Should Bisphosphonates be Continued Indefinitely? An Unusual Fracture

in a Healthy Woman on Long-Term Alendronate

 

 

 

By Jennifer P. Schneider, M.D., Ph.D.

 

Geriatrics  61(1) :31-33, 2006

 

 

            A 59-year old previously healthy woman visiting New York City was riding a subway train one morning when the train jolted. She shifted all her weight to one leg, felt a bone snap, and fell to the floor of the train.  An x-ray in a local emergency room revealed a comminuted spiral fracture involving the upper half of the right femur (Fig 1).   The woman was transferred to an orthopedic hospital, where she was noted to be 5/9” tall, 155 pounds, and in a great deal of pain.  She had no significant medical problems aside from osteoarthritis of the knees and thumbs. Her medications consisted only of hormone replacement therapy and alendronate, 70 mg/week.  She had been taking alendronate for approximately seven years.

The patient had experienced early menopause at age 42 and began hormone replacement therapy (HRT)  at that time. At age 52 she had a bone density DEXA scan, which showed a T-score at the lumbar spine of –2.0. This finding, along with a strong family history of osteoporosis,  led to the addition of alendronate to her HRT regimen. Follow-up DEXA scans showed significant improvement in her bone density. (A DEXA scan done 3 months after the fracture showed a spinal mean T score at L2-L4  of –0.6, and a total femoral T score of –0.9, with the femoral neck showing a T score of –1.4)

Her only prior fracture history was a skiing accident at age 24 resulting in  fractures of her left tibia, fibula, and wrist, all of which healed uneventfully with casting. One day three months prior to the subway accident, however, she had begun to experience moderate pain in her right thigh with every step.  There was no preceding trauma, nor any recent increase in her physical activity   An x-ray of her right femur was read as “There is slight thickening of the cortex of the right femur laterally, significance uncertain. Suspect this is simply normal variation.”  Because the pain persisted, a bone scan was done, and it was read as “Intense focus of radionuclide uptake in the proximal right femur correlating with a focal area of cortical thickening. This finding is very suggestive of a possible underlying osteoid osteoma.  Radiographs reveal no other changes of lytic disease or blastic disease that would suggest primary or secondary neoplastic disease.”  The bone scan was done one week prior to the occurrence of the fracture.

Because the fracture preceded the patient’s fall, it was thought likely that she had a pathologic fracture, perhaps secondary to some metastatic lesion. She was therefore placed in traction and underwent extensive CT scanning – of the chest, abdomen, pelvis, lumbar spine, and the femur, as well as plain x-rays, which revealed no evidence of pathological disease consistent with metastatic or primary lesion suggestive of carcinoma.  Three days later, she was taken to the operating room for placement of an intramedullary titanium rod. The opinion of the orthopedic surgeons after they reviewed the out-of-state x-ray and bone scan  was that it was typical of a stress fracture. The jolt in the moving subway train completed the fracture.

            In the months following, it became clear that the fracture was not uniting. Physical therapy and an extensive trial of an external electrical bone stimulator did not result in significant union of the fracture. An orthopedic trauma specialist recommended she undergo a “revision intramedullary rodding procedure with use of a recon-type nail to aid in fixation of the proximal fragment.”  The surgery was done nine months after the initial fracture.

            At the time of her initial hospitalization, the patient was told to stop her HRT because of risk of deep-vein thrombophlebitis (DVT) related to her immobilization.  She asked about continuing the alendronate, since she was concerned that its suppression of bone turnover might inhibit healing of the fracture. She was told that although this was a theoretical possibility, there was no evidence to that effect, so that there was no reason to stop the drug.  However, after months of delayed healing, the alendronate was stopped.  After the second procedure, there was some delay in healing, but by 6 months it was clear that the fracture was uniting. Two years after her first symptoms of a stress fracture of the femur, she was finally able to get back to her usual level of physical activity.

            After more than two years off alendronate therapy, a DEXA scan showed some decrease in bone density, and the patient was advised to resume taking the drug. One year later, she awoke to find that she had moderate pain in her right foot with every step. There was no preceding trauma nor any increase in activity. The possibility of another nontraumatic stress fracture was considered and again the bisphosphonate therapy was stopped.  Two months later, a bone scan showed intense uptake in the second metatarsal bone, consistent with a stress fracture.

 

Discussion

            This case report describes a previously healthy woman who experienced two nontraumatic stress fractures, four years apart, while on alendronate therapy, and also nonunion of the spiral femoral fracture that resulted from the stress fracture .   A spontaneous stress fracture of the femur is so unusual that neither her orthopedic surgeon nor the radiologist who read the bone scan even considered that diagnosis in their differential. Consequently, the patient was never cautioned about her vulnerability to sustain a completed fracture.

Bisphosphonates – such as alendronate, risendronate and ibandronate  --are inhibitors of bone resorption. Extensive studies have shown that therapy with bisphosphonates improves bone density and decreases fracture risk.1,2,3,4,5 These drugs, especially the oldest one, alendronate, are used by large numbers of post-menopausal women, as well as smaller numbers of men with idiopathic, steroid-induced, hypogonadal, or other causes of osteoporosis. Combined use of bisphosphonates and estrogen gives even greater improvement in bone density.6,7.8  

Unfortunately, increased bone density does not necessarily equate with good bone quality. Bone turnover is a natural part of maintaining bone health. By decreasing osteoclast activity and bone resorption -- and therefore bone formation as well --  microdamage that occurs regularly in bone but is normally repaired might accumulate after long-term use. There have long been concerns about the potential oversuppression of bone turnover during long-term use of bisphosphonates and therefore their long-term safety.  The concern is increased when the bisphosphonate is taken concurrently with another agent that may inhibit bone turnover, such as estrogen.  The current patient package insert (PPI) for Fosamax (alendronate) states, “The long-term effects of combined Fosamax and HRT on fracture occurrence and fracture have not been studied.”  Clearly, such studies are needed.

