Zoledronate Therapy for the Pathological Humeral Fracture in Polyostotic Fibrous Dysplasia: A Case Report

Fibrous dysplasia (FD) of bone is a rare skeletal disease often associated with bone pain, deformities and fractures. The bisphosphonate therapies are reported to be useful for bone pain, but seem to be not suitable for fracture repairs of extremities. This is the first report of zoledronate-induced radiological improvement and long bone fracture union in polyostotic FD. A 30-year-old Japanese female had bilateral shepherd’s crook deformities typical to FD and right pathological femoral fracture and left humeral fracture nonunion. These fractures occurred without major traumas and the humeral fracture was not united for 1 year with conservative therapy. Laboratory blood test results were notable for elevated serum alkaline phosphatase and urine N-terminal cross-linking telopeptide of type I collagen. Her subtrochanteric femoral fracture was percutaneously fixed using Kirschner wires. After surgery, a hip spica cast was applied for 2 months and the orthosis for the next 2 months. Bony union of the femoral fracture was observed 5 months after surgery. Increased bone turnover and typical radiological features suggested that the constant elbow pain was due to both FD itself and humeral nonunion. Considering the possible side effects of zoledronate delaying acute fracture healing, we initiated zoledronate (Zometa(®); Novartis, Tokyo, Japan) therapy after femoral fracture union. Intravenous zoledronate acid was administered at a dose of 2 mg, along with supplementation of calcium (600 mg/day) and vitamin D (alfacalcidol 0.5 μg/day) to limit the risk of osteomalacia and improve the efficacy of bisphosphonate therapy. The patient’s elbow pain rapidly resolved 1 week after treatment. Second therapy with same dose was performed after 6 months. No recurrence of elbow pain was reported and bony union was diagnosed after 1 year from the first administration. This patient is currently doing well without recurrence of bone pain. She can also walk for a short distance with crutches. We presented the case of an FD patient with persistent elbow pain due to FD itself and nonunion of humeral fracture, which was ameliorated promptly by intravenous zoledronate therapies. This case illustrated the benefit of zoledronate treatment in patients with extensive polyostotic FD and pathological fractures of extremities.