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Summary
E. Maury, K. Laoubi, M.-P. Miralles, M. Cohen-Solal, C. Cormier - Paris
Osteonecrosis of the femoral head is not a complication described in the use of bisphosphonates in clinical trials. We report a case of osteonecrosis of the femoral head occurred a year after the completion of a single infusion of zoledronic acid (5 mg) for osteoporosis in a patient of 69 years also treated with anti-aromatase (anastrozole) for breast cancer without bone metastasis.

Osteoporosis was diagnosed in 2006 (T-score -2.8 at the spine and -0.9 at the femoral neck) during follow-up of breast cancer treated with trastuzumab and anastrozole since December 2006. The patient received a single infusion of zoledronate in April 2007 to prevent the risk of fracture. In March 2008, a radiological assessment with MRI of the pelvis and bone scan was performed for investigation of hip pain, revealing osteonecrosis of the femoral head right and a subchondral fracture. Densitometry of June 2008 showed an improvement: T-score -2.3 to -1.5 at the spine and femoral neck, and the rate of serum CTX (high to 7200 pmol / L before infusion) was normalized (2100 pmol / The six months). Since the onset of the subchondral fracture with femoral necrosis, a transiliac bone biopsy with double tetracycline labeling was performed in search of mineralization disorders. This review concluded with osteoporosis at very low level of remodeling, with no arguments to osteomalacia, and prompted discontinuation of bisphosphonate treatment.

Different studies have described bone complications due to bisphosphonates. Osteonecrosis of the jaw is mainly described in patients receiving high doses of intravenous bisphosphonates for the treatment of cancer. Of atypical fractures with low bone turnover on bone biopsies were described as alendronate. Studies on zoledronate had no cases of necrosis of the hip or decrease bone turnover in bone biopsies. Our patient had no collapse in the rate of serum CTX, which offer some space infusions of zoledronate every 18 months. Before this Osteonecrosis of hip with low bone turnover, we form the hypothesis that tolerance of osteoclasts with bisphosphonates may vary from one patient to another, thereby inducing an unreasonable blocking of bone remodeling and also that the osteonecrosis of the femoral head could be favored by the anti-angiogenic effect of bisphosphonates and estrogen deficiency associated with aromatase inhibitors. This necrosis seems similar to hip osteonecrosis of the jaw and bisphosphonates observed in antiangiogenic agents during treatment of prostate cancer.

This case of osteonecrosis of the femoral head with subchondral fracture and bone remodeling collapsed, occurred a year after a single infusion of zoledronic acid for osteoporosis, in combination with anastrozole for the treatment of breast cancer, could be a new complication of bisphosphonate bone. The occurrence of osteonecrosis must be considered for a rational use of bisphosphonates.

Keywords:
Osteonecrosis; Zoledronic Acid; osteoporosis;



This 'looks' like it has been kept somewhat under wraps -