Recently, Odvina and colleagues9  reported on 9 patients, 8 postmenopausal women and 1 man, who sustained unusual spontaneous nonspinal fractures while on alendronate therapy (10 mg/day or 70 mg/week) for 3-8 years.  Three of the 8 women were also on HRT. The present case report above fits into this category of patient.  All 9 patients continued taking alendronate after the fractures.  Six of the 9 patients had delayed or absent fracture healing for 3 months to 2 years during alendronate therapy. 

All the patients had iliac crest biopsies of trabecular bone. The biopsy specimens underwent histomorphometric analyis using tetracycline labeling to study bone metabolic activity. All patients showed markedly suppressed bone formation, with reduced or absent osteoblastic surface in most patients. Matrix synthesis was markedly diminished.

The authors concluded that during long-term alendronate therapy, severe suppression of bone turnover may occur, resulting in increased susceptibility to nonspinal fractures along with delayed healing. “Although coadministration of estrogen or glucocorticoids appears to be a predisposing factor, this apparent complication can also occur with monotherapy.”

In an editorial accompanying the Odvina article, Dr. Susan Ott 10  notes that the bone biopsies showed more suppression than predicted by the biochemical markers.  She concludes, “I believe the current evidence suggests that bisphosphonates should be stopped after 5 yr.  Those patients who remain at a high risk of fractures or who have had fractures despite bisphosphonate therapy could be considered for treatment with intermittent PTH [parathyroid hormone]. . . . In otherwise healthy perimenopausal women who merely have osteopenia, the best therapeutic option is not clear.” 

The patient described in this case report is currently taking calcium supplements and estrogen,  wearing sturdy shoes until her foot fracture heals, and walking one mile daily. 

What should we advise our patients?  Bisphosphonates are stored in bone for up to 10 years after their consumption is stopped,  although their metabolic effects are of shorter duration.  Studies have shown the efficacy of bisphosphonates in the first five years of therapy in improving bone density and diminishing the risk of fractures. After that, until additional studies are done that clarify the  risks of nontraumatic fractures and delayed healing in patients on long-term bisphosphonates,  and which risk factors, if any, can help predict which patients are at increased risk of these adverse events, it is reasonable to suggest to patients to stop the drug after several years, continue weight-bearing exercise and calcium, and wait to see what the next scheduled DEXA scan shows.  References

1. Cummings SR, Black DM, Thompson DE, Applegate WB, Barrett-Connor E, Musliner TA, Palermo L et al. Effect of alendronate on risk of fracture in women with low bone density but without vertebral fractures: Results from the Fracture Intervention Trial. JAMA 1998: 280(24):2077-2082.

2. Pols HAP, Felsenberg D, Hanley DA, Stepan J, Munoz-Torres M, Wilkin TJ, Qin-sheng G, et al. Multinational, placebo-controlled, randomized trial of the Effects of alendronate on bone density and fracture risk in postmenopausal women with low bone mass: Results of the FOSIT study. Osteoporos Int 1999: 9:461-468.

3. Tonino RP, Meunier PJ, Emkey R, Rodrigues-Portales JA, Menkes CJ, Wasnich RD, Bone HG, Santora AC, Wu M, Desai R, Ross PD. Skeletal benefits of alendronate: 7-year treatment of postmenopausal osteoporotic women. 2999. J Clin Endocrinol Metab 85:3109-3115.

4. Black DM, Thompson DE, Bauer DC, Ensrud K, Musliner T, Hochberg MC, Nevitt MC, Suryawanshi S, Cummings SR. Fracture risk reduction with alendronate in women with osteoporisis: The Fracture Intervention Trial. 2000. J Clin Encocrinol. Metab 85:4118-4124.

5. Orwol E, Ettinger M, Weiss S, Miller P, Kendler D, Graham J, Adami S, Weber K, Lorenc R, Pietschmann P, Vandormael K, Lombardi A. Alendronate for the treatment of osteoporosis in men. 2000. N Engl J Med 343:604-610.

6. Ravn p, Bidstrup M, Wasnich RD, Davis JW, McClung MR, Balske A, Coupland C et al. Alendronate and estrogen-progestin in the long-term prevention of bone loss: Four-year results from the early postmenopausal intervention cohort study: A randomized, controlled trial.  Ann Intern Med 1999: 131:935-942. 

7. Bone HG, Hosking D, Devogelaer J-P, Tucci JR, Emkey RD, Tonino RP, Rodriguez-Portales JA, et al. Alendronate and estrogen effects in postmenopausal women with low bone mineral density. J. Clin. Endocrinol. Metab 2000; 85(2):720-726.

8. Lindsay R, Cosman F, Lobo RA, Walsh BW, Harrris ST, Reagan JE, Liss CL, Melton ME, Byrnes CA. Addition of alendronate to ongoing hormone replacement therapy in the treatment of osteoporosis: A randomized, controlled clinical trial. J Clin Endocrinol & Metabol 1999; 84(9):3076-3081.

9. Odvina CV, Zerwekh JE, Sudhaker Rao D, Maalouf  N, Gottschalk FA, Pak CYC. Severely suppressed bone turnover: A potential complication of alendronate therapy. J. Clin. Endocrinol. Metabolism 2005; 90(3):1294-1301.

10 .Ott SM. Editorial: Long-term safety of bisphosphonates.  J. Clin. Endocrinol. Metabolism 2005; 90(3):1897-1899.

 

Jennifer P. Schneider, M.D., Ph.D. is certified in Internal Medicine, Addiction Medicine, and Pain Management. She practices in Tucson, AZ