Atypical femur fractures in a patient with pycnodysostosis: a case report

Pycnodysostosis is a rare autosomal recessive disease due to a mutation in the gene for the enzyme Cathepsin K. It is characterized by short stature, craniofacial dysmorphias, osteosclerosis, and brittle bones. There are only a few reports in the literature describing surgical interventions for long bone fractures in pycnodysostosis patients, most of which describe intramedullary nail treatment of isolated long bone fractures. We describe a case in which a pregnant female with pycnodysostosis presented with a shaft fracture of the left femur following minor trauma and a history of increasing thigh pain. Radiographs obtained in the emergency room also revealed an impending subtrochanteric fracture of the contralateral side. The acute left femoral shaft fracture was treated with an adolescent-sized intramedullary nail; it was decided to defer surgery on the contralateral side until after pregnancy. Three months later, the patient had the contralateral femur prophylactically fixated with a plate and screws. One year after the index surgery, both methods demonstrated satisfactory healing both clinically and radiographically. Although we recommend use of an intramedullary nail for long bone fractures in patients with pycnodysostosis, a plate can be utilized if health conditions or skeletal morphology precludes use of a nail.