Orthopaedic disorders of pycnodysostosis: a report of five clinical cases

Pycnodysostosis is a rare autosomal recessive genetic disorder usually diagnosed at an early age. The few previously published case series have generally focused on maxillofacial manifestations and genetic considerations. The purpose of this study was to evaluate the clinical characteristics and differential diagnosis of pycnodysostosis focusing on its orthopaedic manifestations, which have been poorly described in the literature.

We evaluated clinical and radiographic characteristics of five patients with pycnodysostosis.

Three male and two female patients were included in the study. One patient had consanguineous parents and two had a family history of pycnodysostosis. One patient was of normal height; four with short stature underwent growth hormone treatment. Most patients had bone fractures. All had typical cranial and orofacial manifestations, partial dysplasia of the terminal phalanges and increased bone density. Aplastic acromial ends and spondylolysis were not seen in any patient. Some patients had genu valgus, ankle valgus or sleep apnea; two required tympanic drains for serous otitis media. Two patients experienced nonunion.

Short stature is a consistent feature of pycnodysostosis that can be treated with growth hormone. To our knowledge, serous otitis media, nonunion and other orthopaedic manifestations have not been previously described in pycnodysostosis patients. Intramedullary nailing osteosynthesis can be difficult in these patients because of skeletal sclerosis; therefore, other surgical options should be considered. Nonunion is common in this population. Pycnodysostosis is a poorly described disease, but clinicians should be aware of its potential manifestations in order to appropriately diagnose, manage and follow-up patients.