Bilateral healing of pseudofractures in hypophosphatasia with teriparatide: a case report

Hypophosphatasia is a rare, inherited metabolic bone disease characterized by impaired activity of tissue-nonspecific alkaline phosphatase leading to pathological mineralization of hard tissue, predisposing to poorly healing fractures. Limited access to enzyme replacement therapy makes the treatment of adults with hypophosphatasia challenging. A few case reports have described a beneficial effect of teriparatide on fracture healing in hypophosphatasia. However, this is the first case of a male patient with pediatric-onset hypophosphatasia, not previously exposed to antiresorptive therapy, treated with teriparatide for bilateral femoral pseudofractures.

We report a 59-old white man with pediatric-onset hypophosphatasia who developed bilateral femoral pseudofractures that were successfully treated with teriparatide. At the age of 54 years, our patient complained about reduced physical activity and pain in both hips and femoral bones. X-ray and later computed tomography scan revealed bilateral femoral pseudofractures. Dual energy X-ray absorptiometry showed normal bone mineral density. Not previously exposed to antiresorptive treatment, our patient was treated with conventional doses of teriparatide (Forsteo^®, 20 µg/day, subcutaneous) for 18 months. Markers of bone formation and bone resorption increased twofold at 3 months of treatment. At 6 months of treatment with teriparatide normal levels of alkaline phosphatase as well as pyridoxal 5'-phosphate were measured. Early signs of fracture healing were observed at 6 months, and after 18 months of teriparatide treatment, the complete healing of both femoral pseudofractures was proven by X-ray and a computed tomography scan.

Treatment with teriparatide induces beneficial clinical, biochemical, and radiological responses and may provide an efficient treatment option for adults with hypophosphatasia and pseudofractures or poor healing fractures.