Delayed chance fracture pattern injury in a case of skeletal fluorosis.

Purpose: To document a rare complication of a delayed 'chance fracture pattern'-type injury through the proximal end of a pedicle screw construct in the clinical scenario of skeletal fluorosis.
Methods: A 72-year-old man with fluorosis presented following a fall which resulted in a T12-L1 fracture. Investigations revealed an unstable three-column injury, so the patient was treated with surgical stabilisation using pedicle screw fixation from T11 to L2. He presented 1 month following surgery with worsening back pain. Investigations revealed a fracture through T11 in a 'chance fracture pattern' along the pedicle screw tracts at the proximal end of the construct. An extension of fixation was performed proximally to T8 and he made an uneventful recovery showing fusion at 20-month follow-up.
Results: Complication of delayed pedicle fractures, in a 'chance fracture pattern' at the ends of a pedicle screw fixation constructs are a rarely reported in the literature. The occurrence of such a complication in a hyperostotic spine associated with fluorosis makes this a unique clinical scenario which is previously unreported to the best of our knowledge.
Conclusions: This report highlights a very rare complication of chance fracture pattern injury in the clinical scenario of fluorosis. A hyperostotic stiff spine, poor quality of bone and extension of pedicle screw tracts to anterior cortex during primary surgery may have resulted in the occurrence of this rare complication.