, or recent oral trauma leading to exposed maxillary or mandibular bone. Contributory factors include poor oral hygiene, oral infections, periodontal disease; recent or ongoing corticosteroid administration or chemotherapy; compromised immune status; diabetes or vascular insufficiency; old age; chronic diseases; and malignancies. On average, 1 of every 100,000 patients treated with bisphosphonates orally for osteoporosis or Paget disease of bone may develop BAOMJ-like lesions. Patients with cancer often receive bisphosphonate doses 10 times or higher, and also more frequently, than those used in patients with osteoporosis or Paget disease of bone. Therefore, greater frequency of administration of bisphosphonates, higher dosages, and prolonged use (that is, for more than 2 years) are likely to be factors triggering BAOMJ.

CONCLUSION

The association of bisphosphonate therapy with BAOMJ is rare in noncancer patients and is likely to be a class effect that may occur with use of any bisphosphonate. Whether patients with cancer require such a high frequency of intravenously administered bisphosphonates needs to be investigated. Following established guidelines can decrease the risks of BAOMJ in vulnerable patients. Rather than necrotic bone, current evidence supports an infectious and perhaps immunologic underlying cause for BAOMJ. The estimated incidence of BAOMJ among noncancer patients receiving bisphosphonates is about 0.001%, whereas among patients with cancer receiving intravenous bisphosphonate therapy the incidence is between 0.5% and 4%, depending on the dose, frequency, and duration of therapy (on average, approximately 2%). Nevertheless, the benefits of bisphosphonates far outweigh the risks.

Type I osteogenesis imperfecta and multiple osteochondromas in the same child

A male infant showed a humeral diaphysis fracture at 5 months of age and a distal tibial physis fracture at 2 years of age. A specialized consultant ruled out child abuse. This child had the characteristic features of type I osteogenesis imperfecta: blue sclerae, osseous fragility, and presumably autosomal dominant inheritance, as his father suffered from similar disorders. Later on, multiple painful osteochondromas were also found and some of these were surgically treated. The child's mother showed several peripheral osteochondromas. We describe the follow-up of this patient up to the age of 18 years. To our knowledge, the fortuitous association of these two inherited conditions has not been reported in medical literature.

Dramatic pain relief and resolution of bone inflammation following pamidronate in 9 pediatric patients with persistent chronic recurrent multifocal osteomyelitis (CRMO)

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory, non-infectious osteopathy that affects predominantly patients </= 18 years of age. There is no uniformly effective treatment. Our objective is to describe clinical, magnetic resonance imaging (MRI), and bone resorption response to intravenous pamidronate in pediatric CRMO.

METHODS

We report our prospectively documented experience with all CRMO patients treated with pamidronate between 2003 and 2008 at a tertiary pediatric centre. Pamidronate was administered as intravenous cycles. The dose of pamidronate varied among subjects but was given as monthly to every 3 monthly cycles depending on the distance the patient lived from the infusion center. Maximum cumulative dose was </= 11.5 mg/kg/year. Pamidronate treatment was continued until resolution of MRI documented bone inflammation. Visual analog scale for pain (VAS) and bone resorption marker urine N-telopeptide/urine creatinine (uNTX/uCr) were measured at baseline, preceding each subsequent pamidronate treatment, at final follow-up, and/or at time of MRI confirmed CRMO flare. MRI of the affected site(s) was obtained at baseline, preceding every 2nd treatment, and with suspected CRMO recurrence.

RESULTS

Nine patients (5 F: 4 M) were treated, with a median (range) age at treatment of 12.9 (4.5-16.3) years, and median (range) duration of symptoms of 18 (6-36) months. VAS decreased from 10/10 to 0-3/10 by the end of first 3-day treatment for all patients. The mean (range) time to complete MRI resolution of bone inflammation was 6.0 (2-12) months. The mean (confidence interval (CI)) baseline uNTX/uCr was 738.83 (CI 464.25, 1013.42)nmol/mmol/creatinine and the mean (CI) decrease from baseline to pamidronate discontinuation was 522.17 (CI 299.77, 744.56)nmol/mmol/creatinine. Median (range) of follow-up was 31.4 (24-54) months. Four patients had MRI confirmed CRMO recurrence, which responded to one pamidronate re-treatment. The mean (range) uNTX/uCr change as a monthly rate from the time of pamidronate discontinuation to flare was 9.41 (1.38-19.85)nmol/mmol/creatinine compared to -29.88 (-96.83-2.01)nmol/mmol/creatinine for patients who did not flare by the time of final follow-up.

CONCLUSION

Pamidronate resulted in resolution of pain and MRI documented inflammation in all patients. No patient flared while his/her uNTX/uCr remained suppressed. We propose that pamidronate is an effective second-line therapy in persistent CRMO.

Osteonecrosis of the jaw: who gets it, and why?

Osteonecrosis of the jaw (ONJ) is now defined by the presence of exposed bone in the mouth, which fails to heal after appropriate intervention over a period of six or eight weeks. It is commonly precipitated by a tooth extraction in patients treated with zoledronate, pamidronate or a combination of these agents, for the management of myeloma, breast cancer or prostate cancer. In patients with these malignancies who are treated with bisphosphonates, the overall prevalence is about 5%. There is a need to clearly delineate the incidence of ONJ in osteoporosis patients treated with bisphosphonates, and in appropriate control populations. Based on current evidence, the risk of ONJ in osteoporosis appears to be comparable to that in the general population. It is likely that ONJ results from direct toxicity to cells of bone and soft tissue from high potency bisphosphonates, probably acting through their effects on the mevalonate pathway. The bone in ONJ lesions does not appear to be 'frozen', rather there is very active resorption present, probably stimulated by local infection. This is likely to result in the local release at high concentrations of bisphosphonates. Management focuses on prevention, treatment of infection and cessation of bisphosphonates. The role of surgery is unclear.