Hypoplastic right 12th rib

Case contributed by Rubens Ribeiro de Souza
Diagnosis almost certain

Presentation

Back pain after falling from a horse.

Patient Data

Age: 12 years
Gender: Male
x-ray

Hypoplastic right 12th rib and agenesis of the left 12th rib, simulating a right transverse processes fracture of the first lumbar vertebra. There is also a lumbosacral transitional vertebra with a neo-articulation between a large right tranverse process and the sacrum.

Annotated image

Counting from the first rib, there is only eleven pairs of ribs normally formed.

ct

Hypoplastic right 12th rib and agenesis of the left 12th rib, simulating a right transverse processes fracture of the first lumbar vertebra. There was no sign of bone fracture or damage to abdominal organs.

Case Discussion

At first, due to the back pain presented by the patient and the x-ray images, it was thought to be a right transverse process fracture of the first lumbar vertebrae, but a better second look proved to be a hypoplastic right 12th rib, associated with agenesis of the left 12th rib.

Although the risks to humans of interacting with horses are well known, there
have been no significant reductions in rates of injury or death over the past decades. In contrast,
there have been significant decreases in injuries and fatalities in high risk workplace settings such as
mining and construction 1.

Lumbosacral transitional vertebrae are congenital anomalies of the lumbosacral region which includes lumbarization and sacralization, observed for the first time by Bertolotti. This condition occurs due to defect in the segmentation of the lumbosacral spine during development. The transitional vertebra may have varying formations, the common feature being an atypical lumbosacral articulation between the transverse process of L5 and the sacrum 2.

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