Proximal medial tibial metaphyseal bump-a normal variant

Area of Science:

• Pediatric Radiology
• Skeletal Dysplasias
• Child Abuse Evaluation

Background:

• Skeletal abnormalities are critical in child abuse evaluations.
• Normal variants can mimic abuse, leading to misdiagnosis.
• The tibial bump is a normal variant of the proximal medial tibial metaphysis.

Purpose of the Study:

• To determine the prevalence of the tibial bump in infants undergoing skeletal surveys for child abuse evaluation.
• To differentiate the tibial bump from traumatic findings.

Main Methods:

• Retrospective review of skeletal surveys in infants evaluated for child abuse.
• Assessment for the presence of a tibial bump on the proximal medial tibial metaphysis.
• Recording of fracture healing changes around the tibial bump.

Main Results:

• A tibial bump was identified in 7.7% of cases (20/260).
• The tibial bump was persistent in 70% of cases and showed no signs of fracture healing.
• The finding was more common in younger infants (mean age 3.5 months) and often bilateral.

Conclusions:

• The tibial bump is a common normal variant in infants undergoing skeletal surveys.
• It is not radiographically consistent with a fracture and should not be mistaken for a traumatic finding in child abuse evaluations.