Challenges in surgical orthopaedic treatment in a rare case of pycnodysostosis: sometimes you win, sometimes you learn

Pycnodysostosis (OMIM 265800) is a rare skeletal dysplasia caused by an autosomal recessive lysosomal storage disorder, the prevalence is less than 1 in 100,000 [1]. The cause is a mutation of the CTKS gene (locus 1q21), with a deficit in the activity of cathepsin K enzyme and alteration of the bone resorption process. This results in osteosclerosis and formation of abnormal bone matrix with increased density and a predisposition to pathological fractures of long bones [2e5]. The clinical manifestations are het- erogeneous: delayed growth associated with short stature, craniofacial dysmorphisms, acro-osteolysis and pathologic frac- tures that are difficult to heal. It is possible to find also endocri- nological and haematological pathologies and upper airway obstruction [6e9]. The diagnostic suspicion arises in the presence of short stature, skeletal dysmorphism and a history of repeated fractures.