Bone Abstracts

Background: Fibrodysplasia ossificans progressiva (FOP) is a rare condition characterised by congenital malformation of the great toes and progressive heterotopic endochondral ossification. The disease progresses with episodic flare-ups, resulting in disabling cumulative immobility. The discovery of the ACVR1 gene as the cause of FOP has allowed identification of therapeutic targets. Palovarotene, a retinoic acid receptor gamma agonist, is in phase 2 clinical trials.

Presenting problem: A 7-year-old boy with Hallux valgus, recurrent painful episodes of soft tissue swelling and new abnormal bone formation.

Clinical management: Review of radiographs taken in infancy (Fig. 1) revealed the diagnosis of FOP. This had not been previously recognised, although he had been seen in a Hallux Valgus Clinic. CT of his neck showed subcutaneous ossification in the superficial cervical soft tissues posterior to the C4 – T1 spinous processes measuring 2.3×1.3×5.3 cm (arrow in Fig. 2).

Discussion: As specific treatments are becoming available for FOP, neonatologists, paediatricians, and orthopaedic surgeons should consider the diagnosis if a baby or child presents with bilateral Hallux valgus or episodes of swelling with evidence of ossification. These children should now be referred to a paediatric metabolic bone clinic to consider genetic testing and for further specialist management.

Disclosure: The authors declared no competing interests.

Figure 1 Radiograph of Hallux valgus at 6 months of age.

Figure 2 CT scan of neck, arrow points to ossification posterior to cervical spine.